Condensation enhancement by combining wettability and electric field

Enhancement of condensation heat transfer is a current research focus. In this study, a novel strategy is proposed that combines a hydrophobic wall with oblate droplets under an electric field, and a hydrophilic wall with prolate droplets under an electric field, to enhance condensation nucleation, growth, and detachment. The pseudopotential lattice Boltzmann method model and the leaky dielectric model were developed to investigate the condensation nucleation and growth on the hydrophobic wall, as well as the detachment on the hydrophilic wall. The corresponding condensation heat transfer performance under two combinations was also analyzed. Results show that an electric field with electric capillary number being 5.0 reduces the condensation nucleation time by 37.17 %, 36.44 % and 21.93 % on surface with contact angles of 107°, 124° and 142°, respectively. The narrower and deeper of the cavity, the more significant the enhancement, with the optimum cavity depth and width being 1.15L₀ and 0.46L₀. For droplet growth, the optimal electric capillary number is 3.0 on the surface with contact angles of 107°, whereas it shifts to 5.0 when contact angle is 142°. For prolate droplet on hydrophilic surface, increasing the electric field intensity promotes droplet detachment with heat flux keeping the same level. However, when the wall hydrophilicity decreases to contact angle of 70°, a stronger electric field intensity leads to a reduction in heat flux.