竖置多孔填料床内热湿迁移特性研究

通过对气相达西阻力的定义,提出了更准确、更完善地反映多孔介质内部热质传递现象的“三态-六场”模型,并以此模型对竖置多孔填料床内的热质交换过程进行了数值模拟,分析了典型工况下填料床内部各物理量场的变化规律.计算及分析结果一方面表明了模型的可行性,另一方面也表明竖直多孔窗比水平多孔窗具有更好的蒸发制冷效果.

Heat and Moisture Migration in a Vertical Porous Bed

A general model is developed to describe the heat and moisture migration in unsaturated materials, in which liquid water and water vapor are treated separately. In the model, not only the motion of vapor and air due to the pressure difference, but also the diffusion of vapor to steady air due to the temperature difference and variation of vapor content have been taken into consideration. The concept of "Darcy resistance of gaseous phase" is introduced to describe the interaction between the liquid phase and gaseous phase. Nonlinear coupled partial differential equations are solved numerically using FDM. The relationships between the temperature, liquid content, evaporation rate and the fluid velocity fields are discussed. Calculated results show that the mathematical model and the numerical method are feasible, and the predicting accuracy of the model improved. It is also shown that the vertical porous window has better evaporative refrigeration capability than that of the horizontal one.