9. An ammonia vapour-compression refrigerator has a single-stage, single-acting reciprocating compressor which has a bore of 127 mm, a stroke of 152 mm and a speed of 240 r.p.m. The pressure in the evaporator is 1.588 bar and that in the condenser is 13.89 bar. The volumetric efficiency of the compressor is 80% and its mechanical efficiency is 90%. The vapour is dry saturated on leaving the evaporator and the liquid leaves the condenser at 32°C. Calculate the mass flow of refrigerant, the refrigerating effect, and the power ideally required to drive the compressor. [Ans. 0.502 kg/min ; 9.04 kW; 2.73 kW]

9. A vapour compression plant is powered by a 2kW motor and circulates R12 at 5kg/min. The R12 leaves the condenser at its saturation temperature with a specific enthalpy of 74.59kJ/kg and leaves the evaporated dry saturated with a specific enthalpy of 187.53kJ/kg. Calculate: (a). the dryness fraction at the evaporator inlet (b). refrigeration effect (c). coefficient of performance