Key issues to enable high heat flux removal exceeding 10 Mw/m² by use of metal porous media as a latent heat-transfer device

Heat transfer characteristics of two-phase flow in particle-sintered porous media are experimentally investigated in order to clarify the key issues to enable extremely high heat flux removal exceeding 10 MW/m². The porous media experimented on are stainless steel particle-sintered and bronze particle-sintered compacts. The experiments under some heat flux inputs clarify that the effects of porous structure such as pore size and porosity on the heat transfer characteristics highly depend on the level of the heat flux input. The results suggest that liquid-vapor exchange due to capillary and pumping effects works effectively under several MW/m² in this cooling system. However, under conditions exceeding the heat flux level, permeability for vapor discharge outside the porous medium becomes the most important factor in enabling the heat flux removal of over 10 MW/m². Furthermore, in order to evaluate what kind of porous material is appropriate for higher heat removal, the two-phase flow characteristics in the porous media are simulated by the two-phase mixture model. The results show that utilizing a higher thermal-conductivity matrix facilitates a delay in the onset of the phase change near the heating wall and leads to much higher heat flux removal, even at the same liquid saturation, compared with the case utilizing a lower thermal-conductivity matrix.