The Effect of Hardware Configuration on the Performance of Residential Air Conditioning Systems at High Outdoor Ambient Temperatures

Abstract

A study was performed which investigated the effect of hardware configuration on air conditioning cooling system performance at high outdoor temperatures. The initial phase of the investigation involved the testing of ten residential air conditioning units in psychrometric rooms at Texas A&M University. All units were tested using ARI Standard 210/240 (1989) test procedures. Tests were conducted at indoor conditions of 80'F (26.7'C) db and 67'F (19.4'C) wb, and outdoor db temperatures of 82'F (27.8'C), 95-F (35-C), 100-F (37.8-C), 105-F (40.6-C), 1 10-F (43.3-C), and 120-F (48.90C). The second phase of the research involved the analysis of manufacturers' published cooling performance data for various hardware configurations. For the experimental work, measurements were taken to determine total capacity, system power, EER, and power factor. These results were then compared to manufacturers' predicted values. For the capacity, the experimental results were an average of 2.6% below the manufacturers' published values for outdoor temperatures from 85'F (29.4'C) to 115'F (46.l'C). Experimental power measurements were on average 0.4% above manufacturers' listed results. For the EER, experimental results were an average of 2.9% less than the manufacturers' predicted values. The power factors of all units were above 0.95 for the tested outdoor temperatures. In the analysis of manufacturers' published data, relationships between steady-state performance, cyclic performance, and hardware configuration were investigated for a variety of air conditioning units. A statistical relationship was found between the SEER of a unit and its corresponding EER. The split-system units possessed greater increases in EER for a given increase in SEER than the package or two-speed units. Averages values of EER/SEER for EER's at 95F (350C) were highest for the split-system units, followed by the package and two-speed units, respectively. Normalized capacity, power, and EER curves were investigated at outdoor temperatures from 85F (29.40C) to 115OF (46.1"C). On average, the two-speed units showed the smallest decrease in capacity with an increase in outdoor temperature, followed by the split-system and package-system units. The smallest power increase and smallest EER decrease with an increase in outdoor temperature were exhibited by the split-system units, followed by the two-speed and package-system units.