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At steady state, a refrigeration cycle removes 150 kJ/min of energy by heat transfer from a space maintained at 50 C and discharges energy by heat transfer to surroundings at 15 C. If the coefficient of performance of the cycle is 30 percent of that of a reversible refrigeration cycle operating between thermal reservoirs at these two temperatures, determine the power input to the cycle, in kW.

If heat transfer through the walls and roof of a dwelling is 6.5 105 Btu per day, determine the minimum theoretical power, in hp, to drive a heat pump operating at steady state between the dwelling at 70 F and

(a) the outdoor air at 32 F.

(b) a pond at 40 F.

(c) the ground at 55 F.