高黏介质中内插扭带对换热管换热性能影响

Influences of an inserted twisted tape on the heat transfer performances of a tube with high viscous medium

某石化公司炼油厂第二套常减压装置中换热器的热交换介质为高黏度的原油及其附属产品,在对流换热过程中传热系数低,动能消耗大。针对这一现状,本文设计了一种换热管内插间歇半扭带,利用计算流体力学软件Fluent对内插间歇半扭带换热管在实际工况下的换热过程进行数值模拟,与光滑管、内插连续扭带换热管进行了对比,并给出了间歇半扭带传热元件的优化设计参数。结果表明：内插间歇半扭带大幅提高了换热管内流体的努塞尔数Nu,同时也使换热管内摩擦阻力系数f增大;间歇半扭带换热管的换热效率η比内插连续扭带换热管提高8%-12%;当间歇半扭带的扭曲率y为10、连接杆长度s为345mm时,换热效率η最高,达到2.06。研究结果为该常减压装置换热器强化传热的研究提供了理论依据。

The high viscosity of the heat transfer medium in the crude oil distillation unit in oil refinery process will normally lead to low heat transfer efficiency and high kinetic energy consumption. To solve the problem,this research designed a segmented semi-twisted tape to conduct numerical simulation of the heat transfer process of the tube with a segmented semi-twisted tape under actual conditions,using FLUENT. The heat transfer parameters in plain tube and tube with a continuous twisted tape were compared. The simulation provided optimum design parameters of the segmented semi-twisted tape. The results showed that the segmented semi-twisted tape improved Nu（Nusselt number） of the fluid in a heat transfer tube as well asf（friction factor）,and η（heat transfer efficiency） of the tube with a segmented semi-twisted tape was increased by 8%-12% compared the tube with a continuous twisted tape. The value of η reached the highest number of 2.06 wheny（twist ratio of the segmented semi-twisted tape）was 10 ands（length of the connection rod） was 345mm. The results provided a theoretical basis for the study of enhanced heat transfer of a heat exchanger in a crude oil unit.