An ideal vapor-compression refrigeration cycle, with ammonia as the working fluid, has an evaporator temperature of -20 C, and a condenser pressure of 12 bar. Saturated vapor enters the compressor, and saturated liquid exits the condenser. The mass flow rate of the refrigerant is 3 kg/min.
a) Determine the COP of the refrigerator and net rate of heat removal from the cold box.
b) Determine the rate of heat rejected to the ambient.