天然气液化冷剂管外降膜流动特性数值模拟

降膜流动蒸发是液化天然气工艺中绕管式换热器的核心传热方式.为了研究不同雷诺数、管外径及管间距对烷烃类介质降膜流动管间流型、液膜厚度等参数的影响,基于VOF两相流模型和Level Set两相流模型的耦合模型,进行降膜流动的数值模拟研究,同时搭建可视化实验装置,对数值模型进行实验验证.基于数值模拟结果,拟合得到了适用于烷烃...

Numerical simulation of flow characteristics of falling film outside coolant pipelines during liquefaction of natural gas

Falling film evaporation is the core heat transfer mode of spiral-wound heat exchangers used in the liquefaction process of natural gas. In order to study the impact of different Reynolds numbers, outer diameters and spacings of pipeline on the parameters of the falling film flow of alkane media, such as the flow pattern and liquid film thickness, numerical simulation study of falling film flow was performed with the coupling model based on the VOF and Level Set two-phase flow models. Meanwhile, the numerical simulation model was verified by setting a visual experimental device. In addition,the calculating equation of liquid film thickness applicable to the alkane media was obtained by fitting based on the numerical simulation results. According to the results, the Reynolds number and the outer diameter of pipeline have great influence on the distribution of liquid film thickness. In the case that the outer diameter of pipeline is 4 mm, the liquid film thickness of falling film flow is uniform with poor stability at great Reynolds number(340–1 700). In general, the research results could provide theoretical guidance to the design and the safe and efficient operation of spiral-wound heat exchangers during the liquefaction of natural gas.