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TEKNIK MESIN
FAKULTAS TEKNOLOGI INDUSTRI
UNIVERSITAS MERCU BUANA
MODUL KE SEPULUH
THERMODINAMIKA DASAR
NANANG RUHYAT
SIKLUS RANKINE
The Rankine cycle is a thermodynamic cycle. Like other thermodynamic cycles, the
maximum efficiency of the Rankine cycle is given by calculating the maximum efficiency
of the Carnot cycle. It is named after William John Macquorn Rankine, a Scottish
polymath.
Seorang Insinyur & Fisikawan Skotlandia sekaligus profesor keteknikan di univ. dari
Glasgow tn 1855 Lahir 5 Juli 1820 di Edinburg dan meningal dunia tangal 24 desember
1872 di Glasgow Tahun 1842 W.J.M Rankine memulai usaha pertamanya mempelajari
gejala2 dari panas dan di th 1859 beliau berhasil mengembangkan suatu siklus
termodinamik dari rancang bangun tenaga uap dimana uap air sebagai media untuk
PUSAT PENGEMBANGAN BAHAN AJAR-UMB
MT.http://www.mercubuana.ac.id
Ir. Nanang Ruhyat
THERMODINAMIKA DASAR
1
Rankine cycle is a heat engine with vapor power cycle. The common working fluid is water.
The cycle consists of four processes:
1 to 2: Isentropic expansion (Steam turbine)
2 to 3: Isobaric heat rejection (Condenser)
3 to 4: Isentropic compression (Pump)
4 to 1: Isobaric heat supply (Boiler
PUSAT PENGEMBANGAN BAHAN AJAR-UMB
MT.http://www.mercubuana.ac.id
Ir. Nanang Ruhyat
THERMODINAMIKA DASAR
3
·
Process 1-2: The high pressure liquid enters a boiler where it is heated at constant
pressure by an external heat source to become a saturated vapor. Common heat
sources for power plant systems are coal (or other chemical energy), natural gas, or
nuclear power.
·
Process 2-3: The superheated vapor expands through a turbine to generate power
output. Ideally, this expansion is isentropic. This decreases the temperature and
pressure of the vapor.
·
Process 3-4: The vapor then enters a condenser where it is cooled to become a
saturated liquid. This liquid then re-enters the pump and the cycle repeats.
The exposed Rankine cycle can also present vapor overheating[1] , which reduces the
amount of liquid condensed after the expansion in the turbine.
Rankine cycles describe the operation of steam heat engines commonly found in power
generation plants. In such vapour power plants, power is generated by alternately vaporizing
and condensing a working fluid (in many cases water, although refrigerants such as
ammonia may also be used).
The working fluid in a Rankine cycle follows a closed loop and is re-used constantly. Water
vapour seen billowing from power plants is evaporating cooling water, not working fluid. (NB:
steam is invisible until it comes in contact with cool, saturated air, at which point it
condenses and forms the white billowy clouds seen leaving cooling towers).
Heat input rate (energy per unit time)mass flow rate (mass per unit time)mechanical power
used by or provided to the system (energy per unit time)ηthermodynamic efficiency of the
process (power used for turbine per heat input, unitless)h1,h2,h3,h4these are the "specific
enthalpies" at indicated points on the T-S diagram.
PUSAT PENGEMBANGAN BAHAN AJAR-UMB
MT.http://www.mercubuana.ac.id
Ir. Nanang Ruhyat
THERMODINAMIKA DASAR
5