Enhancement of Vapor Absorption into a Solution Using the Marangoni Effect

为了实现先进的吸收式热泵，开发新的吸收式热泵强化传热传质技术具有重要意义。在大多数商业机器中，通过添加少量各种表面活性剂来增强吸收，本文通过测量吸收过程中的非稳态温度分布，阐明了表面活性剂对吸收过程的强化作用。将少量的辛醇和癸醇添加到测试电池中含有的50质量%的LiBr水溶液中，并通过使用全息干涉测量法进行可视化实验。结果发现，使用显微镜和表面张力的测量的基础上的溶液表面观察，辛醇和癸醇在高于其溶解度的状态下分布在溶液表面上的滴状是最初的原因，剧烈的马兰哥尼对流。提出了产生这种Marangoni对流的机理模型，为开发高效热泵吸收器提供了指导，并对添加少量辛醇的溴化锂水溶液在吸收过程中的Marangoni对流行为进行了可视化研究。介绍了一种利用双脉冲吕比激光干涉测量技术来显示动态阶段油膜流动位移的方法。通过比较有无增感剂（辛醇）时的干涉条纹，可以清楚地看出在有辛醇的情况下发生了Marangoni对流。这些基础研究使我们能够设计高性能的吸收器。

It is highly important to develop a new technology for heat and mass transfer enhancement in the process of refrigerant vapor absorption in order to realize the advanced absorption heat pump. In most commercial machine, absorption enhancement has been done by adding a small amount of various kinds of surfactants, thereby reducing the surface tension of the absorption solution drastically and generating Marangoni convection near the solution surface at the time of refrigerant vapor absorption.This paper clarifies the effect of the surfactant on absorption enhancement by measuring the unsteady temperature distribution in the vapor absorption process by adding a small amounts of octanol and decanol into the aqueous solution of LiBr with 50 mass% contained in a test cell and by conducting a visualization experiment using holographic interferometry. It was found, on the basis of the solution surface observation using a microscope and the measurement of the surface tension, that octanol and decanol in a state higher than their solubilities distributed in the dropwise states on the solution surface were the initial cause of violent Marangoni convection. The model of the mechanism generating this Marangoni convection was presented also a guide dealing with the development of a highly efficient absorber to be used for heat pumps was provided.Furthermore, the effort was made to visualize the Marangoni convective behavior during the steam absorption into a dynamic falling thin film flow of the aqueous solution of LiBr with the addition of small amount of Octanol. An interferometric measuring technique was introduced to visualize the displacement of the film flow in the dynamic stage by using double pulsed luby laser. For the comparison of the interference fringe configurations obtained with and without the aurfactant (Octanol), it was cleary shown the occurrence of the Marangoni convection in case with Octanol. these basic study enables us to design high-performance absorber.