A vapour compression refrigerator uses R-12 as refrigerant and the li…

Question

A vapour compression refrigerator uses R-12 as refrigerant and the liquid evaporates in the evaporator at $-15^\circ\text{C}$. The temperature of this refrigerant at the delivery from the compressor is $15^\circ\text{C}$ when vapour is condensed at $10^\circ\text{C}$. Find the COP

i. There is no under-cooling and

ii. The liquid is cooled by $5^\circ\text{C}$ before expansion by throttling.

Take specific heat at constant pressure for the superheated vapour as $0.64\text{ kJ/kg K}$ and that for liquid as $0.94\text{ kJ/kg K}$.

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