An experimental investigation on the performance of an air conditioner and its operating conditions under constant outdoor moisture content and varied dry-bulb temperature has been accomplished. The test was conducted on an air conditioner using R32 with a nominal cooling capacity of 2.6 kW and the test was carried out in a controlled and standardized test room. During the test, the outdoor temperature was varied from 24 to 36℃ while maintaining the humidity ratio at 14.9 kg vapor per 1 kg of dry air. The indoor compartment was maintained at 27℃ dry-bulb temperature and 19℃ wet-bulb temperature. Generally, as the temperature of outdoor air increases by 1℃, the input power increases by 1.4%, the cooling capacity decreases by 0.9%, and the coefficient of performance decreases by 1.95%. In addition, the outdoor air temperature has a more significant effect on the refrigerant discharge and liquid line temperature than that of refrigerant suction temperature.
The present study investigates numerically the performances of an automotive air conditioning (A/C) system using R134a and R152a as working fluids for various engine running speeds. There are three engine rotation variations, i.e., 1000 rpm, 2000 rpm and 3000 rpm that represent idle, city and high speed conditions, respectively. The compressor volumetric efficiencies for 1000 rpm, 2000 rpm and 3000 rpm are 0.75, 0.65 and 0.55, respectively. The results show that the cooling capacities of R152a are slightly lower than that of R134a at the condensing temperatures of 40oC and 45oC. However, at the condensing temperature of 50oC, the cooling capacity of R152a is higher than that of R134a up to 5.0%. In addition, COPs of R152a are higher than that of R134a for all the condensing temperature. The increase of condensing temperature is more dominant to the COP improvement rather than the increase in engine rotation. The highest COP improvement is 13.5%.
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