THE ROLE OF INTERNAL HEAT EXCHANGER IN AN R744 VAPOR COMPRESSION SYSTEM IN THE HEAT PUMP MODE UNDER VARIOUS CONDITIONS

Abstract

In this paper, the role of the internal heat exchanger (IHX) in a reversible R744 vapor compression system in the heating mode was investigated experimentally and presented. At the first, the optimal refrigerant charge amount for both basic and the IHX systems was determined. Also, the control equations of HPF-maximizing high side pressure were developed and used for both systems. Then, well-tuned systems working at the optimal discharge pressure were compared in two scenarios under various conditions. The results of the experiments reveal the potential benefits of introducing IHX for the R744 system in the heating mode. The efficiency was improved by up to 10.5% by introducing the internal heat exchanger. Also, the benefits of IHX in the frosting conditions were discussed.