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Q6. A vapour compression refrigeration cycle using Ammonia has compressor suction and discharge pressure of 3.413 bar and 11.67 bar respectively. The vapour enters the compressor in a dry saturated state and leaves at a temperature of 105 o C. The liquid refrigerant has 4 K of sub-cooling at entry to the expansion value.

(a) Sketch The cycle on Pressure-specific enthalpy and Temperature-specific entropy diagrams. (4)

(b) Determine EACH of the following:

(i) The percentage of dry vapour entering the evaporator; (3)

(ii) The specific work done; (3)

(iii) The coefficient of performance; (2)

(iv) The isentropic efficiency of the compressor. (2)