- #1

Robert Davidson

- 32

- 4

The author states that the area under the curve represents the heat transferred reversibly. The author didn't state what actual process the curve represents, but I couldn't think of a reversible process where there is an increase in entropy associated with a decrease in temperature. Is there any such process?

In the slide that follows the author uses the same diagram to discuss the case of an irreversible process and concludes that, for the irreversible process, the area under the curve does not equal the heat transfer, but the sum of the heat transfer and entropy generated. My question is this; since the process is irreversible it seems to me the temperature of the system, as a function of entropy would not be defined. Is it legitimate to use the same curve to represent the reversible and irreversible process as the author did? It seems to me all we know is the entropy at state 2 will be the same for the reversible and irreversible process, but the temperature at state 2 need not be.

Is it even legitimate to represent the irreversible process as a continuous (differentiable and integrable) function since the system is not in equilibrium going from state 1 and 2? There seems to be some disagreement among people as to whether or not you can even draw a T-S diagram for an irreversible process.