Question 1
Paper 2Hard10 marksA cyclic engine operates between two thermal reservoirs at and The engine, both reservoirs and an ideal mechanical work store form an isolated assembly. The engine returns to its initial state each cycle, and the work store’s entropy does not change.
For a reservoir at constant temperature, its entropy change is where is the energy received by the reservoir.
State the Clausius form and the Kelvin form of the second law of thermodynamics.
In one proposed cycle, the engine receives from the reservoir, transfers to the reservoir and delivers to the work store.
Assess whether this proposed cycle is consistent with energy conservation and the second law.
The engine continues to receive from the reservoir each cycle. Determine the greatest possible work delivered to the work store per cycle, consistent with the second law, and state whether the limiting cycle is reversible or irreversible.