On The Influence Of Wall For The Flow And Heat Transfer In A Tube Filled With Particles In Non-Darcy Flow Regime

In recent years, porous medium packed channel is used in many fields ofscientific research and industrial engineering, fluid flow and heat transferphenomenon in porous media packed channel has broad prospects in engineeringapplication, many researchers use experimental and numerical simulation method tostudy the characteristic of fluid flow and heat transfer in porous media packed channeland put forward a lot of experimental correlations of flow and heat transfer in porousmedia packed channel, study on flow and heat transfer in porous media packedchannel is one of the frontier research field in the heat and mass transfer phenomena.But with the wide application of the porous medium, wall effect which is non-uniform variation of porosity near the wall in porous medium packed channel isgradually recognized by people, the wall effect is phenomenon that porosity near thewall is larger than internal space porosity, in other words, porosity inside the porousmedia packed channel is not uniform. In this paper, using the experiment method, thewall effect in porous medium packed channel is studied, flow resistance andconvection heat transfer correlations under wall effect in porous media packedchannel is proposed.In the experimental range of flow experiments, the relationship between themodified friction factor and modified Reynolds number is a power function, thechange of coefficient A and B expose the effect of wall effect on the resistancecharacteristics of the porous medium packed channel, and through experiments weknow that the porosity is an important influencing parameter for the resistancecharacteristics of porous media packed channel. In this paper we use the Wilson PlotMethod to process the heat transfer experimental data, and summarize a heat transferlaw with wall effect in porous medium packed channel. Indeed, the confining wall canaffect the resistance characteristics and convection heat transfer of porous mediumpacked channel, because the porosity distribution in porous medium packed channel isuneven. From the variation of the average porosity we can see that, when diameterratio D/d is less than10, the confining wall effect is very obvious, when diameter ratioD/d is less than40but larger than10, it is weak, when diameter ratio D/d is largerthan40,the effect is negligible. Through the analysis of the experimental data and curve fitting, we get the experimental correlations of flow resistance and convectiveheat transfer in porous media packed channel. The proposed experimental correlationsare compared with those existed in literature. This paper provides experimentalevidence for further study on resistance characteristics and convection heat transferrules under confining wall effect in porous medium packed channel in future.