吸收过程的界面非平衡传质机理

针对气体吸收过程,以分子热力学为基础,结合普遍化的化学势推动力通量方程,导出了传质存在时两相界面处的浓度关系,并针对不同情况进行了求解.提出了一个反映液相侧动力学状况的无因次数群Biot数Yo,Yo数越大界面处两相越偏离平衡.界面浓度是与Yo和液相主体浓度密切相关的.对于气相阻力可以忽略的吸收过程,两相传质速率的大小主要取决于液相的溶质界面浓度和液膜厚度.采用激光显微全息干涉技术对甲醇,乙醇,正丙醇静止吸收CO2时的界面浓度进行了测定,试验结果表明了本研究模型的正确性.

Gas-Liquid Interphase Mass Transfer Theory of Absorption Processes

The present paper aims at the understanding on the gas-liquid mass transfer mechanism of absorption process.On the basis of molecule thermodynamics,combining the general chemical potential driving force equation of mass transfer flux,a concentration corrrelation at interface between two phases is derived and solved under different bulk liquid concentrations in absorption process.The computational results show that the interfacial concentration of absorbed component on liquid side is strongly affected by a Biot number Yo and is also bulk concentration dependent.For the absorption process in which the gas phase resistance to mass transfer between two phases is neglectable,the mass transfer rate is mainly dominated by liquid bulk concentration and thickness of liquid film.The CO_2 interfacial concentration on liquid side in stationary absorption by pure methanol,ethanol and n-propanol absorbent respectively are measured using micro laser holographic interference technique to validate the model proposed,the experimental values are in good agreement with the calculated ones.