Modeling the Capillary Inflow of a Liquid to Dry Spots Above Vapor Bubbles as a Factor of Increasing the Critical Heat-Flux Density During the Boiling on a Porous Surface

The authors propose a calculation model for the process of inflow of a liquid from a microfilm to dry spots above vapor bubbles, which occurs in nucleate boiling and is due to the action of capillary forces (Laplace head) in a porous coating on the heating surface. In comparing the value of the heat flux from the heating surface to the interface in the zone of intense evaporation of the liquid and the value of the heat flux to evaporate the liquid sucked through a porous substrate to a dry spot, it turns out that these values are comparable, which explains the effect of rise in the critical density of the heat flux on porous surfaces compared to “smooth” surfaces. A comparison of the results of quantification of this effect with the proposed model and the experimental data obtained during the boiling of water on a porous surface that was formed by nanoparticles precipitated from a nanolfluid has shown their mutual agreement.