Fractal model of mass thermal dispersion coefficient for two-phase flow in porous media
HU Shiwang1, ZHANG Sai1*, WANG Zhenyi1, WANG Xianjun2
1. Kunming University of Science and Technology, Faculty of Mechanical and Electrical Engineering, Kunming, Yunnan 650500, China; 2. Huaneng Lancang River Hydropower INC, Kunming, Yunnan 650214, China
Abstract：The fractal theory was used to describe the microscopic pore throat structure of porous media, and the proportion of two-phase fluid in the pore space was studied. The local head loss caused by the secondary flow due to the change of flow state of the fluid passing through the pore throat structure was taken into consideration. Combining the difference in thermal storage capacity of the two-phase fluid along the way, the expression of the velocity dispersion effect and thermal dispersion coefficient of two-phase fluids in the pore space was derived. The research results indicate that when the saturation is less than 0.1 or greater than 0.9, the changes in velocity dispersion and thermal dispersion coefficient of non-wetting phase fluids are less affected by saturation and are only related to the microscopic pore throat structure. When the pore throat ratio is 1, the local head loss is 0, and there is no velocity dispersion effect or thermal dispersion effect; when the pore throat ratio is between 1 and 200, the velocity dispersion effect and thermal dispersion effect change with changes in saturation, pore throat ratio, and fluid physical parameters. When the pore to throat ratio is greater than 200, the change in velocity dispersion effect is not significant, and the influence on thermal dispersion coefficient is no longer significant, which is inconsistent with the conclusion that the velocity dispersion effect is no longer significant when the pore to throat ratio of saturated porous media is 150. The wall temperature is constant. When the pore to throat ratio is greater than 2, the stagnation of the secondary flow near the wall of the pore throat gap leads to an increase in the heating time. The fluid temperature between the pore throat structural gaps is approximately equal to the temperature of the hole wall. The velocity dispersion and thermal dispersion effects are not affected by temperature.
胡世旺,张赛*,汪振毅,王宪军. 多孔介质两相流动分形质-热弥散系数模型[J]. 排灌机械工程学报, 2024, 42(6): 576-582.
HU Shiwang,ZHANG Sai*,WANG Zhenyi,WANG Xianjun. Fractal model of mass thermal dispersion coefficient for two-phase flow in porous media. Journal of Drainage and Irrigation Machinery Engin, 2024, 42(6): 576-582.
