Example $2$

A cold storage room is being maintained at $2\backslash$deg C using a vapor$-$compression

refrigeration system that uses R$-134$a$.$ The evaporator and condenser

temperatures are $-5$ and $40\backslash$deg C$,$ respectively. The refrigeration load is $20$ tons.

Calculate $(1)$ the mass flow rate of refrigerant, $(2)$ the compressor power

requirement, and $(3)$ the C$.$O$.$P$.($Assume the unit operates under saturated

conditions and the compressor efficiency is $85\%).$