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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

叉排圆翅片圆管的传热与流动分析毕业论文

 2022-07-13 10:07  

论文总字数:33991字

摘 要

随着经济的发展,能耗过高成了制约中国经济进一步发展的因素,提高能源的利用率是有效解决能源问题的手段之一。

本文分为三个部分:首先,文章对翅片管式热交换器的定义、简介、国内外研究、发展现状和应用进行综述。其次,本文通过建立模型,模拟出课题要求的翅片管传热流动的模型,然后采用流体计算软件 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。最后,通过多组实验理论计算设计了一台空气冷却器。

在数值模拟中,本文先建立一个基本模型,对具有相同边界条件的同一模型进行数值模拟,并将模拟结果处理后与手工计算结果进行对比,选取结果最接近的一组作为后续模拟计算的参照组。其次,为保证模拟结果的精确性。然后分别就不同翅片间距、翅片厚度、翅片高度、风速这四个个因素对翅片管换热器的传热系数、范宁摩擦系数、传热热阻这三个流动及传热特性参数的影响进行数值模拟分析。其中,选取不同迎面风速 1.4m/s、2m/s、3.5m/s、4.5m/s和6m/s,不同翅片间距 3mm、 4mm、 5mm、 6mm、 7mm, 不同翅片厚度 0.6mm、 0.8mm、 1mm、 1.2mm,不同翅片高度 41mm、43mm、45mm、47mm,。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,从图中看出换热强烈和换热薄弱以及流动剧烈和流动平稳的区域。然后文中将后处理的 Re 数、Nu 数、传热系数 h、范宁摩擦系数 f 、传热热阻 R 等数据与变量参数(翅片间距 S、翅片厚度δ 、翅片高度 a)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,Re 数增大,Nu 数增大,摩擦系数 f 减小,传热热阻 R 也减小;随着翅片间距增大,Nu 数减小,摩擦系数 f 减小, 对传热热阻 R 的影响较小; 随着翅片厚度增大, Nu 数增大, 摩擦系数 f 明显减小,传热热阻R 也显著减小。且在本文中研究的三个影响因素中,翅片间距、翅片厚度、翅片高度的变化对于翅片管式换热器的流动和传热性能的影响来说影响较大。

关键词:圆翅片管 数值模拟 传热特性 流动特性

Analysis on Heat Transfer and Flow of Fork

Row Circular Finned Pipe

Abstract

With the development of economy, high energy consumption becomes a factor which restricts the further development of China's economy. Improving energy efficiency is one of the most effective means to solve energy problems.

This thesis is divided into three parts. Firstly, this thesis will summarize the definition, a brief introduction, research at home and abroad, the status quo of development and the application of finned tube heat exchanger. Secondly, by establishing this model, this thesis simulates the model of the finned tube heat transfer and flow as the subject requires. Then the fluid calculation software ,Icepak ,is used to make a detailed numerical simulation analysis of some factors that influence the flow and heat transfer performance of the finned tube heat exchanger. Finally, through a lot of theoretical experimental calculation, an air cooler is designed.

In numerical simulation, firstly,a basic model is established in this thesis. It will have a numerical simulation on the same model with the same boundary conditions. The simulation results compare the processed simulation calculation results with manual calculation results. The most reasonable one is chosen as a reference group for subsequent calculations. Secondly, to ensure the accuracy of the simulation results, this thesis makes simulated analysis about the influence of four factors (different fin spacing, fin thickness, fin height and wind speed) to the three flow and heat transfer parameters respectively( the heat transfer coefficient, fanning friction coefficient and the heat resistance of finned tube heat exchanger). Different head on wind speed( 1.4 m/s, 2 m/s, 3.5 m/s, 4.5 m/s and 6 m/s), different fin spacing( 3 mm, 4 mm and 5 mm), different fin thickness (0.6 mm, 0.8mm, 1 mm and 1.2 mm),different fin height( 41 mm, 43 mm, 45 mm and 47 mm) are chosen in this thesis. After calculation, this thesis start with the basic model as an example and make a qualitative analysis of its temperature field, velocity vector field so as to learn about the heat transfer condition of finned tube heat exchanger and see from the diagram the strong flow heat transfer region, the weak heat transfer region, the dramatic flow region and the smooth flow region. Then, a line chart is finished with statistics (Re number, Nu number, heat transfer coefficient h, fanning friction coefficient f, heat transfer resistance R ) and variable parameters,(fin spacing S, fin thickness, fin height a)to make a qualitative analysis of the concrete influential trend of various factors .

Through the simulation calculation and comparison, a conclusion can be made: with the head-on wind speed rising, Re, Nu number increases while friction coefficient f and hot resistance R decrease; with the fin spacing rising, the Nu number and the friction coefficient f decrease while it has little influence on the heat transfer resistance R; with the fin thickness rising,Nu number increases while friction coefficient f and the hot resistance R decrease significantly. Among the four factors studied in this thesis, the flow and heat transfer of finned tube heat exchanger is greatly influenced by the changes of fin spacing, fin thickness and fin height. As a result, the factors should be given top priority in designing a finned tube.

Keywords: Round finned tubes Flow characteristics Numerical Simulation

Numerical simulation of heat transfer characteristics

目录

摘 要

Abstract

符号说明

第一章 绪论 1

1.1 课题背景 1

1.2 翅片管简介 1

1.2.1 按加工工艺分类; 1

1.2.2 如果按翅片形状分类则为: 2

1.3 翅片管国内外研究现状 2

1.4 叉排圆翅片管的应用 5

第二章 翅片管模型的建立 6

2.1 Icepak软件介绍 6

2.1.1 ICEPAK软件介绍 6

2.1.2 快速几何建模 6

2.1.3 强大的zoom-in功能 7

2.1.4 参数化和优化设计功能 7

2.1.5 强大的解算功能 7

2.1.6 先进的网格技术 8

2.1.7 强大的可视化后置处理 8

2.1.8 软件优势 8

2.2 建立模型 9

2.2.1 物理模型 9

2.2.2 三视图 10

2.2.3 模型建立 11

2.2.4 边界条件 11

2.2.5 网格划分 13

2.2.6 网格质量检查 13

2.2.7 网格无关性检查 14

2.2.8 网格划分结果 15

2.3 模拟计算 15

第三章 空冷器设计 18

第四章 数据分析及数据处理 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 26

4.4 计算所得数据与模拟结果分析 27

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