Research Of Forced Convection In A Channel Filled With Porous Media Using Local Thermal Non-equilibrium Model

In this thesis, forced convection in a parallel channel fully filled with porous mediawith internal heat generation and a channel partly filled with porous media has beentheoretically investigated, respectively. By employing the Darcy-Brinkman equation forflow and local thermal non-equilibrium model for heat transfer, analytical solutions ofvelocity and temperature distributions of fluid phase and solid phase in both channels arefirstly derived. Moreover, exact expressions of Nusselt number are also derived. For theformer channel, effects of internal heat generation in fluid phase and solid phase on heattransfer and validity of local thermal equilibrium model in the channel are analyticallystudied. For the latter channel, effects of pertinent parameters on velocity profiles, flowsresistance, mass flow rate in porous region, temperature profiles, Nusselt number and thecomprehensive performance of heat transfer and flow are discussed in detail. It is foundthat:(1) For the former channel, for the specific parameters, the phenomenon of heat fluxbifurcation will occur on the wall; the effect of internal heat generation in fluid phase onNusselt number is much weaker than that in solid phase; when Darcy number is smallerthan10-5, effect of internal heat generation in fluid phase can be neglected; local thermalequilibrium model is invalid with the presence of internal heat generation.(2) For thelatterer channel, when Darcy number is smaller than10-5, effect of Darcy number onvelocity profiles can be neglected. As Darcy number decreases or the thickness of theporous medium region increases, the flow resistance of the channel becomes strong,however, when the thickness of the open region is higher than0.6, Darcy number has littleinfluence on the flow resistance of the channel. As Y1increases, a minimum Nusseltnumber is founded, besides, a maximum Nusselt number is founded for both smaller Biotnumber and ratio of the effective thermal conductivity of fluid phase and the effectivethermal conductivity of solid phase, k. For the specific range of the interfacial, namely,0.001Biint100, Biot number, Nusselt number becomes larger with increasing of the interfacial Biot number, however, beyond this range, the interfacial Biot number canhardly influence Nusselt number. When Darcy number is10-3, the critical point of thecomprehensive performance of heat transfer and flow is Y1=0.2, moreover, the criticalpoint moves to the right with k decreasing. Reduction of Darcy number can result in thepoorer comprehensive performance of heat transfer and flow for the channel partiallyfilled with porous media than that for the smooth channel.