Question

Problem 1 (10 points). Consider a newly invented power cyclic device performing a power cycle while interacting with two thermal reservoirs. The device absorbs 2000 kJ from the hight temperature reservoir at 1000 K, and releases certain amount of heat to the low temperature reservoir at 500 K. Now consider three claims on its thermal efficiency or per ormance: η 70, η 0%, and Y-40%. (a, 4 points) Formulate the entropy production for the cyclic process in terms of the given parameters: temperatures of the reservoirs, thermal efficiency, and heat transfer from high temperature reservoir. (b, 2 points) Find the entropy production for the case -60%, justify the possibility of this invention, and determine whether this is a reversible or irreversible power cycle. (c, 2 points) Find the entropy production for the case 50%, justify the possibility of this invention, and determine whether this is a reversible or irreversible power cycle. (d, 2 points) Find the entropy production for the case -40%, justify the possibility of this invention, and determine whether this is a reversible or irreversible power cycle. Hint: Clausius inequality, T.D. 1st and 2nd laws.

Answer 1

Sol 1000 K 500K T Heak tmansfer from high tmpexahwrs As 꺼 1 Out pu wing 1s+ lao

we wuik the toteel entropy chang ox the Cyel 0 ㄥ

th 一12-1-500 looo A8 「tov ZD 500

th de 3000-1000-0 500 560 1000 I200 0430 ele リ

4