2019 Volume 36 Issue 4 Pages 199-
There is a growing need to expand the upper limit of the operating range of compressors for air-conditioning and refrigeration systems. There are two design approaches to expand the upper limit. One is expansion of the stroke volume, but this increases the load of the sliding bearing as the compressive load of the refrigerant. The other is increasing maximum rotation speed, which increases the shear heat of the oil film; viscosity of the oil then decreases, and the load capacity of the sliding bearing decreases. Incidentally, the refrigerant is dissolved in the oil that lubricates the journal bearing, and the solubility and the dissolving viscosity change depending on the temperature and pressure conditions. The viscosity change of oil due to friction heat and refrigerant dissolving at high rotation speed and high load range cannot be ignored. So, we constructed a thermal elastrohydrodynamic lubrication analysis model that captures changes in viscosity due to oil film temperature and solubility, and clarified the influence of frictional heat generation, solubility and viscosity change on journal bearing characteristics.
