The combined effect of conduction-convection-radiation on natural convec- tion flow of an optically thick Newtonian fluid with gray radiant properties, confined in a porous media square cavity with Darcy-Brinkman-Forc...The combined effect of conduction-convection-radiation on natural convec- tion flow of an optically thick Newtonian fluid with gray radiant properties, confined in a porous media square cavity with Darcy-Brinkman-Forchheimer drag is studied numeri- cally. For a gray fluid, Rosseland diffusion approximation is considered. It is assumed that （i） the temperature of the left vertical wall varies linearly with height, （ii） the right vertical and top walls are at a lower temperature, and （iii） the bottom wall is uniformly-heated. The governing equations are solved using the alternate direct implicit method together with the successive over relaxation technique. The investigation of the effect of governing parameters, namely, the Forschheimer resistance （F）, the temperature difference （A）, and the Plank number （Rd）, on the flow pattern and heat transfer characteristics is carried out. It can be seen that the reduction of flow and heat transfer occur as the Forschheimer resistance is increased. On the other hand, both the flow strength and heat transfer in- crease as the temperature ratio A is increased.展开更多
An overall two-dimensional numerical model of the miniature flat plate capillary pumped loop （CPL） evaporator is developed to describe the liquid and vapor flow, heat transfer and phase change in the porous wick str...An overall two-dimensional numerical model of the miniature flat plate capillary pumped loop （CPL） evaporator is developed to describe the liquid and vapor flow, heat transfer and phase change in the porous wick structure, liquid flow and heat transfer in the compensation cavity and heat transfer in the vapor grooves and metallic wall. The entire evaporator is solved with SIMPLE algorithm as a conjugate problem. The effect of heat conduction of metallic side wall on the performance of miniature flat plate CPL evaporator is analyzed, and side wall effect heat transfer limit is introduced to estimate the performance of evaporator. The shape and location of vapor-liquid interface inside the wick are calculated and the influences of applied heat flux, liquid subcooling, wick material and metallic wall material on the evaporator performance are investigated in detail. The numerical results obtained are useful for the miniature flat plate evaporator performance optimization and design of CPL.展开更多
文摘The combined effect of conduction-convection-radiation on natural convec- tion flow of an optically thick Newtonian fluid with gray radiant properties, confined in a porous media square cavity with Darcy-Brinkman-Forchheimer drag is studied numeri- cally. For a gray fluid, Rosseland diffusion approximation is considered. It is assumed that （i） the temperature of the left vertical wall varies linearly with height, （ii） the right vertical and top walls are at a lower temperature, and （iii） the bottom wall is uniformly-heated. The governing equations are solved using the alternate direct implicit method together with the successive over relaxation technique. The investigation of the effect of governing parameters, namely, the Forschheimer resistance （F）, the temperature difference （A）, and the Plank number （Rd）, on the flow pattern and heat transfer characteristics is carried out. It can be seen that the reduction of flow and heat transfer occur as the Forschheimer resistance is increased. On the other hand, both the flow strength and heat transfer in- crease as the temperature ratio A is increased.
文摘An overall two-dimensional numerical model of the miniature flat plate capillary pumped loop （CPL） evaporator is developed to describe the liquid and vapor flow, heat transfer and phase change in the porous wick structure, liquid flow and heat transfer in the compensation cavity and heat transfer in the vapor grooves and metallic wall. The entire evaporator is solved with SIMPLE algorithm as a conjugate problem. The effect of heat conduction of metallic side wall on the performance of miniature flat plate CPL evaporator is analyzed, and side wall effect heat transfer limit is introduced to estimate the performance of evaporator. The shape and location of vapor-liquid interface inside the wick are calculated and the influences of applied heat flux, liquid subcooling, wick material and metallic wall material on the evaporator performance are investigated in detail. The numerical results obtained are useful for the miniature flat plate evaporator performance optimization and design of CPL.
