温度和热流方向对木材传热特性的影响

Influence of temperature and heat flux direction on wood heat transfer performance

以4种常用木材为实验对象，研究了不同温度和热流方向对木材的导热系数、比热和热扩散率的影响，并分析了热物理性质变化的原因．实验结果表明：温度和热流方向对木材的传热特性影响显著．在25～200℃内，木材导热系数和比热呈现非线性变化，开始是随着温度的升高而逐渐增加，在接近80℃时达到一个峰值，然后又逐渐降低．而木材热扩散率的变化与温度的关系不明显．同一温度下，木材的顺纹（热流平行于纹理方向）导热系数要大于其横纹（热流垂直于纹理方向）导热系数，前者是后者的2．4～3．0倍．

The influence of temperature and heat flux direction on the heat conduction characteristics of four common woods, fir, red pine, white pine and larch, were investigated. The thermal conductivities, specific heat and thermal diffusivities of the woods were measured in the range from 25 ℃ to 200℃. Their measurements were done in longitudinal （parallel to the grain） and transverse （perpendicular to the grain） directions. It was observed that the temperature and heat flux direction influenced strongly the heat conduction of these woods. For instance, the wood＇s thermal conductivities and specific heat increased nonlinearly with the temperature rising to a peakat 80℃, then fell gradually. In addition, the thermal diffusivities of the woods were almost independent of temperature variations in the whole testing range. At the same temperature, the thermal conductivity along the grain was 2.4 to 3.0 times that across the grain. A reasonable explanation for the experimental results was discussed briefly.