Paper 2: Effects of Reciprocating Compressor Valve Design on Performance and Reliability

The effect of flow through compressor valve restrictions on the efficiency of the cylinder is well known. This paper provides a method of predetermining these pressure losses from the geometry of the valve design and the application conditions of the compressor stage. The model analysed is that of flow through multiple restrictions in series. The end result is a derived quantity, the ‘equivalent area’, which is the effective area of a single restriction equivalent to the total effect of the actual multiple restrictions. The relationships involving the effects of equivalent area and all other compressor parameters on compressor performance is presented in non-dimensional form. Tests are described which determined actual values of equivalent area for several valve designs and the correlations are presented, which confirm the ability to predict performance of an untested valve from its design and application. Reliability criteria are hypothesized based on considerations of the motion characteristics of the valve elements. Experimental observations of valve motion are described, and the desired characteristics defined from which the quantitative criteria are obtained. Correlations between criteria limits and field experience are presented.