Efficiency evaluation of a miniature multi-stage compressor under insufficient inter-stage cooling conditions

Abstract

A miniature multi-stage compressor (MMSC) with an integrated inter-stage cooler has been proposed. This study aims to evaluate the efficiency of each stage of the MMSC under insufficient inter-stage cooling conditions through numerical simulation. The results show that the volumetric efficiency of first-stage, second-stage, third-stage and fourth-stage reduced by an average of 1.43%, 1.86%, 2.32%, and 2.56% respectively as suction temperature increases every 10 °C, indicating that the temperature has more remarkable influences on the volumetric efficiency with the increase of pressure and the decrease of cylinder diameter. For every 10 °C increase in temperature, the isentropic efficiencies are all reduced by about 1%. And it should be noted that when the suction temperatures of the second, third, fourth stage cylinder exceed 120 °C, 70 °C, and 50 °C, respectively, the valve flutters severely, indicating that the valve has a poor applicability to the current operating conditions.