### Compressor and the isentropic efficiency of the compressor

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##### Reference no: EM13717737

A refrigeration unit operating on R-134a is used to maintain a freezer at -15°C. The refrigeration unit operates at a suction pressure of 140kPa and a discharge pressure of 900kPa. The condenser of the refrigeration unit is cooled by a water cooled heat exchanger. Cooling water flows through the condenser heat exchanger at a rate of 50kg/min, entering at a temperature of 20°C and leaving at a temperature of 29°C. It is known that the refrigeration unit can be modelled as an ideal vapour compression cycle for the heat rejection, throttling and heat absorption stages; however the compressor is known to be non-isentropic. The discharge temperature from the compressor is 60°C.

1) Determine the mass flow rate of the refrigerant, assuming a constant specific heat for the cooling water of C water=4.184 kJ/(kg.K).

2) What is the required power input to the compressor and the isentropic efficiency of the compressor?

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