Mechanism Of Mass Transfer Enhancement In A Wavy-walled Tube For Pulsatile Flow

With the development of modern industry, heat and mass transfer processes are widely applied to the biochemical and biomedical engineering. To meet the needs of economizing energy and protecting the environment, the compact heat and mass transfer devices with low power consumption have attracted more attention. In many applications it is heat and mass transfer processes that limit the size, performance and efficiency of engineering systems. Primarily for this reason, the studies have been in the last several decades an increasing interest in heat and mass transfer enhancement. There are many results that have been used into practical engineering for steady and pulsatile flow in the channels. But it has not enough studies for pulsatile flow in the tubes. Based on the previous results, the present studies describe the mechanism of mass transfer enhancement in a wavy-walled tube for pulsatile flow by means of electrochemical method and flow visualization technique. We especially focus on the conditions with reverse flow. Main contents of this dissertation are as follows:In chapter 1, the previous studies have been reviewed. These studies indicate that the experimental results agree with the results numerical simulation in the channels. However, there are few results for pulsatile flow in the tubes, especially with reverse flow.In chapter 2, it introduces the experimental apparatus, measurement techniques which have been applied to the current study. Mass transfer rates measured by the electrochemical method. And the flow patterns are visualized by the aluminum dust method.Chapter 3 describes the experimental results. First some results for steady flow in the tubes are confirmed. Then, The effect of operating parameters on the mass transfer enhancement, such as Re_s,P, St, are discussed. Finally, the mechanism of mass transfer enhancement in the tube for pulsatile flow is clarified. It is found that there is an optimal Strouhal number value when the oscillatory fraction of the flow rate P≥1 and the Reynolds number is closed or over the critical value. This characteristic is similar to that in the channel. But the results indicate that the instability is completely different between the channel and the tube. So it is presumed that this behavior is related to the geometry shape of the tube.Chapter 4, 5 indicates the possible extensions of the present work.