Performance of a linear refrigeration compressor with small clearance volume

Abstract

Linear compressors are attractive for domestic refrigerator owing to high efficiency, free piston and possible oil-free operation. Minimizing the clearance volume is an approach to increase the volumetric efficiency thus cooling capacity. This is particularly beneficial for refrigerants that require high displacement due to high friction. However, operation of linear motor with offset may deteriorate the motor efficiency due to earlier saturation. This paper experimentally compares the refrigeration performance of a linear compressor using R1234yf among using various clearance volumes and using an offset of 0 mm. Measurements with different clearances and an offset of 0 mm were carried out for compressor strokes of 11–13 mm and pressure ratios of 2.5–4.0 using R1234yf. The cooling capacity for a pressure ratio of 2.5 and a stroke of 13 mm increases by 12% as the clearance decreases from 1.07 mm to 0.4 mm. Although the motor efficiency is sacrificed, the overall coefficient of performance (CoP) increases particularly for high pressure ratio.