Analysis Of The Effect Factors On Mass Transfer Enhancement In A Wavy-walled Tube For Pulsatile Flow

The high efficiency heat and mass transfer devices are widely used in the fields ofbiochemical engineering, such as designs of reactor and exchanger. The problem that how obtainseffective mass transfer rates in the condition of low flow rate has been paid more and moreattention. As the basal element of heat and mass transfer devices, many investigators have devotedtheirs efforts to the studies on the channels or tubes. There are many results that have been usedinto practical engineering for steady flow and pulsatile flow in two-dimensional channels. But ithas not enough studies for pulsatile flow in the tube, in particular with reverse flow. Based on theprevious results, the present studies describe the effect of transfer characteristic on flow parametersfor pulsatile flow in the tube by means of electrochemical method and flow visualization technique.We especially focus on the conditions with reverse flow. Main contents of this dissertation are asfollows:In chapter 1, the previous studies have been reviewed. These studies indicate that theexperimental results agree with the results numerical simulation for steady flow in the channel. Forpulsatile flow in the channel, a great deal of studies has been done. However, there are few resultsfor pulsafile flow in the tube.In chapter 2, it introduces the experimental apparatus and various measurement techniquesapplied to the current study are given. And the flow patterns are visualized by the aluminum dustmethod. Mass transfer rates measured by the electrochemical method.Chapter 3 describes the experimental results. The effect of the mass transfer enhancement onone of three parameter, that is Re_s, P, St, when the others are fixed is discussed. It is found thatmass transfer enhancement factor E is optimal value at the medium Reynolds number. However,there are smaller values of E at low or high Reynolds numbers. Mass transfer enhancement factoris not remarkable change at the oscillatory fraction of the flow rate P≤1. In our experimentalranges, the mass transfer enhancement factor increases with the oscillatory fraction of the flow rateat P＞1. Except for net flow Reynolds number Re_s=154.8, When P≤1, the mass transferenhancement factor is a slight variety with Strouhal number at the same Reynolds number. At P＞1,there is a peak value of Strouhal number and its value is in the range of 0.3～0.5 even for different P.