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АСТРАХАНСКИЙ ГОСУДАРСТВЕННЫЙ ТЕХНИЧЕСКИЙ
УНИВЕРСИТЕТ
ГУМАНИТАРНЫЙ ИНСТИТУТ
КАФЕДРА «ИНОСТРАННЫЕ ЯЗЫКИ В ИНЖЕНЕРНОТЕХНИЧЕСКОМ ОБРАЗОВАНИИ»
АНГЛИЙСКИЙ ЯЗЫК
ЛОПУХОВА В.Н.
УЧЕБНОЕ ПОСОБИЕ
для студентов II курса
специальности «Холодильная, криогенная техника и
кондиционирование»
Астрахань 2010
1
Составитель:
В.Н.Лопухова, ассистент кафедры «Иностранные языки в
инженерно-техническом образовании»
Рецензент:
О.В. Фёдорова, кандидат педагогических наук, заведующий
кафедрой «Иностранные языки в инженерно-техническом
образовании», доцент
Учебное
пособие
предназначено
для
аудиторной
и
самостоятельной работы студентов II курса Механико-технологического
института специальности «Холодильная, криогенная техника и
кондиционирование». Основной целью пособия является овладение
навыками чтения текстов профессиональной направленности.
В учебное пособие входят десять тематических разделов, каждый
из разделов проиллюстрирован соответствующим текстами и
комплексом упражнений, направленным на овладение
навыками
чтения, перевода и развития устной речи по определённым темам.
Предлагаемые тексты содействуют дальнейшему закреплению
полученных навыков и усвоению специальной терминологии.
Данное учебное пособие предоставляет широкий диапазон для
активной аудиторной и внеаудиторной работы, имеет практическую
ценность, отвечает современным требованиям методики обучения
иностранному языку в вузе и может быть использован для студентов,
углубленно изучающих язык по специальности: «Холодильная,
криогенная техника и кондиционирование».
Сборник иностранных текстов утвержден на заседании кафедры
“ИЯИТО” протокол №11 от 26.05.10.
© Астраханский государственный технический университет
2
UNIT 1
I. Read and translate the text:
Historical applications
The use of ice to refrigerate and thus preserve food goes back to prehistoric
times. Through the ages, the seasonal harvesting of snow and ice was a regular
practice of most of the ancient cultures: Chinese, Hebrews, Greeks, Romans,
Persians. Ice and snow were stored in caves or dugouts lined with straw or other
insulating materials. Rationing of the ice allowed the preservation of foods over the
hot periods. This practice worked well down through the centuries, with icehouses
remaining in use into the twentieth century.
In the 16th century, the discovery of chemical refrigeration was one of the
first steps toward artificial means of refrigeration. Sodium nitrate or potassium
nitrate, when added to water, lowered the water temperature and created a sort of
refrigeration bath for cooling substances. In Italy, such a solution was used to chill
wine.
The first known method of artificial refrigeration was demonstrated by
William Cullen at the University of Glasgow in Scotland in 1748. Cullen used a
pump to create a partial vacuum over a container of ethyl ether, which then boiled ,
absorbing heat from the surrounding air. The experiment even created a small
amount of ice, but had no practical application at that time.
In 1805, American inventor Oliver Evans designed but never built a
refrigeration system based on the vapor-compression refrigeration cycle rather than
chemical solutions or volatile liquids such as ethyl ether.
Jacob Perkins, obtained the first patent for a vapor-compression
refrigeration system in 1834. Perkins built a prototype system and it actually
worked, although it did not succeed commercially.
In 1842, an American physician, John Gorrie, designed the first system for
refrigerating water to produce ice. He also conceived the idea of using his
refrigeration system to cool the air for comfort in homes and hospitals (i.e., airconditioning). His system compressed air, then partially cooled the hot compressed
air with water before allowing it to expand while doing part of the work required to
drive the air compressor. That isentropic expansion cooled the air to a temperature
low enough to freeze water and produce ice, or to flow "through a pipe for
effecting refrigeration otherwise" as stated in his patent granted by the U.S. Patent
Office in 1851. Gorrie built a working prototype, but his system was a commercial
failure.
James Harrison introduced commercial vapor-compression refrigeration to
breweries and meat packing houses. By 1861, a dozen of his systems were in
operation. Australian, Argentinean and American concerns experimented with
refrigerated shipping in the mid 1870s, the first commercial success coming when
3
William Soltau Davidson fitted a compression refrigeration unit to the vessel in
1882.
The first gas absorption refrigeration system using gaseous ammonia
dissolved in water was developed by Ferdinand Carré of France in 1859 and
patented in 1860. Due to the toxicity of ammonia, such systems were not
developed for use in homes, but were used to manufacture ice for sale. In the
United States, the consumer public at that time still used the ice box with ice
brought in from commercial suppliers, many of whom were still harvesting ice and
storing it in an icehouse.
Thaddeus Lowe, an American, held several patents on ice making
machines. His "Compression Ice Machine" would revolutionize the cold storage
industry. In 1869 he and other investors loaded one of Lowe’s refrigeration units
onto an old steamship and began shipping fresh fruit from New York to the Gulf
Coast area, and fresh meat from Galveston, Texas back to New York. Because of
Lowe’s lack of knowledge about shipping, the business was a costly failure, and it
was difficult for the public to get used to the idea of being able to consume meat
that had been so long out of the packing house.
Domestic mechanical refrigerators became available in the United States
around 1911.
Words to the text
to refrigerate - 1) охлаждать;
ethyl ether - этиловый эфир
замораживать; 2) хранить в холоде
to absorb - поглощать
harvesting - заготовка
heat - тепло; теплота
to preserve - хранить (овощи,
application
применение,
продукты)
использование,
insulating materials - изоляционные
vapor-compression
refrigeration
материалы
cycle
цикл
паровой
icehouse - ледник, льдохранилище
компрессионной холодильной
(погреб со льдом или снегом,
машины
заготавливаемыми
зимой
для
chemical solution - химический
хранения продуктов в течение всего
раствор
года)
commercial - коммерческий,
artificial - искусственный
торговый;
Sodium nitrate - нитрат натрия,
brewery - пивоваренный завод
натриевая селитра
vessel - корабль, судно;
cooling - охлаждение
gas absorption - абсорбция газа,
substance - вещество
поглощение газов
to chill - охлаждать, замораживать;
ice box - холодильник
a pump - насос; помпа;
4
II. Fulfill the table using information from the text. (work in pairs or
groups)
D
ate
A
ncient
ages
1
6 century
Inventor /
country
Chinese,
Hebrews, Greeks,
Romans, Persians
Refrige
ration system
Harvest
ing of snow
and ice
How
does it work?
Snow
& ice were
stored
in
caves
lined
with straw or
other
insulating
material
Applic
ation
The
preservation
of foods over
the hot periods
The
first method of
artificial
refrigeration
Oliver
Evans / the USA
1
It
didn’t succeed
comercially
834
The
first system
for
refrigerating
water
James
Harrison
1
882
III. Read the text “Widespread commercial use” and add some information
in this table.
5
IV. Make up different kinds of questions to the text. Ask your partner about
historical application of refrigeration. (Work in pair or group)
I group (Yes/No-questions)
Was harvesting of snow and ice a regular practice of ancient cultures?
II group (Wh-questions)
What did Italian use to chill
wine?
III group (Tag-question)
Ice harvesting became big
business, didn’t it?
V. Skim through the text and say in one sentence what the message of the
is. Answer the questions which follow the text.
Current applications of refrigeration
Probably the most widely-used current applications of refrigeration are for
the air-conditioning of private homes and public buildings, and the refrigeration of
foodstuffs in homes, restaurants and large storage warehouses. The use of
refrigerators in our kitchens for the storage of fruits and vegetables has allowed us
to add fresh salads to our diets year round, and to store fish and meats safely for
long periods. Dairy products are constantly in need of refrigeration, and it was only
discovered in the past few decades that eggs needed to be refrigerated during
shipment rather than waiting to be refrigerated after arrival at the grocery store.
Meats, poultry and fish all must be kept in climate-controlled environments before
being sold. Refrigeration also helps keep fruits and vegetables edible longer.
In commerce and manufacturing, there are many uses for refrigeration.
Mechanical refrigeration is applied in a number of industries. It is possible to
enumerate about 250 branches of technics where cold is applied. Refrigeration is
applied in metallurgical operations, in air conditioning, in chemical and fishing
industries and in many other branches of industry.
Industrial air conditioning is used in food, chemical, textile and
many other industries. It ensures safety by reduction of fatigue and explosion
hazard.
In chemical industry refrigeration is used to liquify gases like oxygen,
nitrogen, propane and methane for example. For the latter purpose it is the
difference of the boiling points of gases that is made use of. For instance, oxygen
at the temperature of -183° C is obtained from liquid air by evaporating its nitrogen
that has a lower boiling point, -196° C. In compressed air purification, it is used to
condense water vapor from compressed air to reduce its moisture content. In oil
refineries, chemical plants, and petrochemical plants, refrigeration is used to
maintain certain processes at their required low temperatures (for example, in the
text
6
alkylation of butenes and butane to produce a high octane gasoline component).
Metal workers use refrigeration to temper steel and cutlery. In transporting
temperature-sensitive foodstuffs and other materials by trucks, trains, airplanes and
sea-going vessels, refrigeration is a necessity.
Other applications are made in manufacture of cigars, in making candy, in
the production of photographic films and similar celluloid products, in surgical
operations and in excavating operations; this process is accomplished by freezing a
ring of quicksand so that tunneling can be done in the hard material. By means of
cold, chemical reactions are regulated on which the output and quality of the
finished products depend.
There is nothing so valuable as cold to man in the manufacture of
explosives, aniline, paints, synthetic rubber, in the metal working industry for
tempering some especially fine and important parts of machines creating their
artificial aging. Such parts will stand moisture and temperature variations and will
keep their initial dimensions for a long time.
Artificial cold is also used in aviation and astronautics – when the work of
aviation motors is studied under the conditions of great height, at low temperatures,
and in rarefied air.
It is especially important for the development of science to study
the behaviour of substances under the conditions of extremely low temperatures
near the absolute zero when it is easier to study the structure of the invisible world
of atoms and molecules.
1.
refrigeration?
2.
home?
3.
4.
5.
6.
7.
What
is
* * *
the most
widely-used
application
of
What does the use of refrigeration allow to do us at
Where is cold applied?
What is used in food and textile industries?
What is refrigeration used in chemical industry to?
What do metal workers use refrigeration to?
Where is it necessary to use refrigeration?
VI. Read and translate the text:
Refrigeration
Refrigeration is the process of removing heat from an enclosed space, or
from a substance, and rejecting it elsewhere for the primary purpose of lowering
the temperature of the enclosed space or substance and then maintaining that lower
temperature. The term cooling refers generally to any natural or artificial process
7
by which heat is dissipated. The process of artificially producing extreme cold
temperatures is referred to as cryogenics.
Cold is the absence of heat, hence in order to reduce a temperature, one
does not "add cold", rather one "removes heat." In order to satisfy the Second Law
of Thermodynamics, some form of work must be performed to accomplish this.
This work is traditionally done by mechanical work but can also be done by
magnetism, laser or other means. However, all refrigeration uses the three basic
methods of heat transfer: convection, conduction, or radiation.
Methods of refrigeration can be classified as non-cyclic, cyclic and
thermoelectric.
Non-cyclic refrigeration: in these methods, refrigeration can be
accomplished by melting ice or by subliming dry ice. These methods are used for
small-scale refrigeration such as in laboratories and workshops, or in portable
coolers.
Ice owes its effectiveness as a cooling agent to its constant melting point of
0 °C (32 °F). In order to melt, ice must absorb 333.55 kJ/kg (approx. 144 Btu/lb) of
heat. Foodstuffs maintained at this temperature or slightly above have an increased
storage life. Solid carbon dioxide, known as dry ice, is used also as a refrigerant.
Having no liquid phase at normal atmospheric pressure, it sublimes directly from
the solid to vapor phase at a temperature of -78.5 °C (-109.3 °F). Dry ice is
effective for maintaining products at low temperatures during the period of
sublimation.
Cyclic refrigeration: this consists of a refrigeration cycle, where heat is
removed from a low-temperature space or source and rejected to a hightemperature sink with the help of external work, and its inverse, the
thermodynamic power cycle. In the power cycle, heat is supplied from a hightemperature source to the engine, part of the heat being used to produce work and
the rest being rejected to a low-temperature sink. This satisfies the second law of
thermodynamics.
A refrigeration cycle describes the changes that take place in the refrigerant
as it alternately absorbs and rejects heat as it circulates through a refrigerator. It is
also applied to HVACR work, when describing the "process" of refrigerant flow
through an HVACR unit, whether it is a packaged or split system.
Heat naturally flows from hot to cold. Work is applied to cool a living space
or storage volume by pumping heat from a lower temperature heat source into a
higher temperature heat sink. Insulation is used to reduce the work and energy
required to achieve and maintain a lower temperature in the cooled space. The
operating principle of the refrigeration cycle was described mathematically by Sadi
Carnot in 1824 as a heat engine.
8
The most common types of refrigeration systems use the reverse-Rankine
vapor-compression refrigeration cycle although absorption heat pumps are used in
a minority of applications.
Cyclic refrigeration can be classified as:
1.
Vapor cycle, and
2.
Gas cycle
Vapor cycle refrigeration can further be classified as:
1.
Vapor compression refrigeration
2.
Gas absorption refrigeration
Thermoelectric refrigeration: thermoelectric cooling uses the Peltier effect
to create a heat flux between the junction of two different types of materials. This
effect is commonly used in camping and portable coolers and for cooling electronic
components and small instruments.
Magnetic refrigeration (or adiabatic demagnetization) is a cooling
technology based on the magnetocaloric effect, an intrinsic property of magnetic
solids. The refrigerant is often a paramagnetic salt, such as cerium magnesium
nitrate. The active magnetic dipoles in this case are those of the electron shells of
the paramagnetic atoms.
A strong magnetic field is applied to the refrigerant, forcing its various
magnetic dipoles to align and putting these degrees of freedom of the refrigerant
into a state of lowered entropy. A heat sink then absorbs the heat released by the
refrigerant due to its loss of entropy. Thermal contact with the heat sink is then
broken so that the system is insulated, and the magnetic field is switched off. This
increases the heat capacity of the refrigerant, thus decreasing its temperature below
the temperature of the heat sink.
Because few materials exhibit the required properties at room temperature,
applications have so far been limited to cryogenics and research.
Other methods of refrigeration include the Air cycle machine used in
aircraft; the Vortex tube used for spot cooling, when compressed air is available;
and Thermoacoustic refrigeration using sound waves in a pressurised gas to drive
heat transfer and heat exchange.
ACTIVE VOCABULARY
refrigeration
–
охлаждение;
замораживание
to remove – удалять, устранять
heat – теплота
to reject – отбрасывать
cooling – охлаждение
artificial - искусственный
to dissipate – рассеивать
to reduce - ослаблять, понижать,
сокращать, уменьшать
to accomplish - совершать,
выполнять; достигать
mechanical work - механическая
работа
9
heat
transfer
теплообмен;
теплоотдача; теплопередача;
convection - конвекция
conduction - проводимость
radiation - излучение
non-cyclic
–
непериодический,
нецикличный
cyclic - циклический, цикличный
thermoelectric - термоэлектрический
dry ice - сухой лёд
melting point - точка плавления
to
absorb
абсорбировать;
поглощать
refrigerant
охлаждающее
вещество, охладитель
vapor - пар; пары; испарения;
to
supply
поставлять;
доставлять
engine - машина, двигатель;
мотор
heat source - источник теплоты,
тепловой источник
heat sink - теплоотвод, радиатор
insulation
–
изоляция,
изоляционный материал
heat engine - тепловой двигатель
VII. Find the Russian equivalents for the English ones:
Second Law of Thermodynamics, subliming dry ice, a cooling agent,
thermodynamic power cycle, HVACR, gas absorption refrigeration, thermoelectric
cooling, adiabatic demagnetization, Vortex tube, spot cooling.
VIII. Find the English equivalents for the Russian ones:
талая вода, передвижная холодильная камера, точка плавления,
атмосферное давление, уменьшать, абсорбционный тепловой насос,
компрессионное охлаждение испарением холодильного агента, тепловой
поток, парамагнитная соль, магнитное поле, теплоёмкость, теплообмен.
IX. Translate the following sentences into Russian:
1) The process of artificially producing extreme cold temperatures
is referred to as cryogenics.
2) Ice owes its effectiveness as a cooling agent to its constant
melting point of 0 °C (32 °F).
3) Dry ice is effective for maintaining products at low temperatures
during the period of sublimation.
4) Heat is removed from a low-temperature space or source and
rejected to a high-temperature sink with the help of external work.
5) Heat is pumped from a lower temperature heat source into a
higher temperature heat sink.
6) The most common types of refrigeration systems use the reverseRankine vapor-compression refrigeration cycle.
7) Magnetic refrigeration is a cooling technology based on the
magnetocaloric effect, an intrinsic property of magnetic solids.
10
8) The active magnetic dipoles are those of the electron shells of the
paramagnetic atoms.
9) A heat sink absorbs the heat released by the refrigerant due to its
loss of entropy.
10) Thermoacoustic refrigeration uses sound waves in a pressurised
gas to drive heat transfer and heat exchange.
X. Fill in the blanks with appropriate words:
1) The term cooling refers generally to any … process.
2) All refrigeration uses the three basic methods of … : convection,
conduction, or radiation.
3) Refrigeration can be accomplished by … or by … in the noncyclic method.
4) Heat is supplied from a high-temperature … to the … .
5) The operating principle of the refrigeration cycle was described
mathematically by … in 1824 as … .
6) Thermoelectric cooling uses the … effect.
7) The paramagnetic salt is often a refrigerant by … refrigeration.
8) Thermal contact with … is broken so that the system is insulated,
and … is switched off.
9) … is used for spot cooling, when … air is available.
10) Foodstuffs maintained at low temperature have an increased … .
XI. Translate into English, using the active vocabulary:
1)
Охлаждение – это процесс удаления теплоты из
закрытого пространства.
2)
Холод – это отсутствие тепла.
3)
Методы охлаждения можно систематизировать как
нецикличный, цикличный и термоэлектрический.
4)
Нецикличные методы используются в лабораториях
и мастерских для охлаждения небольших размеров.
5)
Твёрдая углекислота, известная как сухой лед,
используется в качестве охладителя.
6)
Изоляционный материал уменьшает энергию,
которая требуется для достижения низкой температуры.
7)
Абсорбционный тепловой насос используется в
меньшем объеме.
8)
Эффект Пельтье как правило используют при
охлаждении
электронных
компонентов
и
небольшого
оборудования.
11
9)
Сильное
магнитное
поле
направляется
на
охладитель.
10) Когда магнитное поле отключается, это повышает
теплоёмкость охладителя.
XII. Answer the questions:
1) What is refrigeration?
2) What process is cooling? What is cryogenics?
3) What form of work must be performed to reduce a temperature?
4) What methods of heat transfer does refrigeration use?
5) Where is non-cyclic refrigeration used? What is its refrigerant?
6) How does a refrigeration cycle work?
7) What is insulation used to?
8) How can cyclic refrigeration be classified?
9) What kinds of vapor cycle refrigeration do you know?
10)
What does thermoelectric refrigeration use? Where is it
used?
11)
What is magnetic refrigeration based on? How does it
12)
What other methods of refrigeration do you know?
work?
XIII. Fulfill the table using information from the text:
Method
Refrigerant
How does
it work?
XIV. Tell in short about methods of refrigeration.
12
Applicatio
n
UNIT 2
I. Read and translate the text:
Boiling point
The boiling point of a liquid is the temperature at which the vapor pressure
of the liquid equals the environmental pressure surrounding the liquid. A liquid in a
vacuum environment has a lower boiling point than when the liquid is at
atmospheric pressure. And a liquid in a high pressure environment has a higher
boiling point than when the liquid is at atmospheric pressure. In other words, all
liquids have an infinite number of boiling points.
The normal boiling point (also called the atmospheric boiling point or the
atmospheric pressure boiling point) of a liquid is the special case at which the
vapor pressure of the liquid equals the ambient atmospheric pressure. At that
temperature, the vapor pressure of the liquid becomes sufficient to overcome
atmospheric pressure and lift the liquid to form bubbles inside the bulk of the
liquid.
The heat of vaporization is the amount of heat required to convert or
vaporize a saturated liquid (i.e., a liquid at its boiling point) into a vapor.
Liquids may change to a vapor at temperatures below their boiling points
through the process of evaporation. Evaporation is a surface phenomenon in which
molecules located near the vapor/liquid surface escape into the vapor phase. On the
other hand, boiling is a process in which molecules anywhere in the liquid escape,
resulting in the formation of vapor bubbles within the liquid.
A saturated liquid contains as much thermal energy as it can without boiling
(or conversely a saturated vapor contains as little thermal energy as it can without
condensing).
Saturation temperature means boiling point. The saturation temperature is
the temperature for a corresponding saturation pressure at which a liquid boils into
its vapor phase. The liquid can be said to be saturated with thermal energy. Any
addition of thermal energy results in a phase change.
If the pressure in a system remains constant (isobaric), a vapor at saturation
temperature will begin to condense into its liquid phase as thermal energy (heat) is
removed. Similarly, a liquid at saturation temperature and pressure will boil into its
vapor phase as additional thermal energy is applied.
The boiling point corresponds to the temperature at which the vapor
pressure of the liquid equals the surrounding environmental pressure. Thus, the
boiling point is dependent on the pressure. Usually, boiling points are published
with respect to atmospheric pressure (101.325 kilopascals or 1 atm). At higher
elevations, where the atmospheric pressure is much lower, the boiling point is also
lower. The boiling point increases with increased pressure up to the critical point,
13
where the gas and liquid properties become identical. The boiling point cannot be
increased beyond the critical point. Likewise, the boiling point decreases with
decreasing pressure until the triple point is reached. The boiling point cannot be
reduced below the triple point.
Saturation Pressure, or vapor point, is the pressure for a corresponding
saturation temperature at which a liquid boils into its vapor phase. Saturation
pressure and saturation temperature have a direct relationship: as saturation
pressure is increased so is saturation temperature.
If the temperature in a system remains constant (an isothermal system),
vapor at saturation pressure and temperature will begin to condense into its liquid
phase as the system pressure is increased. Similarly, a liquid at saturation pressure
and temperature will tend to flash into its vapor phase as system pressure is
decreased.
Note: The boiling point of water is 100 °C (212 °F) at standard pressure. On
top of Mount Everest the pressure is about 260 mbar (26 kPa) so the boiling point
of water is 69 °C. (156.2 °F). The normal boiling point of water is 99.97 degrees
Celsius at a pressure of 1 atm (i.e., 101.325 kPa).
The element with the lowest boiling point is helium. Both the boiling points
of rhenium and tungsten exceed 5000 K at standard pressure. Due to the
experimental difficulty of precisely measuring extreme temperatures without bias,
there is some discrepancy in the literature as to whether tungsten or rhenium has
the higher boiling point.
ACTIVE VOCABULARY
boiling point – точка кипения
vapor pressure – давление пара
to equal – быть одинаковым, равным
atmospheric pressure – атмосферное
давление
infinite
–
бесконечный,
бесчисленный
sufficient – достаточный
to overcome (overcame, overcome) –
побороть, победить
heat of vaporization – теплота
испарения,
теплота
парообразования
to convert – преобразовывать;
превращать
14
to contain – содержать в себе,
включать
saturated vapor – насыщенный
пар
saturation
temperature
–
температура насыщения
saturation pressure – давление
насыщения
vapor phase – паровая фаза
to remain – оставаться
constant
–
неизменный,
устойчивый, константный
to
correspond
(to)
–
соответствовать;
согласовываться, соотноситься
dependent on – обусловленный,
зависящий (от обстоятельств)
with respect to – относительно, по
отношению к
identical – такой же, одинаковый,
идентичный
to reduce – понижать, уменьшать
isothermal – изотермический,
изотермичный,
равнотемпературный
helium – гелий
rhenium – рений
tungsten – вольфрам
to exceed – превышать; выходить
за пределы
without bias – объективно
II. Find the Russian equivalents for the English ones:
saturated liquid, environmental pressure, discrepancy, a phase change, a
liquid phase, atmospheric boiling point, the triple point, ambient atmospheric
pressure, vapor point
III. Find the English equivalents for the Russian ones:
непосредственная связь, парообразная фаза, нормальное давление,
точка кипения жидкости, насыщенный пар, бесконечное число,
поверхностное явление, критическая точка
IV. Say whether these sentences are True or False:
1)
A saturated vapor contains as little thermal energy as it
can with boiling.
2)
A liquid in a high pressure environment has a higher
boiling point than when the liquid is at atmospheric pressure.
3)
A vapor at saturation temperature and pressure will
begin to condense into its liquid phase as thermal energy is removed.
4)
At saturation pressure a vapor is converted into its liquid
phase.
5)
Boiling points are published with respect to the
environmental pressure.
6)
The vapor pressure of the liquid equals the ambient
atmospheric pressure at the atmospheric boiling point.
7)
The boiling point cannot be increased beyond the critical
point.
8)
At the vapor point a liquid boils into its vapor phase.
9)
The boiling point decreases with decreasing pressure
until the triple point is reached
10)
Liquids may change to a vapor through the process of
condensation.
15
V. Complete the sentences:
1)
All
liquids
have …
2)
at
the
saturation
temperature a liquid boils …
3)
The boiling point
cannot be reduced …
4)
The
heat
of
vaporization is the amount of heat
required …
5)
Any
addition
of
thermal energy results …
6)
as saturation pressure
is increased
7)
A liquid in a
vacuum environment
has a lower boiling point
than …
8)
A saturated liquid
contains as much thermal energy as
…
9)
tungsten or rhenium
has
10) the boiling point is
dependent …
a) … in a phase change.
b) … to convert a saturated
liquid into a vapor.
c) … the higher boiling point.
d) … on the pressure.
e) … when the liquid is at
atmospheric pressure.
f) … below the triple point.
g) … it can without boiling.
h) … so is saturation
temperature.
i) … an infinite number of
boiling points.
j) … into its vapor phase.
VI. Make up different kinds of questions to the text. Ask your partner about
the boiling point. (Work in pairs or groups)
I group (Yes/No-questions)
Do all liquids have an infinite number of boiling points?
II group (Wh-questions)
What do all liquids have?
III group (Tag-question)
16
All liquids have an infinite
number of boiling points, don’t
they?
VII. Read and translate the text:
Cyclic refrigeration
The vapor-compression cycle is used in most household refrigerators as well
as in many large commercial and industrial refrigeration systems.
The thermodynamics of the cycle can be analyzed on a diagram as shown in
Figure 1.
Figure 1
In this cycle, a circulating refrigerant such as Freon enters the compressor
as a vapor. From point 1 to point 2, the vapor is compressed at constant entropy
and exits the compressor superheated. From point 2 to point 3 and on to point 4,
the superheated vapor travels through the condenser which first cools and removes
the superheat and then condenses the vapor into a saturated liquid by removing
additional heat at constant pressure and temperature. Between points 4 and 5, the
saturated liquid refrigerant goes through the expansion valve (also called a throttle
valve) where its pressure abruptly decreases. That process results in the adiabatic
flash evaporation and auto-refrigeration of a portion of the liquid (typically, less
than half of the liquid flashes). The adiabatic flash evaporation process is
isenthalpic (i.e., occurs at constant enthalpy).
That results in a mixture of liquid and vapor at a lower temperature and
pressure as shown at point 5. The cold liquid-vapor mixture then travels through
the evaporator coil or tubes and is completely vaporized by cooling the warm air
(from the space being refrigerated) being blown by a fan across the evaporator coil
or tubes. The evaporator operates at essentially constant pressure. The resulting
refrigerant vapor returns to the compressor inlet at point 1 to complete the
thermodynamic cycle.
The above discussion is based on the ideal vapor-compression refrigeration
cycle, and does not take into account real-world effects like frictional pressure drop
in the system, slight thermodynamic irreversibility during the compression of the
refrigerant vapor, or non-ideal gas behavior (if any).
Vapor absorption cycle: In the early years of the twentieth century, the
vapor absorption cycle using water-ammonia systems was popular and widely used
but, after the development of the vapor compression cycle, it lost much of its
importance because of its low coefficient of performance (about one fifth of that of
the vapor compression cycle). Nowadays, the vapor absorption cycle is used only
where waste heat is available or where heat is derived from solar collectors.
The absorption cycle is similar to the compression cycle, except for the
method of raising the pressure of the refrigerant vapor. In the absorption system,
the compressor is replaced by an absorber which dissolves the refrigerant in a
suitable liquid, a liquid pump which raises the pressure and a generator which, on
heat addition, drives off the refrigerant vapor from the high-pressure liquid. Some
work is required by the liquid pump but, for a given quantity of refrigerant, it is
much smaller than needed by the compressor in the vapor compression cycle. In an
absorption refrigerator, a suitable combination of refrigerant and absorbent is used.
The most common combinations are ammonia (refrigerant) and water (absorbent),
and water (refrigerant) and lithium bromide (absorbent).
Gas cycle: When the working fluid is a gas that is compressed and
expanded but doesn't change phase, the refrigeration cycle is called a gas cycle. Air
is most often this working fluid. As there is no condensation and evaporation
intended in a gas cycle, components corresponding to the condenser and evaporator
in a vapor compression cycle are the hot and cold gas-to-gas heat exchangers in gas
cycles.
The gas cycle is less efficient than the vapor compression cycle because the
gas cycle works on the reverse Brayton cycle instead of the reverse Rankine cycle.
As such the working fluid does not receive and reject heat at constant temperature.
In the gas cycle, the refrigeration effect is equal to the product of the specific heat
of the gas and the rise in temperature of the gas in the low temperature side.
Therefore, for the same cooling load, a gas refrigeration cycle will require a large
mass flow rate and would be bulky.
Because of their lower efficiency and larger bulk, air cycle coolers are not
often used nowadays in terrestrial cooling devices. The air cycle machine is very
common, however, on gas turbine-powered 'jet' aircraft because compressed air is
readily available from the engines' compressor sections. These jet aircrafts' cooling
and ventilation units also serve the purpose of pressurizing the aircraft.
The Peltier effect uses electricity directly to pump heat; refrigerators using
this effect are sometimes used for camping, or where noise is not acceptable. They
are totally silent, but less energy-efficient than other methods.
18
Other alternatives to the vapor-compression cycle but not in current use
include thermionic, vortex tube, magnetic cooling, Stirling cycle, acoustic cooling,
pulse tube and water cycle systems.
ACTIVE VOCABULARY
vapor-compression
cycle
–
парокомпрессионный цикл
compressor – компрессор
vapor – пар
to superheat – перегревать
condenser – конденсатор
liquid – жидкость
а expansion valve (a throttle valve) –
регулирующий
вентиль
(для
жидкого холодильного агента)
to decrease –уменьшаться
flash evaporation – мгновенное
испарение
evaporator – испаритель
coil – спираль, змеевик
inlet – впуск, вход; входное
отверстие
coefficient
of
performance
–
холодильный
коэффициент
(в
компрессионной
холодильной
машине); тепловой коэффициент (в
абсорбционной
холодильной
машине)
to derive – получать, извлекать
an
absorber
–
абсорбер,
поглотитель (устройство)
to dissolve – растворять
to require – нуждаться (в чём-л.) ;
требовать (чего-л.)
absorbent
–
абсорбент,
поглотитель (вещество)
heat exchanger – теплообменник
reverse – переворачивать
specific
heat
–
удельная
теплоёмкость
cooling device – охлаждающее
устройство
cooling load – тепловая нагрузка
(холодильного оборудования),
расход холода
to expand – расширяться;
увеличиваться в объёме
efficient – эффективный
VIII. Find the Russian equivalents for the English ones:
household refrigerator, a circulating refrigerant, constant pressure, autorefrigeration, evaporator coil, frictional pressure drop, non-ideal gas, solar
collector, high-pressure liquid, lithium bromide, Rankine cycle, thermionic.
IX. Find the English equivalents for the Russian ones:
система охлаждения на торговых предприятиях, дополнительная
теплота,
жидкий
холодильный
агент,
парожидкостная
смесь,
термодинамический цикл, термодинамическая необратимость, отходящая
теплота, аммиак, рабочая жидкость, эффективность, перегретый пар.
19
X. Translate the following sentences into Russian:
1) Тhe vapor is compressed at constant entropy and exits the
compressor superheated.
2) Тhe condenser condenses the vapor into a liquid by removing
additional heat at constant pressure and temperature.
3) Refrigerant’s pressure abruptly decreases, causing flash
evaporation and auto-refrigeration of, typically, less than half of the liquid.
4) The cold liquid-vapor mixture is completely vaporized by
cooling the warm air being blown by a fan across the evaporator tubes.
5) Тhe vapor absorption cycle is used only where waste heat is
available or where heat is derived from solar collectors.
6) The absorption cycle is similar to the compression cycle, except
for the method of raising the pressure of the refrigerant vapor.
7) А generator drives off the refrigerant vapor from the highpressure liquid.
8) Сomponents corresponding to the condenser and evaporator in a
vapor compression cycle are the hot and cold gas-to-gas heat exchangers in
gas cycles.
9) The working fluid does not receive and reject heat at constant
temperature.
10) Because of their lower efficiency and larger bulk, air cycle
coolers are not often used nowadays in terrestrial cooling devices.
XI. Fill in the blanks with appropriate words:
1)
А circulating refrigerant such as Freon enters … as … .
2)
Тhe condenser cools and removes … .
3)
Тhe … refrigerant goes through the … valve.
4)
The … mixture travels through the … coil.
5)
The … cycle uses water-ammonia systems.
6)
In the absorption system the … is replaced by an
absorber, … and a generator.
7)
The gas cycle works on the … cycle.
8)
In the … cycle the refrigeration effect is equal to the
product of … .
9)
The … machine is very common on gas turbinepowered 'jet' … .
10) In the early years of the twentieth century … cycle was
popular and widely used.
20
XII. Translate into English using the active vocabulary:
1.
Парокомпрессионный цикл используют во многих
системах охлаждения на торговых и промышленных предприятиях.
2.
Перегретый пар проходит через конденсатор.
3.
В регулирующем вентиле давление жидкого
холодильного агента уменьшается.
4.
У цикла паропоглащения низкий коэффициент
полезного действия.
5.
Абсорбер растворяет охладитель в подходящей
жидкости.
6.
В абсорбционном холодильнике используется
подходящая комбинация охладителя и абсорбента, например: аммиак
(охладитель) и вода (абсорбент).
7.
Когда рабочей жидкостью является газ, тогда
холодильный цикл называют газовым.
8.
В газовом цикле не используются процессы
конденсации и испарения.
9.
Газовый
цикл
менее
эффективен,
чем
парокомпрессионный.
10.
Устройства охлаждения и вентиляции реактивных
самолетов также служат цели герметизации самолета.
XIII. Answer the questions:
1.
What cyclic refrigeration is used in industrial
refrigeration systems?
2.
Is the vapor-compression cycle or the vapor absorption
cycle popular now? Why?
3.
What refrigerant is used in the vapor-compression cycle
/ vapor absorption cycle / gas cycle?
4.
What are the main components of a typical vaporcompression refrigeration system?
5.
What happens with vapor in the compressor?
6.
How does the condenser work?
7.
What is the cause of flash evaporation?
8.
How is the cold vapor-liquid mixture vaporized?
9.
How is the thermodynamic cycle completed?
10.
What is the coefficient of performance in the vapor
absorption cycle?
11.
Where is the vapor absorption cycle used?
21
12.
What is the compressor replaced by in the vapor
absorption cycle?
13.
What is the most common combination of refrigerant
and absorbent?
14.
What components are there in the gas cycle?
15.
Why is the gas cycle less efficient than the vapor
compression cycle?
16.
What can you say about air cycle coolers?
17.
What other alternatives to the vapor-compression cycle
are there?
XIV. Skim through the text and say in a few sentences what the message of
the text is. Answer the questions which follow.
Celsius is, or relates to,
Celsius temperature conversion formulas
the Celsius temperature scale
To find From
Formula
(previously known as the
°F = (°C × 1.8) +
centigrade scale). The degree
Fahrenheit Celsius
32
Celsius (symbol: °C) can refer
°C = (°F − 32)
to a specific temperature on
Celsius
Fahrenheit
/1.8
the Celsius scale as well as
serve as unit increment to
Kelvin
Celsius
K = °C + 273.15
indicate a temperature interval
Celsius
Kelvin
°C = K − 273.15
(a difference between two
°R = (°C +
temperatures
or
an
Rankine Celsius
273.15)
× 1.8
uncertainty).
“Celsius”
is
°C = (°R ÷ 1.8) –
named after the Swedish
Celsius
Rankine
273.15
astronomer Anders Celsius
(1701 – 1744), who developed
a similar temperature scale two years before his death.
Until 1954, 0 °C on the Celsius scale was defined as the melting point of ice
and 100 °C was defined as the boiling point of water under a pressure of one
standard atmosphere; this close equivalency is taught in schools today. However,
the unit “degree Celsius” and the Celsius scale are currently, by international
agreement, defined by two different points: absolute zero, and the triple point of
specially prepared water. This definition also precisely relates the Celsius scale to
the Kelvin scale, which is the SI base unit of temperature (symbol: K). Absolute
zero—the temperature at which nothing could be colder and no heat energy
remains in a substance—is defined as being precisely 0 K and −273.15 °C. The
triple point of water is defined as being precisely 273.16 K and 0.01 °C.
22
This definition fixes the magnitude of both the degree Celsius and the unit
kelvin as being precisely 1 part in 273.16 parts the difference between absolute
zero and the triple point of water. Thus, it sets the magnitude of one degree Celsius
and the kelvin to be exactly equivalent. Additionally, it establishes the difference
between the two scales’ null points as being precisely 273.15 degrees Celsius
(−273.15 °C = 0 K and 0.01 °C = 273.16 K).
Some key temperatures relating the Celsius scale to other temperature scales
are shown in the table below.
Kelvin
Absolute zero
(precisely,
definition)
by
Melting point of ice
(approximate)
Water’s triple point
(precisely,
definition)
Water's boiling point
(approximate)
0K
Celsius
−27
−459
3.15 °C
.67 °F
273.
15 K
by
0
°C
273.
16 K
Fahrenheit
32
°F
0.01
°C
32.0
18 °F
373.
99.9
211.
1339 K
839 °C
9710 °F
Throughout the world, except in the U.S. and perhaps a few other countries
the Celsius temperature scale is used for practically all purposes. The only
exceptions are some specialist fields (e.g., low-temperature physics, astrophysics,
light temperature in photography) where the closely related Kelvin scale dominates
instead. Even in the U.S., almost the entire scientific world and most engineering
fields, especially high-tech ones, use the Celsius scale. The general U.S. population
(not considering foreign immigrants), however, remains more accustomed to the
Fahrenheit scale, which is therefore the scale that most U.S. broadcasters use in
weather forecasts. The Fahrenheit scale is also commonly used in the U.S. for body
temperatures. The United Kingdom has almost exclusively used the Celsius scale
since the 1970s, with the notable exception that some broadcasters and publications
still quote Fahrenheit air temperatures in weather forecasts (especially during
summer), for the benefit of generations born before about 1950, and airtemperature thermometers sold still show both scales for the same reason.
* * *
1. What does the degree Celsius serve?
2. What define the unit “degree Celsius” and the Celsius scale?
23
3. What is absolute zero?
4. What is the definition between the degree Celsius and the unit kelvin?
5. Where is the Celsius temperature scale used?
XIV. Skim through the text and say in a few sentences what the message of
the text is. Ask some questions to your partner.
Fahrenheit is a temperature scale named after the German-Dutch physicist
Daniel Gabriel Fahrenheit (1686–1736), who proposed it in 1724.
In this scale, the melting point of water is 32 degrees Fahrenheit (written
“32 °F”), and the boiling point is 212 degrees, placing the boiling and melting
points of water exactly 180 degrees apart. On the Celsius scale, the melting and
boiling points of water are exactly 100 degrees apart, thus the unit of this scale, a
degree Fahrenheit, is 5⁄9 of a degree Celsius. The Fahrenheit scale coincides with
the Celsius scale at -40 °F, which
is the same temperature as -40 °C.
Fahrenheit temperature conversion
Absolute zero is −459.67
formulas
°F. The Rankine temperature scale
TC = (TF − 32) × 5/9
was invented to use degrees the
Celsius
TF = (TC × 9/5) + 32
same size as Fahrenheit degrees,
TK = (TC - 273)
so 0 °R would be absolute zero,
namely −459.67 °F.
Kelvin
TF = ((TF − 32) × 5/9)The Fahrenheit scale was
273
the primary temperature standard
TR = TF + 459.67
for climatic, industrial and
Rankine
TF = TR − 459.67
medical purposes in most EnglishAdditional conversion formulas
speaking countries until the 1960s.
In the late 1960s and 1970s, the
Celsius (formerly Centigrade) scale was phased in by governments as part of the
standardizing process of metrication. In the United States and perhaps a few other
countries (such as Belize) the Fahrenheit system continues to be the accepted
standard for non-scientific use. Most other countries have adopted Celsius as the
primary scale in all use. Fahrenheit is sometimes used by older generations in
English speaking countries, especially for measurement of higher temperatures.
24
UNIT 3
I. Read and translate the text:
Icebox
An Icebox was the common appliance for providing refrigeration in the
home before safe refrigerants made compact mechanical refrigerators useful.
Commonly iceboxes were made of wood, most probably for ease of
construction, insulation, and aesthetics: many were handsome pieces of furniture.
Iceboxes had hollow walls that were lined with tin or zinc and packed with
various insulating materials such as cork, sawdust, straw or seaweed. A large block
of ice was held in a tray or compartment near the top of the box. Cold air circulated
down and around storage compartments in the lower section. Some finer models
had spigots for draining ice water from a catch pan or holding tank. In cheaper
models a drip pan was placed under the box and had to be emptied at least daily.
Iceboxes date back to the days of ice harvesting which in a growing
America had hit an industrial high that ran from the mid-19th century to the 1930s
when the refrigerator was introduced into the home. Most municipally-consumed
ice was harvested in winter from snow-packed areas or frozen lakes. Even
Thoreau's Walden Pond was not spared from ice harvesting. The ice was stored in
ice houses, or shipped as far as India by Frederic Tudor, the "Ice King".
With metropolitan growth many of the sources of natural ice became
contaminated from industrial pollution or sewer runoff. As early mechanical
refrigerators became available, they were installed as large industrial plants
producing ice for home delivery. Able to produce clean, sanitary ice year-round,
their product gradually replaced ice harvested from ponds.
With wide-spread electrification and safer refrigerants, mechanical
refrigeration in the home became possible. With the development of the
chlorofluorocarbons (along with the succeeding hydrochlorofluorocarbons and
hydrofluorocarbons), that came to replace the use of toxic ammonia gas, the
refrigerator replaced the icebox. However, because of the prevalence of the icebox
in recent human history, the name "icebox" is still used colloquially for the modern
home refrigerator by older Americans in some regions.
The horse-drawn ice wagon and the daily occupation of the iceman, who
made regular door-to-door deliveries of block ice for iceboxes, was as much a
social institution as the milk man.
25
Apartment buildings had small doors that opened to the ice box from the
back porch. The ice man would bring the block of ice and insert it into the ice box
through this door. Ice was delivered on a regular basis to these buildings and the
people would pay for the ice. Children would go on the ice wagon and take chips
of fallen ice as treats during the summer.
Words to the text:
Icebox – холодильник; ледник
spigot – пробка, кран
mechanical
refrigerator
–
holding tank – сборный танк
холодильный шкаф с машинным
a drip pan – поддон
охлаждением
ice harvesting – заготовка льда
aesthetics – эстетика
to contaminate – загрязнять;
hollow – пустой, полый
отравлять
tin – олово, белая жесть
sewer runoff – канализационная
cork – пробка
сток
sawdust – опилки
prevalence
–
широкая
straw – солома
распространенность
seaweed – морская водоросль
colloquially – разговорный
a tray – поднос
horse-drawn – на конной тяге
II. Say whether these sentences are True or False:
1. An Icebox is the common appliance for providing refrigeration in
the home.
2. Ice was harvested in winter from snow-packed areas or frozen
lakes.
3. From the large block of ice cold air circulated down and around
storage compartments.
4. Mechanical refrigerators are able to produce clean, sanitary ice
year-round.
5. Commonly iceboxes were made of wood.
6. The chlorofluorocarbons and ammonia gas were used as
refrigerants in the iceboxes.
7. Some finer models had trays for draining ice water from a catch
pan or holding tank.
8. The horse-drawn ice wagon was as much a social institution as
the milk man.
9. Iceboxes’ walls were lined with tin or another metal and packed
with various insulating materials such as cork or seaweed.
10. In the mid-19th century to the 1930s the refrigerator was
introduced into the home.
26
III. Make up different kinds of questions to the text. Ask your partner about
the icebox. (Work in pair or group)
I group (Yes/No-questions)
Was an icebox the common appliance for refrigerating in the home?
II group (Tag-question)
An icebox was the common appliance for
refrigerating in the home, wasn’t it?
III group (Wh-questions)
What was an icebox?
IV. Read and translate the text:
Vapor-compression refrigeration
Vapor-compression refrigeration is one of the many refrigeration cycles
available for use. It has been and is the most widely used method for airconditioning of large public buildings, private residences, hotels, hospitals,
theaters, restaurants and automobiles. It is also used in domestic and commercial
refrigerators, large-scale warehouses for storage of foods and meats, refrigerated
trucks and railroad cars, and a host of other commercial and industrial services. Oil
refineries, petrochemical and chemical processing plants, and natural gas
processing plants are among the many types of industrial plants that often utilize
large vapor-compression refrigeration systems.
Refrigeration may be defined as lowering the temperature of an enclosed
space by removing heat from that space and transferring it elsewhere. A device that
performs this function may also be called a heat pump.
The vapor-compression refrigeration cycle consists of condensing coil,
expansion valve, evaporator coil, and compressor.
In the vapor-compression refrigeration cycle, heat is transferred from a
lower temperature source to a higher temperature heat sink. Heat naturally flows in
the opposite direction, and due to the second law of thermodynamics work is
required to move heat from cold to hot. A food refrigerator or freezer works in
much the same way; it moves heat out of the interior into the room in which it
stands.
This most common refrigeration cycle uses an electric motor to drive a
compressor. In an automobile the compressor is usually driven by a belt connected
to a pulley on the engine's crankshaft, with both using electric motors for air
circulation. Since evaporation occurs when heat is absorbed, and condensation
occurs when heat is released, air conditioners are designed to use a compressor to
cause pressure changes between two compartments, and actively pump a
refrigerant around. A refrigerant is pumped into the low pressure compartment (the
27
evaporator coil), where, despite the low temperature, the low pressure causes the
refrigerant to evaporate into a vapor, taking heat with it. In the other compartment
(the condenser), the refrigerant vapour is compressed and forced through another
heat exchange coil, condensing into a liquid, rejecting the heat previously absorbed
from the cooled space. The heat exchanger in the condenser section (the heat sink
mentioned above) is often cooled by a fan blowing outside air through it, or in
some cases, such as marine applications, by other means such as water.
Figure 2
The vapor-compression refrigeration system uses a circulating liquid
refrigerant as the medium which absorbs and removes heat from the space to be
cooled and subsequently rejects that heat elsewhere. Figure 2 depicts a typical,
single-stage vapor-compression system. All such systems have four components: a
compressor, a condenser, an expansion valve (also called a throttle valve), and an
evaporator. Circulating refrigerant enters the compressor in the thermodynamic
state known as a saturated vapor and is compressed to a higher pressure, resulting
in a higher temperature as well. The hot, compressed vapor is then in the
thermodynamic state known as a superheated vapor and it is at temperature and
pressure at which it can be condensed with typically available cooling water or
cooling air. That hot vapor is routed through a condenser where it is cooled and
condensed into a liquid by flowing through a coil or tubes with cool water or cool
air flowing across the coil or tubes. This is where the circulating refrigerant rejects
heat from the system and the rejected heat is carried away by either the water or the
air (whichever may be the case).
The condensed liquid refrigerant, in the thermodynamic state known as a
saturated liquid, is next routed through an expansion valve where it undergoes an
abrupt reduction in pressure. That pressure reduction results in the adiabatic flash
evaporation of a part of the liquid refrigerant. The auto-refrigeration effect of the
adiabatic flash evaporation lowers the temperature of the liquid and vapor
28
refrigerant mixture to where it is colder than the temperature of the enclosed space
to be refrigerated.
The cold mixture is then routed through the coil or tubes in the evaporator.
A fan circulates the warm air in the enclosed space across the coil or tubes carrying
the cold refrigerant liquid and vapor mixture. That warm air evaporates the liquid
part of the cold refrigerant mixture. At the same time, the circulating air is cooled
and thus lowers the temperature of the enclosed space to the desired temperature.
The evaporator is where the circulating refrigerant absorbs and removes heat which
is subsequently rejected in the condenser and transferred elsewhere by the water or
air used in the condenser.
To complete the refrigeration cycle, the refrigerant vapor from the
evaporator is again a saturated vapor and is routed back into the compressor.
Note: Saturated vapors and saturated liquids are vapors and liquids at their
saturation temperature and saturation pressure. A superheated vapor is at a
temperature higher than the saturation temperature corresponding to its pressure.
The most common compressors used in chillers are reciprocating, rotary
screw, centrifugal, and scroll compressors. Each application prefers one or another
due to size, noise, efficiency and pressure issues.
Reciprocating compressors are piston-style, positive displacement
compressors.
Rotary screw compressors are also positive displacement compressors. Two
meshing screw-rotors rotate in opposite directions, trapping refrigerant vapor, and
reducing the volume of the refrigerant along the rotors to the discharge point.
Centrifugal compressors are dynamic compressors. These compressors raise
the pressure of the refrigerant by imparting velocity or dynamic energy, using a
rotating impeller, and converting it to pressure energy.
Scroll compressors are also positive displacement compressors. The
refrigerant is compressed when one spiral orbits around a second stationary spiral,
creating smaller and smaller pockets and higher pressures. By the time the
refrigerant is discharged, it is fully pressurized.
ACTIVE VOCABULARY
vapor-compression refrigeration –
паровое
компрессионное
(парокомпрессионное) охлаждение
oil refinery – нефтеочистительный
завод
to
utilize
–
использовать,
расходовать, употреблять
a
device
–
устройство,
приспособление
to
perform
–
исполнять,
выполнять; делать, совершать
a heat pump – тепловой насос
а expansion valve (a throttle valve)
– регулирующий вентиль (для
жидкого холодильного агента)
29
condensing coil – змеевиковый
конденсатор
evaporator coil – испарительный
змеевик; змеевик испарителя
refrigerator
–
рефрижератор,
холодильник,
холодильная
установка
freezer
–
рефрижератор,
холодильник,
холодильная
установка
interior – внутренняя часть
to drive (drove, driven) – приводить
(к какому-л. состоянию)
evaporation – испарение
condensation
–
сжижение;
конденсирование, конденсация
a compartment – отделение
a liquid – жидкость
heat exchanger – теплообменник
fan – вентилятор
medium – среда
a saturated vapor – насыщенный пар
a superheated vapor – перегретый пар
to reject – отвергать, отклонять;
отказываться
to
undergo
(underwent;
undergone)
–
испытывать,
переносить
adiabatic
–
адиабатический,
адиабатный
to lower – снижать, уменьшать
to
transfer
–
переносить,
перемещать
to
complete
–
завершать,
заканчивать
refrigeration cycle – холодильный
цикл
reciprocating
–
возвратнопоступательный
rotary screw – ротационный
винтовой
centrifugal – центробежный
piston – поршень
displacement – объём чего-л.
to rotate – вращаться
velocity – скорость; быстрота
impeller – рабочее колесо
to convert – преобразовывать;
превращать
a spiral – спираль,
to orbit – вращаться (по орбите)
V. Find the Russian equivalents for the English ones:
air-conditioning, to trap, large-scale warehouse, an abrupt reduction,
condensing coil, to impart, a lower temperature source, discharge point, an
impeller, saturation pressure, stationary spiral, heat exchange coil, piston-style, a
saturated liquid, scroll compressor
VI. Find the English equivalents for the Russian ones:
Холодильный цикл, тепловой насос, энергия давления, испарительный
змеевик, теплоотвод, воздушный карман, электродвигатель, температура
насыщения, динамический компрессор, термодинамическое состояние,
насыщенный пар, динамическая энергия, желательный, объёмный
компрессор, объем охладителя
30
VII. Translate the following sentences into Russian:
1)
Сhemical processing plants and natural gas processing plants
often utilize large vapor-compression refrigeration systems.
2)
Refrigeration may be defined as lowering the temperature of an
enclosed space by removing heat from that space and transferring it elsewhere.
3)
In an automobile the compressor is usually driven by a belt
connected to a pulley on the engine's crankshaft, with both using electric
motors for air circulation.
4)
Air conditioners are designed to use a compressor to cause
pressure changes between two compartments, and actively pump a refrigerant
around.
5)
In the condenser the refrigerant vapour is compressed and forced
through another heat exchange coil, condensing into a liquid.
6)
Circulating refrigerant enters the compressor in the
thermodynamic state known as a saturated vapor and is compressed to a higher
pressure.
7)
The hot vapor is routed through a condenser where it is cooled
and condensed into a liquid by flowing through a coil or tubes with cool water
or cool air flowing across the coil or tubes.
8)
The auto-refrigeration effect of the adiabatic flash evaporation
lowers the temperature of the liquid and vapor refrigerant mixture.
9)
In the evaporator the circulating refrigerant absorbs and removes
heat which is subsequently rejected in the condenser and transferred elsewhere
by the water or air.
10) Centrifugal compressors raise the pressure of the refrigerant by
dynamic energy, using a rotating impeller, and converting it to pressure
energy.
VIII. Fill in the blanks with appropriate words:
1) Heat is transferred from a … source to a higher temperature … .
2) This most common refrigeration cycle uses an … motor to drive
….
3) Since evaporation occurs when heat is absorbed, and
condensation occurs when heat is released,
4) Despite the low … the low pressure causes the … to evaporate
into a vapor.
5) A liquid refrigerant is the … which absorbs and removes … from
the space.
31
6) In the condenser the hot vapor is … and condensed into a … .
7) The rejected … is carried away by either the … or the air.
8) The … reduction results in the adiabatic … of a part of the liquid
….
9) The warm air … the liquid part of the cold … mixture in the
evaporator.
10) In … compressors the refrigerant is compressed when one spiral
orbits around a second stationary spiral.
IX. Translate into English, using the active vocabulary:
1.
Парокомпрессионное охлаждение используется в
домашних холодильниках для хранения продуктов.
2.
Холодильная установка выводит тепло из своей
внутренней части в комнату, где она находится.
3.
В холодольном цикле для приведения в действие
компрессор используется электродвигатель.
4.
Охладитель закачивается в испарительный змеевик,
где давление низкое.
5.
Теплообменник
в
конденсоре
охлаждается
вентилятором.
6.
Парокомпрессионная система состоит из четырех
компонентов: компрессора, конденсора, регулирующего вентиля
и испарителя.
7.
Перенагретый пар – это термодинамическое
состояние горячего сжатого пара.
8.
В регулирующем вентиле насыщенная жидкость
подвергается резкому уменьшению давления.
9.
Холодная смесь проходит через трубы в испарителе.
10. Возвратно-поступательный и ротационный винтовой
компрессоры – это объемные компрессоры.
X. Answer the questions:
1) What is vapor-compression refrigeration used for?
2) Is a heat pump used for refrigeration?
3) What does the refrigeration cycle consist of?
4) What law is the work based on in the vapor-compression
refrigeration cycle?
5) What does the refrigeration cycle use to drive a compresor?
6) What is the medium which absorbs and removes heat?
32
7) What components does the vapor-compression system have?
8) What is the saturated vapor?
9) What is the thermodynamic state of the hot compressed vapor?
10) What happens with the hot vapor in the condenser?
11) Where does the circulating refrigerant reject heat from the
system?
12) What does a saturated liquid undergo in the expansion valve?
13) What lowers the temperature of the liquid and vapor refrigerant
mixture?
14) What happens with the cold mixture in the evaporator?
15) What types of compressor do you know?
16) What compressors are positive displacement compressors?
17) How do rotary screw / centrifugal / scroll compressors work?
XI. Skim through the text and say in one sentence what the message of the
text is. Answer the questions which follow.
A single-stage refrigeration system may include other equipment items that
would be provided in a large commercial or industrial vapor compression
refrigeration system, such as:
 A horizontal or vertical pressure vessel, equipped internally with
a demister, between the evaporator and the compressor inlet to capture
and remove any residual, entrained liquid in the refrigerant vapor because
liquid may damage the compressor. Such pressure vessels are most often
referred to as "suction line accumulators". (In other industrial processes
they are called "compressor suction drums" or "knockout drums".)
 Large commercial or industrial refrigeration systems may have
multiple expansion valves and multiple evaporators in order to refrigerate
multiple enclosed spaces or rooms. In such systems, the condensed liquid
refrigerant may be routed into a pressure vessel, called a receiver, from
which liquid refrigerant is withdrawn and routed through multiple
pipelines to the multiple expansion valves and evaporators.
 Some refrigeration units may have multiple stages which require
the use of multiple compressors in various arrangements.
Refrigeration
application
Domestic
refrigeration
Commer
Short descriptions
Appliances used for keeping
food in dwelling units
Holding and displaying
Typical
refrigerants
used
R-600a,
R-134a
R-134a,
33
cial refrigeration
Food
processing and
cold storage
Industrial
refrigeration
Transpor
t refrigeration
Electroni
c cooling
Medical
refrigeration
Cryogeni
c refrigeration
frozen and fresh food in retail
outlets
Equipment to preserve,
process and store food from its
source to the wholesale distribution
point
Large equipment, typically
25 kW to 30 MW, used for
chemical processing, cold storage,
food processing and district heating
and cooling
Equipment to preserve and
store goods, primarily foodstuffs,
during transport by road, rail, air
and sea
Low-temperature cooling of
CMOS
circuitry
and
other
components in large computers and
servers
R-404A, R-507
R-134a,
R-407C,
R410A, R-507
R-134a,
R-404A, R-507,
R-717
R-134a,
R-407C,
R410A
R-134a,
R-404A, R-507
R-134a,
R-404A, R-507
Ethylene,
Helium
* * *
1.
What other equipment items may a single-stage
refrigeration system include?
2.
Where is a pressure vessel? What is it for? Why?
3.
What do large commercial refrigeration systems have
multiple expansion valves to?
4.
Why do some refrigeration units use multiple
compressors?
5.
What application of regrigeration do you know?
6.
What is industrial refrigeration / transport refrigeration
used for?
7.
Where is electronic cooling used?
34
UNIT 4
I. Read and translate the text:
History of the refrigerator
The first known artificial refrigeration was demonstrated by William Cullen
at the University of Glasgow in 1748, and relied on the vapor-compression
refrigeration process explained by Michael Faraday. Between 1805, when Oliver
Evans designed the first refrigeration machine that used vapor instead of liquid,
and 1902 when Willis Haviland Carrier demonstrated the first air conditioner,
scores of inventors contributed many small advances in cooling machinery. In
1850 or 1851, Dr. John Gorrie demonstrated an ice maker. In 1857, Australian
James Harrison introduced vapor-compression refrigeration to the brewing and
meat packing industries. The absorption refrigerator was invented by Baltzar von
Platen and Carl Munters in 1922, while they were still students at the Royal
Institute of Technology in Stockholm, Sweden. It became a worldwide success and
was commercialized by Electrolux. Other pioneers included Charles Tellier, David
Boyle, and Raoul Pictet.
In a few exceptional cases, mechanical refrigeration systems had been
adapted by the start of the 20th century for use in the homes of the very wealthy,
and might be used for cooling both living and food storage areas. One early system
was installed at the mansion of Walter Pierce, an oil company executive.
Marcel Audiffren of France championed the idea of a refrigerating machine
for cooling and preserving foods at home. His U.S. patents, issued in 1895 and
1908, were purchased by the American Audiffren Refrigerating Machine
Company. Machines based on Audiffren's sulfur dioxide process were
manufactured by General Electric in Fort Wayne, Indiana and marketed by the
Johns-Manville company. The first unit was sold in 1911. Audiffren machines
were expensive, selling for about $1,000 — about twice as much as an automobile
cost at the time.
General Electric sought to develop refrigerators of its own, and in 1915 the
first unit was assembled. In 1916 Kelvinator and Servel came out with two units
among a field of competing models. This number increased to 200 by 1920. In
1918, Kelvinator had a model with automatic controls.
These home units usually required the installation of the mechanical parts,
motor and compressor, in the basement or an adjacent room while the cold box was
located in the kitchen. There was a 1922 model that consisted of a wooden cold
box, water-cooled compressor, an ice cube tray and a 9 cubic foot compartment for
$714. (A 1922 Model-T Ford cost about $450.) In 1923 Frigidaire introduced the
first self-contained unit. About this same time porcelain covered metal cabinets
35
began to appear. Ice cube trays were introduced more and more during the 1920s;
up to this time freezing was not a function of the modern refrigerator.
The first refrigerator to see widespread use was the General Electric
"Monitor-Top" refrigerator introduced in 1927. The compressor assembly, which
emitted a substantial amount of heat, was placed above the cabinet, and surrounded
with a decorative ring. Over 1,000,000 units were produced. This refrigerator used
sulfur dioxide refrigerant. Many units are still functional today.
The introduction of freon expanded the refrigerator market during the
1930s, and freezer units became a little more common and requested during the
1940s. Home units did not go into mass production until after WWII. The 1950s
and 60s saw technical advances like automatic defrosting and automatic ice
making. Developments of the 1970s and 80s brought about more efficient
refrigerators, and environmental issues banned the use of CFC (freon) refrigerants.
Refrigerators used to consume more energy than any other home appliance,
but in the last twenty years, great strides have been made to make refrigerators
more energy efficient. Current models that are Energy Star qualified use 50 percent
less energy than models made before 1993.
Introduction of home freezer units occurred in the United States in 1940,
and frozen foods began to make the transition from luxury to necessity.
Words to the text
to rely – полагаться, надеяться
adjacent
–
расположенный
scores – множество
рядом, смежный, соседний
to contribute – вносить вклад
self-contained – смонтированный
brewing – пивоварение
в общем корпусе
to install – устанавливать
cabinet – шкаф
mansion – большой особняк,
porcelain – фарфор
большой дом
defrosting – размораживание
to issue – выходить
to bann – налагать запрет;
to purchase – покупать
запрещать
sulfur dioxide –
диоксид серы,
to consume - расходовать,
сернистый ангидрид
тратить
to seek – искать, разыскивать;
Energy
Star
–
стандарт
пытаться найти
экономичного
энергопотребления
competing – конкурирующий
электроприборов
II. Fulfill the table using information from the text. (work in pairs or
groups)
D
36
Inventor /
Refrige
Features of
ate
firm
ration system
refrigerator
19
22
St
art of the
20th
century
18
95 –
1908
19
15
19
18
19
22
19
23
19
27
19
30s –
1940s
19
50s –
1960s
19
70s –
1980s
20
00s
III. Make up different kinds of questions to the text. Ask your partner about
historical application of refrigeration. (Work in pair or group)
I group (Yes/No-questions)
Did Carrier demonstrate the first air conditioner?
II group (Wh-questions)
III group (Tag-question)
When did Oliver Evans design
the first refrigeration machine?
37
Dr. John Gorrie
demonstrated an ice maker, didn’t
he?
IV. Skim through the text and say in a few sentences what the message of
the text is. Answer the questions which follow.
The impact of the refrigerator on the home
Virtually all homes in the developed world have a refrigerator of one kind
or another. The invention of the refrigerator has allowed the modern family to
purchase, store, freeze, prepare and preserve food products in a fresh state for
much longer periods of time than was previously possible. For the majority of
families without a sizeable garden in which to grow vegetables and raise livestock,
the advent of the refrigerator along with the modern supermarket led to a vastly
more varied diet and improved health resulting from improved nutrition. Dairy
products, meats, fish, poultry and vegetables can all be kept refrigerated in the
same space within the kitchen (although raw meat should be kept separate from
other foodstuffs for reasons of hygiene).
The refrigerator allows families to consume more salads, fresh fruits and
vegetables during meals without having to own a garden or an orchard. Exotic
foodstuffs from far-off countries that have been imported by means of refrigeration
can be enjoyed in the home because of the availability of domestic refrigeration.
The luxury of freezing allows households to purchase more foods in bulk
that can be eaten at leisure while the bulk purchase provides cost savings (see
economies of scale). Ice cream, a popular commodity of the 20th century, was
previously only available by traveling long distances to where the product was
made fresh and had to be eaten on the spot. Now it is a practically ubiquitous food
item. Ice on-demand not only adds to the enjoyment of cold drinks, but is useful in
first-aid applications, not to mention cold packs that can be kept frozen for picnics
or in case of emergency.
* * *
1.
What has the refrigerator allowed us to do?
2.
What food should be kept separate from other
foodstuffs? Why?
3.
Can exotic foodstuffs be enjoyed in the home? Why?
4.
Can people purchase more foods in bulk?
5.
What does the bulk purchase provide?
6.
What food item is practically ubiquitous thanks to the
refrigerator?
38
V. Read and translate the text:
Refrigerator
A refrigerator (often called a "fridge" for short) is a cooling appliance
comprising a thermally insulated compartment and a mechanism to transfer heat
from it to the external environment, cooling the contents to a temperature below
ambient. Refrigerators are extensively used to store foods which deteriorate at
ambient temperatures; spoilage from bacterial growth and other processes is much
slower at low temperatures. A device described as a "refrigerator" maintains a
temperature a few degrees above the freezing point of water; a similar devices
which maintains a temperature below the freezing point of water is called a
"freezer". The refrigerator is a relatively modern invention amongst kitchen
appliances. It replaced the common icebox which had been placed outside for
almost a century and a half prior, and is sometimes still called by the original name
"icebox".
Freezers keep their contents, usually foods, frozen. They are used both in
households and for commercial use. Most freezers operate at around -18 °C (0 °F).
Domestic freezers can be included as a compartment in a refrigerator, sharing the
same mechanism or with a separate mechanism, or can be standalone units.
Domestic freezers are generally upright units, resembling refrigerators, or chests,
resembling upright units laid on their backs. Many modern freezers come with an
icemaker.
Domestic refrigerators and freezers for food storage are made in a range of
sizes. Amongst the smallest is a 4 L Peltier fridge advertised as being able to hold
6 cans of beer. A large domestic fridge stands as tall as a person and may be about
1 m wide with a capacity of 600 L. Some models for small households fit under
kitchen work surfaces, usually about 86 cm high. Fridges may be combined with
freezers, either stacked with fridge or freezer above, below, or side by side. A
fridge without a true freezer may have a small compartment to make ice. Freezers
may have drawers to store food in, or they may have no divisions (chest freezers).
Fridges and freezers may be free-standing, or built into a kitchen.
Compressor refrigerators are by far the most common type; they make a
noticeable noise. Absorption or Peltier units are used where quiet running is
required; Peltier coolers are used in the smallest refrigerators as they have no bulky
mechanism.
Compressor and Peltier refrigerators are invariably powered by electricity;
absorption units can in principle be designed to be powered by any heat source.
Gas-only and dual power gas/electricity units are available.
Refrigeration units for commercial and for non-food use are made in a huge
range of sizes and styles.
39
Newer refrigerators may include following features:
 Automatic defrosting: In any refrigerator, over time, water vapor
in the air condenses onto the cooling coils as frost, eventually building up
into a thick layer of ice. This ice acts as an insulator, reducing cooling
efficiency. In the past, the ice was removed by periodically emptying the
refrigerator and turning it off to let the ice melt, perhaps aided by hot
water applied by the user (a process known as defrosting). In a
refrigerator equipped for frost-free operation, however, a heater and a
thermostat are fitted around the cooling coils. The cooling is periodically
switched off (with the period varying between every 6 to 24 hours
depending on the model) and the heater is turned on until the temperature
around the coils slightly exceeds the freezing point of water, after which
normal cooling resumes. This melts any frost which has collected around
the coils. Melt water drops into a small gulley, through a small pipe which
drains into a tray on the top of the compressor from which it is then
evaporated into the surrounding air by residual heat generated by the
operation of the compressor.
 A power failure warning, alerting the user by flashing a
temperature display. The maximum temperature reached during the power
failure may be displayed, along with information on whether the frozen
food has defrosted or may contain harmful bacteria;
 Chilled water and ice available from an in-door station, so the
door need not be opened;
 Adjustable shelves and trays that can be moved around to suit the
user;
 A cooling zone in the refrigerator door shelves. Air from the
freezer section is diverted to the refrigerator door, to better cool milk or
juice stored in the door shelf.
Early freezer units accumulated ice crystals around the freezing units. This
was a result of humidity introduced into the units when the doors to the freezer
were opened. This build up of frost required periodic thawing of the units to
maintain their efficiency. Advances in frost-free refrigeration eliminating the
thawing task were introduced in the 1950s. Also, early units featured freezer
compartments located within the larger refrigerator, and accessed by opening the
refrigerator door, and then the smaller internal freezer door; units featuring entirely
separate freezer compartment were introduced in the early 1960s, becoming the
industry standard by the middle of that decade.
Old refrigerators have freon as coolant, which damages the ozone layer.
Now modern refrigerators usually use a refrigerant called HFC-134a (1,2,2,2tetrafluoroethane) instead of freon, which has no ozone layer depleting properties.
40
ACTIVE VOCABULARY
refrigerator (a "fridge") –
рефрижератор, холодильник,
холодильная установка
to deteriorate – ухудшать; портить
a compartment – отделение
standalone – автономный
freezer – морозильная камера
upright – вертикальный
icemaker – льдогенератор
to transfer – переносить, перемещать
to store – хранить, сохранять
spoilage – порча или гниение
пищевых
и
скоропортящихся
продуктов
a
device
–
устройство,
приспособление; механизм
to melt – таять
to drain – отводить воду
to chill – охлаждать, замораживать
to accumulate – накапливать;
собирать
to maintain – поддерживать,
сохранять
appliance – аппарат, прибор;
a capacity – вместимость,
ёмкость
to power – приводить в действие
defrosting – размораживание;
оттаивание
to empty – осушать
a
heater
–
обогреватель;
нагревательный прибор
exceed
–
превышать;
переступать пределы, границы;
выходить за пределы
freezing point – точка замерзания
to resume – возобновлять,
продолжать
thawing – таяние, оттаивание
coolant
–
смазочноохлаждающая
эмульсия
VI. Find the Russian equivalents for the English ones:
comprising, icebox, a cooling appliance, a thermally insulated compartment,
а upright unit, drawer, free-standing, Peltier cooler, dual power gas/electricity unit,
frost-free operation, freezing unit.
VII. Find the English equivalents for the Russian ones:
внешняя среда, температура окружающей среды, отдельный механизм,
автономное устройство, хранение продовольствия, приводить в действие
электричеством,
автоматическое
размораживание,
холодопроизводительность, водосток, остаточное тепло, сигнал о нарушении
энергоснабжения.
VIII. Translate the following sentences into Russian:
1) A refrigerator has a mechanism to transfer heat from it to the external
environment, cooling the contents to a temperature below ambient.
41
2) Domestic freezers are generally upright units, resembling refrigerators,
or chests, resembling upright units laid on their backs.
3) A large domestic fridge stands as tall as a person and may be about 1 m
wide with a capacity of 600 L.
4) Fridges and freezers may be free-standing, or built into a kitchen.
5) Peltier coolers are used in the smallest refrigerators as they have no
bulky mechanism.
6) In any refrigerator, over time, water vapor in the air condenses onto the
cooling coils as frost, eventually building up into a thick layer of ice.
7) By frost-free operation the cooling is periodically switched off and the
heater is turned on until the temperature around the coils slightly exceeds the
freezing point of water, after which normal cooling resumes.
8) A power failure warning alerts the user by flashing a temperature
display.
9) Air from the freezer section is diverted to the refrigerator door, to better
cool milk or juice stored in the door shelf.
10) The accumulation of ice crystals was a result of humidity introduced
into the units when the doors to the freezer were opened.
IX. Fill in the blanks with appropriate words:
1) … from bacterial growth and other processes is much slower at … .
2) Freezers keep their … frozen.
3) Freezers may have … to store food in, or they may have no … .
4) … are used where quiet running is required.
5) Аbsorption units can in principle be designed to be powered by … .
6) Тhe ice was removed by … the refrigerator and … to let the ice melt.
7) Residual … is generated by the operation of the … .
8) Adjustable … and … can be moved around to suit the user.
9) Early freezer units accumulated … around the freezing units.
10) Now modern refrigerators usually use a … called HFC-134a instead of
….
X. Translate into English, using the vocabulary:
1. Холодильник используется для хранения продуктов, которые
портятся при температуре окружающей среды.
2. Холодильник поддерживает температуру немного выше, чем точка
замерзания воды.
3. Устройство, которое поддерживает температуру ниже точки
замерзания воды, называют морозильной камерой.
42
4. Морозильные камеры используются как в быту, так и торговых
целях.
5. Холодильник может быть объединен с морозильной камерой.
6. Талая вода испаряется под влиянием остаточного тепла.
7. Иней накапливается на трубах.
8. Для поддержания эффективности холодильника необходимо
размораживание.
9. Многие современные морозильные камеры изготавливаются с
льдогенераторами.
10. В старых холодильниках в качестве холодильного агента
использовался фреон.
XI. Answer the questions:
1.
What is a refrigerator?
2.
What are refrigerators used to?
3.
What is the difference between a refrigerator and a
freezer?
4.
Are freezers a compartment in a refrigerator or a
separate mechanism?
5.
What kind of units is the freezer?
6.
What is the smallest fridge?
7.
What capacity does the largest domestic fridge have?
8.
Do freezers have compartments?
9.
What freezer has no divisions?
10.
May fridges be built into a kitchen?
11.
What kind of refrigerator works quiet?
12.
Where is Peltier cooler used?
13.
What can refrigerators be powered by?
14.
How does automatic defrosting work?
15.
How is power failure warned?
16.
What is the advance of frost-free refrigeration?
17.
What refrigerant do modern refrigerators use?
XII. Tell in short about refrigerators.
XIII. a) Skim through the text and say in a few sentences what the message
of the text is.
Defrosting is a procedure, performed periodically on refrigerators and
freezers to maintain their operating efficiency. Over time water vapour in the air
condenses on the cooling elements within the cabinet.
43
The resulting ice inhibits heat transfer out of the cabinet increasing running
costs. Furthermore as the ice builds up it takes increasing space from within the
cabinet - reducing the space available for food storage.
Defrosting the unit is achieved by:
 Temporarily removing all food from the cabinet.
 Turning off power to the unit.
 Leaving the doors to the unit open
 Waiting for the ice to melt and draining it appropriately.
Using a towel is advisable when completing this step.
The process may be sped up by mechanical removal of ice, or the
introduction of gentle heat into the cabinet. Placing a pan of hot water in the
cabinet and closing it is an effective method. Using a fan to blow in room
temperature air will also greatly speed up the melting process as well as help to
evaporate the damp surfaces. Any mechanical removal of ice should be done
gently so that the equipment is not damaged.
It is generally recommended that defrosting should be done annually.
Many newer units are described as frost free (or no frost) and do not require
manual defrosting in normal use.
b) Scan the text for the details. Say what is necessary to sped up the
process of derosting.
XIV. a) Skim through the text and say in a few sentences what the message
of the text is. Answer the questions which follow.
A frost free (also called Auto-defrost or no-frost) refrigerator or freezer
incorporates technology to keep the unit from icing up.
The mechanism on a refrigerator involves letting the cooling element heat
up for a short period, melting any ice that has formed upon it and having it drain
through a collecting duct at the back of the unit.
Inside the freezer, dry air is circulated around the cabinet using fans (this is
why such kind of appliances are also called "dynamic", whereas non-frost free ones
are called "static"). Instead of the traditional cooling elements assembled within all
the freezer liner, those of a frost-free system are compact and separated from the
main cabinet space, allowing them to be heated for short periods to dispose of any
ice forming.
While this technique was originally and is mostly applied to freezer
compartments, it can also be used for fridge compartments. A combined
fridge/freezer which applies the frost free system to the freezer compartment only
is usually called "partial frost free", while one which also applies it to the fridge
compartment is called "total frost free". The latter features an air connection
between the two compartments, with the air passage to the fridge compartment
44
regulated by a dumper. In such a way, a controlled minor part of the dry and fresh
air coming from the dynamic cooling element located within the freezer can reach
the refrigerator.
Some newer fridge/freezer models have built-in electronics that monitor
how many times each door is opened and could also average the door open time
which will automatically adjust defrost scheduling, therefore optimizing power
dissipation.
Advantages of frost free
 No need to manually defrost the ice buildup
 Food packaging is easier to see because it's clear of frost
 Most frozen foods don't stick together
 Smells are limited, especially in total frost free appliances, since
the air is constantly circulating
Disadvantages of frost free
 The system is more expensive to run due to higher power
consumption
 A safety device is required to be connected with the heating
element, due to the high instant-power values that can be reached
 The temperature of the freezer contents rises during the
defrosting cycles
 On hot humid days condensation will sometimes form around the
refrigerator doors
* * *
1.
What is the frost free technology used to?
2.
How is ice melt?
3.
What are fans used for in the refrigerators?
4.
Where are elements of a frost free system located?
5.
What is built in some newer freezers?
6.
What are main (dis)advantages of this system?
b) Scan the text for the details. Say what is the difference between "partial
frost free" and "total frost free".
45
UNIT 5
I. Read and translate the text.
Refrigerant
A refrigerant is a compound used in a heat cycle that undergoes a phase
change from a gas to a liquid and back. The two main uses of refrigerants are
refrigerators/freezers and air conditioners.
Until concerns about depletion of the ozone layer arose in the 1980s, the
most widely used refrigerants were the halomethanes R-12 and R-22, with R-12
being more common in automotive air conditioning and small refrigerators, and R22 being used for residential and light commercial air conditioning, refrigerators,
and freezers. Some very early systems used R-11 because its relatively high boiling
point allows low-pressure systems to be constructed, reducing the mechanical
strength required for components. New production of R-12 ceased in the United
States in 1995, and R-22 is to be phased out in 2010. R-134a and certain blends are
now replacing chlorinated compounds. One popular 50/50 blend of R-32 and R125 now being increasingly substituted for R-22 is R410a, often marketed under
the trade name Puron®. While the R-22, R-12 and other ozone depleting
refrigerants are being phased out, they still have value and can be easily sold.
The ideal refrigerant has good thermodynamic properties, is noncorrosive,
and safe. The desired thermodynamic properties are a boiling point somewhat
below the target temperature, a high heat of vaporization, a moderate density in
liquid form, and a relatively high density in gaseous form. Since boiling point and
gas density are affected by pressure, refrigerants may be made more suitable for a
particular application by choice of operating pressure.
Corrosion properties are a matter of materials compatibility with the
components used for the compressor, piping, evaporator, and condenser. Safety
considerations include toxicity and flammability.
Early mechanical refrigeration systems employed sulfur dioxide gas or
anhydrous ammonia, with small home refrigerators primarily using the former.
Being toxic, sulfur dioxide rapidly disappeared from the market with the
introduction of Freon. Ammonia is still used in some large commercial plants, well
away from residential areas, where a leak will not cause widespread injuries.
Use of highly purified liquified propane gas as a refrigerant is gaining favor,
especially in systems designed for R-12, R-22 or R-134a. As such, it is designated
as R-290 and is marketed under the trade name Duracool®. Although propane is
flammable, in home and automotive systems it is present in quantities small
enough to not pose an undue fire hazard if a system should develop a leak.
Moreover, propane is nontoxic. An odorant, such as ethyl mercaptan, can be added
in trace amounts to alert persons of system leaks.
46
Emissions from automotive air-conditioning are a growing concern because
of their impact on climate change. From 2011 on, the European Union will phase
out refrigerants with a global warming potential (GWP) of more than 150 in
automotive air conditioning (GWP = 100 year warming potential of one kilogram
of a gas relative to one kilogram of CO2). This will ban potent greenhouse gases
such as the refrigerant HFC-134a—which has a GWP of 1410—to promote safe
and energy-efficient refrigerants. One of the most promising alternatives is the
natural refrigerant CO2 (R-744). Carbon dioxide is non-flammable, non-ozone
depleting, has a global warming potential of 1, but is toxic and potentially lethal in
concentrations above 5% by volume. R-744 can be used as a working fluid in
climate control systems for cars, residential air conditioning, hot water pumps,
commercial refrigeration, and vending machines.
Recycling refrigerants: CFC's or chlorofluorocarbons are used as
refrigerants in some commercial air conditioning and refrigeration systems. CFC's
are considered to be 100% ozone depleting and are very dangerous to the
environment. In most residential air conditioners and many refrigeration systems it
is R-22 or Freon which is a hydrochlorofluorocarbon or HCFC. HCFC's are
considered to be 5% ozone depleting and are also a danger to the Earth's vital
ozone layer.
As of July 1, 1992 it is illegal to release Freon or other refrigerants into the
atmosphere because they can cause severe damage to the ozone layer. When CFCs
are removed they should be recycled to clean out any contaminants and return it to
a usable condition. Refrigerants should never be mixed together. Some CFCs must
be managed as hazardous waste, even if recycled and special precautions are
required for their transport.
Refrigerants may be divided into three classes according to their manner of
absorption or extraction of heat from the substances to be refrigerated:
Class 1: This class includes refrigerants that cool by the absorption or
extraction of latent heat from the substances to be refrigerated.
Class 2: These refrigerants cool substances by absorbing their sensible
heats. They are air, calcium chloride brine, sodium chloride brine, alcohol, and
similar nonfreezing solutions. The purpose of Class 2 refrigerants is to receive a
reduction of temperature from Class 1 refrigerants and convey this lower
temperature to the area to be air-conditioned.
Class 3: This group consists of solutions that contain absorbed vapors of
liquefiable agents or refrigerating media. These solutions function by nature of
their ability to carry liquefiable vapors, which produce a cooling effect by the
absorption of their latent heat.
ACTIVE VOCABULARY
47
a
refrigerant
–
охлаждающее
вещество, охладитель
a compound – смесь
a heat cycle – тепловой цикл
to undergo (underwent; undergone) –
испытывать, переносить
air conditioner – кондиционер
a ozone layer – озонный слой
halomethane
–
галоидное
производное метана
to
phase
out
–
постепенно
прекращать,
свёртывать
(производство, выпуск)
to substitute (for) – замещать
value – ценность
properties – свойства
noncorrosive – неразъедающий, не
вызывающий ржавления
heat of vaporization – теплота
испарения,
теплота
парообразования
density – плотность
pressure – давление
to include – включать в себя,
содержать в себе
toxicity – токсичность, ядовитость
flammability – воспламеняемость
hazard – опасность
to alert – предупреждать (об
опасности)
to ban – налагать запрет;
запрещать
to promote – содействовать;
поддерживать
safe – безопасный
energy-efficient
–
энергосберегающий, с низким
энергопотреблением
climate control system – система
кондиционирования воздуха
lethal – смертельный; летальный;
смертоносный
illegal – незаконный
to release – выпускать
contaminant – загрязняющее
вещество
precautions
–
меры
предосторожности
extraction – извлечение
latent heat – скрытая, латентная
теплота
brine – соляной раствор,
II. Find the Russian equivalents for the English ones:
a phase change, automotive air conditioning, mechanical strength, blend, a
target temperature, material compatibility, anhydrous ammonia, widespread
injuries, purified liquified propane gas, fire hazard, global warming potential,
vending machine, CFC, sensible heat, sodium chloride, liquefiable agent.
III. Find the English equivalents for the Russian ones:
Истощение озонового слоя, широко применяемый, раствор хлористого
кальция, кондиционирование жилого помещения, охлаждающая среда,
переставать (делать что-л.), хлорсодержащая смесь, термодинамические
свойства, морозоустойчивый растовр, безопасность, опасный для
окружающей среды, диоксид серы, легковоспламеняющийся, токсичный,
48
утечка, углекислый газ, смертоносный, опасные отходы, особые меры
предосторожности.
IV. Translate the following sentences into Russian:
1) In the 1980s the most widely used refrigerants were the
halomethanes R-12 and R-22.
2) R-22 being used for residential and light commercial air
conditioning, refrigerators, and freezers.
3) While the R-22, R-12 and other ozone depleting refrigerants are
being phased out, they still have value and can be easily sold.
4) The desired thermodynamic properties are a boiling point
somewhat below the target temperature, a high heat of vaporization, a
moderate density in liquid form, and a relatively high density in gaseous
form.
5) Corrosion properties are a matter of materials compatibility with
the components used for the compressor, piping, evaporator, and condenser.
6) Early mechanical refrigeration systems employed sulfur dioxide
gas or anhydrous ammonia.
7) Use of highly purified liquified propane gas as a refrigerant is
gaining favor, especially in systems designed for R-12, R-22 or R-134a.
8) From 2011 on, the European Union will phase out refrigerants
with a global warming potential (GWP) of more than 150 in automotive air
conditioning.
9) CFC's or chlorofluorocarbons are used as refrigerants in some
commercial air conditioning and refrigeration systems.
10) Some CFCs must be managed as hazardous waste, even if
recycled and special precautions are required for their transport.
V. Fill in the blanks with appropriate words:
1) A refrigerant undergoes … from a gas to … and back.
2) R-12 is more common in … and small … .
3) R-134a and certain blends are now replacing … .
4) The ideal refrigerant has good … .
5) … considerations include … and flammability.
6) … is still used in some large commercial plants.
7) Propane is … and … .
8) Carbon dioxide is … and potentially … in concentrations above 5% by
volume.
49
9) CFC's are considered to be … ozone depleting and are very dangerous to
the … .
10) The Class 1 of refrigerants cools by the … or extraction of … from the
substances to be refrigerated.
VI. Translate into English, using the vocabulary:
1. Охладитель – это смесь, которую используют в тепловом цикле и
которая подвергается фазовым изменениям из газа в жидкость и наоборот.
2. Охладители применяются в холодильниках, морозильных камерах и
кондиционерах.
3. Охладитель R-11 имеет высокую точку кипения.
4. Охладитель R-22 должны прекратить выпускать в 2010 году.
5. Охладитель R410a заменил охладитель R-22.
6. Будучи токсичным, двуокись серы быстро исчезла с рынка с
введением Фреона.
7. Пропан может присутствовать в небольших количествах в
автомобильных системах охлаждения.
8. Углекислый газ – природный охладитель с потенциалом
глобального потепления 1.
9. Углекислый газ можно использовать в качестве рабочей жидкости в
системах кондиционирования воздуха автомобилей и жилых помещений.
10. Охладители второго класса охлаждают вещество, поглащая
содержащееся в них тепло.
VII. Answer the questions:
1. What is a refrigerant?
2. Where is a refrigerant used?
3. What refrigerants were the most widely used until the 1980s?
Where were they used?
4. What refrigerant did early systems use? Why?
5. What compounds is R-134a replacing now?
6. What is R410a?
7. What properties does the ideal refrigerant have?
8. What is a matter of materials compatibility?
9. What did mechanical refrigeration systems employ as a
refrigerant?
10. Why did sulfur dioxide rapidly disappear from the market?
11. Where is ammonia still used?
12. What can you say about propane as a refrigerant?
50
13. What will the European Union phase out from 2011 on?
14. What is GWP?
15. What can you say about CO2 (R-744)?
16. What refrigerants are dangerous and illegal to release? Why?
17. How many classes may refrigerants be divided into? What are
they?
VIII. Skim through the text and say in a few sentences what the message of
the text is. Answer the questions which follow.
Numbering
The R-# numbering system was developed by DuPont1 and systematically
identifies the molecular structure of refrigerants made with a single halogenated
hydrocarbon. The meaning of the codes is as follows:
 Rightmost digit: Number of fluorine atoms per molecule.
 Tens digit: One plus the number of hydrogen atoms per
molecule.
 Hundreds digit: The number of carbon atoms minus one. Omitted
for methyl halides, which have only one carbon atom.
 Thousands digit" Number of double bonds in the molecule.
This is omitted when zero, and in practice is rarely used, since most
candidate compounds are unstable.
 A suffix with a capital B and a number indicates the number of
bromine atoms, when present. This is rarely used.
 Remaining bonds not accounted for are occupied by chlorine
atoms.
 A suffix of a lower-case letter a, b, or c indicates increasingly
unbalanced isomers.
 As a special case, the R-400 series is made up of zeotropic blends
(those where the boiling point of constituent compounds differs enough to
lead to changes in relative concentration because of fractional
distillation) and the R-500 series is made up of so-called azeotropic
blends. The rightmost digit is assigned arbitrarily by ASHRAE2, an
industry organization.
1
Du Pont Company (United Kingdom) Ltd – "Дюпон" (английский филиал американской
корпорации "Дюпон де Немур энд К°" [Du Pont de Nemours & Co]; производит различную
химическую продукцию, синтетическое волокно орлон [Orlon] и дакрон [Dacron])
2
ASHRAE от American Society of Heating, Refrigerating and Air-conditioning Engineers
Американское общество инженеров по отоплению, охлаждению и кондиционированию воздуха
51
For example, R-134a has 4 fluorine atoms, 2 hydrogen atoms, 2 carbon
atoms, with an empirical formula of tetrafluoroethane. The "a" suffix indicates that
the isomer is unbalanced by one atom, giving 1,1,1,2-Tetrafluoroethane. R-134
without the "a" suffix would have a molecular structure of 1,1,2,2Tetrafluoroethane—a compound not especially effective as a refrigerant.
The same numbers are used with an R- prefix for generic refrigerants, with
a "Propellant" prefix (e.g., "Propellant 12") for the same chemical used as a
propellant for an aerosol spray, and with trade names for the compounds, such as
"Freon 12". Recently, a practice of using HFC- for hydrofluorocarbons, CFC- for
chlorofluorocarbons, and HCFC- for hydrochlorofluorocarbons has arisen, because
of the regulatory differences among these groups.
 rightmost digit – самая правая цифра
 tens digit – цифра разряда десятков
 double bond – двойная связь
 fractional distillation – фракционная дистилляция, дробная
перегонка, фракционная перегонка
***
1. What developed the R-# numbering system? What does it identify?
2. What does rightmost digit / tens digit / hundreds digit / thousands digit
mean?
3. What is a suffix of a lower-case letter a, b, or c?
4. What is R-400 / R-500 made up of?
5. What is ASHRAE?
IX. Skim through the text and say in a few sentences what the message of
the text is. Ask some questions to the text.
Freon
Freon is DuPont's trade name for its chlorofluorocarbon3 and
hydrochlorofluorocarbon refrigerants, used in air conditioning and refrigeration
systems. Each Freon is designated by a number; for instance, Freon-11 is
trichlorofluoromethane, while Freon-12 is dichlorodifluoromethane4. Freons are
odorless, colorless, nonflammable, and noncorrosive. They were initially
developed in the early 20th century as an alternative to the toxic gases that were
previously used as refrigerants, such as ammonia, chloromethane, and sulfur
dioxide. Freon, in this case dichlorodifluoromethane, was invented by Thomas
3
4
См. глоссарий
См. глоссарий
52
Midgley, Jr. during this time. Today, most uses of Freon have been phased out due
to the negative effects that chlorofluorocarbons and hydrochlorofluorocarbons have
on the Earth's ozone layer.
"Freon" is a trade name for a family of haloalkane refrigerants
manufactured by DuPont and other companies. These refrigerants were commonly
used due to their superior stability and safety properties: they were not flammable
nor obviously toxic as were the fluids they replaced. Unfortunately, these chlorinebearing refrigerants reach the upper atmosphere when they escape. In the
stratosphere, CFCs break up due to UV-radiation, releasing their chlorine atoms.
These chlorine atoms act as catalysts in the breakdown of ozone, which does
severe damage to the ozone layer that shields the Earth's surface from the Sun's
strong UV radiation. The chlorine will remain active as a catalyst until and unless
it binds with another particle, forming a stable molecule. CFC refrigerants in
common but receding usage include R-11 and R-12. Newer and more
environmentally-safe refrigerants include HCFCs (R-22, used in most homes
today) and HFCs (R-134a, used in most cars) have replaced most CFC use. HCFCs
in turn are being phased out under the Montreal Protocol and replaced by
hydrofluorocarbons (HFCs), such as R-410A, which lack chlorine.
Newer refrigerants are currently the subject of research, such as
supercritical carbon dioxide, known as R-744. These have similar efficiencies
compared to existing CFC and HFC based compounds.
trichlorofluoromethane – трихлорфторметан
dichlorodifluoromethane – дихлордифторметан
X. Tell in short about refrigerants.
53
UNIT 6
I. Read and translate the text.
Gas-absorption refrigerator
The absorption refrigerator is a refrigerator that utilizes a heat source to
provide the energy needed to drive the cooling system rather than being dependent
on electricity to run a compressor. These refrigerators are popular where electricity
is unreliable, costly, or unavailable, where noise from the compressor is
problematic, or where surplus heat is available, e.g., from turbine exhausts or
industrial processes.
An absorption refrigerator is similar to a regular compressor refrigerator in
that the refrigeration takes place by evaporating a liquid with a very low (sub-zero)
boiling point. In both cases, when a liquid evaporates or boils, it takes some heat
away with it, and can continue to do so either until the liquid is all boiled, or until
everything has become so cold that the sub-zero boiling point has been reached.
The difference between the two is how the gas is changed back into a liquid so that
it may be used again. A regular refrigerator uses a compressor to increase the
pressure on the gas, and then condenses the higher pressure gas back to a liquid by
heat exchange with a coolant (usually air). An absorption refrigerator uses a
different method that requires no moving parts and is powered only by heat.
Principles: Absorptive refrigeration uses a source of heat to provide the
energy needed to drive the cooling process. The most common use is in
commercial climate control and cooling of machinery. Absorptive refrigeration is
also used to air-condition buildings using the waste heat from a gas turbine or
water heater. The process is very efficient, since the gas turbine produces
electricity, hot water and air-conditioning.
The basic thermodynamic process is not a conventional thermodynamic
cooling process based on Charles Law. Instead, it is based on evaporation, carrying
heat, in the form of fast-moving (hot) molecules from one material to another
material that preferentially absorbs hot molecules.
The most familiar example is human sweating. The water from sweat
evaporates and is "absorbed" into cool dry air, carrying away heat in fast-moving
water molecules. However, absorptive refrigerators differ in that they regenerate
their coolants in a closed cycle, while people drink water recycled outside their
bodies.
The classic gas absorption refrigerator cools by evaporating liquid ammonia
in a hydrogen environment. The now-gaseous ammonia is then absorbed
(dissolved) into water, and then later separated (boiled off from the water) by a
small source of heat. This drives off the dissolved ammonia gas which is then
54
condensed into a liquid. The liquid ammonia then enters the hydrogen-charged
evaporator to repeat the cycle.
A similar system, common in large commercial plants, uses a solution of
lithium bromide salt and water. Water is evaporated under low pressure from the
coils that are being chilled. The water is absorbed by a lithium bromide/water
solution. The water is driven off the lithium bromide solution using heat.
Another variant uses air, water, and a salt solution. Warm air is passed
through a sprayed solution of salt water. The spray absorbs humidity from the air.
The air is then passed through an evaporative cooler. Humidity is removed from
the cooled air with another spray of salt solution. The salt solution is regenerated
by heating it under low pressure, causing water to evaporate. The water evaporated
from the salt solution is recondensed, and rerouted back to the evaporative cooler.
Process: A single-pressure absorption refrigerator uses three substances:
ammonia, hydrogen gas, and water, whereas large industrial units generally use
only two, a refrigerant such as ammonia, and an absorbent such as water (with an
expansion valve) and pump. Normally, ammonia is a gas at room temperature
(with a boiling point of -33°C), but the system is pressurized to the point that the
ammonia is a liquid at room temperature.
The cooling cycle starts at the evaporator, where liquefied anhydrous5
ammonia enters. The "evaporator" contains another gas (in this case, hydrogen),
whose presence lowers the partial pressure of the ammonia in that part of the
system. Because a substance's boiling point changes with pressure, the lowered
partial pressure of ammonia changes the ammonia's boiling point, bringing it low
enough that it can now boil below room temperature, as though it wasn't under the
pressure of the system in the first place. When it boils, it takes some heat away
with it from the evaporator - which produces the "cold" desired in the refrigerator.
The next step is getting the liquid ammonia back, as now it's a gas and
mixed with hydrogen. Getting the hydrogen away is simple, and this is where the
"absorber" comes in. Ammonia readily mixes with water, and hydrogen does not.
The absorber is simply a downhill flow of tubes in which the mixture of gases
flows in contact with water being dripped from above. Once the water reaches the
bottom, it's thoroughly mixed with the ammonia, and the hydrogen stays still
(though it can flow freely back to the evaporator).
At this point, the ammonia is a liquid mixed with water and still not usable
for refrigeration, as the mixture won't boil at a low enough temperature to be a
worthwhile refrigerant. It's now necessary to separate the ammonia from the water.
This is where the heat from the flame comes in. When the right amount of heat is
applied to the mixture, the ammonia bubbles out. This phase is called the
5
Anhydrous means there is no water in the ammonia, which is critical for exploiting its sub-zero
boiling point.
55
"generator". The ammonia isn't quite dry yet - the bubbles contain gas but they're
made of water, so the pipe twists and turns and contains a few minor obstacles that
pop the bubbles so the gas can move on. The water that results from the bubbles
isn't bad - it takes care of another need, and that is the circulation of water through
the previous absorption step. Because that water has risen a bit while it was
bubbling upwards, the flow of that water falling back down due to gravity can be
used for this purpose. The maze that makes the ammonia gas go one way and the
bubble water go the other is called the "separator".
The next step is the condenser. The condenser is a sort of heat sink or heat
exchanger that cools the hot ammonia gas back down to room temperature.
Because of the pressure and the purity of the gas (there is no hydrogen here), the
ammonia condenses back into a liquid, and at that point, it's suitable as a
refrigerant and the cycle starts over again.
ACTIVE VOCABULARY
an
absorption
refrigerator
–
абсорбционная
холодильная
машина,
абсорбционный
холодильник
to
utilize
–
использовать,
расходовать, употреблять
unreliable – ненадёжный
costly – дорогостоящий
surplus – избыток, резерв
to be similar to – быть похожим
(подобный) на что-л., кого-л.
to take place (took, taken) –
происходить, случаться; состояться,
иметь место
to reach – достигать, доходить;
простираться
to drive (drove, driven) – приводить
(к какому-л. состоянию)
air-condition – кондиционировать
a gas turbine – газовая турбина
a water heater – водонагреватель
a molecule – молекула
hydrogen – водород
to boil off – выкипать; испаряться
a solution – раствор
56
a pump – насос
an
expansion
valve
–
расширительный
клапан,
регулирующий вентиль
to
pressurize
–
создавать
давление, оказывать давление,
anhydrous – безводный
to contain – содержать в себе,
включать
partial pressure – парциальное
давление
to
mix
–
смешивать,
перемешивать
to drip – капать
bottom – низ, нижняя часть, дно
to separate – отделять, разделять
a pipe – труба;
to pop – выталкивать, выводить
a bubble – пузырь
a maze – лабиринт
a
separator
–
сепаратор;
отделитель;
разделитель;
центрифуга
a condenser – конденсор
a heat sink – радиатор; теплоотвод
a heat exchanger – теплообменник
to exert - приводить в действие
absorber – абсорбер, поглотитель
VI. Find the Russian equivalents for the English ones:
a cooling system, turbine exhaust, a low (sub-zero) boiling point,
аbsorptive refrigeration, a conventional thermodynamic cooling process, human
sweating, а hydrogen-charged evaporator, a solution of lithium bromide salt, a
sprayed solution of salt water, а single-pressure absorption refrigerator, liquefied
anhydrous ammonia, a worthwhile refrigerant.
VII. Find the English equivalents for the Russian ones:
источник теплоты, резерв тепловой мощности, приводиться в действие
теплотой, кондиционировать, быстродвигающиеся молекулы, водородная
среда, испаряться из воды, водный раствор, солевой раствор, комнатная
температура, цикл охлаждения, безводный аммиак, циркуляция воды.
VIII. Translate the following sentences into Russian:
1) The absorption refrigerator is a refrigerator that utilizes a heat source to
provide the energy needed to drive the cooling system rather than being dependent
on electricity to run a compressor.
2) A regular refrigerator condenses the higher pressure gas back to a
liquid by heat exchange with a coolant.
3) The basic thermodynamic process is not a conventional thermodynamic
cooling process based on Charles Law.
4) The liquid ammonia enters the hydrogen-charged evaporator to repeat
the cycle.
5) Water is evaporated under low pressure from the coils that are being
chilled.
6) The water evaporated from the salt solution is recondensed, and
rerouted back to the evaporative cooler.
7) The system is pressurized ammonia to the point that it is a liquid at
room temperature.
8) When ammonia boils, it takes some heat away with it from the
evaporator.
9) When the right amount of heat is applied to the mixture, the ammonia
bubbles out.
10) The maze that makes the ammonia gas go one way and the bubble
water go the other is called the "separator".
57
IX. Fill in the blanks with appropriate words:
1) The absorption refrigerators are popular where … is unreliable.
2) An absorption refrigerator is … a regular compressor refrigerator.
3) A regular refrigerator uses a … to increase the pressure on the gas.
4) Absorptive refrigeration uses … from a gas turbine to air-condition.
5) The … gas absorption refrigerator cools by … liquid ammonia in a …
environment.
6) The absorption refrigerator uses a … salt and water in large … .
7) The salt solution is regenerated by … it under … pressure.
8) The lowered … pressure of ammonia changes the ammonia's … .
9) The condenser is a sort of … .
10) In the … the mixture of gases flows in contact with water.
X. Translate into English, using the vocabulary:
1. Абсорционный холодильник – это холодильник, который
использует тепловой источник для приведения в действие системы
охлаждения.
2. Охлаждение происходит при испарении жидкости с очень низкой
точкой кипения.
3. Абсорбционное охлаждение используется в основном в торговых
системах кондиционирования воздуха и охлаждении машинного
оборудования.
4. Аммиак растворяется в воде, а затем испаряется при небольшом
источнике тепла.
5. Один из видов абсорционного холодильника использует воздух,
воду и солевой раствор.
6. Большие промышленные установки используют только два
вещества: аммиак в качестве охладителя и вода как абсорбент.
7. В испарителе находится водород, который понижает парциальное
давление аммиака.
8. Чтобы отделить аммиак от воды необходимо применить тепло.
9. Конденсор охлаждает горячий газообразный аммиак до комнатной
температуры.
10. В абсорбере (поглотителе) водород отделяется от аммиака при
помощи воды.
XI. Answer the questions:
1.
58
What is an absorption refrigerator?
2.
Where is it popular?
3.
What is an absorption refrigerator similar to a regular
compressor refrigerator in?
4.
Where is absortive refrigeration used? Why?
5.
What is the basic thermodynamic process based on?
6.
How does the classic gas absorption refrigerator cool?
7.
What can absorption refrigerators use as a refrigerant /
absorbent?
8.
What substances does a single-pressure absorption
refrigerator use?
9.
Where does the cooling cycle start?
10.
What does “anhydrous” mean?
11.
What is the function of hydrogen?
12.
What can change a substance’s boiling point?
13.
What produces the “cold” in the refrigerator?
14.
What happens in the absorber?
15.
What phase is called the “generator”?
16.
What happens in the separator”?
17.
What is the condenser?
18.
Does hydrogen mix readily with water?
XII. Tell about the gas-absorption refrigerator.
XIII. Skim through the text and say in a few sentences what the message of
the text is. Answer some questions which follow the text.
The Einstein refrigerator is a type of refrigerator co-invented in 1926 by
Albert Einstein and former student Leó Szilárd, who were awarded U.S. Patent
1,781,541 on November 11, 1930. The machine is a single-pressure absorption
refrigerator, similar in design to the gas absorption refrigerator. The refrigeration
cycle uses ammonia (pressure-equalizing fluid), butane (refrigerant), and water
(absorbing fluid). It has been claimed that the Einstein refrigerator is portable,
made of inexpensive, nonmoving parts, operates silently, and is very reliable.
However, ammonia leaks caused problems among the earlier models, and whether
it can cool things adequately is unknown.
Einstein undertook this invention as a way of helping along his former
student. He used the knowledge he had acquired during his years at the Swiss
Patent Office to get valid patents for the invention in several countries. The
refrigerator was not immediately put into commercial production, but rights to use
the patents were sold to companies such as Electrolux of Sweden, and the funds
obtained supported Szilárd for several years. Electrolux manufactures a similar
59
Gas-absorption refrigerator design invented by Baltzar von Platen and Carl
Munters in 1922 under the brand name Dometic.
***
1. What type of refrigerator is the Einstein refrigerator?
2. What is refrigerant / absorbent in this refrigerator?
3. What are characteristics of this refrigerator?
4. Were there problems among the earlier models? What are they?
5. What company were rights to use the patents sold to?
60
UNIT 7
I. Read and translate the text.
Heat
In physics, heat, symbolized by Q, is energy transferred from one body or
system to another due to a difference in temperature. In thermodynamics, the
quantity TdS is used as a representative measure of heat, which is the absolute
temperature of an object multiplied by the differential quantity of a system's
entropy measured at the boundary of the object. Heat can flow spontaneously from
an object with a high temperature to an object with a lower temperature. The
transfer of heat from an object, to another object with an equal or higher
temperature, however, can happen only with the aid of a heat pump. High
temperature bodies, which often result in high rates of heat transfer, can be created
by chemical reactions (such as burning), nuclear reactions (such as fusion taking
place inside the Sun), electromagnetic dissipation (as in electric stoves), or
mechanical dissipation (such as friction). Heat can be transferred between objects
by radiation, conduction and convection. Temperature is used as a measure of the
internal energy or enthalpy that is the level of elementary motion giving rise to heat
transfer. Heat can only be transferred between objects, or areas within an object,
with different temperatures (as given by the zeroth law of thermodynamics), and
then, in the absence of work, only in the direction of the colder body (as per the
second law of thermodynamics). The temperature and phase of a substance subject
to heat transfer are determined by latent heat and heat capacity. A related term is
thermal energy, loosely defined as the energy of a body that increases with its
temperature
The first law of thermodynamics states that the energy of a closed system is
conserved. Therefore, to change the energy of a system, energy must be transferred
to or from the system. Heat and work are the only two mechanisms by which
energy can be transferred to or from a control mass. Heat is the transfer of energy
caused by the temperature difference. The unit for the amount of energy transferred
by heat in International System of Units SI is the Joule, though the British Thermal
Unit and the calorie are still occasionally used. The unit for the rate of heat transfer
is the Watt (J/s).
Specific heat is defined as the amount of energy that has to be transferred to
or from one unit of mass or mole of a substance to change its temperature by one
degree. Specific heat is a property, which means that it depends on the substance
under consideration and its state as specified by its properties. Fuels, when burned,
release much of the energy in the chemical bonds of their molecules. Upon
changing from one phase to another, a pure substance releases or absorbs heat
without its temperature changing. The amount of heat transfer during a phase
61
change is known as latent heat and depends primarily on the substance and its
state.
Thermal energy is a term often confused with that of heat. Loosely
speaking, when heat is added to a thermodynamic system its thermal energy
increases and when heat is withdrawn its thermal energy decreases. In this point of
view, objects that are hot are referred to as being in possession of a large amount of
thermal energy, whereas cold objects possess little thermal energy. Thermal energy
then is often mistakenly defined as being synonym for the word heat. This,
however, is not the case: an object cannot possess heat, but only energy. The term
thermal energy when used in conversation is often not used in a strictly correct
sense, but is more likely to be only used as a descriptive word. In physics and
thermodynamics, the words “heat”, “internal energy”, “work”, "enthalpy" (heat
content), "entropy", "external forces", etc., which can be defined exactly, i.e.
without recourse to internal atomic motions and vibrations, tend to be preferred
and used more often than the term thermal energy, which is difficult to define.
Heat is related to the internal energy U of the system and work W done by
the system by the first law of thermodynamics:
which means that the energy of the system can change either via work or via
heat flows across the boundary of the thermodynamic system. In more detail,
Internal energy is the sum of all microscopic forms of energy of a system. It is
related to the molecular structure and the degree of molecular activity and may be
viewed as the sum of kinetic and potential energies of the molecules; it is
comprised of the following types of energies:
Type
Sensible
energy
Latent
energy
Chemical
energy
Nuclear
energy
Energy
interactions
Thermal
62
Composition of Internal Energy (U)
the portion of the internal energy of a system
associated with kinetic energies (molecular translation,
rotation, and vibration; electron translation and spin; and
nuclear spin) of the molecules.
the internal energy associated with the phase of a
system.
the internal energy associated with the atomic bonds in
a molecule.
the tremendous amount of energy associated with the
strong bonds within the nucleus of the atom itself.
those types of energies not stored in the system (e.g.
heat transfer, mass transfer, and work), but which are
recognized at the system boundary as they cross it, which
represent gains or losses by a system during a process.
the sum of sensible and latent forms of internal energy.
energy
ACTIVE VOCABULARY
to transfer – переносить, перемещать
specific heat – теплоёмкость;
quantity – количество; число
удельная теплоёмкость
measure –мера; единица измерения
bond – связь
entropy – энтропия
to
release
–
избавлять,
spontaneously – самопроизвольно
освобождать
a heat pump – тепловой насос;
to
absorb
–
впитывать;
охладитель
поглощать
heat
transfer
–
теплообмен;
to depend on – зависеть (от коготеплоотдача; теплопередача
л., чего-л.)
burning – горение, сгорание
to
increase
–
возрастать,
fusion – плавление
увеличиваться;
расти;
friction – трение
усиливаться
internal energy – внутренняя энергия
to decrease – уменьшаться,
enthalpy
–
теплосодержание,
убывать, сокращаться
энтальпия
to possess – владеть, иметь,
to
determine
–
определять,
обладать
устанавливать
boundary – граница; предел;
latent heat – скрытая, латентная
nuclear energy – атомная энергия
теплота
interactions – взаимодействие
heat capacity – теплоёмкость
mole – моль, грамм-молекула
thermal energy – тепловая энергия
II. Find the Russian equivalents for the English ones:
the aid of a heat pump, molecular structure, absence of work, the degree of
molecular activity, a representative measure of heat, potential energy, British
Thermal Unit, electron translation, electromagnetic dissipation, mass transfer, to
multiply, a phase change
III. Find the English equivalents for the Russian ones:
Изменение температуры, перепад (разность) температур, тепловой
поток, абсолютная (термодинамическая) температура, молекулярная
активность, удельная теплоёмкость, кинетическая энергия, нулевой,
межатомная связь, химическая связь, границы системы, закрытая система,
чистое вещество
IV. Translate the following sentences into Russian:
63
1) Тhe quantity TdS is used as a representative measure of heat, which is
the absolute temperature of an object multiplied by the differential quantity of a
system's entropy measured at the boundary of the object.
2) Heat can only be transferred between objects with different
temperatures and then, in the absence of work, only in the direction of the colder
body.
3) The temperature and phase of a substance subject to heat transfer are
determined by latent heat and heat capacity.
4) Heat and work are the only two mechanisms by which energy can be
transferred to or from a control mass.
5) The unit for the amount of energy transferred by heat in International
System of Units SI is the Joule, though the British Thermal Unit and the calorie are
still used.
6) Specific heat is the amount of energy that has to be transferred to or
from one unit of mass or mole of a substance to change its temperature by one
degree.
7) Upon changing from one phase to another, a pure substance releases or
absorbs heat without its temperature changing.
8) Heat is related to the internal energy U of the system and work W done
by the system by the first law of thermodynamics.
9) Sensible energy is the portion of the internal energy of a system
associated with kinetic energies of the molecules.
10) Nuclear energy is the tremendous amount of energy associated with
the strong bonds within the nucleus of the atom itself.
V. Say whether these sentences are True or False:
1) Heat can flow from an object with a lower temperature to an object with
a high temperature.
2) Temperature is used as a measure of the thermal energy or enthalpy.
3) The energy of a closed system is conserved.
4) The energy of the system can change either via temperature or via heat
flow.
5) The unit for the rate of heat transfer is the Joule.
6) Сold objects possess a large amount of thermal energy.
7) Internal energy is the sum of all microscopic forms of energy of a
system.
8) Internal energy may be viewed as the sum of latent and potential
energies of the molecules.
9) Thermal energy is the sum of latent and sensible forms of internal
energy.
64
10) Heat is enrgy transferred from one body to another due to a difference
in temperature .
VI. Translate into English, using the vocabulary:
1. Теплота – это энергия, которая перешла от одного тела к другому
благодаря разнице в температуре.
2. Тепловой насос может помочь теплопередаче от одного объекта
другому.
3. Тело с высокой температурой может возникнуть при химических и
атомных реакциях.
4. Тепловая энергия повышается с температурой тела.
5. Скрытая теплота зависит от вещества и его состояния.
6. Внутреннюю энергию можно рассматривать как сумму
кинетической и потенциальной энергии молекул.
7. Внутренняя энергия – это сумма всех форм энергии системы.
8. Внутренняя энергия связана со строением молекулы и уровнем
малекулярной активности.
9. Теплота может переходить самопроизвольно от тела с высокой
температурой к телу с низкой температурой.
10. Джоуль – единица энергии, переданной теплом.
VII. Make up different kinds of questions to the text. Ask your partner
about heat. (Work in pair or group)
I group (Yes/No-questions)
Is heat energy transferred from one body to another?
II group (Wh-questions)
What is heat?
III group (Tag-question)
Heat is energy, isn’t it?
VIII. Skim through the text and say in a few sentences what the message of
the text is. Answer the questions which follow the text.
In modern terms, heat is concisely defined as energy in transit. Scottish
physicist James Clerk Maxwell, in his 1871 classic Theory of Heat, was one of the
first to enunciate a modern definition of “heat”. In short, Maxwell outlined four
stipulations on the definition of heat. One, it is “something which may be
transferred from one body to another”, as per the second law of thermodynamics.
Two, it can be spoken of as a “measurable quantity”, and this treated
mathematically like other measurable quantities. Third, it “can not be treated as a
65
substance”; for it may be transformed into something which is not a substance, e.g.
mechanical work. Lastly, it is “one of the forms of energy”. Similar such modern,
succinct definitions of heat are as follows:
 In a thermodynamic sense, heat is never regarded as being stored
within a body. Like work, it exists only as energy in transit from one body
to another; in thermodynamic terminology, between a system and its
surroundings. When energy in the form of heat is added to a system, it is
stored not as heat but as kinetic and potential energy of the atoms and
molecules making up the system.
 The noun heat is defined only during the process of energy
transfer by conduction or radiation.
 Heat is defined as any spontaneous flow of energy from one
object to another, caused by a difference in temperature between two
objects.
 Heat may be defined as energy in transit from a high temperature
object to a lower temperature object.
 Heat is an interaction between two closed systems without
exchange of work is a pure heat interaction when the two systems,
initially isolated and in a stable equilibrium, are placed in contact. The
energy exchanged between the two systems is then called heat.
 Heat is a form of energy possessed by a substance by virtue of
the vibrational movement, i.e. kinetic energy, of its molecules or atoms.
 Heat is the transfer of energy between substances of different
temperatures.
* * *
1.
Who was one of the first to enunciate a modern
definition of “heat”?
2.
What are four stipulations on the definition of heat?
3.
Can heat be stored within body?
4.
In what form can energy be stored?
5.
Why can heat flow from one object to another?
6.
Is heat the transfer of energy between substances of
different temperatures?
IX. Read and translate the text:
Heat transfer mechanisms
Heat transfer is a path function (process quantity), as opposed to a point
function (state quantity). Heat flows between systems that are not in thermal
equilibrium with each other; it spontaneously flows from the areas of high
66
temperature to areas of low temperature. When two bodies of different temperature
come into thermal contact, they will exchange internal energy until their
temperatures are equalized; that is, until they reach thermal equilibrium. The
adjective hot is used as a relative term to compare the object’s temperature to that
of the surroundings (or that of the person using the term). The term heat is used to
describe the flow of energy. In the absence of work interactions, the heat that is
transferred to an object ends up getting stored in the object in the form of internal
energy.
As mentioned previously, heat tends to move from a high temperature
region to a low temperature region. This heat transfer may occur by the
mechanisms of conduction and radiation. In engineering, the term convective heat
transfer is used to describe the combined effects of conduction and fluid flow and
is regarded as a third mechanism of heat transfer.
Conduction is the most significant means of heat transfer in a solid. On a
microscopic scale, conduction occurs as hot, rapidly moving or vibrating atoms
and molecules interact with neighboring atoms and molecules, transferring some of
their energy (heat) to these neighboring atoms. In insulators the heat flux is carried
almost entirely by phonon vibrations.
Fire test used to test the heat transfer through firestops and penetrants used
in construction bounding.
The "electron fluid" of a conductive metallic solid conducts nearly all of the
heat flux through the solid. Phonon flux is still present, but carries less than 1% of
the energy. Electrons also conduct electric current through conductive solids, and
the thermal and electrical conductivities of most metals have about the same ratio.
A good electrical conductor, such as copper, usually also conducts heat well. The
Peltier-Seebeck effect exhibits the propensity of electrons to conduct heat through
an electrically conductive solid. Thermoelectricity is caused by the relationship
between electrons, heat fluxes and electrical currents.
Convection is usually the dominant form of heat transfer in liquids and
gases. This is a term used to characterize the combined effects of conduction and
fluid flow. In convection, enthalpy transfer occurs by the movement of hot or cold
portions of the fluid together with heat transfer by conduction. For example, when
water is heated on a stove, hot water from the bottom of the pan rises, heating the
water at the top of the pan. Two types of convection are commonly distinguished,
free convection, in which gravity and buoyancy forces drive the fluid movement,
and forced convection, where a fan, stirrer, or other means is used to move the
fluid. Buoyant convection is because of the effects of gravity, and hence does not
occur in microgravity environments. The conventional sign convention is that
when a body releases heat into its surroundings, Q < 0 (-); when a body absorbs
heat from its surroundings, Q > 0 (+).
67
Radiation is the only form of heat transfer that can occur in the absence of
any form of medium; thus it is the only means of heat transfer through a vacuum.
Thermal radiation is a direct result of the movements of atoms and molecules in a
material. Since these atoms and molecules are composed of charged particles
(protons and electrons), their movements result in the emission of electromagnetic
radiation, which carries energy away from the surface. At the same time, the
surface is constantly bombarded by radiation from the surroundings, resulting in
the transfer of energy to the surface. Since the amount of emitted radiation
increases with increasing temperature, a net transfer of energy from higher
temperatures to lower temperatures results
Other heat transfer mechanisms
 Latent heat: Transfer of heat through a physical change in the
medium such as water-to-ice or water-to-steam involves significant
energy and is exploited in many ways: steam engine, refrigerator etc.
 Heat pipes: Using latent heat and capillary action to move heat,
heat pipes can carry many times as much heat as a similar sized copper
rod. Originally invented for use in satellites, they are starting to have
applications in personal computers.
Heat transfer rate or heat flow per unit time, is denoted by:
It is measured in watts. Heat flux is defined as rate of heat transfer per unit
cross-sectional area, and is denoted q, resulting in units of watts per square metre,
though slightly different notation conventions can be used.
ACTIVE VOCABULARY
heat
transfer
–
теплообмен;
теплоотдача; теплопередача
equilibrium – равновесие, баланс
to exchange – обменивать
to equalize – делать равными;
выравнивать; уравнивать
interaction – взаимодействие
internal energy – внутренняя энергия
to tend – иметь тенденцию (к чемул.) ; клониться, склоняться (к чемул.)
to occur – происходить, случаться,
совершаться
68
conduction – теплопроводность
radiation – излучение, радиация
a solid – твёрдое тело
heat flux – тепловой поток
electric current – электрический
ток
conductivity – проводимость;
ratio – коэффициент; степень
convection – конвекция
movement – движение (вообще
или
какой-л.
вид);
передвижение, перемещение
fluid – текучая среда (жидкость, газ)
heat pipe – тепловая труба
to distinguish – различить
to carry – нести, переносить
gravity – сила тяжести
to denote – отмечать (знаком,
buoyancy – плавучесть
меткой) , обозначать
absence – недостаток, отсутствие
to measure – измерять, мерить
to charge – заряжать
satellite – сателлит, спутник
emission – распространение
surface – поверхность
to emit – испускать, выделять
to involve – привлекать, вовлекать
втягивать, влечь за собой
X. Find the Russian for:
fluid flow, rapidly moving atom, forced convection, a path function,
buoyant convection, thermal equilibrium, heat transfer rate, electromagnetic
radiation, phonon vibrations, net transfer of energy, the absence of work
interaction, capillary action, electron fluid, convective heat transfer, conductive
solid
XI. Find the English for:
поток тепла, естественная конвекция, энергетический поток,
выталкивающая сила, точечная функция, тепловое излучение, определение
температуры воспламенения, заряженная частица, тепловой контакт,
изменение физических свойств, фононный поток, тепловое равновесие,
теплопроводность
XII. Translate the following sentences into Russian:
1) Heat flows between systems that are not in thermal equilibrium
with each other.
2) When two bodies of different temperature come into thermal
contact, they will
exchange internal energy until their temperatures are equalized.
3) The term convective heat transfer is used to describe the
combined effects of
conduction and fluid flow.
4) In conduction hot, rapidly moving atoms and molecules interact
with neighboring atoms and molecules, transferring some of their energy to
these neighboring atoms.
5) The Peltier-Seebeck effect exhibits the propensity of electrons to
conduct heat through an electrically conductive solid.
69
6) In convection, enthalpy transfer occurs by the movement of hot
or cold portions of the fluid together with heat transfer by conduction.
7) Thermal radiation is a direct result of the movements of atoms
and molecules in a material.
8) The movements of charged particles result in the emission of
electromagnetic radiation, which carries energy away from the surface.
9) Using latent heat and capillary action to move heat, heat pipes
can carry many times as much heat as a similar sized copper rod.
10) Heat flux is defined as rate of heat transfer per unit crosssectional area, and is denoted q, resulting in units of watts per square metre.
XIII. Fill in the blanks with appropriate words:
1.
Heat spontaneously flows from the areas of …
temperature to areas of … temperature.
2.
By the thermal contact two bodies reach thermal … .
3.
Conduction is the most significant means of … in ….
4.
In insulators the … is carried almost entirely by …
vibrations.
5.
Thermoelectricity is caused by the relationship between
electrons, … and electrical … .
6.
In free convection … and … forces drive the fluid
movement.
7.
… is the only means of heat transfer through a vacuum.
8.
Heat pipes use … and … to move heat.
9.
… is defined as rate of heat transfer per unit crosssectional area.
10.
Heat transfer rate is … in watts.
XIV. Translate into English, using the active vocabulary:
1. Два тела с разной температурой обмениваются внутренней
энергией, пока их температуры не сравняются.
2. При отсутствии взаимодействия с другими тела теплота
сохраняется в теле в виде внутренней энергии.
3. Существуют
три
механизма
теплообмена:
теплопроводность, излучение и конвекция.
4. Теплопроводность – это средство передачи тепла в твердых
телах.
5. Тепло- и электропроводность большинства металлов имеет
почти один и тот же коэффициент.
70
6. Конвекция – это преобладающая форма теплообмена в
жидкостях и газах.
7. Различают два типа
конвекции: естественная и
вынужденная.
8. Излучение – это единственная форма теплопередачи,
которая может происходить в отсутствии какой-либо среды.
9. Теплопередача посредством изменения физических свойств
привлекает значительное количество энергии.
10. Интенсивность теплопередачи измеряется в ваттах.
XV. Answer the questions:
1.
Where does heat flow?
2.
When do two bodies exchange internal energy?
3.
What is thermal equilibrium?
4.
What are three mechanisms of heat transfer?
5.
What is conduction?
6.
When does conduction occur?
7.
What is convection?
8.
How does heat transfer occur in convection?
9.
What types of convection do you know?
10.
In which convection do gravity and buoyancy forces
drive the fluid movement?
11.
What form of heat transfer can occur in the vacuum?
12.
What is thermal radiation?
13.
What results in the emission of electromagnetic
radiation?
14.
What is heat transferred through in the medium such as
water-to -ice?
15.
What do heat pipes use to move heat?
XVI. Tell us about heat and heat transfer.
XV. a) Skim through the text and say in one sentence what the message of
the text is. Answer the questions which follow.
A related principle, Newton's law of cooling, states that the rate of heat loss
of a body is proportional to the difference in temperatures between the body and its
surroundings. The law is
71
Q = Heat transfer in Watts
h = Heat transfer coefficient
A = Surface area of the heat being transferred
T0 = Temperature of the object's surface
Ta = Temperature of the surroundings
This form of heat loss principle is sometimes not very precise; an accurate
formulation may require analysis of heat flow, based on the (transient) heat transfer
equation in a nonhomogeneous, or else poorly conductive, medium. The following
simplification may be applied so long as it is permitted by the Biot number, which
relates surface conductance to interior thermal conductivity in a body. If this ratio
permits, it shows that the body has relatively high internal conductivity, such that
(to good approximation) the entire body is at same uniform temperature as it is
cooled from the outside, by the environment. If this is the case, then it is easy to
derive from these conditions the behavior of exponential decay of temperature of a
body. In such cases, the entire body is treated as lumped capacitance heat reservoir,
with total heat content which is proportional to simple total heat capacity, and the
temperature of the body.
For example, simplified climate models may use Newtonian cooling instead
of a full (and computationally expensive) radiation code to maintain atmospheric
temperatures.
* * *
1.
What does Newton’s law of cooling state?
2.
What does the Biot number relate?
3.
Why is the form of heat loss principle sometimes not
very precise?
b) Scan the text for details. Say what depends on the Biot number.
72
UNIT 8
I. Read and translate the text.
Heat engine
A heat engine is a physical or theoretical device that converts thermal
energy to mechanical output. The mechanical output is called work, and the
thermal energy input is called heat. Heat engines typically run on a specific
thermodynamic cycle. Heat engines are often named after the thermodynamic
cycle they are modeled by. They often pick up alternate names, such as
gasoline/petrol, turbine, or steam engines. Heat engines can generate heat inside
the engine itself or it can absorb heat from an external source. Heat engines can be
open to the atmospheric air or sealed and closed off to the outside (Open or closed
cycle).
In engineering and thermodynamics, a heat engine performs the conversion
of heat energy to mechanical work by exploiting the temperature gradient between
a hot "source" and a cold "sink". Heat is transferred from the source, through the
"working body" of the engine, to the sink, and in this process some of the heat is
converted into work by exploiting the properties of a working substance (usually a
gas or liquid).
Heat engines are often confused with the cycles they attempt to mimic.
Typically when describing the physical device the term 'engine' is used. When
describing the model the term 'cycle' is used.
In thermodynamics, heat engines are often modeled using a standard
engineering model such as the Otto cycle (4-stroke/2-stroke). Actual data from an
operating engine, one is called an indicator diagram, is used to refine the model.
All modern implementations of heat engines do not exactly match the
thermodynamic cycle they are modeled by. One could say that the thermodynamic
cycle is an ideal case of the mechanical engine. One could equally say that the
model doesn't quite perfectly match the mechanical engine. However,
understanding is gained from the simplified models, and ideal cases they may
represent.
In general terms, the larger the difference in temperature between the hot
source and the cold sink, the larger is the potential thermal efficiency of the cycle.
On Earth, the cold side of any heat engine is limited to close to the ambient
temperature of the environment, or not much lower than 300 kelvins, so most
efforts to improve the thermodynamic efficiencies of various heat engines focus on
increasing the temperature of the source, within material limits.
ACTIVE VOCABULARY
73
heat engine – тепловой двигатель
to convert – преобразовывать;
превращать
thermal energy – тепловая энергия
mechanical output – механическая
мощность
energy input – потребляемая энергия
to
generate
–
производить;
генерировать, делать
an external source – внешний
источник
to perform – выполнять; совершать
exploiting – эксплуатация
temperature gradient – перепад
температуры, градиент температуры
a working substance – рабочее
вещество, рабочее тело
Otto cycle – цикл Отто, цикл с
воспламенением от искрового
разряда
stroke – ход, такт
thermal efficiency – тепловой
кпд, термический кпд
to limit – ограничивать; ставить
предел
ambient
temperature
–
температура окружающей среды
effort – усилие, попытка
to improve – улучшаться;
совершенствоваться
thermodynamic
efficiency
–
термодинамический кпд
to focus – сосредоточиваться;
концентрироваться
II. Say whether these sentences are True or False:
1) A heat engine converts thermal energy to mechanical input.
2) Internal energy input is called heat.
3) Heat engines can generate heat inside and outside the engine itself.
4) Heat engines can absorb heat from an external source.
5) Heat engines can be open to the atmospheric air or closed off to the
outside.
6) A heat engine performs the conversion of heat energy to mechanical
work by exploiting the temperature gradient between a cold "source" and a hot
"sink".
7) Some of the heat is converted into work by exploiting the properties of a
working substance.
8) The Otto cycle is a standard engineering model of heat engines.
9) The potential thermal efficiency of the cycle doesn’t depend on the
difference in temperature between the hot source and the cold sink.
10) most efforts to improve the thermodynamic efficiencies of various heat
engines focus on decreasing the temperature of the source.
III. Ask different kinds of questions about heat according to the pattern.
Work in pair or group.
I group (Yes/No-questions)
74
Is a heat engine a physical device?
II group (Wh-questions)
What is a heat engine?
device, isn’t it?
IV. Read and translate the text.
III group (Tag-question)
A heat engine is a physical
Heat pump
A heat pump is a machine or device that moves heat from one location (the
'source') to another location (the 'sink'), using work. Most heat pump technology
moves heat from a low temperature heat source to a higher temperature heat sink.
Common examples are:
 Food refrigerators and freezers
 Air conditioners and reversible-cycle heat pumps for providing
thermal comfort
 Water chillers
 Stirling cryocooler
According to the second law of thermodynamics heat cannot spontaneously
flow from a colder location to a hotter area; work is required to achieve this. Heat
pumps differ in how they apply this work to move heat, but they can essentially be
thought of as heat engines operating in reverse. A heat engine allows energy to
flow from a hot 'source' to a cold heat 'sink', extracting a fraction of it as work in
the process. Conversely, a heat pump requires work to move thermal energy from a
cold source to a warmer heat sink. Since the heat pump uses a certain amount of
work to move the heat, the amount of energy deposited at the hot side is greater
than the energy taken from the cold side by an amount equal to the work required.
Conversely, for a heat engine, the amount of energy taken from the hot side is
greater than the amount of energy deposited in the cold heat sink since some of the
heat has been converted to work.
One common type of heat pump works by exploiting the physical properties
of an evaporating and condensing fluid known as a refrigerant.
A simple stylized diagram of a heat pump's vapor-compression refrigeration
cycle: 1) condenser, 2) expansion valve, 3) evaporator, 4) compressor.
The working fluid, in its gaseous state, is pressurized and circulated through
the system by a compressor. On the discharge side of the compressor, the now hot
and highly pressurized gas is cooled in a heat exchanger called a condenser until it
condenses into a high pressure, moderate temperature liquid. The condensed
refrigerant then passes through a pressure-lowering device like an expansion valve,
capillary tube, or possibly a work-extracting device such as a turbine. This device
then passes the low pressure, barely liquid (saturated vapor) refrigerant to another
75
heat exchanger, the evaporator where the refrigerant evaporates into a gas via heat
absorption. The refrigerant then returns to the compressor and the cycle is repeated.
In such a system it is essential that the refrigerant reaches a sufficiently high
temperature when compressed, since the second law of thermodynamics prevents
heat from flowing from a cold fluid to a hot heat sink. Similarly, the fluid must
reach a sufficiently low temperature when allowed to expand, or heat cannot flow
from the cold region into the fluid. In particular, the pressure difference must be
great enough for the fluid to condense at the hot side and still evaporate in the
lower pressure region at the cold side. The greater the temperature difference, the
greater the required pressure difference, and consequently more energy is needed
to compress the fluid. Thus as with all heat pumps, the energy efficiency (amount
of heat moved per unit of input work required) decreases with increasing
temperature difference. Thus a ground-source heat pump, which has a very small
temperature differential, is relatively efficient. (Figures of 75% and above are
quoted.)
Due to the variations required in temperatures and pressures, many different
refrigerants are available. Refrigerators, air conditioners, and some heating systems
are common applications that use this technology.
In HVAC applications, a heat pump normally refers to a vapor-compression
refrigeration device that includes a reversing valve and optimized heat exchangers
so that the direction of heat flow may be reversed. The reversing valve switches the
direction of refrigerant through the cycle and therefore the heat pump may deliver
either heating or cooling to a building. Because the two heat exchangers, the
condenser and evaporator, must swap functions, they are optimized to perform
adequately in both modes. As such, the efficiency of a reversible heat pump is
typically slightly less than two separately-optimized machines.
In plumbing applications, a heat pump is sometimes used to heat or preheat
water for swimming pools or domestic water heaters.
In somewhat rare applications, both the heat extraction and addition
capabilities of a single heat pump can be useful, and typically results in very
effective use of the input energy. For example, when an air cooling need can be
matched to a water heating load, a single heat pump can serve two useful purposes.
Unfortunately, these situations are rare because the demand profiles for heating and
cooling are often significantly different.
ACTIVE VOCABULARY
heat pump – тепловой насос,
обратная тепловая машина
heat source – тепловой источник
heat sink – теплоотвод
76
reversible-cycle –
цикл
chiller – охладитель
обратимый
cryocooler – криогенный охладитель
to achieve – достигать
to apply – использовать, употреблять
to extract - вытаскивать, извлекать;
fraction – доля, часть
to require – нуждаться (в чём-л.) ;
требовать (чего-л.)
properties – свойства
state – состояние
a heat exchanger – теплообменник
a device – устройство, прибор
capillary tube – волосная трубка,
капиллярная трубка
energy efficiency – кпд по
энергии, энергетический кпд,
выход
по
энергии,
энергетический выход)
unit of input – единица затрат
HVAC – отопление, вентиляция
и кондиционирование воздуха
to include – включать в себя,
содержать в себе
a reversing valve – реверсивный
клапан, реверсивный гидро- или
пневмораспределитель
to optimized – оптимизировать
to switch – переключать
to deliver – доставлять
to swap – менять, обменивать
mode – способ
essential
–
важнейший;
необходимый; основной
to
prevent
–
предотвращать,
предупреждать
V. Find the Russian equivalents for the English ones:
temperature difference, working fluid, a ground-source heat pump,
reversible-cycle heat pump, temperature differential, the discharge side of the
compressor, to preheat, thermal comfort, input energy, a pressure-lowering device,
to operate in reverse, a work-extracting device
VI. Find the English equivalents for the Russian ones:
Отопительная система, газообразное состояние, реверсивный клапан,
водяной охладитель, реверсивный тепловой насос, регулирующий вентиль,
нагреватель воды, физические свойства, отвод теплоты, теплопоглощение,
конденсат, перепад давлений
VII. Translate the following sentences into Russian:
1.
Most heat pump technology moves heat from a low
temperature heat source to a higher temperature heat sink.
2.
Heat pumps can essentially be thought of as heat engines
operating in reverse.
3.
A heat pump requires work to move thermal energy
from a cold source to a warmer heat sink.
4.
For the heat pump the amount of energy deposited at the
hot side is greater than the energy taken from the cold side by an amount
equal to the work required.
77
5.
On the discharge side of the compressor, the now hot
and highly pressurized gas is cooled in a heat exchanger.
6.
The expansion valve passes the low pressure, barely
liquid refrigerant to another heat exchanger.
7.
The pressure difference must be great enough for the
fluid to condense at the hot side and still evaporate in the lower pressure
region at the cold side.
8.
The reversing valve switches the direction of refrigerant
through the cycle and therefore the heat pump may deliver either heating
or cooling to a building.
9.
The efficiency of a reversible heat pump is typically
slightly less than two separately-optimized machines.
10.
Both the heat extraction and addition capabilities of a
single heat pump can be useful, and typically results in very effective use
of the input energy.
VIII. Fill in the blanks with appropriate words:
1.
A heat pump uses … to move heat.
2.
A heat engine allows energy to flow from a hot … to a
cold heat … .
3.
The working fluid is … through the system by a … .
4.
In the … the hot highly pressurized gas condenses into a
high pressure, moderate temperature … .
5.
In the evaporator the refrigerant … into a gas via … .
6.
The energy efficiency decreases with increasing …
difference.
7.
A ground-source heat pump has a very small … .
8.
The reversing … switches the direction of … through
the cycle.
9.
A heat pump is sometimes used to … water for
swimming pools.
10.
A heat pump normally refers to … device.
IX. Translate into English, using the active vocabulary:
1. Тепловой насос – это устройство, которое перемещает
теплоту из одного положение в другое.
2. Теплота не может самопроизвольно переходить из холодного
места в более горячее в соответствии со вторым законом
термодинамики.
78
3. Тепловой насос работает, используя физические свойства
конденсата.
4. Рабочая жидкость в газообразном состоянии циркулирует в
системе при промощи компрессора.
5. После конденсора охладитель проходит через регулирующий
клапан или капиллярную трубку.
6. Чем больше перепад температуры, тем больше перепад
давлений.
7. Энергитический выход уменьшается с увеличением перепада
температур.
8. Реверсивный клапан может изменить направление теплового
потока.
9. Эффективность реверсивного теплового насоса достаточно
небольшая.
10. Тепловой насос можно использовать для нагревания воды.
X. Answer the questions:
1.
2.
3.
4.
What is a heat pump?
What devices use a heat pump?
What physical law is the heat pump work based?
What is the difference between a heat engine and a heat
5.
6.
the system?
7.
condenser?
8.
the evaporator?
9.
10.
11.
12.
13.
14.
What does a heat pump exploit in its work?
In what state is the working liquid circulated through
pump?
What does the refrigerant pass through after the
What kind of refrigerant does an expansion valve pass to
What does the energy efficiency depend on?
Is a ground-source heat pump efficient?
How can the direction of heat flow be reversed?
What may the heat pump do using the reversing valve?
What is the efficiency of the reversible heat pump?
What is the heat pump used in plumbing applications?
XI. Skim through the text and say in a few sentences what the message of
the text is. Answer the questions which follow.
79
When comparing the performance of heat pumps, it is best to avoid the
word "efficiency" which has a very specific thermodynamic definition. The term
coefficient of performance6 (COP) is used to describe the ratio of useful heat
movement to work input. Most vapor-compression heat pumps utilize electrically
powered motors for their work input. However, in most vehicle applications shaft
work, via their internal combustion engines7, provide the needed work.
In cooling mode a heat pump's operating performance is described as its
energy efficiency ratio8 (EER) or seasonal energy efficiency ratio (SEER), and
both measures have units of BTU/(h·W). A larger EER number indicates better
performance. The manufacturer's literature should provide both a COP to describe
performance in heating mode and an EER or SEER to describe performance in
cooling mode. Actual performance varies, however, and depends on many factors
such as installation, temperature differences, site elevation, and maintenance.
Heat pumps are more effective for heating than for cooling if the
temperature difference is held equal. This is because the compressor's input energy
is largely converted to useful heat when in heating mode, and is discharged along
with the moved heat via the condenser. But for cooling, the condenser is normally
outdoors, and the compressor's dissipated work is rejected rather than put to a
useful purpose.
For the same reason, opening a food refrigerator or freezer heats up the
kitchen rather than cooling it because its refrigeration cycle rejects heat to the
indoor air. This heat includes the compressor's dissipated work as well as the heat
removed from the inside of the appliance.
***
1. What does the term coefficient of performance mean?
2. What does a vapor-compression heat pump utilize for its work input?
3. What is EER? What unit does it have?
4. What does a COP / an EER or SEER describe?
5. What factors does actual performance depend on?
6. What is a heat pump more effective for heating or cooling? Why?
XII. Scan the text for details. Tell about the difference between air-sourced
and ground-sourced heat pump. Ask some questions to your partner.
Heat pumps can be air-sourced or ground-sourced (geothermal heating).
The technologies are developing rapidly: COPs (coefficient of performance)
have risen from COP=3 to COP=4 or even COP=5 over the last five years. Heat
коэффициент полезного действия, кпд
двигатель внутреннего сгорания
8
коэффициент эффективности использования энергии
6
7
80
pumps are now becoming popular choices for home-heating as well as for cooling
— especially in areas with less severe winters.
Those buying air-source heat pumps should look closely at its COP, the
outside temperature range in which that COP is effective, the cost of installation,
how much heat it can move, and how much noise it generates.
Air-source heat pumps do not work well when temperatures fall below
around −5°C (23°F).
Ground-source heat pumps typically have higher COPs than air-coupled
heat pumps, because they draw heat from ground or groundwater, and this is at a
relatively constant temperature all year-round below a depth of about eight feet
(2.5 m). The tradeoff for this improved performance is that a ground-coupled heat
pump is usually more complicated due to the need for wells or buried coils, and
thus is also usually much more expensive to install than an air-coupled heat pump.
XI. Tell about the heat pump.
81
UNIT 9
I. Read and translate the text:
History of air conditioning
While moving heat via machinery to provide air conditioning is a relatively
modern invention, the cooling of buildings is not. The ancient Romans were known
to circulate aqueduct water through the walls of certain houses to cool them. As
this sort of water usage was expensive, generally only the wealthy could afford
such a luxury.
Medieval Persia had buildings that used cisterns and wind towers to cool
buildings during the hot season: cisterns (large open pools in a central courtyards,
not underground tanks) collected rain water; wind towers had windows that could
catch wind and internal vanes to direct the airflow down into the building, usually
over the cistern and out through a downwind cooling tower. Cistern water
evaporated, cooling the air in the building.
In 1820, British scientist and inventor Michael Faraday discovered that
compressing and liquefying ammonia could chill air when the liquefied ammonia
was allowed to evaporate. In 1842, Florida physician Dr. John Gorrie used
compressor technology to create ice, which he used to cool air for his patients in
his hospital in Apalachicola, Florida. He hoped eventually to use his ice-making
machine to regulate the temperature of buildings. He even envisioned centralized
air conditioning that could cool entire cities. Dr. Gorrie died in 1855 and the idea
of air conditioning faded away for 50 years.
Early commercial applications of air conditioning were manufactured to
cool air for industrial processing rather than personal comfort. In 1902 the first
modern electrical air conditioning was invented by Willis Haviland Carrier.
Designed to improve manufacturing process control in a printing plant, his
invention controlled not only temperature but also humidity. The low heat and
humidity were to help maintain consistent paper dimensions and ink alignment.
Later Carrier's technology was applied to increase productivity in the workplace,
and The Carrier Air Conditioning Company of America was formed to meet rising
demand. Over time air conditioning came to be used to improve comfort in homes
and automobiles. Residential sales expanded dramatically in the 1950s.
In 1906, Stuart W. Cramer of Charlotte, North Carolina, USA, was
exploring ways to add moisture to the air in his textile mill. Cramer coined the term
"air conditioning," using it in a patent claim he filed that year as an analogue to
"water conditioning". He combined moisture with ventilation to "condition" and
change the air in the factories, controlling the humidity so necessary in textile
plants. Willis Carrier adopted the term and incorporated it into the name of his
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company. This evaporation of water in air, to provide a cooling effect, is now
known as evaporative cooling.
The first air conditioners employed toxic or flammable gases like ammonia,
methyl chloride, and propane which could result in fatal accidents when they
leaked. Thomas Midgley, Jr. created the first chlorofluorocarbon gas, Freon, in
1928. The refrigerant was much safer for humans but was later found to be harmful
to the atmosphere's ozone layer. The blend most used in direct-expansion comfort
cooling is an HCFC known as R-22. Several non-ozone depleting refrigerants have
been developed as alternatives, including R-410A, known by the brand name
"Puron".
Innovation in air conditioning technologies continue, with much recent
emphasis placed on energy efficiency and for improving indoor air quality. As an
alternative to high global warming refrigerants, such as R-134a in cars' and R-22,
R-410A in residential air conditioning, natural alternatives like CO 2 (R-744) have
been proposed.
ACTIVE VOCABULARY
aqueduct – акведук, водопровод
cistern – цистерна, бак; ёмкость,
резервуар (для хранения воды)
to envision – представлять себе,
предвидеть
to fade away – исчезать
to
improve
–
улучшать;
совершенствовать
humidity – влажность, степень
влажности
moisture – влага
to condition – кондиционировать
помещение
evaporative cooling – охлаждение
испарением
to
employ
–
применять,
использовать
flammable
–
огнеопасный;
легковоспламеняющийся
to leak – давать течь; подтекать
harmful – вредный, губительный;
blend – смесь
innovation
–
нововведение,
новшество
indoor – комнатный
air quality – качество воздуха
to propose – предлагать
II. Say whether these sentences are True or False:
1. Ammonia could chill air when the liquefied ammonia was
allowed to evaporate.
2. Air conditioning and the cooling of buildings are modern
inventions.
3. Ammonia was much safer for humans.
4. Ice-making machine may regulate the temperature of buildings.
83
5. Cisterns were large open pools in a central courtyards or
underground tanks.
6. R-410A is the most used blend in direct-expansion comfort
cooling.
7. Carrier’s invention controlled not only temperature but also
humidity.
8. Internal vanes of the wind towers directed the airflow down into
the building.
9. He combined moisture with ventilation to "condition".
10. "Puron" is the brand name of several non-ozone depleting
refrigerants.
III. Make up sentences and translate them into Russian.
1. air, gases, the, flammable, first, employed, conditioners.
2. technology, ice, create, was, compressor, to, used.
3. was, the, to, aqueduct, through, houses, water, of, circulated,
them, walls, cool.
4. air, the, was, modern, in, invented, first, conditioning, 1902,
electrical.
5. collected, rain, the, in, water, cisterns, was.
6. atmosphere's, to, layer, Freon, the, is, ozone, harmful.
7. homes, comfort, to, conditioning, in, improve, came, air.
8. continue, technologies, in, conditioning, air, innovation.
9. the, cooling, cistern, evaporated, air, water.
10. effect, provides, of, in, a, air, evaporation, water, cooling.
IV. What do the following numbers refer to?
1928, 744, 1906, 134, 1820, 410, 1842, 22, 1902
V. Ask different kinds of questions about heat according to the pattern.
Work in pair or group.
I group (Yes/No-questions)
Is air condotoining a modern invention?
II group (Wh-questions)
What is air conditioning provided?
provided by
III group (Tag-question)
Air conditioning is
machinery, isn’t it?
V. Read and translate the text:
84
Air conditioning
The term air conditioning most commonly refers to the cooling and
dehumidification of indoor air for thermal comfort. In a broader sense, the term can
refer to any form of cooling, heating, ventilation or disinfection that modifies the
condition of air. An air conditioner (AC or A/C in North American English, aircon
in British and Australian English) is an appliance, system, or mechanism designed
to stabilise the air temperature and humidity within an area (used for cooling as
well as heating depending on the air properties at a given time), typically using a
refrigeration cycle but sometimes using evaporation, most commonly for comfort
cooling in buildings and transportation vehicles.
Air conditioning engineers broadly divide air conditioning applications into
comfort and process.
Comfort applications aim to provide an indoor environment that remains
relatively constant in a range preferred by humans despite changes in external
weather conditions or in internal heat loads.
Comfort air conditioning makes deep plan buildings feasible. Without air
conditioning, buildings must be built narrower or with light wells so that inner
spaces receive sufficient outdoor air via natural ventilation. Air conditioning also
allows buildings to be taller since wind speed increases significantly with altitude
making natural ventilation impractical for very tall buildings. Comfort applications
for various building types are quite different and may be categorized as
 Low-Rise Residential buildings, including single family houses,
duplexes, and small apartment buildings.
 High-Rise Residential buildings, such as tall dormitories and
apartment blocks
 Commercial buildings, which are built for commerce, including
offices, malls, shopping centers, restaurants, etc.
 Institutional buildings, which includes hospitals, governmental,
academic, and so on.
 Industrial spaces where thermal comfort of workers is desired.
In addition to buildings, air conditioning can be used for comfort in a wide
variety of transportation including land vehicles, trains, ships, aircraft, and
spacecraft.
Process applications aim to provide a suitable environment for a process
being carried out, regardless of internal heat and humidity loads and external
weather conditions. Although often in the comfort range, it is the needs of the
process that determine conditions, not human preference. Process applications
include these:
 Hospital operating theatres, in which air is filtered to high levels
to reduce infection risk and the humidity controlled to limit patient
85
dehydration. Although temperatures are often in the comfort range, some
specialist procedures such as open heart surgery require low temperatures
(about 18 °C, 64 °F) and others such as neonatal relatively high
temperatures (about 28 °C, 82 °F).
 Cleanrooms9 for the production of integrated circuits,
pharmaceuticals, and the like, in which very high levels of air cleanliness
and control of temperature and humidity are required for the success of
the process.
 Facilities for breeding laboratory animals. Since many animals
normally only reproduce in spring, holding them in rooms at which
conditions mirror spring all year can cause them to reproduce year round.
 Aircraft air conditioning. Although nominally aimed at providing
comfort for passengers and cooling of equipment, aircraft air conditioning
presents a special process because of the low air pressure outside the
aircraft.
 Data processing centers
 Textile factories
 Physical testing facilities
 Plants and farm growing areas
 Nuclear facilities
 Chemical and biological laboratories
 Mines
 Industrial environments
 Food cooking and processing areas
In both comfort and process applications the objective may be not only to
control temperature, but also humidity, air quality, air motion, and air movement
from space to space.
Refrigeration air conditioning equipment usually reduces the humidity of
the air processed by the system. The relatively cold (below the dewpoint)
evaporator coil condenses water vapor from the processed air, (much like an ice
cold drink will condense water on the outside of a glass), sending the water to a
drain and removing water vapor from the cooled space and lowering the relative
humidity. Since humans perspire to provide natural cooling by the evaporation of
perspiration from the skin, drier air (up to a point) improves the comfort provided.
The comfort air conditioner is designed to create a 40% to 60% relative humidity
in the occupied space. In food retailing establishments’ large open chiller cabinets
act as highly effective air dehumidifying units.
"чистая комната" – в электронной промышленности - производственные помещения с
высочайшей степенью защиты от пыли и других загрязнений
9
86
Some air conditioning units dry the air without cooling it, and are better
classified as dehumidifiers. They work like a normal air conditioner, except that a
heat exchanger is placed between the intake and exhaust. In combination with
convection fans they achieve a similar level of comfort as an air cooler in humid
tropical climates, but only consume about a third of the electricity. They are also
preferred by those who find the draft created by air coolers discomforting.
ACTIVE VOCABULARY
air
conditioning
–
кондиционирование воздуха
dehumidification
–
осушение
(воздуха)
to
modify
–
видоизменять,
корректировать, изменять
an appliance – приспособление,
устройство
vehicle – транспортное средство
external – внешний, наружный
internal – внутренний
heat load – тепловая нагрузка
feasible – реальный, выполнимый,
осуществимый
residential – жилой
high-rise – высотный; многоэтажный
suitable – годный, подходящий,
пригодный, соответствующий
to limit – ограничивать
procedure – процедура, процесс,
операция
to require – нуждаться (в чём-л.) ;
требовать (чего-л.)
facilities
–
средства,
оборудование
air quality – качество воздуха
air motion – движение воздуха
humidity – влажность, степень
влажности (воздуха)
dewpoint – температура таяния,
температура конденсации
unit – устройство, установка
to dry – сушить; высушивать
an
air
cooler
–
воздухоохладитель
energy input – потребляемая
энергия
V. Find the Russian equivalents for the English ones:
Data processing center, high-Rise Residential building, air movement, in a
broader sense, food retailing establishment, spacecraft, exhaust, air properties,
open chiller cabinet, humidity load, internal heat load, operating theatre, duplexe,
infection risk
VI. Find the English equivalents for the Russian ones:
Открытый воздух, испарительный змеевик, среда в помещении,
относительная
влажность,
естественная
вентиляция,
естественное
охлаждение, относительно постоянный, влагопоглотитель, малоэтажное
здание, впускное отверстие, погодные условия, неудобство, диапазон
комфортных условий
87
VII. Translate the following sentences into Russian:
1.
The term air conditioning most commonly refers to the
cooling and dehumidification of indoor air for thermal comfort.
2.
An air conditioner is an appliance designed to stabilise
the air temperature and humidity.
3.
By comfort applications an indoor environment remains
relatively constant in a range preferred by humans despite changes in
external weather conditions.
4.
Process applications aim to provide a suitable
environment for a process being carried out, regardless of internal heat
and humidity loads and external weather conditions.
5.
The objective of both comfort and process applications
may be not only to control temperature, but also humidity, air quality, air
motion, and air movement from space to space.
6.
Cleanrooms require very high levels of air cleanliness
and control of temperature and humidity.
7.
Refrigeration air conditioning equipment usually
reduces the humidity of the air processed by the system.
8.
The comfort air conditioner is designed to create a 40%
to 60% relative humidity in the occupied space.
9.
In dehumidifiers a heat exchanger is placed between the
intake and exhaust.
10.
In food retailing establishments large open chiller
cabinets act as highly effective air dehumidifying units.
VIII. Fill in the blanks with appropriate words:
1. The term air conditioning can refer to any form of … , heating,
ventilation or … that … the condition of air.
2. Inner spaces of buildings can receive sufficient outdoor air via …
.
3. … presents a special process because of the low air pressure
outside the aircraft.
4. An air conditioner uses … or … for comfort cooling in
buildings.
5. Air conditioning applications are divided into … and … .
6. the … of the air is usually reduced by refrigeration air
conditioning equipment.
7. The relatively cold … coil condenses … from the processed air.
88
8. Dehumidifiers dry the air without … it.
9. In hospital operating theatres … is controlled to limit patient
dehydration.
10. Humans perspire to provide … .
IX. Translate into English, using the active vocabulary:
1.
Кондиционирование воздуха – это процесс
видоизменения состояния воздуха.
2.
Холодильный цикл используется кондиционером
для комфортного охлаждения в здании или транспортном средстве.
3.
Для производства микросхем необходим высокий
уровень чистоты воздуха и контроль температуры и влажности.
4.
Кондиционеры создают 40 – 60 % относительной
влажности.
5.
Кондиционирование воздуха можно использовать
для удобства в различных видах транспорта.
6.
Цель кондиционирования воздуха – не только
контролировать температуру, но и влажность, касчество воздуха и
движение воздуха.
7.
В операционных воздух фильтруется, чтобы
уменьшить риск инфекционных заболеваний.
8.
Испарительный змеевик сжижает водяной пар из
воздуха.
9.
В многоэтажных зданиях естественная вентиляция
становиться непрактичной при использовании кондиционирования
воздуха.
10.
Влагопоглатители осушают воздух, не охлаждая его.
X. Answer the questions:
1. What is air conditioning?
2. What is the aim of comfort application / process application of air
conditioning?
3. How may comfort applications be categorized?
4. Where can air conditioning be used for comfort?
5. What conditions are required for hospital operating theatres?
6. What procedure requires low / high temperatures?
7. What is a cleanroom?
8. What can you say about aircraft aire conditioning?
9. What another process applications do you know?
10. For what is the evaporator coil used?
89
11. Is the humidity reduced by air conditioning equipments?
12. What is a dehumidifier? What is the difference between a
dehumidifier and a normal air conditioning?
XI. Skim through the text and say in a few sentences what the message of
the text is. Give the titel to this text. Answer the questions which follow.
A poorly maintained air-conditioning system can occasionally promote the
growth and spread of microorganisms, such as Legionella pneumophila, the
infectious agent responsible for Legionnaires' disease, or thermophilic
actinomycetes. Conversely, air conditioning, including filtration, humidification,
cooling, disinfection, etc., can be used to provide a clean, safe, hypoallergenic
atmosphere in hospital operating rooms and other environments where an
appropriate atmosphere is critical to patient safety and well-being. Air conditioning
can have a positive effect on sufferers of allergies and asthma.
In serious heat waves, air conditioning can save the lives of the elderly.
Some local authorities even set up public cooling centers for the benefit of those
without air conditioning at home.
Poorly operating air conditioning systems can generate sound levels that
contribute to hearing loss, if exposures are endured over a long term. These levels
are similar to the exposure of living near a busy highway or airport for a
considerable length of time. Properly functioning air conditioners are much quieter.
***
1. What is the reason of the growth and spread of the infectious agent?
2. What can provide a hypoallergenic atmosphere in the room?
3. When can air conditioning save the lives of the elderly?
4. What can poorly operating air conditioning systems contribute?
XII. Scan the text for details. Tell about the feature of the air conditioning
energy use.
It should be noted that in a thermodynamically closed system, any energy
input into the system that is being maintained at a set temperature (which is a
standard mode of operation for modern air conditioners) requires that the energy
removal rate from the air conditioner increase. This increase has the effect that for
each unit of energy input into the system (say to power a light bulb in the closed
system) requires the air conditioner to remove that energy. In order to do that the
air conditioner must increase its consumption by the inverse of its efficiency times
the input unit of energy. As an example presume that inside the closed system a
100 watt light bulb is activated, and the air conditioner has an efficiency of 200%.
90
The air conditioner's energy consumption will increase by 50 watts to compensate
for this, thus making the 100 W light bulb utilise a total of 150 W of energy.
Note that it is typical for air conditioners to operate at "efficiencies" of
significantly greater than 100%, see Coefficient of performance.
XIII. Tell in short about the air conditioning.
91
UNIT 10
I. Read and translate the text paying attention to the vocabulary.
Air conditioner
An air conditioner is an appliance, system, or mechanism designed to
extract heat from an area. In construction, a complete system of heating,
ventilation, and air conditioning is referred to as HVAC. Its purpose, in the home
or in the car, is to provide comfort during hot days and nights.
An air conditioner uses the refrigeration cycle which as we have known
consists of condensing coil, expansion valve, evaporator coil, and compressor.
In the refrigeration cycle, a heat pump transfers heat from a lower
temperature heat source into a higher temperature heat sink. Heat would naturally
flow in the opposite direction.
The most common refrigeration cycle uses an electric motor to drive a
compressor. Since evaporation occurs when heat is absorbed, and condensation
occurs when heat is released, air conditioners are designed to use a compressor to
cause pressure changes between two compartments, and actively pump a
refrigerant around. A refrigerant is pumped into the cooled compartment (the
evaporator coil), where the low pressure and low temperature cause the refrigerant
to evaporate into a vapor, taking heat with it. In the other compartment (the
condenser), the refrigerant vapour is compressed and forced through another heat
exchange coil, condensing into a liquid, rejecting the heat previously absorbed
from the cooled space.
Many traditional air conditioners in homes or other buildings are single
rectangular units used to cool an apartment, a house or part of it, or part of a
building. Air conditioner units need to have access to the space they are cooling
(the inside) and a heat sink; normally outside air is used to cool the condenser
section. For this reason, single unit air conditioners are placed in windows or
through openings in a wall made for the air conditioner; the latter type includes
portable air conditioners.
Window and through-wall units have vents on both the inside and outside,
so inside air to be cooled can be blown in and out by a fan in the unit, and outside
air can also be blown in and out by another fan to act as the heat sink. The controls
are on the inside.
A large house or building may have several such units. Should virtually
every room be cooled with its own air conditioning unit, most of the day, it would
be less expensive to use central air conditioning, though that may not be physically
possible.
Central air conditioning, commonly referred to as central air (US) or aircon (UK), is an air conditioning system which uses ducts to distribute cooled
92
and/or dehumidified air to more than one room, or uses pipes to distribute chilled
water to heat exchangers in more than one room, and which is not plugged into a
standard electrical outlet.
With a typical split system, the condenser and compressor are located in an
outdoor unit; the evaporator is mounted in the air handling unit (which is often a
forced air furnace). With a package system, all components are located in a single
outdoor unit that may be located on the ground or roof.
Central air conditioning performs like a regular air conditioner but has
several added benefits:
 When the air handling unit turns on, room air is drawn in from
various parts of the house through return-air ducts. This air is pulled
through a filter where airborne particles such as dust and lint are removed.
Sophisticated filters may remove microscopic pollutants as well. The
filtered air is routed to air supply ductwork that carries it back to rooms.
Whenever the air conditioner is running, this cycle repeats continually.
 Because the central air conditioning unit is located outside the
home, it offers a lower level of noise indoors than a free-standing air
conditioning unit.
ACTIVE VOCABULARY
air conditioner – кондиционер,
установка
кондиционирования
воздуха
an appliance – аппарат, устройство
to extract – извлекать
HVAC – система отопления,
вентиляции и кондиционирования
воздуха
condensing coil – змеевиковый
конденсатор
expansion valve – регулирующий
вентиль
evaporator coil – испарительный
змеевик
evaporation – испарение
to occur – происходить, случаться
condensation – конденсирование,
конденсация
compartment – отделение
to pump – закачивать
to cause – послужить причиной,
поводом (для чего-л.)
to force through – проталкивать,
продавливать
to reject – отторгать
rectangular – прямоугольный
access – доступ
portable
–
портативный,
переносный, передвижной
air conditioners.
vent – входное или выходное
отверстие; отдушина
central air – центральная система
кондиционирования воздуха
duct –воздуховод
pipe – труба, трубопровод
to distribute – распространять
split system – раздельная система
отопления и вентиляции
93
to
mount
–
монтировать,
устанавливать
air handling unit – аппарат для
кондиционирования воздуха
outdoor – на открытом воздухе
benefit – польза
to pull – тянуть, тащить
dust – песчинка, пылинка; пыль
pollutant – загрязняющий агент
to route – направлять
to offer – предлагать
II. Find the Russian equivalents for the English ones:
outdoor unit; heat exchange coil; an airborne particle; a complete system of
heating, ventilation, and air conditioning; a single rectangular unit; heat source;
central air; a portable air conditioner; an air handling unit; pressure changes; a
package system
III. Find the English equivalents for the Russian ones:
автономный аппарат для кондиционирования воздуха; наружный
воздух; сложный фильтр; нагревание, вентиляция и кондиционирование
воздуха; обратный воздуховод; центральная система кондиционирования
воздуха; теплоотвод; сухой воздух; противоположное направление;
охлаждённая вода
IV. Translate the following sentences into Russian:
1. A complete system of heating, ventilation, and air conditioning is
referred to as HVAC.
2. The purpose of air conditioning, in the home or in the car, is to
provide comfort during hot days and nights.
3. In the evaporator coil the low pressure and low temperature
cause the refrigerant to evaporate into a vapor.
4. In the the condenser the refrigerant vapour is compressed and
forced through another heat exchange coil.
5. Air conditioner units need to have access to the space they are
cooling and a heat sink.
6. Single unit air conditioners are placed in windows or through
openings in a wall made for the air conditioner.
7. Outside air can be blown in and out by a fan to act as the heat
sink.
8. Central air conditioning uses ducts to distribute cooled and/or
dehumidified air to more than one room.
9. With a package system, all components are located in a single
outdoor unit that may be located on the ground or roof.
94
10. Because the central air conditioning unit is located outside the
home, it offers a lower level of noise indoors than a free-standing air
conditioning unit.
V. Fill in the blanks with appropriate words:
1. An air conditioner is … designed to extract heat from an area.
2. A … transfers heat from a lower temperature heat source into a
higher temperature heat sink.
3. A compressor actively … a refrigerant around.
4. Air conditioners in homes are … units.
5. In the … the refrigerant is evaporated into a vapor and takes …
with it.
6. The refrigerant vapour … into a liquid and … the heat.
7. Window and … units have … on both the inside and outside.
8. It would be less expensive to use … .
9. Central air conditioning uses … to distribute … to heat
exchangers.
10. The evaporator is mounted in the … in a typical split system.
VI. Translate into English, using the active vocabulary:
1. Кондиционер – это устройство, которое удаляет теплоту из
комнаты в жаркие дни.
2. Аппарату для кондиционирования воздуха необходим
доступ к пространству, которое он охлаждает, и теплоотвод.
3. Кондиционеры устанавливаются в окнах либо в отверстиях в
стенах.
4. В оконных устройствах есть отверстия на внутренней и
внешней сторонах.
5. В каждой комнате может быть свой собственный
кондиционер.
6. Центральная
система
кондиционирования
воздуха
использует воздуховоды для распространения охлажденного воздуха.
7. В обычной раздельной системе вентиляции конденсор и
компрессор находятся во внешней части аппарата, а испаритель во
внутренней.
8. Воздух проходит через фильтр, который удаляет частицы
пыли.
9. У центрльной системы кондиционирования воздуха уровень
шума в помещении ниже, чем у автономных аппаратов.
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10. Существуют передвижные устройства кондиционирования
воздуха.
VII. Answer the questions to the text:
1. What is an air conditioner? For what is it used?
2. What does it use to extract heat from an area?
3. What does the refrigeration cycle consists of?
4. What does an air conditioner use to pump a refrigerant around?
5. What happens with a refrigerant in the evaporator coil / the
condenser?
6. Where is an air conditioner placed?
7. What do air conditioner units need to cool the space?
8. How can inside and outside air be blown in the unit?
9. May a large house have several air conditioner units?
10. What is central air condotioning? What does it use to work?
11. What is the difference between a split system and a package
system?
12. For what are filters used?
VIII. a) Read the text. Write questions to the answers.
Thermostats
Thermostats control the operation of HVAC systems, turning on the heating
or cooling systems to bring the building to the set temperature. Typically the
heating and cooling systems have separate control systems (even though they may
share a thermostat) so that the temperature is only controlled "one-way". That is, in
winter, a building that is too hot will not be cooled by the thermostat. Thermostats
may also be incorporated into facility energy management systems in which the
power utility customer may control the overall energy expenditure. In addition, a
growing number of power utilities have made available a device which, when
professionally installed, will control or limit the power to an HVAC system during
peak use times in order to avoid necessitating the use of rolling blackouts. The
customer is given a credit of some sort in exchange.
1. _______________________________?
the operation of HVAC systems.
2. _______________________________?
"one-way".
3. _______________________________?
separate control systems.
4. _______________________________?
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into facility energy management systems.
5. _______________________________?
to control the overall energy expenditure.
6. _______________________________?
to avoid necessitating the use of rolling blackouts.
b) Scan the text for details. Tell some sentences about a thermostat.
IX. Tell about the air conditioner.
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GLOSSARY
absolute temperature - another name for thermodynamic temperature
absorbent - a substance that absorbs
absorber - 1) a person or thing that absorbs
2) physics a material that absorbs radiation or causes it to lose
energy
adiabatic - (of a thermodynamic process) taking place without loss or gain
of heat
air conditioning - a system or process for controlling the temperature and
sometimes the humidity and purity of the air in a house, etc
boiling point - the temperature at which a liquid boils at a given pressure,
usually atmospheric pressure at sea level; the temperature at which the vapour
pressure of a liquid equals the external pressure
capillary tube - a glass tube with a fine bore and thick walls, used in
thermometers, etc
chlorofluorocarbon - any of various gaseous compounds of carbon,
hydrogen, chlorine, and fluorine, used as refrigerants, aerosol propellants, solvents,
and in foam: some cause a breakdown of ozone in the earth's atmosphere
compressor - any reciprocating or rotating device that compresses a gas
coolant - 1) a fluid used to cool a system or to transfer heat from one part of
it to another 2) a liquid, such as an emulsion of oil, water, and soft soap, used to
lubricate and cool the workpiece and cutting tool during machining
dehumidifier - a device for reducing the moisture content of the
atmosphere
dew point - the temperature at which water vapour in the air becomes
saturated and water droplets begin to form
dichlorodifluoromethane - a colourless nonflammable gas easily liquefied
by pressure: used as a propellant in aerosols and fire extinguishers and as a
refrigerant.
dry ice - solid carbon dioxide, which sublimes at -78.5°C: used as a
refrigerant, and to create billows of smoke in stage shows Also called: carbon
dioxide snow
Du Pont - "Дюпон" (английский филиал американской корпорации
"Дюпон де Немур энд К°" [Du Pont de Nemours & Co]; производит различную
химическую продукцию, синтетическое волокно орлон [Orlon] и дакрон
[Dacron]) Du Pont Company (United Kingdom) Ltd
enthalpy - a thermodynamic property of a system equal to the sum of its
internal energy and the product of its pressure and volume Symbol: H Also called:
heat content, total heat
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entropy , -pies - a thermodynamic quantity that changes in a reversible
process by an amount equal to the heat absorbed or emitted divided by the
thermodynamic temperature. It is measured in joules per kelvin Symbol: S
gas turbine - an internal-combustion engine in which the expanding gases
emerging from one or more combustion chambers drive a turbine. A rotary
compressor driven by the turbine compresses the air used for combustion, power
being taken either as torque from the turbine or thrust from the expanding gases
heat capacity - the heat required to raise the temperature of a substance by
unit temperature interval under specified conditions, usually measured in joules per
kelvin. Symbol: Cp (for constant pressure) or Cv (for constant volume)
heat engine - an engine that converts heat energy into mechanical energy
heat exchanger - a device for transferring heat from one fluid to another
without allowing them to mix
heat pump - a device, as used in a refrigerator, for extracting heat from a
source and delivering it elsewhere at a much higher temperature
heat sink - a metal plate specially designed to conduct and radiate heat
from an electrical component
Icebox - 1) a compartment in a refrigerator for storing or making ice 2) an
insulated cabinet packed with ice for storing food
ice house - a building for storing ice
internal energy - the thermodynamic property of a system that changes by
an amount equal to the work done on the system when it suffers an adiabatic
change. It is the sum of the kinetic and potential energies of its constituent atoms,
molecules, etc Symbol: U or E
latent heat - (no longer in technical usage) the heat evolved or absorbed by
unit mass (specific latent heat) or unit amount of substance (molar latent heat)
when it changes phase without change of temperature;
melting point - the temperature at which a solid turns into a liquid. It is
equal to the freezing point
mole - the basic SI unit of amount of substance; the amount that contains as
many elementary entities as there are atoms in 0.012 kilogram of carbon-12. The
entity must be specified and may be an atom, a molecule, an ion, a radical, an
electron, a photon, etc Symbol: mol
nuclear energy - energy released during a nuclear reaction as a result of
fission or fusion Also called: atomic energy
Otto cycle - an engine cycle used on four-stroke petrol engines (Otto
engines) in which, ideally, combustion and rejection of heat both take place at
constant volume
ozone layer - the region of the stratosphere with the highest concentration
of ozone molecules, which by absorbing high-energy solar ultraviolet radiation
protects organisms on earth Also called: ozonosphere
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partial pressure - the pressure that a gas, in a mixture of gases, would exert
if it alone occupied the whole volume occupied by the mixture
Peltier effect - the production of heat at one junction (связывание,
соединение, объединение) and the absorption of heat at the other junction of a
thermocouple (термоэлемент, термопара; термостолбик) when a current is
passed around the thermocouple circuit. The heat produced is additional to the heat
arising from the resistance of the wires
phonon - a quantum of vibrational energy in the acoustic vibrations of a
crystal lattice
Rankine cycle - the thermodynamic cycle in steam engines by which water
is pumped into a boiler at one end and the steam is condensed at the other
Etymology: named after W. J. M. Rankine (1820-72), Scottish physicist
refrigerant - 1) a fluid capable of changes of phase at low temperatures:
used as the working fluid of a refrigerator 2) a cooling substance, such as ice or
solid carbon dioxide 3) causing cooling or freezing
rhenium - a dense silvery-white metallic element that has a high melting
point. It occurs principally in gadolinite and molybdenite and is used, alloyed with
tungsten or molybdenum, in high-temperature thermocouples. Symbol: Re; atomic
no.: 75; atomic wt.: 186.207; valency: -1 or 1-7; relative density: 21.02; melting
pt.: 3186°C; boiling pt.: 5596°C (est.)
sodium chloride - common table salt; a soluble colourless crystalline
compound occurring naturally as halite and in sea water: widely used as a
seasoning and preservative for food and in the manufacture of chemicals, glass,
and soap. Formula: NaCl Also called: salt
Sodium nitrate - white crystalline soluble solid compound occurring
naturally as Chile saltpetre and caliche and used in matches, explosives, and rocket
propellants, as a fertilizer, and as a curing salt for preserving food such as bacon,
ham, and cheese (E251). Formula: NaNO3
stroke - a single complete movement or one of a series of complete
movements
temperature gradient - the rate of change in temperature in a given
direction, esp in altitude
toxicity - 1) the degree of strength of a poison 2) the state or quality of
being poisonous
tungsten - a hard malleable ductile greyish-white element. It occurs
principally in wolframite and scheelite and is used in lamp filaments, electrical
contact points, X-ray targets, and, alloyed with steel, in high-speed cutting tools.
Symbol: W; atomic no.: 74; atomic wt.: 183.85; valency: 2-6; relative density:
19.3; melting pt.: 3422±20°C; boiling pt.: 5555°C Also called: wolfram
working substance - the fluid, esp water, steam, or compressed air, that
operates an engine, refrigerator, etc.
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