A small, variable-speed controlled scroll compressor for household air conditioners has been developed with improved performance at low operating speeds and light load conditions. This scroll compressor has discharge bypass ports and valves that connect the compression chambers and discharge chamber when overcompression occurs. This study measured the performance of compressors and the pressure change of the compression chamber. Performance of the scroll compressor is better than that of the rotary compressor, not only for the standard heating and cooling conditions, but also for low-speed and low-pressure ratio conditions. Gives construction details of the scroll compressor and results of testing. The performance of this scroll compressor is higher than that of conventional rolling-piston-type rotary compressors, not only in the standard cooling and heating conditions, but also for low speeds and low compression pressure ratios.

KEYWORDS: performance, variable speed motors, compressors, scroll compressors, domestic, unit air conditioners, rotary compressors, comparing.