Modeling of heat transfer conditions in cooling lubricant emulsions with low-boiling continuous media in narrow gaps

Abstract

© 2016 Elsevier LtdThe article analyzes the behavior of the cooling lubricant emulsions of oil-in-water type in a limited volume of narrow gaps. Vapor phase which has been generated by heating the emulsion to a temperature that exceeds the boiling point of water, modifies substantially the conditions of interaction between the dispersed droplets of oil with friction surfaces. Nucleation and growth of vapor bubbles stimulates heat transfer due to the pulsating character of motion of the emulsion and associated with it breakup of the oil droplets. A model of “hot” turbulence has been proposed in the double emulsion of the dispersed phase (oil and steam), initiated by the growth of vapor bubbles. In order to assess the effectiveness of the cooling lubricant emulsion, the mechanisms of hydrodynamic fragmentation of droplets of lubricating oil under conditions of narrow gaps were taken into account. The model was used to estimate the empirical constants in the dependence of the critical temperature from volumetric concentration of oil for AA 5182 aluminum cooling lubricant emulsion E1 (Januszkiewicz et al., 2004), separating the lubrication regime from the “dry” slip regime. It was shown that the model estimates are in good agreement with the experimental data. Therefore, the obtained results indicate that the model representations of this work do not contradict the physical nature of the complex process of heat transfer.