界面湍流下溴化锂水溶液膜流吸收强化的研究

Study on Absorption Enhancement for Flowing Film of LiBr Aqueous Solution Accompanying Interfacial Turbulence

利用降膜吸收试验系统 ,研究了在不同的溶液降膜流动雷诺数 Re下 ,无活性介质和加有3× 1 0 -5质量浓度 2 -乙基己醇的溴化锂水溶液降膜吸收强化过程 .结果表明 ,上述两种情况下 ,降膜吸收随 Re的增加 ,溶液侧平均换热系数和吸收传质系数均增大 ;且在 Re<80下 ,加有 2 -乙基己醇的吸收效果比无活性介质的吸收有明显的增强 ,随 Re进一步增加 ,强化效果逐渐变得不明显 .利用激光全息干涉技术 ,观察了流动液膜吸收过程中膜内溶液温度和质量分数变化引起的干涉条纹变化以及液膜流动的表面状况 .观察到 ,加有活性介质吸收中引起的干涉条纹较无活性介质的分布密 ,条纹要细 ,且液膜表面还出现不规则扰动 .

To study the heat and mass transfer enhancement process for flowing film of LiBr aqueous solution affected by interfacial turbulence and induced by addition of surfactant (2 ethyl 1 hexanol), the absorption experiments for falling film of LiBr aqueous solution were carried out to investigate the absorption enhancement. The experimental results show that the average coefficients of convection heat and mass transfer increase with the falling film Reynolds number under the cases with and without addition of 2 ethyl 1 hexanol.When Re <80, the vapor absorption with the 2 ethyl 1 hexanol is enhanced well over that without surfactant. And with the Re increasing, the absorption enhancement diminishes. Laser holographic interferometry technology was adopted to observe the evolvement of interferometry strips during the flowing film absorption, which is related to the variation of the concenttration and temperature of LiBr aqueous solution at the local region in the film. It is observed that the trips with the addition of 2 ethyl 1 hexanol are denser and slimmer than that without surfactant. And there is an irregular undulation happened on the surface of the flowing film during the absorption of surfactant, which is an interfacial turbulence resulted from the variation of the surface tension of the solution during the absorption.