Influence of clearance height on performance of water-lubricated single-screw air compressor

Abstract

Addressing the growing need of oil-free compressed air has drawn the development of the water-lubricated single-screw air compressor (WLSSAC). For WLSSAC, clearance height is an important design parameters relevant to compressor performance. In this study, a thermodynamic model of the working process of a WLSSAC is established in consideration of the viscous friction power consumption and mass transfer between water and wet air. The theoretical model is simulated by Matlab software, and the accuracy of the theoretical model is verified by experimental results. The influence of each leakage path on the rate of leakage flow, viscous friction power consumption, and efficiency are analyzed using the proposed model. The effects of clearance height on adiabatic efficiency, volumetric efficiency, and specific power are calculated and discussed. Results show that the viscous friction power consumption caused by wall velocity decreases gradually with the increase in clearance height, while the viscous friction power consumption caused by pressure difference increases gradually in each leakage path. With the increase in clearance height, the rate of leakage flow increases gradually, the adiabatic and volumetric efficiencies decrease gradually, and the specific power increases gradually. The clearance height is recommended to be 0.03–0.06 mm for the design of WLSSAC.