The effect of binary solution concentration and laser heating configuration on non-isothermal heat transfer and evaporation rate

Abstract

The control over heat exchange and evaporation of multicomponent and binary films of solutions is widely applied. Some technologies necessitate homogenous mixing of liquids and uniform particle deposition, as well as increased heat transfer and enhanced mixing of liquids. To date, there are practically no research works on the effect of local heating and concentration of volatile components on increased convection and heat transfer. The article examines the effect of ethanol concentration (from 0 to 90 %) on heat transfer in binary liquids, as well as the effects of single- and two-point laser heating on heat transfer. It has previously been shown that during uniform heating and local laser heating, a highly inhomogeneous temperature field forms in a single-component liquid, leading to a nonuniform deposition of colloidal particles. The experimental data of the presented article indicate that two-point heating and a small concentration of ethanol destabilize the dynamic and temperature field, leading to a much more uniform temperature distribution. For the first time it is found that the contribution of the convective velocity in he heat transfer coefficient during the transition from water to water-alcohol solution is approximately equal to 135 %. The transition of a stable velocity field to a chaotic one is determined by the ratio of the thermal to soluble Marangoni number. The paper examines the influence of various key factors on the heat transfer coefficient of a binary liquid. Two characteristic heat exchange modes are implemented at changes in alcohol concentrations. The obtained results will serve to apply a new mechanism of transfer enhancement for chemical and biochemical reactors, to intensify heat transfer during cooling of surfaces, as well as for homogeneous particle deposition during the creation of microfilms.