Development of an In-Cylinder Heat Transfer Correlation for Reciprocating Compressors
Abstract
The gas superheating that takes place throughout the suction system and inside the cylinder of reciprocating compressors adversely affects their overall efficiency. Simulation models adopted in the design of reciprocating compressors are generally based on lumped formulation and rely on empirical correlations for different physical phenomena, including the gas-to-wall heat transfer in the cylinder. The present paper reports a numerical study of heat transfer inside the cylinder of a simplified geometry of reciprocating compressor, considering the effect of fluid flow through the valves. Predictions for the instantaneous heat transfer at the walls are obtained for actual operating conditions and compared with estimates given by correlations commonly adopted for reciprocating compressors. It is shown that the increase of heat transfer during the suction and discharge processes is not properly accounted for by such correlations. Based on the predictions, a new correlation for the in-cylinder heat transfer is put forward and tested in different operating conditions.