A house has a winter heating requirement of 30 kJ/s and a summer cooling require

Question

A house has a winter heating requirement of 30 kJ/s and a summer cooling requirement of 60 kJ/s. Consider a heat-pump installation to maintain the house temperature at 20 °C in the winter an 25 °C in the summer. This requires circulation of the refrigerant through interior exchanger coils at 30 °C in the winter and 5 °C in the summer. Underground coils provide the heat source in the winter and the heat sink in the summer. For a year- round ground temperature of 15 °C, the heat transfer characteristics of the coils necessitate refrigerant temperatures of 10 °C in winter and 25 °C in summer. What are the minimum power requirements for winter heating and summer cooling?

Explanation / Answer

assuming the ideal condition

COP in summer = Tc/(Th-Tc) = 278/(298 -278) = 13.9

so power req for summer cooling = 60/13.9 = 4.32 KJ/s

COP in winter = Th/(Th-Tc) = 303/(303-283) = 15.15

so power req for winter heating = 30/15.15 = 1.98 kJ/s

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