Behaviour of refrigerant mixtures with gas/liquid injection

In this paper, the impact of gas/liquid injection on the behaviour of new alternative refrigerant mixtures such as; R-410A, R-507, R-407C, and R-404A are discussed, analysed and presented. The test results were obtained using an air–source heat pump set up with enhanced surface tubing heat exchanger under various gas/liquid injection ratios. Performance tests were conducted according to the ARI/ASHRAE Standards. The performance data demonstrated that as gas/liquid injection increases compressor head pressure and discharge temperature decrease and this has a positive effect in protecting the compressor. The effect of gas/liquid injection on mixture behaviour varies from mixture to another depending upon the mixture composition. Furthermore, hot gas injection appears to have a significant and positive influence on the COP. The performance of refrigerants R-407C and R-404A has been enhanced with 5% gas injection and mix of gas and liquid 5% injection, respectively. The data presented in these figures also show that other hot gas injection ratios and gas/liquid mix degrade the heat exchanger performance. Copyright © 2003 John Wiley & Sons, Ltd.