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Q2. A vapor compression refrigeration plant using R134a operates between saturation temperatures of -20°C and +25ºC.

The plant produces 200 kg/hour of ice at -12°C from water at +20ºC.

The refrigerant enters the expansion valve at the rate of 531 kg/hour with 5 K of sub-cooling.

The isentropic efficiency of the compressor is 93.1%.

(a) Sketch the cycle on p-h and T-s diagrams.

(b) Calculate EACH of the following:

(i) The temperature of the refrigerant entering the compressor;

(ii) The temperature of the refrigerant leaving the compressor;

(iii) The cycle co-efficient of performance.

Note: for water C_p = 4.187 kJ/kg K

For ice C_p = 2.1 kJ/kg K and enthalpy of fusion = 335 kJ/kg