木材导热系数的研究

本文运用非平衡态热力学线性理论分析了含水率在纤维饱和点以下木材的传热,结果表明木材中的水蒸汽和束缚水参与了传热,木材导热系数由传导导热系数与因水蒸汽和束缚水扩散产生的两个等效导热系数组成。推广Siau关于木材细胞的导热理论,依据水分吸附和扩散的原理,导出了木材弦向和径向导热系数计算公式,与已发表的36种气干材弦向实验值和23种气干材径向实验值符合较好。分析木材径向传热的方法也适用于木材纵向传热。

STUDIES ON THERMAL CONDUCTIVITY OF AIR-DRIED WOOD

Heat transfer of wood with the moisture content below the fiber satuation point was analysed by the liner theory of non-equilibrium thermodynamics. The results showed that diffusion of water vapour and bound water contributed to the heat transfer and thermal conductivity of wood consisted of one coefficient of heat conduction and two equivalant coefficients arising from the diffusion of water vapour and bound water. The expressions of three coefficients were derived by extended Siau's theory on heat transfer of wood and the principle of water sorption and fluid diffusion. It was found that the theoretical valuesl coincided with the experimental valuesfor tangential thermal conductivity of thirty-six wood spicies and radial thermal conductivity of twenty-three, respectively. The methods that have been used to analyse the radial thermal conductivity are also suitable for the longitudinal thermal conductivity.