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毕业论文网 > 毕业论文 > 理工学类 > 热能与动力工程 > 正文

单根椭圆翅片管的传热与流动分析毕业论文

 2022-07-13 22:04:09  

论文总字数:41660字

摘 要

本文分为三个部分:首先,文章对翅片管式热交换器的定义、结构、国内外研究和发展现状进行综述。其次,本文通过理论计算设计了一台空气冷却器,以对其形成完整的全面的了解。最后,文中采用流体计算软件Icepak 对影响翅片管式换热器流动和传热性能的因素进行数值模拟分析。

数据处理中分别就不同翅片间距、翅片厚度、翅片长短轴等几个因素对翅片管换热器的传热系数、范宁摩擦系数、传热热阻这三个参数的影响进行数值模拟分析。计算结束后,本文先以基本模型为例对其温度场、速度矢量场、速度标量场进行定性分析以了解整个翅片管式换热器的传热状况。然后文中将后处理的数、数、传热系数、范宁摩擦系数、传热热阻等数据与变量参数(翅片间距、翅片厚度,翅片长轴,翅片短轴)整理成折线图的形式,以定性分析各因素的具体影响趋势。

通过模拟计算并比较数据得出结果:随着迎面风速增大,数增大,数增大,摩擦系数减小,传热热阻也减小;随着翅片间距增大,数减小,摩擦系数减小,对传热热阻的影响较小;随着翅片厚度增大,数增大,摩擦系数明显减小,传热热阻也显著减小。

关键词:椭圆翅片管 数值模拟 传热特性 流动特性

Analysis of flow and heat transfer in a single elliptical fin tube

Abstract

From the global view, the paper will be departed into three stages. Firstly, a roughly review of the definition, structure, domestic and foreign research and the current development conditions about finned tube heat exchanger was given. Secondly, in order to form a more comprehensive understanding of the heat exchanger, an air-cooler through traditional theoretical calculation methods was designed. Finally, the numerical simulation analysis was carried out about how the following factors(fin spacing, fin thickness,fin long shaft,fin short shaft ) impact the flow and heat transfer characteristics of finned tube heat exchanger with the fluid calculation software-Icepak.

And then, changing one of the five assumed factors (fin spacing, fin thickness, fin height,fin long shaft,fin short shaft ) alone and collecting enough useful dates for some more analysis in detail helped to find the specific influence mechanism on the heat transfer coefficient, the fanning friction factor and the heat transfer resistance of finned tube heat exchanger. After all the numerical simulation work was over, two different data processing algorithm were token into consideration at the aim of helping readers to understand the whole influence mechanism better.On the one hand, the software Icepak could read some distribution map like the temperature field,the velocity vector field and the speed of scalar field from which the reader could easily discriminate the region where the heat transfer was strong and the area with enhanced flowing.On the other hand, drafting the number, number, heat transfer coefficient, the fanning friction factorand heat transfer resistance,after the post processing with variable parameters (fin spacing, fin thickness, fin long shaft,fin short shaft) into line graph forms made it convenient to analyze the specific factors' influencing trend on finned tube exchanger.

At last, after the numerical simulation and comparative analysis, the following results can be achieved: with the increasing of wind speed, thenumber, and number are both enhanced, while the fanning friction factorand the thermal resistance of decrease; with the increasing of fin spacing, thenumber and the fanning friction factor both experience a decreasing process, but the heat transfer resistance remains basically unchanged; with the increasing of fin thickness, the number increase which means that the heat transfer is enhanced remarkably, but on the contrary, the fanning friction factorand the thermal resistance ofreduce significantly; With the increasing of fin height, thenumber and the fanning friction factor both ascend, while the heat transfer resistance go through a decreasing process.

Keywords: elliptic tube fin;numerical simulation;heat transfer characteristic;flow characteristic

目 录

摘 要 I

Abstract II

第一章 绪论 1

1.1 引言 1

1.2 椭圆翅片管的简介及优点 1

1.2.1椭圆翅片管的简介 1

1.2.2椭圆翅片管的优点 2

1.3椭圆翅片管的应用

1.4椭圆翅片管国内外的研究现状 4

1.5结语 4

第二章 翅片管模型建立 5

2.1 翅片管物理模型及介绍 5

2.2 翅片管几何模型 8

2.3 典型翅片管换热器—空冷器设计 10

2.4 软件模拟结果与理论计算结果对比 13

2.5 小结 14

第三章 数值模型建立 15

3.1 边界条件 15

3.2 数值参数设定及模型建立 16

3.2.1 模型建立 16

3.2.2 网格划分 16

3.2.3 网格质量检查 17

3.2.4 网格划分展示 18

3.2.5 网格无关性检查 20

3.3 小结 22

第四章 数据处理及分析 23

4.1 传统理论计算方法 23

4.2 相关控制方程 25

4.3 模拟结果后处理计算 25

4.4 模拟结果云图分析 27

4.5 模拟数据汇总及分析 34

4.5.1 翅片间距对换热器流动和传热性能的影响 34

4.5.2 翅片厚度对换热器流动和传热性能的影响 36

4.5.3 翅片长轴对换热器流动和传热性能的影响 38

4.6 小结 40

第五章 结果与展望 41

5.1 模拟结论 41

5.2 未来展望 41

参考文献 43

致谢 46

附录 48

第一章 绪论

1.1 引言

随着经济的发展,工业生产的规模及能源的消耗日趋增加,翅片管换热器作为一种重要的强化传热设备,其性能的提高能达到节约能源降低生产成本的目的,受到了广泛的关注和研究[1]。数值模拟的方法目前对单相流动和传热过程相对比较成熟,其计算精度可以满足工程要求,通过模拟的方法得到具有工程意义的参数。换热器是量大面广的通用设备,换热过程则是换热器的核心控制过程[2,3]。翅片管式换热器是空调,制冷,化工等工业领域广泛采用的一种换热器形式,对它的研究不仅有利于提高其换热效率和整体性能,而且对改进翅片管式换热器的设计形式有着重要的指导意义,长期以来,国内外的学者对换热器传热性能进行了大量的理论和实验研究。但是这些研究主要集中在圆管圆翅片,圆管矩形翅片等类型,很少有文献报道椭圆翅片管的换热和流动特性[4]

1.2 椭圆翅片管的简介及优点

1.2.1椭圆翅片管的简介

翅片管热交换器可以由一根或若干根翅片管组成,翅片管是翅片管热交换器中的主要换热元件,椭圆翅片管由基管和翅片组成而成,基管为椭圆管[5]。管内外流体通过管壁及翅片进行热交换,由于翅片扩大了传热面积,使换热得以改善。翅片可以各自加在每根单管上,也可以同时与数根管子相连接。 椭圆翅片管的基本几何尺寸包括 [6]

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