换热器表面碳酸钙垢析晶过程与换热的实验研究

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摘要

污垢的存在不仅使换热设备的换热效率下降，浪费能源、资源，产生巨大经

济损失而且使很多能源高效利用的技术方法失去可行性，如低品位能源的利用、

高效强化换热技术等。因此，污垢在流体中的形成、扩散和在换热表面的粘附、

生长等过程和特性的研究是抑制污垢生长技术发展的前提。评价强化管的强化换

热效果要观测在洁净状态和结垢状态下不同材质和不同强化方式的强化换热管的

换热系数，并以此为目标函数来优化强化管的强化方式和参数。

在碳酸钙析晶污垢结垢初始阶段静态实验中，将换热设备常用的金属材料（紫

铜、黄铜、不锈钢 304 和316）做成实验挂片垂直悬挂于碳酸钙过饱和溶液中，在

溶液温度分别为 35℃和 60℃，碳酸钙浓度分别为 0.5mmol/l 和1.0mmol/l，溶液 pH

值分别为 10 和11 时，共 32 种实验工况，详细研究了在无流体流动的扰动和重力

作用下，溶液中成垢物质通过成垢粒子表面反应机理和污垢颗粒扩散粘附机理两

种生长方式控制下以及两种生长机理之间竞争机制下，不同水质参数（溶液温度、

碳酸钙浓度、溶液 pH 值）和金属材料下，结垢量、诱导期和表面碳酸钙污垢的晶

型、比例和尺寸等生长特性。探究碳酸钙溶液从过饱和、诱导期到生长阶段前期

这一结垢初始阶段，Ca2+和CO32-在溶液中和换热表面发生的成核、晶核长大、絮

凝团聚、扩散、粘附等过程中的热力学、动力学、力学和生长机理等规律做了深

入研究和分析归纳。结果表明：当流体中碳酸钙处于过饱和状态时，首先本体溶

液中进行均相成核及晶核生长，形成的污垢颗粒其中一部分通过扩散和粘附而附

着在换热表面或表面污垢上使换热表面结垢增多；过饱和溶液与换热表面浸润一

段时间后，碳酸钙成垢粒子在换热表面进行异相成核及晶核生长，也使换热表面

结垢增多。当流体水质参数改变或换热表面参数发生变化时，会影响这两种结垢

方式的强弱，从而改变换热表面结垢量。如果流体水质参数改变使碳酸钙过饱和

度（饱和指数）很小或很大时，换热表面结垢量均较少；只有当碳酸钙过饱和度

（饱和指数）适中时，才会使表面结垢量最多。

但在实际工程应用中，均存在着流体流动和重力沉降的作用，换热表面上结

垢使传热效率降低, 流动阻力增大, 因此造成能源损失和浪费、甚至造成安全事故。

因此, 人们在采用传热效果较好的强化管来提高传热效率的同时，也日益关注其抗

垢性能。本文在碳酸钙析晶污垢结垢静态实验基础上又进行了动态实验，对两种

斜翅管（平直斜翅管和锯齿斜翅管）和光管进行对比实验，研究不同流体参数，

即流速（0.04m/s 和0.07m/s）和碳酸钙浓度（0.5mmol/l、1.0mmol/l 和2.0mmol/l）

和斜翅管的强化参数（实验中仅改变了肋形，未进行翅高、翅数和翅间距等参数

的改变）对结垢前后强化传热比和污垢热阻以及结垢诱导期的影响，以求获得更

好的强化传热比和抗垢性能。结果表明：流速增大时使成垢物质的扩散传质系数

增大也使表面污垢晶体受到的剥蚀剪力增强，两个相反作用的强弱则要视具体流

体流态、换热管参数等情况而定，实验中浓度越小流速改变时污垢热阻相差越小。

相同条件下，浓度增大使结垢量和污垢热阻增大。锯齿斜翅管的结垢量和污垢热

阻均高于平直斜翅管，但其总换热系数和强化换热比仍高于后者，两种斜翅管的

结垢量和污垢热阻与光管相差不大，但总换热系数远高于光管，因此在洁净状态

和结垢状态下均具有较好的传热效果。

本课题受到上海市重点学科建设项目（S30503）和上海市研究生创新基金第

五期（JWCXSL1101）的支持。

关键词：碳酸钙析晶污垢初始阶段强化换热表面反应扩散粘

附

ABSTRACT

Both the heat transfer efficiency of heat transfer equipments decreases and the

energy and resources are wasted by fouling. So there is enormous economic loss and

even make the technologies and methods of high-efficient energy use infeasible, such as

low-grade energy use, high-efficient heat transfer enhancement technology and so on.

Therefore, the processes and characteristics of the fouling form and diffusion in fluid,

then adhesion and growth on heat transfer surface must be totally researched. It is the

prerequisite to develop the technologies of repression the growth of fouling. The

evaluation of heat transfer efficiency of enhanced tubes must measure the heat transfer

coefficient at both clean condition and fouling condition of different materials and

enhancements of enhanced tubes. And the heat transfer efficiency at both clean and

fouling conditions is set as the objective function to optimize the enhancements and

parameters of enhanced tubes.

At the static experiments of the initial stage of calcium carbonate crystallization

fouling, the common used materials in heat transfer equipments (copper, brass, stainless

steel304 and 316) was produced as coupons which was vertical suspended in the

calcium carbonate super-saturation solution. The temperature of the solution is 35℃

and 60℃, the concentration is 0.5mmol/l and 1.0mmol/l and the pH value is 10 and 11,

so the experiment conditions are 32 in all. The growth menchanisms of foulant ions

reaction at heat transfer surface and fouling crystal particles diffusion and adhesion on

surface and the competition relationship between them have been detailed researched

without fluid flow and gravitational settling influence. The characteristics of fouling

mass, induction period and the crystal phases, proportion and size of fouling crystals

and so on at different water chemical parameters and metal materials have been

researched, too. The initial stage processes include the fluid from super-saturation,

induction period to the earlier stage of growing period. The thermodynamical, kinetic

and mechanical regulation and growth mechanism of Ca2+ and CO32- nucleation, growth,

flocculation, reunion, diffusion and adhesion and so on have got. The results show that

when the fluid is super-saturated, the homogeneous nucleation and nuclei grow firstly

happened in bulk solution, part fouling crystal particles diffusion and adhesion on the

heat transfer surface or the fouling crystals on heat transfer surface. After the fluid

wetting the heat transfer surface, the calcium carbonate ions and moleculars will

heterogeneous nucleation and nuclei grow on heat transfer surface. If the water

chemical parameters or heat transfer surface change, the two fouling growth rates also

change and the fouling mass on surface will be affected. If the water chemical

parameters make the super-saturation or saturation index very small or very big, the

fouling mass is both less; only when the super-saturation or saturation index is moderate,

the fouling mass will be more.

But actually, the fluid flow and gravitational settling are both exist. Fouling on heat

transfer surface not only decreases the heat transfer efficiency but also increases the

flow resistance. So, to enhance the heat transfer coefficient of enhanced tubes, the

anti-fouling performance shall also improve. This paper did the dynamic experiments

which used the plain tube and two oblique fin tubes and different velocity (0.04m/s and

0.07m/s), calcium carbonate concentration (0.5mmol/l, 1.0mmol/l and 2.0mmol/l). The

influences of different parameters on heat transfer enhancement, fouling resisrance and

induction period at both clean and fouling conditions have got to the best heat transfer

enhancement and anti-fouling performance of enhanced tubes. The results show that the

diffusion coefficient of foulant substance and the denudation shear are both increase

when the fluid velocity increase. The two opposing effects which is more important

depends on the flow pattern, calcium carbonate concentration and heat transfer tube and

so on. At the same conditions, the fouling mass and resistance are bigger when

concentration is bigger. The fouling mass and resistance of saw-tooth oblique fin tube

are bigger than straight oblique fin tube, but the heat transfer coefficient and heat

transfer coefficient enhanced ration are bigger. The fouling mass and resistance of two

oblique fin tube and plain tube are no big difference, but heat transfer coefficient are

well above plain tube, so the oblique fin tubes have greater heat transfer performance at

both clean and fouling conditions.

This research is support by the Shanghai Leading Academic Discipline Project

(S30503) and the Innovation Fund Project For Graduate Student of Shanghai

(JWCXSL1101).

Key Words: Calcium carbonate crystallizaition fouling, Initial stage,

Heat transfer enhancement, Surface reaction, Diffusion and adhesion

中文摘要

ABSTRACT

第一章绪论 .............................................................................................................. 1

1.1 研究背景 .......................................................................................................... 1

1.2 污垢研究的发展简史 ...................................................................................... 3

1.3 抗垢强化换热技术研究进展 .......................................................................... 4

1.4 析晶污垢诱导期研究进展 .............................................................................. 6

1.4.1 污垢分类 ................................................................................................ 6

1.4.2 污垢形成过程 ........................................................................................ 7

1.4.3 析晶污垢诱导期 .................................................................................... 9

1.5 本文主要研究内容及创新点 ......................................................................... 11

1.5.1 本文主要研究内容 ............................................................................... 11

1.5.2 创新点 .................................................................................................. 12

第二章碳酸钙析晶污垢生长过程分析 .................................................................... 14

2.1 结垢过程热力学分析 .................................................................................... 15

2.2 结垢过程动力学分析 .................................................................................... 20

2.3 结垢过程力学分析 ........................................................................................ 21

2.3.1 范德华力 .............................................................................................. 22

2.3.2 静电双层力 .......................................................................................... 23

2.3.3 流体剥蚀剪力 ...................................................................................... 24

2.4 结垢过程的控制机理分析 ............................................................................ 26

2.5 结垢饱和指数分析 ........................................................................................ 29

2.6 本章总结 ........................................................................................................ 35

第三章静态实验及结果分析 .................................................................................... 38

3.1 碳酸钙污垢静态实验系统 ............................................................................ 38

3.1.1 实验目的 .............................................................................................. 38

3.1.2 实验原理 .............................................................................................. 38

3.1.3 实验系统简介 ...................................................................................... 39

3.1.4 实验步骤 .............................................................................................. 40

3.2 实验结果与分析 ............................................................................................ 41

3.2.1 结垢量 .................................................................................................. 41

3.2.2 污垢微观形貌 ...................................................................................... 47

3.2.3 pH 值对结垢过程的影响 .................................................................... 62

3.2.4 碳酸钙浓度对结垢过程的影响 .......................................................... 86

3.2.5 温度对结垢过程的影响 ...................................................................... 86

3.2.6 金属材料对结垢过程的影响 .............................................................. 88

3.2.7 过饱和度和饱和指数对结垢过程的影响 .......................................... 95

3.3 本章总结 ........................................................................................................ 95

第四章动态实验及结果分析 .................................................................................... 98

4.1 碳酸钙污垢动态实验系统 ............................................................................ 99

4.1.1 实验系统简介 ...................................................................................... 99



4.1.2 实验步骤 ............................................................................................ 101

4.2 污垢热阻动态测量原理 .............................................................................. 103

4.3 实验结果与分析 .......................................................................................... 104

4.3.1 结垢诱导期 ........................................................................................ 104

4.3.2 污垢热阻 ............................................................................................ 106

4.3.3 污垢形貌 ............................................................................................. 113

4.3.4 流速对结垢过程的影响 .................................................................... 126

4.3.5 浓度对结垢过程的影响 .................................................................... 127

4.3.6 斜翅管管参数对结垢过程的影响 .................................................... 129

4.4 本章总结 ...................................................................................................... 130

第五章结论与展望 .................................................................................................. 133

5.1 全文总结 ...................................................................................................... 133

5.2 未来展望 ...................................................................................................... 135

主要符号表 .................................................................................................................. 136

参考文献 ...................................................................................................................... 140

在读期间公开发表的论文和承担科研项目及取得成果 .......................................... 148

致谢 .......................................................................................................................... 150

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摘要：

摘要污垢的存在不仅使换热设备的换热效率下降，浪费能源、资源，产生巨大经济损失而且使很多能源高效利用的技术方法失去可行性，如低品位能源的利用、高效强化换热技术等。因此，污垢在流体中的形成、扩散和在换热表面的粘附、生长等过程和特性的研究是抑制污垢生长技术发展的前提。评价强化管的强化换热效果要观测在洁净状态和结垢状态下不同材质和不同强化方式的强化换热管的换热系数，并以此为目标函数来优化强化管的强化方式和参数。在碳酸钙析晶污垢结垢初始阶段静态实验中，将换热设备常用的金属材料（紫铜、黄铜、不锈钢304和316）做成实验挂片垂直悬挂于碳酸钙过饱和溶液中，在溶液温度分别为35℃和60℃，碳酸钙浓度分别为0....

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