For a pair of thermal reservoirs at 700 K (hot) and 300 K (cold), an engineer evaluates two heat-engine cycles that each absorb Qh=2.0kJ of energy from the hot reservoir per cycle.
Cycle I is a reversible engine operating between the two reservoirs.
Cycle II is a real engine that produces 0.80 kJ of work per cycle and rejects the remainder of Qh to the cold reservoir.
(a) Determine the work output per cycle for Cycle I.
(b) For Cycle II, calculate the entropy change of the universe that occurs in one complete cycle.
(c) Using your results from parts (a) and (b), compute the amount of useful work that is not obtained in Cycle II because of entropy generation.
(d) If design improvements reduce the entropy generated per cycle in Cycle II to one-half of the value found in part (b) while Qh remains 2.0 kJ, determine the new work output that the improved engine could theoretically achieve.