A heat pump is to be used for heating a house in winter. The house is to be maintained at 70°F at all times. When the temperature outdoors drops to 40°F, the heat losses from the house are estimated to be 75,000 Btu/h. Determine the minimum power [Btu/h] required to run this heat pump if heat is extracted from the outdoor air at 40°F.

Explanation:

Temperature of the house,

Convert to rankine,

Heat is extracted at 40°F i.e

Calculate the coefficient of performance of the heat pump, COP

The minimum power required to run the heat pump is given by the formula:

...............(*)

Where the heat losses from the house,

Substituting these values into * above

a 2,000 calorie based diet.