论文总字数：20932字

摘 要

由于不凝性气体降低了冷凝表面附近蒸汽的分压，使得蒸汽饱和温度降低，从而降低了温差。此外，冷凝蒸汽通过不凝性气体层到达壁表面是扩散过程，不凝性气体增加了扩散过程的阻力。因此冷凝热交换时的表面传热系数降低。

众多研究表明，少量的不凝性气体就会严重影响抑制蒸汽的凝结换热。例如质量含量仅为0.5％的空气在蒸汽中的存在就会将自然对流凝结换热系数降低50％。不凝性气体的存在使其蒸汽冷凝换热的换热效率严重下降。

为了对含不凝性气体的蒸汽的冷凝换热现象有更深入的了解,得到变化规律来优化实际应用中的蒸汽冷凝换热，必须通过实验来分析不凝性气体影响蒸汽冷凝的情况。对不凝性气相变换热的研究具有很高的生态效益和经济效益。

实验对象是烟气冷凝余热回收再热消白系统中采用氟塑料材质的前后间壁式换热器，探讨的是含各种不凝性气体的蒸汽在换热器中传热系数的变化趋势，总结一般规律和经验公式以及最佳传热系数。燃煤锅炉排烟中蕴含的热量约占燃料热值的4% ～ 8%，该研究可提高这部分热量回收的效率，减少烟气余热的浪费，从而显著提高锅炉的热效率，对资源节约和生态环境保护都有着重要意义，并对其它设备的冷凝换热过程有一定的借鉴意义。

关键词：不可凝气体，冷凝，蒸汽，换热器

ABSTRACT

Since the non-condensable gas lowers the partial pressure of the vapor near the condensing surface, the steam saturation temperature is lowered, thereby lowering the temperature difference. In addition, the condensed vapor passes through the non-condensable gas layer to reach the wall surface as a diffusion process, and the non-condensable gas increases the resistance of the diffusion process. Therefore, the surface heat transfer coefficient at the time of condensation heat exchange is lowered.

Numerous studies have shown that a small amount of non-condensable gas will seriously affect the condensation heat transfer of steam suppression. For example, the presence of air with a mass content of only 0.5% in steam will reduce the natural convective condensation heat transfer coefficient by 50%. The presence of non-condensable gases severely reduces the heat exchange efficiency of the steam condensation heat transfer.

In order to have a deeper understanding of the condensation heat transfer phenomenon of steam containing non-condensable gas, and to obtain the law of variation to optimize the steam condensation heat transfer in practical applications, it is necessary to analyze the situation of non-condensable gas affecting steam condensation through experiments. The research on non-condensable gas phase heat conversion has high ecological and economic benefits.

The experimental object is a front and rear wall-type heat exchanger using fluoroplastic material in the flue gas condensation waste heat recovery reheating whitening system, and the change trend of heat transfer coefficient of steam containing various non-condensable gases in the heat exchanger is discussed. Summarize general rules and empirical formulas as well as optimal heat transfer coefficients. The heat contained in the flue gas of coal-fired boilers accounts for about 4% to 8% of the calorific value of the fuel. This study can improve the efficiency of this part of heat recovery and reduce the waste of flue gas waste heat, thereby significantly improving the thermal efficiency of the boiler, saving resources and Ecological environmental protection has important significance and has certain reference significance for the condensation heat transfer process of other equipment.

Keywords: non-condensable gas, condensation, steam, heat exchanger

目 录

摘要 I

ABSTRACT II

第一章 绪论 1

1.1 研究背景及意义 1

1.2 研究现状 2

1.2.1 含有不凝性气体蒸汽冷凝现象及机理 2

1.2.2 含不凝性气体的蒸汽冷凝研究现状 5

1.2.3 湿烟气除湿技术的发展现状 7

1.3 本文的主要工作 8

第二章 实验部分 10

2.1 实验系统 10

2.2 实验方案设计 12

2.3 实验设备介绍 14

第三章 实验结果与讨论 18

3.1 实验数据分析和处理 18

3.1.1混合气体组分计算 18

3.1.2冷凝传热系数计算原理 18

3.1.3不确定度分析 19

3.1.3试验可靠性（重复性）验证 20

3.2 氧气含量对冷凝传热的影响 21

3.3 氧气体积分数对冷凝的拟合分析 23

3.4 本章小结 24

第四章 结论与建议 24

4.1 主要研究成果 24

4.2 实验中的不足 24

致 谢 25

参考文献 26

绪论

研究背景及意义

随着中国经济和科技的发展，我们对能源的需求也相应不断增加。然而传统能源不能过度开采使用，这就要求我们必须得到提高能源的利用效率。

环境质量的好坏对我们的身体健康有着直接影响，我们越来越意识到环境保护的重要性，这就要求我们的耗能设备同时满足节能和环保的需要，尽量使得能源清洁无污染。

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