Consider an R-134a vapor-compression refrigeration cycle used to maintain a cold region at temperature To when the ambient temperature is TH = 80°F. The saturated vapor enters the compressor at 15°F below Tc, and the compressor operates adiabatically with an isentropic efficiency of 80%. The saturated liquid exits the condenser at 95°F. There is no pressure drops through the evaporator or condenser, and the refrigerating capacity is 1 ton. In this problem, you will select the value of Tr. Select a value for T, between -20°F and 20°F. (a) Plot the T-s diagram. (b) Determine the mass flow rate of the refrigerant in lb/min. (c) Determine the coefficient of performance. (d) Determine the maximum coefficient of performance when a Carnot refrigerator operates between thermal reservoirs at the ambient temperature (TH) and the temperature you selected for the cold region (To). Compare this coefficient with that obtained in part (c). (e) Determine the coefficient of performance if this system is used as a heat pump for heating a building.