高温圆管内多孔介质耦合换热的辐射作用

Effects of radiation on the coupled heat transfer in a high temperature tube filled with porous media

通过数值模拟圆管内填充多孔介质的辐射对流耦合换热,研究高温固体骨架辐射效应对温度分布及换热的影响.基于局部非热平衡模型分别建立流体和固相能量方程,采用蒙特卡罗法求解固体骨架的辐射换热;对不考虑热辐射引起的温度场偏差和管壁发射率以及多孔结构参数的影响进行讨论.结果表明:多孔固体骨架的辐射效应对入口段温度场的影响明显,不考虑辐射将导致较大偏差,壁温为1 500K时最大偏差为16%.管壁发射率对温度场影响较小,壁温为1 500K时影响小于3%.孔隙率或孔径增大,壁面辐射热流密度比例增加,辐射效应体现明显.

The effects of radiation from solid matrix on the temperature distribution and heat transfer were numerically investigated by simulating the coupled heat transfer in a tube filled with porous media.The energy equations of fluid and solid phases were built with the local thermal non-equilibrium model.Monte Carlo method was used to solve the radiative heat transfer of solid matrix.The temperature discrepancy and effects of wall emissivity and structure parameters of porous media were analyzed without radiation.The results show that radiation strongly affects the temperature of the entrance region and a substantial discrepancy occurs when the radiation is neglected.The maximum deviation is 16% at the wall temperature of 1 500 K.The effect of wall emissivity on the temperature is small,which is less than3% at the wall temperature of 1500 K.In addition,when the porosity is high and pore diameter increases,the ratio of wall radiative heat flux increases and the effects of radiation become obvious.