Question

A heat pump receives heat from a lake that has an average winter time temperature of 6°C and supplies heat into a house having an average temperature of 27°C as shown in Fig.1. (a) If the house loses heat to the atmosphere at the rate of 64,000 kJ/h, determine the minimum power supplied to the heat pump, in kW. (b) A heat exchanger is used to transfer the energy from the lake water to the heat pump. If the lake water temperature decreases by 5°C as it flows through the lake water-to-heat pump heat exchanger, determine the minimum mass flow rate of lake water, in kg/s. Neglect the effect of the lake water pump.

Answer 1

Answer:

Concept: Consider the data, The temperature of heat source of a heat pump TH=27°C=27+273 The temperature of stnk of a heat pump is, TL=6°C=6+373=279K Part - (a) Now calculate the power supplied The heat lost to the atmosphere, QH=6000kJ/h hence,the COP of a reversible heat pump is, Now calculate the minimum power input to the pump Hence the minimum power supply is, Part- (b) Consider the minimum mass flow rate of lake, and the rate of heat absorbed by the 3 lake is, The amount of heat supplied...