对流干燥时水分蒸发扩散过程的热力学条件

Thermodynamic Condition of Water Evaporation and Diffusion in the Convective Drying Process

从非平衡热力学理论和相平衡原理出发 ,对多孔介质对流干燥过程中水分蒸发、扩散过程的物理机制进行了分析 ,结果表明 :干燥操作的热力学条件是干燥介质处于未饱和状态 ,干燥时驱动水分蒸发、扩散过程的驱动势是广义热力学力 ,且物料温度愈低、干燥介质温度愈高、相对湿度愈小 。

On the base of non equilibrium thermodynamic theory and phase equilibrium principle, the physical mechanism of surface water evaporation and vapor diffusion is analyzed in the convective drying of porous material, and the thermodynamic condition of convective drying process is established. A new driving potential of water evaporation and vapor diffusion is set up and the effect of the drying medium temperature and humidity on the driving potential is discussed.