Response of a Microheater - Solution System with a Lower Critical Solution Temperature under a Powerful Local Heat Impact. Experimental Methodology
A. A. Igol'nikov, S. B. Ryutin, P. V. Skripov
Institute of Thermophysics, Ural Branch, Russian Academy of Sciences, Yekaterinburg, Russia
Keywords: pulse heating, wire probe, two-component solution, lower critical temperature of solution, diffusion spinodal, heat transfer intensification, unstable states
Abstract
The paper describes a methodology for the experimental study of a powerful heat release in a microsized probe immersed in a two-component solution with a lower critical solution temperature. Experimental data on overheating relative to the liquid - liquid spinodal and thermal impact on the stability of the system for a water - PPG-425 solution are presented. The following conclusion is made for a solution whose near-critical mass fraction of PPG-425 is 30%: despite the high density of the heat flux through the heater surface (9.2-13.7 W/m2), its temperature stabilizes at a value exceeding the equilibrium temperature of the liquid - liquid system by approximately 150 K. It is shown that the heat exchange process is stable against changes in the heating parameters: the nature of heat transfer by the solution remains the same. It is revealed that the heat transfer coefficient is several times greater than the corresponding value obtained for water.
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