Solved Problem 6.5 - Adiabatic Efficiency of a R134a Compressor

Consider the R134a refrigerator compressor 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 [53.9 kJ/kg] .

• c) Using R134a refrigerant tables determine the adiabatic efficiency of the compressor [η _C = 92%] .

• 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.

Solution Approach:

Discussion: This is a feasible compressor design - the adiabatic efficiency is higher than we expected however within an acceptable range (less than around 95%).