基于流型特性的天然气组分混合物管内流动凝结换热特性研究

Optimization design of heat exchanger is one of the key technologies within the current LNG process. However, there are significantly few investigations on the condensation heat transfer characteristics of methane and its hydrocarbon mixtures, which are main components of natural gas. This project focuses on experimental and analytical studies of the flow pattern based condensation heat transfer characteristics of methane and its hydrocarbon mixtures in a horizontal plain tube. A special test section will be designed to obtain the accurate experimental results in different operational conditions which are close to the actual process. The influences of flow pattern transitions on the condensation heat transfer characteristics will be examined and discussed. The flow pattern transition mechanisms for mixtures will be demonstrated. This study will be not only an important theoretical research for the engineering thermodynamics theory, but also a continued need of further development of China’s liquefied natural gas (LNG) technology.

冷箱换热器的优化设计是天然气液化流程中的核心技术之一，而对于低温冷箱换热器内典型天然气组分——甲烷及其烷烃混合物的流动凝结换热特性研究却很少见到报道。本项目以天然气液化流程中的换热器为技术切入点，拟开展典型天然气组分——甲烷及其烷烃混合物在水平光滑管内基于流型特性的流动凝结换热特性研究，设计特殊结构的实验测试段，获取天然气组分混合物精确的流动凝结换热基础数据，掌握混合物流型转变规律，阐述流型机制转变对流动凝结换热的影响，揭示其流型转变特性不同于纯质的原因，探索基于流动特性的天然气液化流程中冷箱换热器的优化设计方法。本项工作不仅对于基础热工理论的研究具有重要的理论意义，而且对于推动我国自主液化天然气核心技术的发展具有重要的实用意义。

本项目围绕典型天然气组分甲烷及其烷烃混合物在水平光滑管内基于流型特性的流动凝结换热特性开展实验和关联式研究。设计并搭建了一套水平管内流动冷凝传热及两相流动特性研究实验系统。实验测得纯质甲烷、乙烷及其混合物的水平管内流动冷凝传热实验数据，以及在绝热和冷凝两种工况下的水平管内两相流型数据，分析了各实验参数对传热系数及流型转变的影响；提出了甲烷、乙烷及其混合物的新绝热两相流型图，获得了较好的预测结果，并分别对纯质与混合物提出相应的环状流与非环状流的流型转换标准。另外，根据实验数据的对比和分析结果，分别提出了基于流型判别的纯质和混合物的新传热关联式，获得了与实验数据较为一致的结果。