Unformatted text preview: orm between the same
pressure limits. Proof that Steady-Flow Devices Deliver the Most and
Consume the Least Work when the Process Is Reversible
We have shown in Chap. 6 that cyclic devices (heat engines, refrigerators, and
heat pumps) deliver the most work and consume the least when reversible
processes are used. Now we will demonstrate that this is also the case for individual devices such as turbines and compressors in steady operation.
Consider two steady-flow devices, one reversible and the other irreversible,
operating between the same inlet and exit states. Again taking heat transfer to
the system and work done by the system to be positive quantities, the energy
balance for each of these devices can be expressed in the differential form as
dpe The right-hand sides of these two equations are identical since both devices
are operating between the same end states. Thus,
dqact dwact dqrev dwrev dwrev dwact dqrev dqact dqrev T ds or However,...
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