13. A R-134a mechanical vapor-compression refrigerator works between an evaporator and condenser saturation temperatures of -10C and 48C, respectively. The vapor at the compressor inlet is superheated to 0C whereas that at the compressor exit is superheated to 70C. At the exit of the condenser, the liquid is sub-cooled to 40C. Calculate with the aid of R-134a chart and by assuming 1 kg/s of refrigerant passing through the evaporator: (a) Isentropic efficiency of the compression process. (b) (c) (d) Refrigeration effect of the refrigerator. Power input to the compressor. COP of the refrigerator. [Ans: (a) 0.78; (b) 145 kW; (c) 45 kW; (d) 3.22]