Propane is used in a vapor-compression refrigeration system for a household refrigerator that has a refrigerating capacity of 900 btu/h. refrigerant enters the evaporator at -15°f and exits at 20°f. the isentropic compressor efficiency is 75%. the refrigerant condenses at 110°f and exits the condenser subcooled at 100°f. there are no significant pressure drops in the flows through the evaporator and condenser. determine the evaporator and condenser pressures, each in lbf/in2 , the mass flow rate of refrigerant, in lb/min, the compressor power input, in horsepower, and the coefficient of performance