On the reduction of heat generation in lubricants using microscale additives

This work is concerned with the identification of microscale properties of additives for base lubricants in order to reduce heat generation. An application of specific interest is the thin film lubrication of bearings. In order to isolate the thermal effects in the fluid film, we assume that the bearing and housing are insulated. A relation for the temperature rise in the fluid film between the bearing and housing is developed as a function of the rotation speed, the viscosity of the base lubricant and properties of the additives, namely (1) their viscosities, (2) their mass density, (3) their heat capacity and (4) volume fraction, which are free design parameters. Nondimensionalization of the developed relations allows for the construction of a design parameter space which can identify desirable parameter combinations that deliver a target value of heat generation reduction and simultaneously deliver the appropriate overall viscosity of the modified lubricant mixture.