An inventor presents a cyclic device that interacts with two thermal reservoirs:
• It absorbs 800J of energy as heat from a high-temperature reservoir at 700K.
• It rejects 320J of energy as heat to a low-temperature reservoir at 400K.
• It delivers the remainder of the absorbed energy as useful work in each cycle.
(a) Determine the amount of work produced by the device in one complete cycle.
(b) For the high-temperature reservoir, calculate the magnitude and sign of the entropy change per cycle.
(c) Repeat part (b) for the low-temperature reservoir.
(d) Using your results, find the total entropy change of the universe for one cycle.
(e) Discuss whether the device is permissible under the second law of thermodynamics. If it is not, propose one specific quantitative modification to the heat-interaction values that would make a revised device just barely comply with the second law.