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14/15 Semester 3
Chem. Eng. Thermodynamics
(TKK-2137)
Instructor: Rama Oktavian
Email: [email protected]
Office Hr.: M.13-15, Tu. 13-15, W. 13-15, Th. 13-15, F. 09-11
Outlines
1. Heat engine (Power from heat)
2. Steam power plant
3. Carnot cycle power plant
4. Rankine cycle power plant
Heat engine
TH
QH
W
HE
QC
TC
HE = heat engine
TH = high temp. reservoir
TC = cold temp. reservoir
Heat engine
W  QH  QC
TH
QH
HE
QC
TC
h  1
QC
QH
W
Thermal efficiency:
Net work output
h = ----------------------Heat absorbed
h
W
QH

QH  QC
QH
For 100% efficiency, QC = 0
(impossible)
Heat engine
Production power from heat:
The potential energy of tides - possible source of power
hydroelectric power is generated by conversion of the
potential energy of water into work
Combustion of fuel – the most important power source:
- power plant : steam power plant, coal power plant, NG
power plant
Internal combustion engine: -Otto and Diesel engine
Steam power plant
Produces steam in boiler
Steam power plant
Carnot cycle for steam power plant:
idealized cycle would be represented on t-s diagram
1 2 is the vaporization process
2 3 is a reversible, adiabatic
expansion of saturated vapor into
the two-phase region
3 4 is a partial condensation
process
4 1 takes the cycle back to its
origin
Ideal Rankine cycle
 simplest real power plant cycle is Rankine




cycle
pump, 4 - 1
boiler, 1 - 2
turbine, 2 – 3
condenser,
3-4
Rankine cycle
 allowing for inefficiencies in turbine and
pump
Rankine cycle
 Ex. 8.1
Rankine cycle
increase η – increase boiler pressure
 increase in pressure has QH entering at higher t
 trade-off occurs
due to change in
Δs
Cengel, Y. A., Introduction to
Thermodynamics and Heat Transfer,
McGraw-Hill,1997
Rankine cycle
increase η – lower condenser pressure
THIS RESULTS IN MORE AVAILABLE WORK
Cengel, Y. A., Introduction to
Thermodynamics and Heat Transfer,
McGraw-Hill,1997
Rankine cycle
increase η – SUPERHEATING STEAM
 superheating steam gives a higher TH for QH addition.
 also avoids condensing in
the turbine.
Cengel, Y. A., Introduction to
Thermodynamics and Heat Transfer,
McGraw-Hill,1997
Rankine cycle
increase η – INTERMEDIATE REHEAT CYCLE
 MULTIPLE REHEAT STAGES ARE POSSIBLE
 REDUCES CONDENSATION AT THE TURBINE DISCHARGE
Cengel, Y. A., Introduction to
Thermodynamics and Heat Transfer,
McGraw-Hill,1997
Rankine cycle
Regenerative Rankine Cycle
Rankine cycle
Regenerative Rankine Cycle
this method can increase the boiler feed water temperature but
it lowers steam flow to the turbine