Effect of using a porous gas cooler on the performance of trans‐critical carbon dioxide refrigeration cycle

Abstract

AbstractUsing porous gas coolers is a novel method that can be used to enhance performance parameters in the trans‐critical carbon dioxide refrigeration cycle. The behavior of trans‐critical carbon dioxide and the effect of using porous gas coolers in refrigeration systems are researched in this experimental study. Cycle coefficient of performance, heat rejection rate, evaporator cooling capacity, evaporator cooling capacity enhancement factor, coefficient of performance enhancement factor, power consumption per ton of refrigeration, and pressure drop were investigated as functions of gas cooler outlet temperature, gas cooler porosity, gas cooler pressure ratio, and air ambient temperature. Porosities of 100% (empty gas cooler; no steel balls are used during this test), 48%, 40%, and 34% were considered. Experiments were conducted at 4°C evaporating temperature and 5°C superheat. Evaporator cooling capacity and evaporator cooling capacity enhancement factor are increased by about 103% and 35.4% when reducing gas cooler outlet temperature and porosity up to 36°C and 34%, respectively. Results of this study showed that cycle coefficient of performance, coefficient of performance enhancement factor, and gas cooler heat rejection rate can be increased up to 94.4%, 55.8%, and 85.5%, respectively when reducing gas cooler porosity and gas cooler outlet temperature up to 34% and 36°C. Increasing the gas‐cooler pressure ratio up to 1.341 and reducing gas cooler porosity up to 34% resulted in an increase of about 76.2% in the coefficient of performance. A decrease in power consumption per ton of refrigeration by about 43.9% is recorded when decreasing gas cooler inlet pressure and porosity up to 84 bars and 34%, respectively. Experiments revealed that a decrease in pressure drop of about 43.7% can be achieved by increasing gas cooler outlet temperature up to 52.1°C and keeping gas cooler porosity at 34%. The cycle coefficient of performance can be increased by decreasing air outside ambient temperature.