1. Thermodynamics and Efficiency
1690/1698
1803/1824
1784
1854/1862
Steam engine
Definition Entropy
Heat  Work
Theory of efficiency

2. Evolution of concept: Heat  Work
vacuum
Steam-Water pump
Thomas Savery
1698

3. Evolution of concept: Heat  Work
Steam-Water pump
Using a Piston
Denis Papin
1690

4. Evolution of concept: Heat  Work
The Proprietors of the Invention for Raising Water by Fire
Thomas Newcomen +
(Thomas Savery)
Efficiency: 2-5 %

5. Evolution of concept: Heat  Work
James Watt
Steam engine
Efficiency: 25 %
1784

6. Steam engines: Work and Heat
 Is the amount of (useful) work limited?
 Is there an alternative medium for steam?
Thermodynamical model system: heat engine
(useful)
work
Heat
(flow)
Sadi Carnot

7. Steam engines: Carnot cycle
 Is the amount of (useful) work limited?
 Is there an alternative medium for steam?
(useful)
work
Heat
(flow)
Sadi Carnot
TH and TC separated: no internal losses
Process steps: isotherms and adiabats
 Idealized cycle: reversible process
 Arbitrary medium: perfect gas

8. Steam engines: Carnot cycle
 Is the amount of (useful) work limited?
 Is there an alternative medium for steam?
(useful)
work
Heat
(flow)
Sadi Carnot
Transformation of heat
into work always
involves losses
(QC)
1824
Maximal efficiency
depends on
(TH -TC)
TH and TC separated: no internal losses
Process steps: isotherms and adiabats
 Idealized cycle: reversible process
 Arbitrary medium: perfect gas

9. Fundaments of thermodynamics
First law: conservation of energy U
Rudolf Clausius
Second law:
transformations
(processes)
1854
Äquivalenzwert
der Verwandlung
R. Clausius Philosophical Magazine, 12 (1856) p.81

10. Fundaments of thermodynamics
First law: conservation of energy U
Second law: transformations
Sadi Carnot
(useful)
work
Heat
(flow)
Rudolf Clausius
Transformation of heat
into work always
involves losses
(QC)
1850
Maximal efficiency
depends on
(TH -TC)
1865
For all reversible
cyclic processes
1824

11. Fundaments of thermodynamics
First law: conservation of energy U
Second law: transformations
Hermann von Helmholtz
Free (useful) work
Helmholtz free energy

12. Fundaments of thermodynamics
First law: conservation of energy U
Second law: transformations
Mechanical energy (work)
Josiah Gibbs
Free (useful)
non-mechanical
work
Gibbs free energy

13. Modern classical thermodynamics
The entropy (spontaneously) always increases
until thermodynamic equilibrium is reached

14. Modern classical thermodynamics
ENTROPY ║
Heat +
Temperature
The total entropy (spontaneously) always increases
until thermodynamic equilibrium is reached

16. Heat Q vs Work W and efficiency
reversible
Sadi Carnot ( )
Carnot cycle

17. Heat Q vs Work W and efficiency
reversible
reversible
Heat engine
Carnot cycle

18. Heat Q vs Work W and efficiency
reversible
reversible
reversible
Heat engine
Carnot cycle

19. Heat Q vs Work W and efficiency
reversible
reversible
Heat engine
Carnot cycle

20. Heat Q vs Work W and efficiency
reversible
Carnot cycle
for a perfect gas
and for a
Carnot cycle
for ANY MEDIUM
Carnot cycle

21. Heat Q vs Work W and efficiency
Clausius
irreversible
Heat flows spontaneously from a hot source to a cold sink

22. Heat Q vs Work W and efficiency
Clausius
Maximal work done by the system: for a reversible process

23. Heat Q vs Work W and efficiency
Refrigeration needs work