基于孔喉模型的多孔介质对流换热系数的分形研究

Study of Fractal Convection Heat Transfer Coefficient in Porous Media Based on Pore and Throat Model

多孔介质作为一种良好的蓄热和换热材料,在工农业生产中有着广泛应用,获取准确和适用范围广的多孔介质对流换热系数有重要的研究价值。本文先介绍了多孔介质分形理论基础,然后基于多孔介质孔喉模型并结合分形理论、渗流理论及对流换热理论对多孔介质对流换热系数关联式进行理论推导,最后将得出的对流换热系数与传统对流换热系数进行对比并进行了修正。修正后的分形解与传统解比较一致,在孔隙率0.25~0.5的范围偏差较小,而其形式也验证了外部绕流比内部管流更接近多孔介质流动本质。

Porous media has a wide range of applications in the industrial and agricultural production as one kind of good heat storage and exchange material. It has important research value to get an accurate and wide application convection heat transfer coefficient of porous media. The paper introduced the fractal theory foundation of porous media at first. Then it theoretically derived the formula of convection heat transfer coefficient based on pore and throat model, percolation theory, fractal theory and convection theory. Finally, it compared the fractal convection heat transfer coefficient with traditional solution and corrected the fractal convection heat transfer coefficient. It gets a corrected formula in accordance with the tradition formula well when the porosity range from 0.25 to 0.5 and the form of the formula confirms that external flow accords with the nature of porous media better.