Investigation on saturated vapor and two-phase refrigerant injection in the rotary compressor for the extreme hot and cold conditions

Abstract

Vapor injection has been widely applied in the rotary compressor to improve the heating capacity and reduce the discharge temperature in the cold condition. However, under the evaporation temperature below −20 °C or the condensation temperature above 60 °C, the discharge temperature is still relatively high, which limits compressor performance and its continuous operation time. To keep the optimal performance and further reduce discharge temperature, this paper focuses on the two-phase refrigerant injection and proposes a mathematical method to investigate the effect of injection vapor quality on the compressor performance. Based on the proposed method, some performance parameters including cooling capacity, heating capacity, EER(COP), power, discharge mass flow rate and discharge temperature have been calculated and an experiment is conducted to test these performance parameters. The calculation errors between calculated and tested results are within 4% and it indicates that the proposed method is accurate to investigate saturated vapor and two-phase refrigerant injection characteristics. The simulated results show that the use of two-phase refrigerant injection results in the trade of a slight drop in cooling capacity, heating capacity and EER(COP) for a large drop in discharge temperature, which is valuable and meaningful for engineering application under the extreme hot and cold conditions.