The microwave drying equipment test showed that the temperature distribution in wood was uniform during the microwave vacuum drying process, and there was no fixed distribution pattern of overall internal high, external high and external low or external high and internal low. Uniform, there is no obvious integral moisture gradient in the direction of wood thickness; with the decrease of wood moisture content, the moisture distribution inside the wood is more uniform; in the early stage of wood drying, there is moisture accumulation on the surface of the wood.
In the course of microwave drying, when the moisture content of wood is below the fiber saturation point, there is no obvious internal high and external low moisture content field and fixed internal high and external low temperature field.
Therefore, the effect of moisture gradient on moisture diffusion and heat diffusion can be neglected during microwave drying of wood. Moisture migration in wood is mainly driven by the total pressure gradient, which is removed by osmotic flow in the form of liquid water or steam. When the moisture content of wood is below the fiber saturation point, the absorbed water in the wood itself does not move, but moves toward the adjacent area.
没有评论:
发表评论