文档介绍：Thermodynamics and Statistical Mechanics
Heat Engines and Refrigerators
1
Thermo & Stat Mech - Spring 2004 Class 17
Carnot Cycle
A Carnot cycle is an idealized cycle that operates between two heat reservoirs at temperatures T1 and T2, where T1 > T2. It can operate as a heat engine, or a refrigerator.
A Carnot cycle is reversible, so DS = 0 for the cycle.
2
Thermo & Stat Mech - Spring 2004 Class 17
Carnot Cycle (Heat Engine)
3
Thermo & Stat Mech - Spring 2004 Class 17
Carnot Cycle
For an isothermal process:
For an adiabatic process:
4
Thermo & Stat Mech - Spring 2004 Class 17
Carnot Cycle
5
Thermo & Stat Mech - Spring 2004 Class 17
Path 1
6
Thermo & Stat Mech - Spring 2004 Class 17
Paths 2, 3, and 4
7
Thermo & Stat Mech - Spring 2004 Class 17
Carnot Cycle
Divide 1 by 3 and then 2 by 4, and
8
Thermo & Stat Mech - Spring 2004 Class 17
Carnot Cycle
For the entire cycle, Q = W + DE, and DE = 0.
The total heat equals the total work, Q = W.
W = Q1 – Q2
Conservation of energy.
Q1 = Q2 + W
9
Thermo & Stat Mech - Spring 2004 Class 17
Thermal Efficiency (h)
If T2 = 0, h = 1 (100%)
10
Thermo & Stat Mech - Spring 2004 Class 17