论文总字数：31959字

摘 要

日益小型化的电子器件和设备的散热问题促使脉动热管这种新型高效的传热元件得到越来越广泛的研究。与普通热管不同，脉动热管是集相变传热、显热传热于一体，涉及多学科的复杂的汽液两相流系统，具有高效传热潜力，应用背景广泛的优点。

本文通过对三种充液率、三种体积配比的乙醇-水双工质脉动热管实验研究数据分析，得到了热管冷热段均温、传热温差、传热热阻随功率、充液率和配比的变化规律，探究了乙醇-水双工质脉动热管内部工质的饱和压力、干度、潜热传热量、显热传热量、质量流量和流速随加热功率的变化特性，并对比了充液率、体积配比对以上参数的影响特性。同时，通过乙醇及水纯工质热物性参数的对比，了解乙醇、水纯工质热物性随温度的变化规律；进行了乙醇-水脉动热管双工质热物性在不同充液率、不同体积配比下随温度的变化规律的研究，确定了双工质热物性如饱和压力、干度、单位工质单位温升潜热和显热等的计算方法；发现充液率、体积配比、功率和热物性等对脉动热管的传热性能都有影响。

实验结果分析表明：当功率从5W升到300W时，热管的传热热阻随着功率增加而减小，并趋于平稳到0.1℃/W左右。其中中小功率对热管传热性能的影响较明显；其中，显热传热占总传热量的份额较大，并随功率的增加而减少，显热热份额可从99%最小降到75%，而潜热份额随功率增加而增大，可从1%最大升到25%；相同体积配比和相同加热功率时，充液率越大，显热传热份额越大，潜热份额越小；相同充液率和加热功率时，乙醇工质体积配比的增加，显热传热份额减少，而潜热传热份额增大。结果还显示，乙醇-水混合工质脉动热管的质量流量和流速随功率增大先快速增大并在高位振荡下降，其中充液率越高，流速越快。混合工质单位温升传热量、显热传热量和潜热传热量都随温度的升高而增大，其中单位温升的显热传热份额减小，而潜热传热份额增大。

关键字：脉动热管；传热热阻；热物性；乙醇-水混合工质

Study on thermal properties of working fluids and heat transfer performance of ethanol-water pulsating heat pipes

Abstract

With the miniaturization of electronic components and system, as well as continuous increase in the power density, the pulsating heat pipe (PHP) become more and more important in the thermal management .The PHP utilizes phase change heat transfer and oscillating motion to transport heat, which is related to complex heat transfer mechanism, surface characteristics, and mechanical system vibration. An extra high heat transport capability resulting in wide applications can be provided by the PHP.

In this paper, based on the data analysis of ethanol-water pulsating heat pipe experiment with three kinds of charging rate, three kinds of double working medium volume ratio, the evolutions of average temperature, heat transfer temperature difference and thermal resistance with power, filling ratio and matching ratio are obtained. The evolutions of working fluid saturation pressure, dryness, heat transfer latent heat, sensible heat transfer, mass flow rate and flow rate with power are studied, as well as influences of charging rate, filling ratio and matching ratio on characteristics above. At the same time, by comparing working fluid thermal parameters of pure ethanol and water, change rules of thermal properties with temperature can be gain. The variations of thermal properties at different filling rate, volume ratio with temperature of ethanol-water pulsating heat pipe are studied. The physical properties are determined such as heat, saturation pressure, the dryness and latent heat of per unit mass unit temperature rise; It is found that filling ratio, volume ratio, power and thermal properties and other heat transfer have impacts on the performance of the pulsating heat pipe.

The experimental results show that: the power rises from 5W to 300W, thermal resistance of the heat pipe decreases as the power increases, and leveled off to 0.1 ℃ / W. and small power have more obvious effect on heat transfer performance. Wherein, the sensible heat take up larger share of the total heat transfer, and is reduced while power increasing, sensible heat can drop from 99% to 75% minimum, while the share of the latent heat increases while power increasing, from 1 % maximum rises to 25%; with the same volume ratio and heating power, the more filling rate is, the more share of Sensible heat is, the less latent heat is. With the same filling rate and heating power, when filling rate of ethanol increases, Sensible heat increases, yet the latent heat reduces. Also, the results shows that mass flow and velocity of working fluid in alcohol-water mixed pulsating heat pipe increases with the power increasing and decreases at high oscillation, in which the higher filling rate is, the faster flow is. With temperature increasing, the heat transfer quantity per degree, the sensible heat and the latent heat increase, the share of latent heat increase, yet the share of sensible heat reduces.

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Key words: pulsating heat pipe; thermal resistance; thermal properties; Two working fluids

目录

摘要 ...........................................................................................................................Ⅰ

ABSTRACT.............................................................................................................Ⅱ

第1章 绪论 ............................................................................................................1

1.1 脉动热管介绍及其应用背景 ........................................................................1

1.1.1 脉动热管简介 ......................................................................................1

1.1.2 脉动热管的工作原理及特点 ..............................................................2

1.1.3 脉动热管的应用 ..................................................................................2

1.2 研究现状 ........................................................................................................3

1.2.1 实验研究的现状 ..................................................................................3

1.2.2 理论研究 ..............................................................................................7

1.3 应用研究的现状及展望 ................................................................................7

• 1. 本课题研究内容 .............................................................................................8

第2章 实验系统及装置简介 ............................................................................9

2.1 试验系统组成及原理 ....................................................................................9

2.1.1 实验装置 .............................................................................................9

2.1.2 工作原理 .............................................................................................9

2.2 实验主要设备简介 ......................................................................................10

2.2.1 脉动热管 ............................................................................................10

2.2.2 加热及保温装置 ................................................................................12

2.2.3 冷却装置 ............................................................................................13

2.2.4 测温装置 ............................................................................................13

• • 1. 数据采集系统 ..................................................................................14

第3章 乙醇-水双工质脉动热管实验结果及分析……............................15

3.1 实验数据的处理 ..........................................................................................15

3.2 实验数据分析 ..............................................................................................16

3.2.1 乙醇-水脉动热管冷热端温度及温差随功率的变化 ………….....16

3.2.2 乙醇-水双工质脉动热管传热热阻随功率的变化 .........................19

3.3 乙醇-水双工质脉动热管流动传热性能分析 .............................................20

3.4乙醇-水双工质热物性随功率的变化 ..........................................................22

• 1. 本章小结 .......................................................................................................27

第4章 乙醇-水双工质脉动热管热物性计算及分析 .............................28

4.1 乙醇、水单工质热物性对比 ......................................................................28

4.2 乙醇-水双工质热物性计算及分析 …........................................................31

4.2.1乙醇-水双工质热物性计算方法 ………............................................31

4.2.2乙醇-水双工质热物性的对比分析 ...….............................................32

4.3 本章小结 ……………………......................................................................39

第5章 结论与展望 ............................................................................................40

5.1 结论 ..............................................................................................................40

5.2 展望 ..............................................................................................................41

参考文献 .................................................................................................................42

致谢 ..........................................................................................................................45

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