Refrigerant R134a is used as a working fluid in a heat pump

Refrigerant R134a is used as a working fluid in a heat pump. It maintains the inside temperature of a building at 22 degree C when the outside temperature is 5 degree C. Saturated vapor enters the compressor at -8 degree C and exits at 50 degree C and 10 bar. Saturated liquid exits the condenser at 10 bar. The mass flow rate of the refrigerant is 0.2 kg/s. Determine the: Compressor power in kW Isentropic compressor efficiency rate of heat transfer provided to the building in kW and the coefficient of performance

Solution

COP= T(HOT) / T(HOT)- T (COLD)

= 22/ (22-5) = 1.29

Compressor Power = Q cond. / COP

Compressor Power = Q cond./ 1.29

Also we have

COP = Q / electrical energy needed