TY - JOUR TI - Research on heat transfer characteristics of long-distance pipe-line under shutdown and maintenance conditions AU - Xu Ying AU - Zhang Kaijing AU - Zhu Yuanyuan AU - Chen Shu AU - Zhao Shaodong AU - Liu Xiaoyan AU - Ma Chuan JN - Thermal Science PY - 2024 VL - 28 IS - 5 SP - 3937 EP - 3949 PT - Article AB - When a long-distance pipeline is shut down for maintenance due to corrosion and damage, the process of cooling down and waxing of crude oil in the pipeline is accompanied by complex phase change heat transfer, and it is important to obtain its temperature drop law to reasonably control the shutdown time and formulate restart plan. In this paper, the heat transfer problem of long-distance pipelines under operation and maintenance conditions was studied and refined. Considering the influence of flow and wax precipitation characteristics of crude oil on heat transfer, a multi-field coupled action model was established and analyzed by numerical simulation in combination with the wide-phase interface partitioning method of crude oil. The evolution of the original flow and temperature fields in the pipeline at typical locations of the maintenance pipeline was revealed, and the reasonable maintenance time was proposed based on the change of liquid phase rate. The research in this thesis refined the heat transfer mechanism of the solidified phase change of crude oil for long-distance pipeline shutdown.