A water cooler using R12 refrigerant works between 30C to 9C. Assuming the volumetric and mechanical...

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A water cooler using R12 refrigerant works between 30°C to 9°C. Assuming the volumetric and mechanical efficiency of the compressor to be 80 and 90% respectively, and the mechanical efficiency of motor to be 90%, and 20% of useful cooling is lost into water cooler, find: 1) The power requirement of the motor 2) Volumetric displacement of the compressor Given Cp (saturated vapour at 30°C) = 0.7 kJ/kg K (Solution) The properties of F12 at 30°C and 2°C are: Temp °C Pressure (Bar) Liquid 30 5 7.45 3.626 hf (kJ/kg) 64.6 40.7 Vapour Sg (kJ/kg K) Sf hg (kJ/kg) (kJ/kg K) 0.2399 199.6 0.6854 0.1587 189.7 0.6942 Vs m³/kg 0.0235 0.0475 A water cooler using R12 refrigerant works between 30°C to 9°C. Assuming the volumetric and mechanical efficiency of the compressor to be 80 and 90% respectively, and the mechanical efficiency of motor to be 90%, and 20% of useful cooling is lost into water cooler, find: 1) The power requirement of the motor 2) Volumetric displacement of the compressor Given Cp (saturated vapour at 30°C) = 0.7 kJ/kg K (Solution) The properties of F12 at 30°C and 2°C are: Temp °C Pressure (Bar) Liquid 30 5 7.45 3.626 hf (kJ/kg) 64.6 40.7 Vapour Sg (kJ/kg K) Sf hg (kJ/kg) (kJ/kg K) 0.2399 199.6 0.6854 0.1587 189.7 0.6942 Vs m³/kg 0.0235 0.0475