For an outdoor air temperature of 20°f, 45,000 btu/hr is required to maintain the temperature in a house at 72°f. a heat pump using r-22 as the refrigerant is used to supply this heat. the r-22 leaves the evaporator at p = 45 psi, t - 12°f and the condenser operates at a pressure of 250 psi. assuming an isentropic compressor efficiency of 82%, determine: a) the refrigerant flow rate, b) the compressor power input, and c) the coefficient of performance