Problem 6.9 - Adiabatic Efficiency of a High Pressure R134a Compressor

Recall Problem 4.12 , in which we evaluated a R134a heat pump system using a compressor under the conditions shown below.

• a) Carefully plot the actual and isentropic compression processes on the h-s diagram and indicate the actual and isentropic specific work done to drive the compressor on the plot.

• b) Using R134a refrigerant tables determine the specific work required to drive the compressor [43.5 kJ/kg] .

• c) Using R134a refrigerant tables determine the adiabatic efficiency of the compressor [η _C = 78%] .

• d) Discuss these results and determine if this is a feasible compressor design.

Derive all equations used starting from the basic energy equation for a flow system and the equation for adiabatic efficiency of a compressor.