A quick discrete-continuous phase interaction model for pore-scale heat and mass transfer of droplets in porous foams

In view of the limitations of existing physical-numerical models of mist/stream flow in porous foam, we established a multi-scale physical model of mist/stream flow in porous foam and developed a numerical solution program based on OpenFOAM. In this work, we discussed in detail the modeling methods for heat and mass transfer processes of mist/stream flow in porous foam and verified the models. A numerical study on the spray cooling on a surface covered with porous foam was conducted based on the established numerical model. The effects of spray height and heat flux on the flow and heat transfer characteristics were discussed. When the spray height is 9 mm, the upward curling effect of the vortex structure and the splashing phenomena due to droplets hitting the skeleton surface result in the flow field being filled with a large number of tiny droplets. As the spray height increases to 17 mm, the vortex structure disappears, and the airflow exits from the side boundary of the computational domain. The mass of droplets flowing out of the boundary with the airflow accounts for 5.2 % of the total spray mass. Additionally, a relationship was identified between liquid film flow, heat flux, and phase change. Finally, a quantitative analysis was conducted on the effects of spray height and foam skeleton on phase transition. As the spray height decreases, the phase change mass on the foam skeleton surface decreases. At spray heights of H = 9, 12, and 17 mm, the mass fractions of phase change accounted for 73.6 %, 78.4 %, and 75.4 % of the total spray mass, respectively. At a spray height of H = 17 mm, and the heat fluxes q = 16.22, 20.00, 23.95, and 24.97 W/cm², the foam skeleton surface contributed 26.1 %, 20.3 %, 16.8 %, and 14.7 % of the phase change mass, respectively.