Evaluation of air-conditioning compressor performance for assessment of load management potential

Abstract

Residential air-conditioning contributes heavily to the electrical utilities' summer peak demand. Cycling programs in which utilities turn off air-conditioning compressors a certain percentage of each hour through remotely-controlled switches can help reduce this high electrical demand. The normal duty cycle, or run-time of a compressor must be greater than the controlled run-time otherwise there would be no effective reduction in the average hourly compressor demand.The Tennessee Valley Authority conducted a field test in which continuous electrical demand of air-conditioning compressors was recorded on magnetic tape. Duty cycles were computed from one-minute readings provided by some specialized magnetic tape translation equipment and software and then correlated with hourly electrical demand, area temperatures and cycling schedules.Statistical Analysis System (SAS) computer procedures were then used to perform the analysis of the data and to prepare tables of compressor operating statistics by hour-of-day and temperature.Results of the analysis indicated that the majority of air-conditioning compressors were running enough at peak demand times to be effective in significantly reducing the average hourly compressor demand if cycling had been implemented. The conclusions of this evaluation were used to develop operating strategies in TVA's air-conditioner and water heater load management program, Cycle & Save.