CONDENSATION IN TWO-DIMENSIONAL POROUS MEDIA BASED ON HYBRID LATTICE BOLTZMANN METHOD

A hybrid lattice Boltzmann model is developed to numerically investigate vapor condensation in two-dimensional porous media, aiming to elucidate the underlying coupling mechanisms among multiphase flow, phase change, and heat transfer. To verify the accuracy of the hybrid lattice Boltzmann model, simulations of saturated vapor condensing on vertically oriented hydrophilic and horizontally oriented hydrophobic subcooled walls are first conducted. It is then applied to simulate condensation in uniform porous structures. The results indicate that high-temperature vapor initially condenses into discrete droplets upon contact with subcooled porous media, which subsequently coalesce into continuous liquid films. As the condensate flows through pore spaces between solid layers, the gas-liquid interface exhibits periodic "concave-convex" deformations due to capillary effects. The transport of condensate is significantly hindered by viscous resistance, and liquid blockage may occur within the pores. Parametric studies are conducted to explore the effects of surface wettability, porosity, fluid thermophysical properties, and pore arrangement on the condensation behavior. It is found that reducing the wall contact angle from 53° to 29° enhances the total condensate volume by approximately 10.9% and effectively suppresses liquid blockage. An increase in porosity by 9.37% leads to a 28.07% increase in condensation mass. Fluids with higher thermal diffusivity promote more efficient heat transfer, thereby accelerating the condensation process. In contrast, when thermal conductivity and heat input are fixed, increasing the fluid’s specific heat capacity reduces the amount of energy available for phase change, thus hindering condensation. Based on a comparative analysis of four different pore structures, an optimized design featuring higher porosity at the inlet and outlet and lower porosity in the central region is proposed. This configuration increases the condensate yield by approximately 5.11% while mitigating flow obstruction.