Design a domestic heating system that uses a heat pump to extract heat from the earth to heat a house. The evaporator is to be made of long lengths of plastic pipe buried below the frost line at a constant temperature of 50.0°F. The heat pump system must provide 200. × 103 Btu/h to the house at 70.0°F.
Specify the refrigerant; the length, diameter, and type of plastic to be used for the evaporator piping; the mass flow rate of the refrigerant; and the compressor efficiency. Also determine the pumping losses (i.e., the pressure drop) in the evaporator.
Estimate or compute an appropriate temperature differential between the outside and the inside of the condenser and the evaporator.