Numerical Simulation Study of Natural Convection Effects on Temperature Drop during Shutdown of Buried Hot Oil Pipelines

To enhance energy conservation and reduce consumption in long-distance crude oil transportation pipelines and minimize the occurrence of pipe blockage, This paper investigates the impact of natural convective heat transfer during the shutdown of buried hot oil pipelines on the temperature drop after the shutdown. Using the computer-aided engineering (CAE) software ANSYS Fluent, the temperature field distribution and temperature drop process under the conditions of simple conduction and considering natural convection in the pipeline are simulated. By comparing the temperature drops under the two heat transfer models, the influence of natural convective heat transfer on the temperature drop process and its significance for maintaining the pipeline’s thermal energy during the shutdown period are analyzed. The study shows that after considering the effect of natural convection, the high-temperature area expands from the center of the pipeline to the lower part of the pipeline, and the internal temperature difference in the pipeline decreases. The effect of natural convection on the early temperature drop of the pipeline is significantly greater than that in the later stage. The research results have reference value for optimizing the shutdown operation strategy of thermal oil pipelines and reducing the re-transportation energy consumption.