Approaching the performance limit for economized cycles using simplified cycles

Modifications such as economization aim to improve the efficiency of vapor compression equipment by cooling the refrigerant during the compression process. A previous study (Mathison et al., 2010) explored the theoretical limit to cycle performance with economizing, which was defined as the performance when a saturated vapor state was maintained in the compressor by continuously injecting a two-phase mixture. However, achieving continuous injection and controlling the quality of the injected refrigerant poses a substantial challenge. Therefore, the current paper investigates the ability of an economized cycle with saturated vapor injection through a finite number of ports to approach the limiting cycle performance. For an air-conditioner using R-410A with an evaporation temperature of 5 °C and a condensing temperature of 40 °C, the model predicts that injecting saturated vapor through three ports will improve the COP by 12%, which is approximately 67% of the maximum benefit provided by economizing in the limiting case.