| Title |
Effects of Refrigerant and Oil Charges on the Performance of an Refrigeration System |
| Keywords |
COP ; 성능계수 ; Capacity ; 냉동용량 ; Automobile air conditioner ; 자동차 공조기 ; R134a ; 냉매134a ; PAG ; 폴리알킬렌글리콜 ; Oil charge ; 냉동기유 주입량 ; Refrigerant charge ; 냉매 충진량 |
| Abstract |
In this study, effects of refrigerant and oil charges on the performance of a refrigeration system simulating an automobile air conditioner have been experimentally investigated using R134a and PAG oil. Measurements were taken in a breadboard type refrigeration test unit with a compressor used for a commercial automobile air-conditioner under a set of condition imposed upon normally to automobile air conditioners. Both the COP and capacity decreased rapidly as the oil charge increased because of the decrease in vapor pressure of the circulating refrigerant/oil mixture. The excess oil left in the evaporator also caused heat transfer degradation resulting in a decrease in capacity and in turn COP. It was found that there is an optimum refrigerant charge at which the COP becomes the maximum. Below this optimum charge, both the capacity and COP increased as the refrigerant charge increased and above the optimum charge, both of them remained almost constant. Hence, the COP seems to be the most important factor in determining the optimum refrigerant charge. When the system was undercharged, the refrigerant at the condenser exit lost subcooling and showed a sign of poor miscibility. |