Experimental investigation on twin screw refrigeration compressor with different capacity control methods

Slide valve and variable-speed control are commonly used in twin screw refrigeration compressors independently to regulate the refrigerating capacity of the compressor. In this paper, the pressure fluctuation characteristics, noise characteristics, and thermodynamic performance of a twin screw refrigeration compressor with slide valve and variable-speed control at the same volume flow rate are tested and compared. The relationship among pressure fluctuation, noise characteristics, and thermodynamic performance is investigated, when the evaporating temperature and the condensing temperature are set to 6 °C and 36 °C, respectively. Results show that the compressor with variable-speed control has better comprehensive characteristics than that with slide valve. The noise of the compressor with variable-speed control is lower than that of the compressor with the slide valve and the reduction of noise reaches 10.52 dB(A) at the volume flow rate of 381.07 m³•h⁻¹. The thermodynamic performance under part-load conditions of the compressor with variable-speed control is better than that of the compressor with slide valve. The improvement of COP and total efficiency reaches 33.57% and 38.16% at the volume flow rate of 381.07 m³•h⁻¹.