风叶型隔板换热器的流动和传热性能研究

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摘要

管壳式换热器是现今使用最广泛的一种换热器，主要适用于石油、化工等行业。

壳侧流体的流动和换热性能的优化对于换热器整体性能的提高具有主导作用，因此对

其壳侧的流场和温度场进行探讨，就显得尤为重要。

本文在现有管壳式换热器的基础上，开发出一种新型的管壳式换热器——风叶型

隔板换热器，主要针对其壳侧的隔板结构进行优化，以达到优化流动和换热性能的目

的。建立几何模型之后，选用 Realizable k-ε模型、标准壁面函数法和 SIMPLE 算法，

进行 Fluent 数值模拟。为了研究几何结构对性能的影响，在不同雷诺数下，通过改变

隔板间距、隔叶片数目、管束长度等结构参数，模拟对应结构的流场和温度场，对 6

种不同结构的风叶型隔板换热器进行建模，每个模型取 7个工况点，得到大量数据，

基于计算数据对流动机理进行了分析。本文得出了如下结论：

1) 风叶型隔板换热器的结构比较复杂，网格划分的工作难度较大，最终使用

ICEM 来进行网格划分，使得网格数量和质量均能满足计算要求。

2) 风叶型隔板换热器在壳侧的流体呈现三股流束的螺旋流动，且速度、压力和温

度的分布都随着壳侧结构的改变而发生周期性波动。

3) 改变隔板数目，当隔板数目 11、9和6，对应的隔板间距分别为 80 mm、100 mm

和160 mm，分别建立物理模型并进行 CFD 数值模拟，得到各种不同结构下的流速、

温度和压力场的数据，研究结果表明，隔板间距为 D=160 mm 时，换热器的综合性能

最好。

4) 模拟的结果表明，隔板的形状对换热器的性能产生了显著影响，隔板为 3片风

叶相对于隔板为 2片风叶的换热器，换热系数 h增大了 4%-8.4%，压降P增大 2%-4%，

综合性能比 h/P增大了 2%-4.4%，所以 3片风叶对应的换热器性能要优于 2片风叶。

5) 改变换热管束的总长度，当长度为 L=800mm 和L=640mm 时，分别进行建模

和数值模拟，并得到流场和温度、压力场的数据。发现当 L=800mm 时，换热器的综

合性能更好。

6) 针对模拟所得到的各种不同结构的换热器数据，选用了性能比 h/P和熵产单

元数 Ns 进行评价，并得出温差传热引起的熵产在总熵产中占主导地位。

7) 与折流杆换热器进行对比，发现风叶型隔板的综合性能比更加优良，因此推及

此换热器具有经济效益和发展前景。

关键词：管壳式换热器非结构化网格周期性波动性能评价

ABSTRACT

Tube-and-shell heat exchangers are the most widely used heat exchanges in petroleum,

chemical and other industries today, which are with simple structure, secure and stable

performance and mature technology. Fluid flow and heat transfer performance optimization

in the shell side has a leading role in the improvement of the overall performance of the

heat exchanger, so research the new efficient shell-and-tube heat exchangers and study their

flow and temperature fields in the shell side is particularly important.

On the basis of the existing shell and tube heat exchangers, a new kind of

shell-and-tube heat exchanger is developed —a heat exchanger with blade-typed baffles.

The main work focuses on the structure is optimization of the shell side, in order to achieve

the purpose of optimizing the flow and heat transfer performance. After creating geometric

model, choose the Realizable k-ε solving model, standard wall function method and

SIMPLE algorithm and do numerical simulation in Fluent. In order to study the impact of

different geometric structures to the performance under different Reynolds numbers, by

changing the structural parameters, such as the number of baffles, blade numbers, and

length of heat tube , simulate corresponding flow and temperature fields under every

structure . 6 different models of heat exchangers with a blade-type baffle were built in this

paper. Each model was simulated under 7 kinds of conditions. Lots of basic data were

obtained. Based on the simulated data, the mechanism of heat transfer enhancement was

analyzed. The main conclusions are as follows:

1) The heat exchanger with blade-type separator structure is very complex, so the work

of meshing is quite difficult. Ultimately one software of meshing ——ICEM was used, and

both quantity and quality of the grid can meet the requirements of numerical computing.

2) There are triple helix flow in the shell side fluid of blade-type separator heat

exchanger, and the distribution of velocity, pressure and temperature present periodical

fluctuations with the changes of structure in the shell side.

3) Change the number of baffles. When the baffles’ number are 10, 8, and 5, the

corresponding space between adjacent baffles are 80mm, 100mm and 160mm ,respectively,

create a physical model and do the CFD simulation, obtained the data of flow rate,

temperature and pressure field under variety of different structures. Then results show that

when the separation distance is 160mm, the overall performance of the shell-and-tube heat

exchanger is the best.

4) Change the number of blades. When the baffle is composed of three blades and two

blades, simulate respectively, and obtained the corresponding velocity, temperature and

pressure field. The simulation results show that the shape of the baffle produced a

significant impact on the performance of the heat exchanger. When the separator are 3, the

heat transfer coefficients and pressure drop are larger, but the heat transfer coefficient

increased with a larger extent than pressure drop, so we can draw the conclusion that heat

exchanger performance of the baffle with 3 blades corresponds is superior to the two ones..

5) Change the total length of the tubes, crate the mode and do numerical simulation of

the length of 800mm and 640mm, respectively, and obtain the data of the flow field and

temperature, pressure field. The results show that when L is 800mm, the overall

performance of heat exchanger is better.

6) For various simulation data of different structures, h/P and the unit number of

entropy generation Ns were selected as performance evaluation parameter from the point of

the first and the second law of thermodynamics in this article. And we draw the conclusion

that entropy generation caused by heat transfer because of temperature difference dominates

in the total entropy production.

7) Compared with the performance of square rod and round rod baffle heat exchanger,

we find that shell-and-tube heat exchanger with blade-typed baffle heat transfer is better.

Thus research the heat exchanger of blade-typed is of good economic benefit and

development prospect.

Key words: shell-and-tube heat exchanger, unstructured grid, periodical

fluctuations, performance evaluation.

摘要

ABSTRICT

第一章绪论 ·························································································· 1

§1.1 前言 ···························································································· 1

§1.2 强化传热技术 ··············································································· 1

§1.3 CFD 模拟研究 ··············································································· 6

§1.4 管壳式换热器的国内外研究现状 ························································ 6

§1.5 换热器的性能评价 ········································································· 8

§1.6 本课题的研究内容 ········································································· 9

§1.6.1 课题的提出及研究意义 ·························································· 9

§1.6.2 本文的研究内容 ··································································· 9

第二章风叶型隔板管壳式换热器的数学物理模型 ············································ 11

§2.1 物理模型与假设 ··········································································· 11

§2.2 数学物理方程 ············································································· 12

§2.3 几何模型 ···················································································· 13

§2.4 网格的划分 ················································································ 15

§2.5 边界条件 ··················································································· 18

§2.6 求解模型的设置 ·········································································· 19

§2.6.1 湍流模型 ·········································································· 19

§2.6.2 SIMPLE 算法简介································································ 20

§2.6.3 壁面函数法 ······································································· 20

§2.7 计算过程 ···················································································· 21

§2.8 本章小结 ··················································································· 21

第三章风叶型隔板换热器的流动性能分析 ···················································· 23

§3.1 流动特性 ··················································································· 23

§3.2 速度分布 ··················································································· 24

§3.3 隔板数目对流动性能的影响 ···························································· 25

§3.3.1 速度分布 ·········································································· 26

§3.3.2 压力分布 ·········································································· 26

§3.4 隔板形状对流动性能的影响 ···························································· 29

§3.4.1 速度分布 ·········································································· 29

§3.4.2 压力分布 ·········································································· 30

§3.5 管束长度对流动性能的影响 ···························································· 31

§3.6 局部阻力分布 ············································································· 31

§3.7 本章小结 ··················································································· 33

第四章风叶型隔板换热器的换热性能研究 ···················································· 35

§4.1 壳程的 h和Nu ············································································ 35

§4.2 壳侧的温度分布 ·········································································· 36

§4.3 隔板间距对换热性能的影响 ···························································· 38

§4.4 隔板形状对换热性能的影响 ···························································· 40

§4.5 管束长度对换热性能的影响 ···························································· 41

§4.6 模拟结果的可信度分析 ································································· 43

§4.7 局部对流换热系数 Num ································································· 43

§4.8 本章小结 ··················································································· 45

第五章风叶型隔板换热器的强化传热评价 ···················································· 46

§5.1 性能比 h/P ·············································································· 46

§5.1.1 隔板间距对 h/P的影响 ······················································ 46

§5.1.2 叶片数对 h/ P的影响 ························································ 46

§5.1.3 管束总长度对 h/ P的影响 ·················································· 47

§5.2 熵产分析法 ················································································ 47

§5.2.1 Be 数的探讨 ······································································· 48

§5.2.2 熵产单元数 Ns ··································································· 51

§5.3 与其他纵流管壳式换热器性能的对比················································· 53

§5.4 本章小结 ···················································································· 55

第六章总结和展望 ·················································································· 57

§6.1 总结 ························································································· 57

§6.2 展望 ························································································· 58

附录：符号表 ························································································· 59

参考文献 ······························································································· 60

在读期间公开发表论文和承担科研项目及取得成果 ·········································· 64

致谢 ··································································································· 65

第一章绪论

§1.1 前言

随着现代工业日新月异的高速发展，人们对于能源的需求也在持续增长。而能源短

缺、不可再生能源的储备有限等严峻的现实问题也摆在眼前，开发新型能源成为了全人

类当务之急的大事。因此，研究和开发高效节能装备成为了全世界共同关注的焦点，我

国也将不遗余力地推广高效能源。

换热器是一种应用非常普遍的设备，它以一定的传热方式将一种流体的热量传递给

他种流体，在动力、化工、炼油、食品、航空、轻工等许多工业部门都广泛使用。例如

电厂热力系统的除氧器，冷水塔给水加热器，动力工业中锅炉设备中使用的过热器、省

煤器、空气预热器；冶金工业中高炉的热风炉，用于炼钢生产工艺中的空气或煤气预热；

蒸发器、冷凝器等；制糖工业和造纸工业的糖液蒸发器和纸浆蒸发器，都是热交换器的

实例。在化学工业和石油化学工业的生产过程中，应用换热器的场合更是数不胜数。在

航天航空工业中，为了技术取出发动机及辅助动力装置在运行时所产生的大量热量，换

热器也是不可缺少的重要部件。高效换热器的迅速发展，不仅意味着传热技术会在很大

程度上得以推广，而且可以带来良好的节能效果。通过应用高效的节能技术，可使能源

节省率达到10%以上。近年来，高效换热器的研究在不断地更新和发展。

国内外非常重视换热器的研究[1]：例如美国传热研究公司（Heat Transfer Research

Inc.）即 HTRI；英国传热及流体服务中心（Heat Transfer and Fluid Flow Service）即 HTFS，

他们长期从事传热与流体等相关课题的研究，积累了丰富经验，并取得了丰硕的研究成

果，这些经验和成果不仅被广泛地运用于原子能等高端工业之中，而且还在一般工业上

使用。中国关于换热器的研究也取得了长足的发展，例如兰州石油机械研究所、通用机

械研究所、抚顺机械设备制造有限公司、中石化南京化工机械等都是我国内资管壳式换

热器的龙头企业。基于换热器在石油、化工、电力、冶金、船舶、机械、食品、制药等

诸多行业的需求在持续增长，未来一段时间，我国换热器产业还将保持稳定增长。

§1.2 强化传热技术

传统的管壳式换热器具备了结构简单、可靠性高、适应压力范围广、选择范围大、

成本低，制造方便和技术成熟等优点，特别是在处理大流量、高温度和高压等参数的情

况下，管壳式换热器更凸显其优势。

提高换热器的紧凑型及动力效率与强化换热过程紧密相关[2]。换热表面的流动阻力

和绕流特性在很大程度上决定了传热过程的强度及换热器的效率。在化工、动力及其他

某些工业领域，日益广泛地采用大型的换热设备，它的主要部件是外绕流的管束，提高

流体动力荷载和换热器的容量。

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摘要：

摘要管壳式换热器是现今使用最广泛的一种换热器，主要适用于石油、化工等行业。壳侧流体的流动和换热性能的优化对于换热器整体性能的提高具有主导作用，因此对其壳侧的流场和温度场进行探讨，就显得尤为重要。本文在现有管壳式换热器的基础上，开发出一种新型的管壳式换热器——风叶型隔板换热器，主要针对其壳侧的隔板结构进行优化，以达到优化流动和换热性能的目的。建立几何模型之后，选用Realizablek-ε模型、标准壁面函数法和SIMPLE算法，进行Fluent数值模拟。为了研究几何结构对性能的影响，在不同雷诺数下，通过改变隔板间距、隔叶片数目、管束长度等结构参数，模拟对应结构的流场和温度场，对6种不同结构的风叶...

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