Mass Transfer Characteristics Of Non-newtonian Fluid In Wavy-walled Tubes For Pulsatile Flow

With the rapid development of China's economy and industry,energy shortages andenvironmental pollution have become seriously deterioration.In the fields of biology and chemical engineering,the high efficiency and energy saving of heat exchange equipment are increasingly important.Thus,the purpose of this study is to provide some references for designing high-efficiency and low-consumption heat exchange equipment.As the basic unit of the heat transfer device,the flow path had been studied by many people for various kinds of two-dimensional and three-dimensional flow paths.A large number of experimental and numerical simulation results show that improving the mass transfer efficiency can be started by changing the shape of the flow path,improving the fluid medium,and changing the flow state.This paper mainly investigated the influence of oscillatory fraction on flow structure and mass transfer enhancement factor in the three-dimensional sinusoidal wavy-walled tube for pulsatile flow using PIV(particle image velocimetry)and electrochemical methods.Two research methods complement each other to find the optimal oscillatory fraction under the pulsatile flow.The main contents of this article are as follows:The first chapter mainly reviewed the previous research results and summarized the relevant research results at home and abroad.Existing research including the 2D and 3D,steady flow and unsteady flow,Newtonian fluids and Non-Newtonian fluid,etc.,but there are rare studies on oscillatory fraction of the flow rate on mass transfer enhancement factor.The second chapter introduced the general the experimental apparatus and described the principles and methods of PIV and electrochemistry used in this experiment.The third chapter provided the experimental results.In the PIV experiment,the net flow Reynolds numbersRe and the vibration frequency St number were fixed and studied the influence of the vibration separation rate on the flow structure.The experimental results show that the higher the vibration fraction is,the more complex the flow structure is,and the better the corresponding mass transfer effect is.In addition,based on the previous studies on the influence of vibration frequency St number on phase shift,this paper studied the influence the vibration points rate on phase shift and found that the oscillatory fraction of the flow rate had little impact on phase shift.In the electrochemical mass transfer experiment,in the case of same fixed net flow Reynolds numbersRe and the vibration frequency St,the influence of the oscillatory fraction of the flow rate on mass transfer enhancement was studied.The resultsshow that the higher the vibration fraction is,the larger the mass transfer coefficient is,which is consistent with the experimental results of PIV.With the increasing oscillatory fraction of the flow rate,,mass transfer coefficient of reinforcement E arrived its peak value at P = 3;when P > 3,with the increase of oscillatory fraction the mass transfer coefficient E present decreasing trend.Thus,the optimal oscillatory fraction is P = 3.The fourth chapter summarized the results of this research.