The increasing demand for high efficiency in the field of energy production has also had an impact on reciprocating compressors. In this case, the need to reduce losses is one of the most important challenges. In the past, most studies were focused only on the analysis of valve pressure losses. More recently, interest has been extended to the prediction of the losses through pocket valves and cylinder ducts, these losses being a crucial aspect of a more accurate estimate of the absorbed power.
The use of CFD simulation has shown great potential for the study of the entire reciprocating compressor, but is still limited by high computational costs. Recently the authors have presented a simplified CFD approach: the actual valve geometry is replaced with an equivalent porous region, which has significantly increased the speed of calculation while ensuring accuracy as well.
Based on this approach, a new methodology for the evaluation of pocket valve losses is presented. Since the pocket losses have been proven to be independent of the actual valve installed, a set of CFD simulations using a parameterized geometry of the pocket valve was performed and the relationship between the losses of the pocket and its geometrical features was obtained. An analytical response surface was defined using the values of the geometrical dimensions as inputs and the pocket flow coefficient as output. Finally, the response surface was validated through a set of test cases performed on different geometries with the actual valve and the results have shown good predictability of the tool.