Yang Kun, Huang Wei, Li Xin, Wang Jiabing
School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Entropy (Basel). 2020 Oct 26;22(11):1214. doi: 10.3390/e22111214.
The heat transfer and entropy generation in a tube filled with double-layer porous media are analytically investigated. The wall of the tube is subjected to a constant heat flux. The Darcy-Brinkman model is utilized to describe the fluid flow, and the local thermal non-equilibrium model is employed to establish the energy equations. The solutions of the temperature and velocity distributions are analytically derived and validated in limiting case. The analytical solutions of the local and total entropy generation, as well as the Nusselt number, are further derived to analyze the performance of heat transfer and irreversibility of the tube. The influences of the Darcy number, the Biot number, the dimensionless interfacial radius, and the thermal conductivity ratio, on flow and heat transfer are discussed. The results indicate, for the first time, that the Nusselt number for the tube filled with double-layer porous media can be larger than that for the tube filled with single layer porous medium, while the total entropy generation rate for the tube filled with double-layer porous media can be less than that for the tube filled with single layer porous medium. And the dimensionless interfacial radius corresponding to the maximum value of the Nusselt number is different from that corresponding to the minimum value of the total entropy generation rate.
对充满双层多孔介质的管道内的传热和熵产生进行了分析研究。管道壁面受到恒定热流作用。采用达西 - 布林克曼模型描述流体流动，并采用局部热非平衡模型建立能量方程。通过解析推导得到了温度和速度分布的解，并在极限情况下进行了验证。进一步推导了局部和总熵产生以及努塞尔数的解析解，以分析管道的传热性能和不可逆性。讨论了达西数、毕奥数、无量纲界面半径和热导率比对流和传热的影响。结果首次表明，充满双层多孔介质的管道的努塞尔数可能大于充满单层多孔介质的管道的努塞尔数，而充满双层多孔介质的管道的总熵产生率可能小于充满单层多孔介质的管道的总熵产生率。并且对应于努塞尔数最大值的无量纲界面半径与对应于总熵产生率最小值的无量纲界面半径不同。
