Numerical study on the optimal design of injection-hole geometries of a twin rotary compressor in a liquid injection heat pump

Abstract

In a liquid injection heat pump, it is very essential to control the compressor discharge temperature without wet-compression problems at extreme outdoor conditions. The objective of this study was to optimize the injection-hole geometries of a liquid injection heat pump in order to prevent the risk of wet compression while reducing compressor discharge temperature at overload cooling conditions. In this study, a simulation model for predicting the performance of a liquid injection heat pump was developed and validated. The optimum injection-hole geometries were determined to obtain the maximum multiplication ratio, which led to a lower instant injection mass flow rate in terms of R- and theta-directional positions. In addition, the injection-hole diameter was minimized to prevent wet-compression while obtaining the target injection mass flow rate. The discharge temperature of the optimized compressor was decreased by 9.2 degrees C over the baseline compressor while maintaining the same risk for wet compression at the overload cooling test condition. (C) 2016 Elsevier Ltd. All rights reserved.