大规格建陶坯体对流干燥热质耦合传递的数值模拟

HEAT AND MASS TRANSFER INSIDE PORCELAIN TILES DURING CONVECTIVE DRYING PROCESS

以Whitaker的体积平均方程为基础,推导出多孔介质内部热质传递的等效耦合扩散模型,并对瓷质砖坯体干燥过程进行了数值分析和实验测定。探讨了干燥介质参数(湿度、温度和流速)和坯体物性参数(有效导热系数和有效扩散系数)对干燥过程的影响。结果表明,温度高、流速快、湿度小的热空气有利于干燥,其中,改变风速对干燥速率的影响很小,介质的温度和湿度对干燥影响较大,但有可能造成干燥缺陷。有效扩散系数对坯体内湿度的分布影响很大,而有效导热系数对坯体内湿度的分布几乎没有影响。

The equivalent diffusion model of heat and mass transfer in porous media was established based on Whitaker＇s local volume average equations. The numerical analysis of the porcelain tile during the convective drying process was made and the numerical solutions agreed well with the experimental results. The effects of the drying medium parameters and the tile physical parameters on the drying process were investigated. The results show that hot air with high temperature, flow speed, low humidity is in favor of drying, in which the temperature and humidity have the obvious effect and the flow rate has little effect on the drying rate. The effective diffusion coefficient has a great influence on the humidity distribution inside the tile, and the effective thermal conductivity has little impact on the humidity distribution.