Page 142 - DJJ20063- Thermodynamics 1

DJJ20063- Thermodynamics 1

Q41

4
Boiler 1

Turbine W12
Compressor

Condenser
3 2
W34

Q23

T

4 1
T1

T2
3 2

s
B
A
Fig 4.2.1-1 The Carnot cycle

This paper, called ‘Reflection on the Motive Power of Heat’ was written by Carnot
before the enunciation of the First and Second Laws of Thermodynamics. It is a

remarkable piece of original thinking, and it laid the foundations for the work of Kelvin,

Clausius and others on the second law and its corollaries.

A brief summary of the essential features is as follows:

4 to 1: The heat energy is supplied to the boiler resulting in evaporation of the

water, therefore the temperature remains constant.

1 to 2: Isentropic expansion takes place in the turbine or engine.
2 to 3: In the condenser, condensation takes place, therefore the temperature

remains constant.

3 to 4: Isentropic compression of the wet steam in a compressor returns the

steam to its initial state.
133 | P a g e