A Parametric Computational Fluid Dynamics Analysis of the Valve Pocket Losses in Reciprocating Compressors

The reduction of pressure losses is one of the most important challenges for the efficiency increase of a reciprocating compressor. Since the absorbed power is strongly affected by the losses through pocket valves and cylinder ducts, an accurate prediction of these losses is essential. The use of computational fluid dynamics (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. A set of CFD simulations using a parameterized geometry of the pocket valve was performed to evaluate the relationship between the losses of the pocket and its geometrical features. An analytical response surface (RS) 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.