电池极片涂层的耦合传热传质特性研究

Characteristics study of coupling heat and mass transfer for wet coating of battery electrode

中文关键词: 电池极片涂层  传热传质特性  多孔介质干燥理论  动态网格法

英文关键词: Coating of battery electrode  heat and mass transfer characteristics  drying theory of porous media  dynamic mesh method

中文摘要:

      为探究电池极片涂层传热传质特性，基于动态网格法和多孔介质干燥理论建立了极片涂层干燥数理模型，采用了文献中实验数据验证了该模型的可靠性，其中模型的误差在±15%以内。基于该模型，对比研究了不同设计参数下涂层的传热传质特性影响规律。结果表明，随初始涂层厚度的增大，涂层的蒸发速率和孔隙排空速率先显著增加再降低。同样地，随初始极片运动速度的增大，涂层的蒸发速率和孔隙排空速率先显著增加再降低。随初始含水饱和度的增大，涂层的蒸发速率和孔隙排空速率线性增大。这是因为涂层在传热传质过程中会经历升速干燥阶段、恒速干燥阶段和降速干燥阶段，其在运动干燥过程中干燥位置不断发生变化，局部区域会提前达到恒速干燥阶段和降速干燥阶段，受到上述综合影响，不同设计参数下涂层的干燥速度不同。其中，工程建议初始运动速度采用0.15m/s，可获得涂层更大的蒸发速率。本研究可为电池极片涂层的传热传质特性的改善提供理论依据。

英文摘要:

      In order to study the characteristics of heat and mass transfer for coating of electrode, a drying mod-el of coating is established based on drying theory of porous media and dynamic mesh method. The model is proved reliable because its errors are within ±15% by experimental data in literature. Through this model, the influences of heat and mass transfer of coating are compared and analyzed under different design parameters. The results show that the evaporation rate of pore emptying rate first increases and then decreases for coating with the increase of initial coating thickness. Likewise, the evaporation rate of pore emptying rate increases first and then decreases with the increase of ini-tial coating motion velocity. The evaporation rate of pore emptying rate increases with the increase of initial water saturation. This is because the heat and mass transfer processes can be divided into increased speed, constant speed, and reduced speed drying stages. Meanwhile, the drying position changes with the drying time increases, the local area advances to the constant speed or reduced speed drying stages. Affected by the combined influences, the drying rate of coating is different un-der different design parameters. The initial motion velocity is suggested to select 0.15m/s to obtain a higher evaporation rate of wet coating in engineering. The above research can provide the theoretical basis for improvement of heat and mass transfer characteristics of coating.