Numerical analysis on the effects of refrigerant injection on the scroll compressor

Refrigerant injection is an effective method to improve the performance of the scroll compressor and its system under high compression ratio working conditions. This paper intends to find the exhaustive relationship between the injection parameters and the compressor’s performance. Based on a thermodynamic model, the effects of various parameters of refrigerant injection on general performance and inner compression process of scroll compressor have been investigated. As a result, it is found that the injected scroll compressor will get the maximum indicated efficiency when the ratio of inner compression ratio and outer compression ratio is a right value. The right value is 1 for the isentropic compression process, and smaller than 1 for a real compression process. Finally, the effects of all the injection factors on the compression work, refrigerant mass flow rate, p–h diagram, volumetric efficiency, and indicated efficiency are investigated detailedly.