部分填充n层多孔复合系统传热及熵产研究
首发时间:2019-01-11
摘要:为确定自由边界流动下多孔复合系统中流动传热性能,对部分填充n层多孔介质的多孔复合系统开展研究。分别采用Darcy-Brinkman模型和局部非热平衡模型描述系统中的流动和传热。在多孔/流体交界面处,动量和热量采用应力、热通量跳跃边界条件来描述;其余中间界面采用应力、热通量连续边界条件来描述。得到了系统中的速度场、温度场和熵产率等物理场。针对部分填充3层多孔介质的复合系统进行了研究,结果表明:局部熵产率在不同多孔层交界面处存在跳跃现象,大部分多孔区固体相的局部熵产率大于流体相的局部熵产率。在多孔区与自由流体区交界面附近,流体相的局部熵产率大于固体相的局部熵产率;随应力跳跃系数的增加,整体努赛尔特数和摩擦因子减小,总熵产率增加;同样,随自由流体层厚度的增加,整体努赛尔特数和摩擦因子而减小,总熵产率增加。
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Analytical heat transfer and entropy generation of partially filled n-layer porous composite system
Abstract:In order to determine the heat transfer performance in a porous composite system under free boundary flow, a porous composite system partially filled with n-layer porous media was studied. Darcy-brinkman model and local thermal non-equilibrium model are used to describe the flow and heat transfer in the system. At the porous/fluid interface, momentum and heat are described by stress and heat flux jump boundary conditions; at other intermediate interfaces, momentum and heat are described by stress and heat flux continuous boundary conditions. The physical fields such as velocity field, temperature field and entropy generation in the system are obtained. In addition, the porous composite system partially filled with three layers of porous medium were studied. The results show that: The local entropy generation jump at the interface of different porous layer, the local entropy generation of solid phase in most porous regions are higher than that of liquid phase, near the interface between porous and free fluid regions, the local entropy generation of liquid phase is higher than that of solid phase; With the increase of stress jump coefficient, the nusselt number and friction factor decrease, and the total entropy generation increases; In addition, With the increase of thickness of free fluid layer, the nusselt number and friction factor decrease, and the total entropy generation increases.
Keywords: n-layer porous media partial filling local thermal non-equilibrium entropy generation
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