Study of the Breathing Effect of Reciprocating Compressor Under Duty Cycle Regulation (DCR) Capacity Control by Simulation and Experiment

Abstract

Duty Cycle Regulation is a new method for capacity control of reciprocating compressor. Like other suction-valve-unloaded methods, the DCR method would inevitably cause the Breathing Effect. In this article, the internal flow and heat transfer in the compressor under DCR control are analyzed using CFD simulation. The geometrical model of the breathing effect has already been worked out. The numerical analysis and experimental research have been fulfilled. The flow conditions of the breathing effect during the DCR process, the temperature field in suction chamber and cylinder after some breathing effect cycles, and the capacity regulation results using DCR method are obtained. FLUENT is used to compute temperature variation after some periods of regulation. It is found that after 20 periods of regulation the suction temperature is about 32K higher than the one in normal process of compressor. Through the numerical analysis and experiment, it could be concluded that the temperature rise resulted from the breathing effect affects the suction and discharge temperature, capacity and energy consumption. Based on the results of this work, the performance of reciprocating compressor could be improved by eliminating the influence of breathing effect.