Abstract Long-distance transport of oil and gas in the harsh subsea environment needs reliable pipeline thermal management to prevent wax deposition and hydrate formation. Multilayer pipeline with the PCM-matrix composite material, made of microencapsulated phase change material particles (MicroPCM particles) and polymer matrix material, is proposed as an effective method to meet the flow assurance challenges owing to its thermal energy storage. Compared with the direct applications of PCM, the PCM-matrix composite material can avoid the possible leakage of its liquid phase and decrease the installation difficulty. Theoretical studies are carried out to investigate the proposed multilayer insulation system in a long horizontal pipeline, which embeds an intermediate insulation layer made of the PCM-matrix composite layer. Considering the storage or release of the latent heat and the changes of thermal properties during the phase change process, the global characteristics of the PCM-matrix composite layer is calculated based on the porous media theory. A pseudo-3D model coupled to the finite difference numerical method is developed to simulate the start-up and shut-in transient processes. To address the liquid and solid states of PCM and their interface, the model for the PCM-matrix composite layer is constituted in the form of enthalpy conservation. The influence of the thermal properties of different matrix and PCM materials on the cooldown time is examined. By analyzing the temperature distributions of produced fluid during start-up and shut-in, the current study shows that the use of MicroPCM particles in the composite layer can prolong the maximum cooldown time. In addition, the geometrical parameters, such as the volume fraction of MicroPCM particle and the thickness of the composite layer, are found to also play a role in affecting the extent of the prolongation of the cooldown time.

中文翻译：

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MicroPCM颗粒长距离多层管道热行为研究

摘要 在恶劣的海底环境中长距离输送油气需要可靠的管道热管理，以防止蜡沉积和水合物形成。由微封装相变材料颗粒（MicroPCM 颗粒）和聚合物基体材料制成的 PCM-基体复合材料的多层管道被提出作为一种有效的方法来应对由于其热能存储带来的流动保证挑战。与PCM的直接应用相比，PCM-基体复合材料可以避免其液相的可能泄漏并降低安装难度。进行了理论研究，以研究在长水平管道中提出的多层绝缘系统，该系统嵌入了由 PCM 矩阵复合层制成的中间绝缘层。考虑相变过程中潜热的储存或释放以及热性能的变化，基于多孔介质理论计算了PCM-基体复合层的全局特性。开发了与有限差分数值方法耦合的伪 3D 模型来模拟启动和关闭瞬态过程。为了解决PCM的液态和固态及其界面，PCM-矩阵复合层的模型以焓守恒的形式构成。研究了不同基体和 PCM 材料的热性能对冷却时间的影响。通过分析开、关井采出液温度分布，目前的研究表明，在复合层中使用MicroPCM颗粒可以延长最大冷却时间。此外，还发现几何参数，如 MicroPCM 颗粒的体积分数和复合层的厚度，也对冷却时间延长的程度产生影响。