Experimental and Simulated Investigation of Lubrication Characteristics of a Water-Lubricated Bearing in a Single-Screw Compressor

Abstract

Water-lubricated single-screw compressors (WSSCs) have developed rapidly in recent years because they can supply oil-free compressed air at considerably low costs. However, a major technical obstacle is that the conventional bearing arrangement of a star wheel shaft is prone to wear failure, which makes it difficult for WSSCs to run properly for long periods of time. To solve this problem, a star wheel thrust bearing with new liquid groove was proposed in this paper. Pulsating forces (i.e., bearing forces) acting on a star wheel shaft by compressing air were calculated through the dynamic analysis of the star wheel shaft system. A mathematical model of hydraulic water films in the bearing sliding clearance was established to describe the influence of water injection pressure on water film pressure distribution and its bearing capacity. Lubrication characteristics were compared between two types of hydrostatic thrust bearings (HTBs) with different grooves to illustrate that the new structure is more suitable for WSSCs. The reasonability of the proposed model and simulation results were verified using an axial thrust bearing test rig developed by the authors. In addition, variation parameters of hydrostatic film thickness between the sliding surfaces of the star wheel axial thrust bearing were measured. The results show that the instability of the water film thickness and axial vibration of the star wheel were suppressed, thereby avoiding the contact of solid materials between the end face of the axial thrust bearing. This study provides a structural optimization pattern of star wheel axial thrust bearings used in water-lubricated single-screw compressors.

Experimental Investigation on the Effect of Water Cooling on a Dry Twin-Screw Air Compressor for Proton Exchange Membrane Fuel Cells

“…Ous et al built an experimental platform to monitor the temperature and relative humidity of the air upon suction and exhaust of a compressor under a constant pressure and water injection rate and at variable compressor operating speeds in order to develop effective humidification and cooling schemes for fuel cell stacks as well as cooling for compressors [25]. Xie et al studied the lubrication characteristics of a water-lubricated bearing in a single-screw compressor, verifying the reasonability of the proposed model and simulation results with the help of an axial thrust bearing test rig developed by the authors [26].…”

A Review of Recent Research and Application Progress in Screw Machines

“…They [100] also studied the effects of rotating speed and design parameters on water-lubricated bearing characteristics in an air TSC, considering surface roughness and bending deformation of the shaft at the same time. Xie et al [101] compared the water lubrication characteristics between two types of hydrostatic thrust bearings with different grooves to illustrate that the new structure was more suitable for SSCs. Hou et al [102] experimentally measured the axial force on rotors of a TSC for the first time and compared the experimental results with two models, for providing a more accurate reference for the design and choice of bearings.…”