超低密度植物纤维材料干燥特性和动力学模型

根据干燥动力学理论,分别设定95、100、105℃为热风对流干燥参数和80、160、240 W为微波干燥参数,对植物纤维发泡材料的热风对流和微波干燥的干燥特性进行了研究,并对干燥动力学特性进行数学模型拟合。研究表明,当绝对含水率≤100%,植物纤维发泡材料的热风对流干燥出现传热传质困难,干燥效率降低。而微波干燥速率稳定,干燥曲线呈近似直线线性关系。植物纤维发泡材料的干燥动力学模型可由多项式模型来表示。

Drying characteristics and kinetic models for plant fibre-based ultra-low density mats

Drying is the most energy and time consuming step in the manufacture of ultra-low density plant fibre-based foaming mat(ULD mat) because of its high initial moisture content(MC).The drying characteristics of the ULD mat was examined under 6 drying conditions: convective hot-air drying at 3 temperatures(95,100 and 105 ℃) and microwave drying under 3 microwave powers(80,160 and 240 Watt).Three drying models,including diffusion model,Page model and the forth-order polynomial equation,were fitted to describe the moisture ratio(moisture at given time to initial moisture) in relation to drying time.The results indicated that the time needed for drying the mat from 600% to 10%(dry base) decreased by 24% and 60% with increasing temperature from 95 to 105 ℃ for the convective hot-air drying and power from 80 to 240 Watt for the microwave drying,respectively.The microwave drying had an even drying rate,while the convective hot-air drying showed 3 distinctive stages: fast drying stage from 600% to 250% MC,slowing-down stage from 250% to 100% MC and slow drying stage from 100% to 10% MC.The forth-order polynomial model fitted the data better than did the diffusion and Page models in terms of R2,while the coefficients in the forth-order polynomial model can be expressed as the second-order polynomial equation of drying parameters,i.e.,temperature for the convective hot-air drying and power for the microwave drying.The results should provide data and basis for the design of industrial manufacture line.