抄録
The effective thermal conductivity both perpendicular and parallel to fiber axes (the former is named perpendicular arrangement and the latter is named parallel arrangement) of unidirectionally oriented polyester and cotton fiber assemblies was measured on the presence of humidity gradient. And the property of the effective thermal conductivity and the contribution of water transfer to the heat transfer were discussed. The results gave the following conclusions.
(1) Both on the presence and the absence of humidity gradient, the experimental results show that the effective thermal conductivity for both perpendicular arrangement and parallel arrangement of unidirectionally oriented fiber assembly falls with the increase of the volumetric ratio, and reaches a minimum value. And above that volumetric ratio, it rises with the increase of the volumetric ratio. However, the rate of rise for parallel arrangement is larger than that for perpendicular arrangement. The volumetric ratio at the minimum of the effective thermal conductivity on the presence of humidity gradient is lower than that on the absence of humidity gradient for both arrangement.
(2) The effect of the water transfer on the effective thermal conductivity become greater with the decrease of the volumetric ratio for both arrangements. This is due to the reason that the contribution of the water transfer to the effective thermal conductivity is based on the transfer of water from high temperature to low temperature and the radiative heat transfer on the participation of water.
