The performance (thermal efficiency) of refrigeration units and heat pumps is expressed in terms of
coefficient of performance (COP).
The Coefficient of Performance of refrigeration (COPR) is defined as the ratio of the desired output of
the refrigeration unit to the work input from external work .
The COP of the VAR refrigeration system is comparatively lower when compared to the VCR refrigeration
system.
Where QL = The desired output.ie. the heat transferred from the refrigerated space to the refrigerant.
Q_gen = The heat energy provided at the generator transferred from the exhaust gas
W(pump,in)= The work done by the pump. (This is very small often neglected in the cycle analysis).
This implies that the COP of the VAR system (COPVAR) = (Desired Output)/(Required Input)
= QL/(Q_gen + W(pump,in) )
But W (pump,in) is neglected, therefore;
(COPVAR) = QL/Q_gen
There are many elements affecting the overall performance of the absorption thermal systems. The major factors that affect the COP of the Absorption method of refrigeration are the type of refrigerant used and the temperature ranges (operating pressures) of the components.