导　　师： 江楠

学科专业： 080706

授予学位： 硕士

作　　者： ;

机构地区： 华南理工大学

摘　　要： 针翅管作为一种高效强化传热管,具有扩大传热面积,增强流体湍流度,提高传热系数,减少污垢及防止振动的优势。由于针翅管换热器内部结构的复杂性,以往的研究大都集中在实验研究上,在数值模拟方面的研究较匮乏。 本文采用Fluent对针翅管换热器进行了数值模拟研究。通过改变针翅管结构参数及工艺条件对针翅管换热器壳程流体的流动、传热及阻力性能进行了系统的研究,主要包括以下内容: 在分析针翅管换热器流动特性和阻力的基础上,分别以热水-冷水和热水-柴油为传热介质利用正交设计进行了针翅管数值模拟,得到了其传热性能曲线。在本文所选的4针翅管的4个影响因素中,以各组总换热系数K作为考查指标分析,其中针翅间距s是最为敏感的。采用壳程ho//△p作为考查指标分析,其中针翅长度l是最为敏感的。 本文还以水和柴油为换热对象,利用三维模型对2种不同规格的直针翅管以及30 0、45 0和60 0的斜针翅管换热器的壳程温度场、压降和传热性能进行了模拟;并将直针翅管、斜针翅管与光滑管进行了比较。模拟结果表明,斜针翅管的压降为光滑管的1.06～1.4倍,总传热系数约是光滑管的1.7～3倍。直针翅管换热器的壳程压降约是光管换热器的1.1～3倍,总换热系数约是光管换热器的2～3.6倍。在相同的条件下,斜针翅管换热器比直针翅管换热器综合性能更优。 在低流速下,斜针翅管的强化传热效果显著,能降低壳程流动阻力,其综合换热性能较好。但随着流速的增加,综合换热性能迅速下降,逐渐不如光管的综合换热性能好,说明在实际应用中应综合考虑来选择合适的倾斜角,β/(°/)为30～45之间存在一个合适的倾斜角,其综合换热性能较好。 通过对三种不同针翅形状的针翅管换热器的压降△p、总换热系数K、综合换热性能ho//△p的模拟结果比较,得到滴形针翅的针翅管换热器的传热和阻力性能都比圆柱形针翅的好,椭圆针翅的传热性能不及滴形和圆柱形针翅,但是阻力是三者中最小的。 As a high-effective special shape tube for enhanced heat transfer, the pin finned tube has many good characteristics such as extending the heat transfer surface, intensifying the fluid turbulence, enhancing the transfer coefficient, less shell-side fouling, and prevention of flow induced vibration. Because of the complicated configuration of the heat exchangers with pin finned tube, previous studies focused on their experiments and there are no many researches on their numerical simulations. The heat exchangers with pin finned tube have been simulated by means of FLUENT. By changing structural parameters and process conditions, this paper investigates flow behavior, heat transfer and resistance performance of shell-and-tube heat exchangers with pin finned tube. The main contents are as follows: Based on the analysis of portrait flow pin fin tube flowing characteristics, The heat exchangers with pin finned tube of orthogonality design were simulated using hot water /(cold water/) and diesel oil as heat-transfer medium, and the heat transfer performance curve obtained. From the result of orthogonality design, the sensitive degree diversity for four factor are educed. From the perspective of the total heat transfer coefficient, pin fin portrait distance among of four factors is the most sensitive. From the perspective of the comprehensive heat transfer performance, pin-fin length is the most sensitive, and in the future study of heat exchangers, the main work should be on changing the portrait distance or incline degree of pin fin can achieve the further optimize and compact purpose. Numerical simulations were conducted for hot water flowing in tube side of heat exchanger with diesel oil as heat-transfer medium flowing in shell side, utilizing three-dimensional model. Temperature field and heat transfer performances in shell side of the heat exchanger with two different specifications of straight-pin fin tub and angle of inclination 30 0, 45 0, 60 0- inclined-pin fin tub were simulated. Pressure drop is about 1.06~1.4 times greater than that at same flow condition and heat transfer enhancement of inclined-pin-fined tube is about 1.7~3 times greater than that of smooth tube heat exchanger. Pressure drop of straight-pin fin tub is about 1.1~3 times and heat transfer enhancement of straight-pin fin tub is about 2~3.6 times greater than that of smooth tube heat exchanger. At low velocity, heat transfer enhancement effect of the inclined-pin tube exchanger significantly reduces the flow resistance of the shell, and its comprehensive heat transfer performance is better, but as the velocity increases, the integrated heat transfer performance decreased rapidly, and gradually as light tubes. It shows the practical application should be taken into account to select the appropriate angle. Between 30 0and 45 0, there is a right angle, and its the integrated heat transfer performance is better and occupy less space. Through three different shapes of pin fin pins about the fin tube heat exchanger which are pressure drop△p, the total heat transfer coefficient K, Composite heat transfer performance ho //△p, comparison of simulation results show that heat transfer and pressure drop performance of the drop-shaped pin fins are better than that of the circular pin fins and the elliptical pin fins. Heat transfer performance of the elliptical pin fins less than the drop-shaped and cylindrical pin fins, but the resistance of it is best among the three pin fin pins.

关 键 词： 针翅管换热器 数值模拟 正交设计 斜针翅

分 类 号： [TK172]

领　　域： [动力工程及工程热物理]