A heat engine receives heat from a constant volume tank filled with 2 kg of air. The

Question:

A heat engine receives heat from a constant volume tank filled with 2 kg of air. The engine produces work that is stored in a work reservoir and rejects 400 kJ of heat to a heat reservoir at 300 K. During the process the temperature of the air in the tank decreases to 300 K.
(a) Determine the initial temperature of the air that will maximize the work and the thermal efficiency of the engine.
(b) Evaluate the total entropy change of this isolated system, the work produced, and the thermal efficiency for the initial air temperature in the tank from part (a) and at 100 K above and below the answer to part (a).
(c) Plot the thermal efficiency and the entropy generation as functions of the initial temperature of the air. Comment on your answers. Assume constant specific heats for air at 300 K.