A refrigeration cycle operating between two reservoirs receives energy QC from a cold reservoir at TC 5 275 K and rejects energy QH to a hot reservoir at TH 5 315 K. For each of the following cases, determine whether the cycle operates reversibly, operates irreversibly, or is impossible: (a) QC 5 1000 kJ, Wcycle 5 80 kJ. (b) QC 5 1200 kJ, QH 5 2000 kJ. (c) QH 5 1575 kJ, Wcycle 5 200 kJ. (d) 5 6.

Athin walled concentric tube exchanger is used to cool engine oil from 160°c to 60°c with water that is available at 25°c acting as a coolant. the oil and water flow rates are each at 2 kg/s, and the diameter of the inner tube is 0.5 m and the corresponding value of the overall heat transfer coefficient is 250 w/m2. oc. how long must the heat exchanger be to accomplish the desired cooling? cpwater=4.187 kj/kg-candcpengine el=2.035 kj/kg·°c, oil . 120]