表面辐射对部分填充吸湿性多孔介质的封闭腔体内热湿耦合传递的影响

根据多孔介质热质传递原理,基于有限元的方法数值分析了具有表面热辐射的部分填充吸湿性多孔介质的封闭腔体内部自然对流流动及热湿耦合传递过程,探讨了表面发射率、Rayleigh数和Darcy数等参数对封闭腔体内部自然对流流动及热湿耦合传递过程的影响,研究结果表明,壁面热辐射的作用可以提高多孔介质内部的温度,而且随着表面发射率的增大,多孔介质内部的水分逐步向其右上角迁移和聚集。另外,Darcy数、多孔介质与空气的热导率比对方腔内部多孔介质的热量传递和水分迁移影响较小。

Effects of thermal radiation on natural convection heat and moisture transfer in rectangular enclosures partially filled with hygroscopic porous medium

This paper deals with the effects of thermal radiation on natural convection heat and moisture transfer in rectangular enclosures partially filled with hygroscopic porous medium. The governing equations for the momentum, heat and moisture transfer were solved by the finite element method. The radiative heat transfer is calculated by making use of the radiosity of the surfaces that assumed to be grey. Comparisons with experimental and numerical results in the literature have been carried out. Effects of thermal radiation, Rayleigh number, Darcy number and a ratio, R_k, of thermal conductivity on natural convection, heat and moisture transfer in both free fluid and hygroscopic porous medium were analysed. It was found that the surface thermal radiation significantly alters the distribution of the temperature in rectangular enclosures and moisture content of hygroscopic porous medium even if the given emissivity is quite small, but there are no remarkable temperature and moisture content changes with the increase of emissivity from 0.5 to 1.0. The mean temperature at the interface and the moisture content in hygroscopic porous medium decrease with the increase of Ra. The Nu_c on the side walls in the free flow and porous medium regions increase with the increase of Ra. The temperature and moisture content distributions change little in porous medium during heat and moisture content transfer with the increase of R_k while the mean convective Nusselt number on the side walls of rectangular enclosures changes very little in a range of given Da and R_k.