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在木材干燥过程中,将热量传递给木材,同时将木材中水份带走的媒介物质,称为干燥介质。干燥开始前,首先要预热。预热木材的介质是饱和湿空气或接近饱和的湿空气,空气中的水蒸气将有一部分穿过界面层到达湿木材的表面,并在表面上凝结成水。此时水蒸气所含的汽化潜热变为显热,传给木材表面,并由表面传入内部,木材温度逐渐升高。当木材表面温度等于介质温度时,木材表面的水蒸气分压力等于循环蒸汽流的分压力,互相传递的水蒸气数量处于平衡状态。同时,由于木材内部的温度低于表面温度,干燥介质中的热将通过表面向内部传递。
In the wood drying process, the heat is transmitted to the wood, while the moisture in the wood away from the media, known as the drying medium. Before drying begins, warm up first. The medium for preheating the wood is saturated or nearly saturated moist air. Part of the water vapor in the air passes through the interfacial layer to the surface of the wet wood and condenses into water on the surface. At this point the latent heat of vaporization of steam into sensible heat, passed to the surface of the wood, and from the surface into the interior, timber temperature gradually increased. When the temperature of the wood surface is equal to the medium temperature, the partial pressure of water vapor on the surface of the wood is equal to the partial pressure of the circulating steam flow, and the amount of water vapor transferred to each other is in an equilibrium state. In the meantime, since the temperature inside the wood is lower than the surface temperature, heat in the drying medium will be transmitted to the interior through the surface.