孔隙分布对多孔介质内流动和传热的影响

Effect of Pore Distribution on Flow and Heat Transfer in Porous Media

采用Sierpinski地毯分形技术建立多孔介质内流动和传热模型,通过改变固体基质位置研究了孔隙分布结构对多孔介质内流动特性和热效率的影响,3种孔隙分布为每分形一次固体基质分布在中心位置（A）、分布在中上方（B）和分布在右上方（C）,当流体稳定流过多孔介质时,不同的孔隙分布表现出不同流动和传热特性.结果表明,孔隙分布是影响多孔介质传输特性和传热效率的重要因素,无量纲渗透率k＊C〉k＊B〉k＊A,多孔介质孔隙率大于0.8时更明显;流体流过不同孔隙分布的多孔介质时,相同孔隙率时与流体接触的固体基质面积A〉B〉C,传热效果A最佳、C最差.孔隙分布影响了无量纲局部熵产率,在3种孔隙分布下用Be表示的热传导引起的熵产率占主导.

Sierpinski carpet was used as the model of porous media by changing the position of solid matrix in the model to study the effect of pore distribution on the transmission characteristics and heat transfer efficiency of porous media. The three pore distributions were distributed in a fractal primary solid matrix at the center（A）, in the upper middle（B）, and in the upper right（C）. When the fluid flowed stably through the porous media model, the different pore distribution showed different flow and heat characteristics. The results showed that the pore distribution was an important factor affecting the transmission characteristics and heat transfer efficiency of porous media. The dimensionless permeability was expressed as k＊Ck＊Bk＊A. Especially when the porosity of porous media was more than 0.8, the effect of pore distribution on porous media permeability was more obvious. When the fluid flows through porous media with different pore distributions, the area of the fluid-solid contacting surface at the same porosity is ABC, and the heat transfer effect shows that A is the best and the C is the worst. At the same time, the pore distribution affects the change of the dimension of the non-dimensional local entropy. The pore distribution influences the dimensionless local entropy generation, and the entropy generation caused by heat conduction represented by Be is the main entropy in the three kinds of pore distribution.