A power cycle operating at steady state receives energy by heat transfer at a rate QH at TH = 1800 K and rejects energy by heat transfer to a cold reservoir at a rate QC at TC = 600 K. For each of the following cases, determine whether the cycle operates reversibly, operates irreversibly, or is impossible.

(A) QH =500kW, QC =100kW
(B) QH = 500 kW, Wcycle = 250 kW, QC = 200 kW
(C) Hot reservoir at Q = 1000°R
(D) Wcycle =350kW, QC =150kW

Refrigerant-134a enters the compressor of a refrigerator as superheated vapor at 0.14 mpa and -10°c at a rate of 0.05 ka/s and leaves at 0.8 mpa and 50°c. the refrigerant is cooied in the condenser to 0.72 mpa and 26'c. it is then throttled to 0.15 mpa. sketch the t-s diagram for the system and evaluate: 6) the rate of heat removai from the refrigerated space (kw), it) the power input to the compressor (kw), ii) the isentropic efficiency of the compressor (%), and iv) the cop of the refrigerator.