4. An industrial refrigerator uses R-134a to keep the cooled space at -18 °C. Heat is rejected to cooling

water flowing at 0.25 kg/s that enters the condenser heat exchanger at 15 °C and leaves at 23 °C. The

R-134a enters the condenser at 1.2 MPa and 70 °C and leaves at 46.32 °C. The R-134a at the compressor

inlet is 60 kPa and -20 °C, and the compressor loses heat to the surroundings at a rate of 450 W.

Determine (i) the quality of the R-134a at the evaporator inlet, (ii) mass flow rate of refrigerant, (iii) the

rate of cooling, (iv) the COP, and (v) the theoretical maximum cooling rate for the same power input to

the compressor. (Watch "Vapor compression example-2")