A 10-kW cooling load is to be served by operating an ideal vapor-compression refrigeration cycle with its evaporator at 400 kPa and its condenser at 800 kPa. Calculate the refrigerant mass flow rate and the compressor power requirement when refrigerant-134a is used.

0.0625kg/s

0.9031kW

Explanation:

At state 1, enthalpy and entropy are determined from table R-134a.

P1 = 400kpa

h1 = 255.55kj

S1 = 0.92691

h2 = 270kj/kg

Enthalpy at states 3 and 4 can be gotten from the pressure and state with data from a-12

h3 = h4 = 95.48kj/kg

1.)

The mass flow rate

= QL/h1 - h4

= 10/255.55-95.48

= 10/160.07

= 0.0625kg/s

2.)

The power requirement

= 0.0625(270-255.55)

= 0.9031 kW