反对称热流边界条件下双弥散多孔介质内对流传热研究

Convective Heat Transfer in Bi-Disperse Porous Media under Asymmetric Heat Flux Boundary Conditions

在多孔介质研究中一般施加对称热流或温度边界条件,为了探究反对称热流边界条件下双弥散多孔介质平板通道内的强迫对流传热,课题组基于Neild-Kuznetsov双速度双温度方程进行研究。应用正常模式降阶法,求得两相速度解析解;应用间接解耦法,求得两相温度解析解。计算结果表明:反对称加热方式对双弥散多孔介质的传热特性有较大的影响,而对称加热情形传热率最高;双弥散多孔介质平板通道存在临界有效导热系数比kcr,当k> kcr时,两相无量纲温度之间的关系发生变化;双弥散效应增强,对流换热效果提升。文中解析解可应用于任意热流比情形下的双弥散多孔介质平板通道传热分析。

Symmetric heat flux or temperature boundary conditions are generally imposed in the study of porous media.Based on the Neild-Kuznetsov two-velocity two-temperature equation,the forced convective heat transfer in a parallelplate channel filled with a bi-disperse porous medium was analyzed under the asymmetric heat flux boundary condition.The analytical solution of two-phase velocities were obtained by using the normal mode reduction method and that of twophase temperatures were done by using the indirect decoupling method. The results indicate that asymmetric heating has great influence on the thermal characteristics of bi-disperse porous medium,however,the symmetrical heating leads to the highest heat transfer rate. There is critical effective thermal conductivity ratios (kcr) in the bi-disperse porous medium. When k > kcr,the relationship between the dimensionless temperature of the two phases changes. An enhancement in the bi-dispersion effects leads to an increase in the heat transfer rate. Finally,the asymptotic behavior of Nusselt number was also investigated. The present analytical solutions can be applied to the thermal analysis of bidisperse porous parallel-plate channels under arbitrary heat flux ratios.