论文总字数：30237字

摘 要

通过管内插入扭带进行强化传热是目前工业中强化传热应用较广泛的一种技术,因而受到人们的关注。本文分析了矩形槽螺旋扭带的强化传热机理，利用 Gambit 软件建立三维模型并划分网格，运行Fluent软件进行了流动和换热的数值模拟，得出了管内温度场、压力场和速度场的分布。

本文以水为工质,通过数值模拟的方法,研究了内插矩形槽扭带换热管中的流体流动和传热情况。将五种矩形槽扭带管与光滑管的换热能力和阻力系数进行了比较。在雷诺数在300～2000范围内，努塞尔特数随着雷诺数的增大而增大。与空管数据相比较,插矩形槽扭带管的努塞尔准数Nu提高了107.21%，强化传热想效果十分显著。此外,减小扭转比也能使得努塞尔特数提高, 对于管内插槽扭带, 扭转比分别5/3,5/6和5/9，努塞尔特数相对光滑圆管增大了107.21％，193.75％和152.71％。对于管内插槽扭带, 扭转比分别5/3,5/6和5/9，努塞尔特数相对光滑圆管增大了107.21％，193.75％和152.71％。此外，插矩形槽扭带管随着雷诺数的增大，摩擦阻力系数不断变小。对于插不同尺寸矩形槽扭带管，矩形槽尺寸的大小对摩擦阻力系数 的影响极小。同时改变扭带的扭转比对改变摩擦阻力系数 也有显著的影响，随着扭转比的减小，摩擦阻力系数 将不断增大。

关键词：换热管；扭带；强化传热；数值模拟

ABSTRACT

The fluid flow and heat transfer of the tube fitted with rectangle groove twisted tape insert

Given the vast numbers of heat exchangers used in the Process industry for viscous fluid, substantial capital and operating cost savings can be achieved by employing twisted tapes to improve their heat transfer performance. So people are interested in the using of twisted-tape insert. In this paper, the strengthening heat transfer mechanism in spiral groove tube was analyzed. The 3D models were built and meshed by the software of Gambit, the numerical simulation of flow and heat transfer in these tubes were carried out by applying the Fluent software, from which we got the distribution of temperature field, stress field and the velocity field.

Taking water as the working medium, this paper used experimental methods and numerical simulation methods to study the fluid flow and heat transfer of the tube fitted with rectangle groove aluminum twisted tape insert. Compared the Heat transfer ability and flow resistance coefficient in five rectangle tubes and smooth tube, during the Reynolds number range of 300~2000, as Reynolds number increases Nusselt number increases. The Nusselt number of the tube fitted with rectangle groove aluminum twisted tape insert are 107.21% greater than those of plain tube and the heat transfer enhancement is very remarkable. At the same time, reducing the twist ratio can increase the Nusselt number. The Nusselt number of the tube fitted with twisted tape insert (the twist ratio is 5/3,5/6,5/9 ) is 107.21％，193.75％, 152.71％greater than those of plain tube. We can observe that as Reynolds number of the tube fitted with rectangle groove aluminum twisted tape insert increases，flow resistance coefficient decreases. Using different sizes of rectangle groove，flow resistance coefficient remains stable. However，reducing the twist ratio can increase the flow resistance coefficient effectively.

Keywords:

heat transfer tube，twisted tape insert, heat transfer enhancement,

目 录

摘 要 Ⅰ

ABSTRACT Ⅱ

符号说明 Ⅶ

第一章 绪 论

1.1 课题研究背景及意义

1.2 强化传热技术 1

1.3 扭带强化传热机理 3

1.4 国内外强化传热研究 4

1.5 小结 5

第二章 数学模型 6

2.1 数值方法和数值模拟软件 6

2.2 数值模拟计算的几何模型 7

2.3 数值模拟计算的物理模型 8

2.4 网格独立性分析 10

2.5 光管有效性验证 13

2.6 小结 14

第三章 实验结果及讨论 15

3.1不同矩形槽扭带对流场的影响 15

3.2不同矩形槽扭带对传热的影响 16

3.3不同矩形槽扭带对摩擦因子的的影响 18

3.4不同矩形槽扭带对热性能因子的影响 20

第四章 矩形槽扭带管的应用设计

4.1换热器概述 24

4.2确定设计方案 28

4.3确定物性参数 28

4.4传热量及平均温差 29

4.5估算传热面积及传热面结构 30

4.6管程及壳程结构计算 32

4.7需用传热面积 35

4.8阻力计算 35

4.9设计结果一览表 37

第五章 结论和展望 38

5.1 本文结论 38

5.2存在的问题及展望 39

参考文献 41

致 谢 44

符号说明

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