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

高效气体吸收是保护地球环境的重要技术之一。在之前的文章中，我们提出了一种利用冷凝过程和雾形成的物理气体吸收的新概念，并进行了验证实验。在气体吸收的冷凝法中，二氧化碳等可溶气体的传质速率在实际中受到扩散过程的影响是一个显著的特点，其扩散速度比在溶剂液体中快。因此，与传统的物理方法如降液膜法相比，这种方法的气体吸收速度更快。结果表明，该方法的气体吸收率主要取决于冷凝膜。另一方面，在垂直冷却管内强制对流冷凝时，由于蒸汽的流动方向与重力方向相反，冷凝在冷却壁上的液体表面呈波浪状，管内会出现冷凝液的泛水、液滴夹带、脉动等各种现象。因此，可以期望利用管内逆流波流增强冷凝换热，从而获得更高的吸收系统性能。因此，本研究作为开发高性能、环境友好型热能回收系统的基础研究，对逆流波流强化气体吸收和冷凝换热的可能性及机理进行了深入研究。

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.