STUDY ON THE ENHANCEMENT MECHANISM OF GAS ABSORPTION AND CONDENSATION HEAT TRANSFER BY THE COUNTERCURRENT WAVY FLOW

高效气体吸收技术是保护地球环境的重要技术之一。本文提出了一种利用冷凝过程和雾化的物理气体吸收新概念，并进行了验证实验。在冷凝法气体吸收中，二氧化碳等可溶性气体的传质速率实际上受混合气体中扩散过程的影响是一个显著的特点，混合气体的扩散速度比溶剂液体快。因此，与传统的物理方法如降液膜法相比，该方法的气体吸收速率更快。并阐明了该方法的气体吸收速率主要取决于冷凝液膜。另一方面，在垂直冷却管内的强制对流冷凝中，由于蒸汽的流动方向与重力方向相反，冷凝液在冷却壁面上的凝结液面呈波浪形，管内会出现液泛、液滴夹带和凝结液脉动等现象。因此，希望通过管内逆流波纹流强化冷凝换热，以获得更高的吸收系统性能。从这个角度来看，在本研究中，作为一个高性能和环境友好的热能回收系统的开发基础研究，对逆流波形流强化气体吸收和冷凝传热的可能性和机理进行了详细的研究。

High efficiency of gas absorption is one of the important techniques for the protection of global environment. In our previous paper, a new concept of physical gas absorption by utilizing condensation process and mist formation was proposed and its proof experiment was conducted. In the condensate method for gas absorption, it is a remarkable feature that the mass transfer rate of soluble gas such as Carbon Dioxide are affected practically by the diffusion process in the mixed gas with faster diffusivity than in the solvent liquid. Consequently the rate of gas absorption by this method is faster compared with the conventional physical methods such as the falling liquid film method. And it was clarified that the rate of gas absorption by means of this methods depended mainly on the condensate film. On the other hand, in the forced convection condensation inside a vertical cooled tube, in which the flow direction of vapor is against gravity force, the surface of liquid condensed on the cooled wall becomes wavy, and various phenomena such as flooding, droplet entrainment and pulsation of condensate could appear in a tube. Therefore, it is expected that the enhancement of condensation heat transfer by the counter-current wavy flow in a tube might be available to get the higher performance of the absorption system.From this view point, in this study, as a basic research for the development of a high-performance and environment-friendly thermal energy recovery system, detailed investigations have been conducted to understand the possibility and the mechanism of die enhancement of gas absorption and condensation heat transfer by the countercurrent wavy flow.