Based on blanked suction test data, equations for the prediction of the volumetric and compression efficiencies for a reciprocating compressor have been developed. Experimental evidence shows that these equations can be used to compute the coefficient of performance of a vapor-compression refrigeration system with an expected accuracy of +/-10%.

In the operation of positive displacement compressors, deviations from ideal performance arise due to various losses, with a resulting decrease in capacity and an increase in power input. The most important losses are pressure drop within the compressor, valve inefficiency due to imperfect mechanical action, deviation from isentropic compression, etc. It is often impractical to consider all these losses individually.l However, their collective effect upon ideal compressor performance is usually characterized by the following three parameters: volumetric efficiency, compression efficiency and mechanical efficiency. These three parameters are normally determined experimentally.

A simple experimental test for a reciprocating compressor is the blanked suction test. Such test data are available from compressor manufacturers. If it is assumed that the characteristics of the losses in a compressor do not vary significantly with load, then the blanked test data can be used to evaluate the actual performance of a given compressor.

In the present paper, an attempt is made to derive relations for the actual volumetric and compression efficiencies in terms of blanked suction test data. Analytical results derived for these parameters agree very closely with available experimental data.