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首页> 外文期刊>International Journal of Heat and Mass Transfer >Analysis of thermally developing forced convection heat transfer in a porous medium under local thermal non-equilibrium condition: A circular tube with asymmetric entrance temperature
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Analysis of thermally developing forced convection heat transfer in a porous medium under local thermal non-equilibrium condition: A circular tube with asymmetric entrance temperature

机译：局部热非平衡条件下多孔介质中热发展的强制对流换热分析：入口温度不对称的圆形管

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摘要

Thermally developing forced convective heat transfer in a circular tube filled with a fluid-saturated porous medium is analytically investigated under local thermal non-equilibrium (LTNE) condition. In this study, we assume the forced convection within the porous medium obeys Darcy's law, the tube has a constant temperature wall and possess an entrance with variable circumferential temperature distribution. Under these conditions, closed-form exact solutions of the fluid and solid phases temperatures are derived by using the method of separation of variables. The finite element (FE) analysis software COMSOL Multiphysics is employed to numerically model the studied problem. The good agreement between the presented analytical solutions and the FE solutions verifies the validity of the analytical solutions presented. Meanwhile, the consistency of the axisymmetric analytical solutions in the case of uniform entrance temperature with the existing analytical solutions in the literature confirms again the correctness and the reliability of the presented analytical solutions. Given the entrance temperature can be an arbitrary well-defined function, the presented analytical solutions are of general applicability. The subsequent parametric studies are carried out based on the presented analytical solutions. It is demonstrated that the temperature fields are non-axisymmetrical with respect to the circumferential coordinate, which is induced by the asymmetric entrance temperature. Besides, the Peclet number and the Biot number play significant roles in heat transfer. The increase of the Peclet number will result in the transition of thermally developing forced convection to the fully developed regime, while the temperature difference between the fluid and solid phases decreases with increasing the Biot number. Moreover, as a limiting case, the LTNE model degenerates to the LTE model when the Biot number approaches infinity. Our findings are of benefit to provide deep insights into the thermal behavior of forced convection in a porous circular tube with asymmetric entrance temperature under LTNE condition. (C) 2018 Elsevier Ltd. All rights reserved.
机译：在局部热非平衡（LTNE）条件下，对在充满流体饱和多孔介质的圆管中进行的热发展强迫对流换热进行了分析研究。在这项研究中，我们假设多孔介质内的强制对流遵守达西定律，该管具有恒定的温度壁，并具有可变的圆周温度分布的入口。在这些条件下，通过使用变量分离方法可以得出流体和固相温度的闭式精确解。使用有限元（FE）分析软件COMSOL Multiphysics对所研究的问题进行数值建模。所提出的分析解决方案与有限元解决方案之间的良好一致性验证了所提出的分析解决方案的有效性。同时，在入口温度均匀的情况下，轴对称解析解与文献中现有解析解的一致性再次证实了所提出解析解的正确性和可靠性。给定入口温度可以是任意定义明确的函数，则所提出的分析解决方案具有普遍适用性。随后的参数研究是基于提出的分析解决方案进行的。结果表明，温度场相对于圆周坐标是非轴对称的，这是由不对称的入口温度引起的。此外，Peclet数和Biot数在传热中起重要作用。 Peclet数的增加将导致热发展的强制对流过渡到完全发展的状态，而液相和固相之间的温差随Biot数的增加而减小。而且，作为极限情况，当毕奥数接近无穷大时，LTNE模型退化为LTE模型。我们的发现有助于深入了解LTNE条件下入口温度不对称的多孔圆管中强制对流的热行为。 （C）2018 Elsevier Ltd.保留所有权利。

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