Thermo-hydrodynamic Analysis of Journal Bearings Operating With Non-newtonian Oils

Abstract

Abstract In recent years, sustainability has been one of the topics of major concern in technological progress, and reducing energy consumption is one of the biggest challenges. The refrigeration industry is responsible for about 20% of the overall electricity used worldwide. The miniaturization, mass reduction and increased rotation speeds lead to higher shear rates. In turn, at these levels, many oils may exhibit non-Newtonian behaviors. The ability to assess non-Newtonian effects can help in choosing and developing more efficient lubricants, where even small increases in efficiency can represent significant energy savings. Thus, this paper investigates the effects of using different non-Newtonian oils in a typical journal bearing of a household refrigerator compressor. For this purpose, a thermo-hydrodynamic model was proposed where the modified Reynolds equation for fluids obeying the power law coupled with the energy equation are solved using the finite volume method in an iterative process. The cavitation boundary is calculated using the equation of conservation of mass and updated at each iteration. The parameters of the power law curve fitting were obtained from experimental data fitting. The results obtained show that even for small deviations from Newtonian behavior, significant variations in load capacity and friction force can be observed. Under the same operating conditions, the load capacity and friction force are 67% and 64%, respectively, lower for the bearing operating with an alkylbenzene oil than with a polyolester oil, while the consistency parameter at To(m0) is 90% lower.