Several industries such as metal processing, food and beverages and pharmaceuticals are characterized by using emulsions of immiscible liquids which pre-determines the efficiency and quality of their products. Unfortunately, current technology applications of emulsions of liquids in industries are associated with several drawbacks that impact negatively on the industrial processes, therefore, resulting in poor quality products. To this end, researchers have been looking for alternative methods of successful applications of an emulsion of immiscible liquids in industries by creating special units for forcing of interactions dispersed phase. It promotes to obtain the desired results and have identified prediction of suitable hydrodynamic conditions as new promising solutions.
Presently, thermal processes in emulsions with phase changes is studied not sufficiently deeply, that result to complexity in designing and operating the industrial equipment because an ambiguous behavior of the dispersed phase of emulsions. It is necessary to take into account in more detail the characteristics of heat transfer in a heterogeneous medium of the emulsion flow. Therefore, structural modeling representation of the behavior of boiling emulsions, which influence on effectiveness industrial technologies, is of significant practical and science importance. Detail specified models provide adequate description and representation of experimental results, unlike general analytical methods.
The reason for this is a large number of dimensional parameters and regimes heat transfer which involved in formatting of complex processes of boiling liquid emulsions in non-isothermal conditions. As structural elements have been used mechanisms of the elementary physical phenomena to purposefully represent composition of complex processes because they are much simple and accept theoretical models. In consequence of this, became possible enabled efficiently simulation of complex heat transfer in non-isothermal liquid emulsions and in particular consider the phase transitions in explicit form.
Generally, in the unstable emulsion the boundary between physical phenomena of the breakage and coalescence is defined by the maximum stable size droplets, which is resistant to breakage. Furthermore, it also takes into account influence hydrodynamic conditions on the mechanisms of such kinetic processes. Heat transfer in non-isothermal conditions complicates the interaction droplets of dispersed phase by expanding number of the mechanisms of the elementary physical phenomena resulting in hot turbulence due to the forced convection. The resulting pulsations in the emulsion flow not only stimulate heat transfer, but can also lead to the destruction of the droplets of the dispersed phase.
Professor Alexander Rozentsvaig and Dr. Cheslav Strashinskii at Kazan Federal University investigated the modeling representation of breakup processes of subcooled droplets of dispersed phases in emulsion volume in result of nucleate boiling of a continuous phase. The authors used the physical models in form of mechanisms of the elementary physical phenomena and the experimental data to evaluate the interrelation of mechanisms the hydrodynamic and heat transfer phenomena. Their work is published in the journal, International Journal of Heat and Mass Transfer.
The authors observed that boiling of the overheated continuous phase of liquid-liquid emulsions resulted in perturbations similar to the usual turbulence of homogenous liquid. The formation of vapor nuclei and subsequent growth of vapor bubbles influence on the hydrodynamic characteristics of boiling continuous medium. For instance, it turned out that the quality of metal processing was improved by 10-18% by controlling the conditions of dispersion of the emulsions under minimum quantity cooling lubrication.
Therefore, the developed model by Rozentsvaig and Strashinskii would be useful for expansions frameworks existing models about breakup of droplets under influence complex interconnected hydrodynamic and thermophysical processes in liquid emulsions. This will help to create optimal conditions for production and advance product quality in numerous industries.
Rozentsvaig, A., & Strashinskii, C. (2018). Droplets behavior of subcooled dispersed phase under nucleate boiling of continuous phase of liquid emulsion. International Journal of Heat and Mass Transfer, 125, 1274-1283.Go To International Journal of Heat and Mass Transfer