Performance investigation of vapor and liquid injection on a refrigeration system operating at high compression ratio

• Experimental study is made for vapor and liquid injection with suction port.
• Adopting injection proves to be effective in reducing the discharge temperature.
• The liquid injection is recommended with a maximum injection ratio of 10%.
• The subcooling is proposed as a controlling parameter of injection ratio.

In this study, the performance of an R22 refrigeration system of 9.6 kW cooling capacity injecting vapor and liquid refrigerant to compressor inlet through accumulator is analyzed at high compression ratio experimentally. Results obtained in this study are compared and discussed for better performance of refrigeration system with respect to the injection type and ratio. In vapor injection, the COP decreased with increasing injection ratio while in the liquid injection, the COP increased up to 10% of injection ratio and decreased beyond that. Thus, the liquid injection up to 10% is recommended at high compression ratio in order to minimize the performance decrease and extend operating range of a refrigeration system. In addition, the subcooling for liquid injection could be considered as a proper parameter to control the injection for the reliable operation in the liquid injection case.