基于LBM的多孔骨架热物性对固液相变的影响研究

Research on the influence of solid liquid phase change in porous skeleton media based on LBM method

对不同物性骨架对固液相变过程的影响研究可为中低温相变储能技术的应用和发展奠定理论基础。文章基于格子玻尔兹曼方法(LBM),采用两区域焓—多孔介质模型研究了方腔内无填充多孔介质骨架固液相变过程,从孔隙尺度分析了相变过程的流动和传热机理,探讨了方腔内填充不同导热系数的骨架对于相变过程的影响。结果表明:在无填充多孔介质骨架方腔内固液相变过程中传热方式由热传导逐渐向自然对流换热转变,形成向右倾斜的糊状区;它的存在导致相变材料不能完全融化,且在方腔的左侧壁面处存在上窄下宽的固相相变材料;在填充多孔介质骨架方腔内,融化的初始阶段,高导热系数多孔骨架的相变材料融化速率较大,对相变换热起到了明显的促进作用,而当相变过程发展至准稳态阶段,受到右壁面处的低温影响和糊状区的综合作用,相变过程受到明显的抑制,且骨架的导热系数越大,其融化率越低。

Changes of heat transfer and flow filled with different thermal conductivity skeleton on the solid-liquid phase change process set the theoretical foundation for the application and development of low temperature phase change energy storage technology. This paper has adopted the two-zone enthalpy-porous model to study the solid-liquid phase transition process based on the Lattice Bohamann Method（LBM）. On this basis, the solid-liquid phase change process in porous media was studied based on the pore scale to mainly analyze the influences of porous thermal conductivity on the phase change process. The results show that the heat conduction gradually shifts to the natural convection heat transfer which results in an above narrow and under thick mushy region. Because of the existence of the mushy zone, the phase change material does not completely melt causing a narrow top and wider bottom of the solid material at the left wall of the square cavity. For the solid liquid phase transition process of porous media, the high thermal conductivity porous skeleton has a higher melting rate. However, when the phase transition develops to the quasi steady state, the porous skeleton with high thermal conductivity has a significant effect on the natural convection heat transfer which indicates that the melting rate is less than that of the porous skeleton with low thermal conductivity.