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

Rk

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 Nuc 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 Rk while the mean convective Nusselt number on the side walls of rectangular enclosures changes very little in a range of given Da and Rk.