溶液除湿中基于水蒸气压差的传质系数

分析了溶液除湿系统中气液界面间传质过程的影响因素,以气液界面间传质的直接驱动力——溶液表面蒸气压与湿空气中水蒸气分压差为基础,提出了以蒸气压差为变量的传质系数关联式,采用已公开发表的实验数据(Li Cl溶液,纤维规整型填料)拟合获取关联式中常数项,得到除湿过程传质系数关联式。采用不同结构填料(Li Cl溶液,PVC规整型填料)已公开发表的实验数据对该关联式进行验证,实验值与计算值相对偏差为-10.48%~5.28%。为进一步验证该关联式,搭建了热泵型溶液除湿系统(Li Br溶液,翅片管式热湿交换器),用获得的实验数据对得到的关联式进行验证,相对偏差为-1.8%~12.8%。3组实验值与计算值的对比表明,以蒸气压差为主要变量的传质系数关联式对规整型填料溶液除湿器传质系数的模拟计算具有较高的计算精度。

Mass transfer coefficient for liquid dehumidification based on vapor pressure difference

The influencing factors for mass transfer of gas-liquid interface in liquid desiccant system are analyzed. A mass transfer correlation is given in dimensionless form based on the driving force of mass transfer, which is the vapor pressure difference through gas-liquid interface. The constants in the correlation are fitted based on published experimental data of LiCl-H₂O-air system in a column packed with cross corrugated cellulose. Another group of published experimental data of LiCl-H₂O-air system in a column packed with polyvinyl chloride is used for validating the correlation, with the relative deviation between experimental and calculated results from -10.48% to 5.28%. Moreover, a liquid dehumidification system driven by heat pump is set up, with LiBr-H₂O as desiccant and finned tube heat exchanger as packings, and the experimental data are used for validating the correlation. The result shows that the deviation is -1.8%-12.8%. All these results show that the correlation has a high accuracy for mass transfer coefficient prediction in liquid dehumidifier with structured packings.