Mesoscopic lattice Boltzmann simulation of droplet jumping condensation heat transfer on the microstructured surface

Abstract

Dropwise condensation heat transfer on the micropillared surfaces is modeled using the 2D multiphase lattice Boltzmann method. Dynamic evolution of condensate droplets and heat transfer performance on the vertical micropillared surfaces with different wettability is investigated. The condensate mass and critical departure radius of droplets decrease as the surface wettability weakens. The superhydrophobic surface with the contact angle of 155° exhibits the highest heat flux. The released latent heat of saturated vapor results in a higher temperature at two-phase interface than elsewhere and a greater temperature gradient near the solid-liquid contact area. When the droplet detaches from the surface, the heat flux is reduced greatly. In addition, we concentrate on droplet jumping dynamics induced by merging on the microspined and microgrooved surfaces, especially considering the coupled phase change heat transfer process. Compared to the microgrooved surface, microspined structure is beneficial to improve the jumping velocity of droplets due to restricting the liquid bridge expansion and increasing the counteraction of substrate towards liquid bridge. Smaller width and height of microgroove can reduce the critical departure size as well as increase the jumping velocity.