Quantitative Elastohydrodynamic Film-Forming for an Oil/Refrigerant System

Abstract

The first calculations of film thickness for an oil/refrigerant system using quantitative elastohydrodynamics are reported in this work. It is demonstrated that primary measurements of the properties of the oil/refrigerant system can be employed to accurately predict film thickness in concentrated contacts. An unusual response to lubricant inlet temperature is revealed, wherein the film thickness may increase with temperature as a result of decreasing refrigerant solubility in oil when the inlet pressure is high. There is competition between the reduction in viscosity of the oil and the reduction of refrigerant concentration with increased temperature. For high inlet pressure, the dilution effect is dominant, whereas for low inlet pressure, the temperature dependence of the viscosity of the solution dominates over the range of inlet temperatures considered. It seems that only central film thicknesses have been experimentally measured for oil/refrigerant systems leaving these calculations as the only means of assessing the minimum.