RESPONSE OF A MICROHEATER-SOLUTION SYSTEM WITH A LOWER CRITICAL SOLUTION TEMPERATURE UNDER INTENSE LOCAL HEATING: A MODEL FOR HEAT TRANSFER ENHANCEMENT DURING SPINODAL DECOMPOSITION
A.V. Melkikh1,2, A.A. Gubin1,2
1Ural Federal University, Yekaterinburg, Russia
2Institute of Thermal Physics, Ural Branch of the Russian Academy of Sciences, Yekaterinburg, Russia
Keywords: spinodal decomposition, Marangoni effect, Cahn-Hilliard equation, phase transition, heat transfer, numerical simulation
Abstract
A numerical model of spinodal decomposition of a thermally unstable, partially miscible liquid under pulsed heating is developed. The model is based on a system of differential equations describing heat and mass transfer. Simulations are performed over time intervals of up to 40 ms. When a cylindrical probe is heated, the surrounding liquid separates into two immiscible phases. Due to the surface tension gradient (Marangoni effect), droplets of these phases move both toward and away from the probe, leading to a significant enhancement of heat transfer. The resulting time-dependent probe power and the relative change in the heat transfer coefficient are in good agreement with experimental data obtained from pulsed heating of an aqueous PPG-425 solution.
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