多孔介质干燥过程分形孔道网络模型与模拟:Ⅱ.数值模拟与试验验证

为验证笔者建立的自然多孔介质干燥分形孔道网络模型(袁越锦,杨彬彬,焦阳,等.多孔介质干燥过程分形孔道网络模型与模拟:I.模型建立.中国农业大学学报,2007,12(3):65-69)的正确性,采用新鲜土豆切片进行热风对流干燥试验,并对干燥过程进行数值模拟。结果表明:分形孔道网络模型模拟得到的多孔介质内部温度、水分含量的分布与响应较规则孔道网络模型的更接近试验结果;分形孔道网络模型能合理地解释目前常用干燥理论所不能解释的湿斑和不规则干燥前沿等现象;多孔介质的喉径分布对干燥有显著影响,喉径分布不均匀程度越高,干燥时间越长;孔隙分形维数的大小与干燥时间无确定性关系。孔道网络模型考虑了多孔介质孔道细观结构对干燥过程的影响,在预测多孔介质内部水分分布与响应方面更接近真实干燥过程。

Fractal pore network simulation on the drying of porous media:Ⅱ. Experimental study and numerical simulation

A drying experimental study of potato slices,as an example of a real porous body,was conducted and its numerical simulation was carried out under the same environmental condition.The drying dynamic character of potato slices was obtained by the simulations of both a fractal pore network model and a regular one.The experimental and simulation results indicate that the drying kinetics, as well as the distributions of moisture and temperature inside the porous body,from the fractal pore network model are more consistent with that obtained from the drying experiments than that from the regular one.The wet patch appeared during the simulation process and this similar contour was also observed on the potato slices in the experiments.The throat size distribution in pore network of the porous media affects the drying process dramatically during the simulations.The higher the uneven degree of the throat size distribution was,the longer the drying time.There was no certain correlation between the pore fractal dimension and the drying time.