果蔬多孔介质干燥传热传质过程的孔道网络模拟及试验

Pore network study of heat and mass transfer process for drying of fruit and vegetable porous media

为研究果蔬多孔介质干燥的传热传质机理,确定其内部不同物理结构特性对干燥过程的影响,本文运用孔道网络理论和热质传递原理等知识,建立了果蔬多孔介质干燥传热传质的孔道网络模型,并进行了以苹果切片为典型代表的果蔬多孔介质热风干燥试验,模拟分析了苹果切片的含水率、温度场和湿分场等情况.结果表明:建立的模型能够较好地模拟果蔬多孔介质干燥过程;其温度场表现为四周区域温度高,中心区域温度低,而湿分场则相反,呈现出四周区域低,中心区域高的趋势;果蔬物理结构参数对干燥过程的影响显著,孔隙率越大,果蔬干燥所需时间越长;配位数越小,对应的干燥时间越短.研究结果为果蔬多孔介质干燥工艺及品质分析提供了理论基础.

In order to study the mechanism of heat and mass transfer of fruit and vegetable porous media and to determine the influence of different physical structure on their drying process,the model of heat and mass transfer processes for drying of fruit and vegetable porous media was established by applying the knowledge of pore network and the principle of heat and mass transfer.An experimental study on drying of apple slice as the typical representative of the fruit and vegetable porous media was conducted in order to validate this model.The moisture content,temperature field and moisture field of apple slices were analyzed.The simulation and experimental results indicated that the established model can simulate the drying process of fruit and vegetable porous media.The physical structure parameters of fruits and vegetables have a significant effect on the drying process.The bigger the porosity is,the longer the time of fruit and vegetable drying is.The smaller the coordination number is,the shorter the corresponding drying time is.The results of this study provide a theoretical basis for the drying process and quality analysis of fruit and vegetable porous media.