Numerical computation on hydro-thermal coupling soil temperature field when buried pipeline is shut down

Considering the influence of moisture migration and ice-water phase change, heat conduction model and hydro-thermal coupling model are adopted to carry out numerical calculation in the light of the change of hydro-thermal coupling soil temperature field when buried hot oil pipeline is shut down. After that, the change laws of soil temperature field at different time and the axial temperature drop curve of crude oil pipeline are obtained. The results show that when the hydro-thermal coupling model and heat conduction model have respectively been used to calculate the pipeline axial temperature drop and the soil temperature of the radial space at different locations, the difference of calculation results is greater. The temperature field calculation results calculated by using the former model are significantly higher than the latter, but the axial temperature drop rate is significantly lower than the latter model. With the extending of the shutdown time, the soil temperature field contour that has been calculated by using the hydro-thermal coupling model appears centrosymmetric ellipse distribution. And the isotherms move relatively slowly. The moisture migration and ice-water phase change have a great influence on the non-steady heat transfer of buried pipeline, and the influence can not be ignored in the calculation process.