Question 17 –Heat pump systems
19
MEE 4042 Refrigeration Machines
2022-2023, Spring
A vapor-compression heat pump with a heating capacity of 500
kJ/min is driven by a power cycle with a thermal efficiency of
25%. For the heat pump, Refrigerant R134ais compressed from
saturated vapor at -10 °Cto the condenser pressure of 10 bar.
The isentropic compressor efficiency is 80%. Liquid enters the
expansion valve at 9.6 bar and 34 °C. For the power cycle, 80%
of the heat rejected is transferred to the heated space. a)
Determine the power input to the heat pump compressor in kW.
b) Evaluate the ratio of the total rate that heat is delivered to the
heated space to the rate of heat input to the power cycle. c)
Determine the refrigerant flow rate.