论文总字数：27900字

摘 要

两相环路热虹吸管是一种高效的传热设备，在电子元器件散热、余热回收和太阳能热利用等领域已经得到广泛应用。但是两相环路热虹吸管在工作过程中内部工质发生沸腾和冷凝相变换热及复杂的两相流动等问题，特别涉及热管工质在金属壁面下相变传热机理极为复杂。本文提出一种“内窥式”两相环路热虹吸管（TPLT）的测试装置和可视化方法，通过容器设计准则和内部的传热和流动理论分析，获得了传热极限参数，为后期的“内窥式”可视化实验提供了理论依据。

本文研制了一种 “内窥式”TPLT。其主要结构参数包括：蒸发段壳体长度0.3m，冷凝段管长为288mm。热管内工质为丙酮，主要工作温度范围在0~120℃。此外，基于TPLT内部工质流动为单向流以及蒸汽腔Bo数建立了有效充液率模型并获得“内窥式”TPLT有效充液量约为0.157~0.308kg，对应充液率范围在45~87.1%之间。

基于管壳式换热器中流体的努塞尔数（Nu），建立了冷凝段传热极限模型；采用均相模型分析了两相循环流动极限。计算热管在不同工作条件下的各项传热极限，同时计算了不同工作条件（冷却水温度、流量和充液率）下的沸腾极限和声速极限。结果表明：在不同工作温度下该热管传热能力主要受限于冷凝极限与循环流动极限，热管传热能力随着冷却水流量增加而增大、随着冷却水温度降低而增加，当冷却水温度由2℃提升到12℃时，热管冷凝极限由162.14W降低到143.07W；热管正常工作范围内（293~393K）循环流动极限在热管充液率lt;75%时随工作温度上升而增加，在gt;75%充液率时出现先升高后降低趋势。

关键词：内窥式；两相环路热虹吸管；传热极限；可视化

Abstract

Two-phase loop thermosiphon is a kind of efficient heat transfer equipment which has been widely used in the fields of heat dissipation of electronic components, waste heat recovery and solar energy heat utilization. However, during the working process of the two-phase thermosiphon, the internal working medium will experience boiling and condensing phase transformation heat and complex two-phase flow, which are related to the extremely complex heat transfer mechanism of the heat pipe working medium under the metal wall. In this paper, a test device and visualization method of "endoscopic" two-phase loop thermosiphon (TPLT) are proposed. The design and operation theoretical limit parameters are obtained through the container design criteria and the theoretical analysis of internal heat transfer and flow, which provides a theoretical basis for the later "peeping in" visualization experiments.

In this paper, an "endoscopic" TPLT is developed. The main structural parameters include: the shell length of the evaporation section is 0.3m, and the tube length of condensation section is 288mm. The working medium in the heat pipe is acetone, and the main working temperature range is 20~120 ℃. In addition, based on the unidirectional flow of working fluid in TPLT and the number of Bo in the steam cavity, an effective filling rate model is established. The "endoscopic" TPLT's effective filling rate is about 0.157-0.308kg, and the corresponding filling rate range is 45-87.1%.

Based on the Nusselt number (nu) of the fluid in the shell and tube heat exchanger, the heat transfer limit model of the condensation section is established, and the two-phase circulating flow limit is analyzed by using the homogeneous model. The heat transfer limits of heat pipe under different working conditions are calculated, and the boiling limits and sound speed limits under different working conditions (cooling water temperature, flow rate and liquid filling rate) are calculated. The results show that the heat transfer capacity of the heat pipe is mainly limited by the condensation limit and circulation flow limit at different operating temperatures. The heat transfer capacity of the heat pipe increases with the increase of cooling water flow rate and the decrease of cooling water temperature. When the cooling water temperature rises from 2 ℃ to 12 ℃, the condensation limit of the heat pipe decreases from 162.14W to 143.07W, and the circulation flow in the normal working range of the heat pipe (293-393K) .The dynamic limit increases with the increase of working temperature when the filling rate of heat pipe is less than 75%, and increases first and then decreases when the filling rate is more than 75%.

Key Words: Endoscopic type；Two-phase loop thermosiphon；The heat transfer limit；Visualization

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 两相环路热虹吸管（TPLT）工作原理 1

1.3 两相环路热虹吸管（TPLT）应用研究进展 2

1.4 两相环路热虹吸管（TPLT）传热机理研究进展 3

1.5 本文主要研究内容 6

第二章 “内窥式”两相环路热虹吸管研制 8

2.1 引言 8

2.2 TPLT设计 8

2.3 TPLT加工 9

2.4 传热工质及充液量分析 12

2.5 “内窥式”可视化实验台概念设计 19

2.6 本章小结 20

第三章 两相环路热虹吸管理论传热极限分析 21

3.1 引言 21

3.2 TPLT理论传热极限 21

3.2.1 声速极限 21

3.2.2 沸腾极限 22

3.2.3 冷凝极限 22

3.2.4 循环流动极限 24

3.3 传热极限分析 28

3.3.1 传热极限分布一般规律 28

3.3.2 冷却水流量的影响 29

3.3.3 冷却水温度的影响 29

3.3.4 充液率的影响 30

3.4 本章小结 31

第四章 结论与展望 33

4.1 结论 33

4.2 展望 33

参考文献 35

致谢 37

第一章 绪论

1.1研究背景及意义

能源是人类生存、生产以及进行社会活动的基础，随着现代社会的发展和科学技术的进步，人类对于生活品质的要求也在不断提高，全球能源的消耗量也急剧增加。但是传统的化石燃料资源却是有限的，过分依赖于化石能源会限制人类社会的发展，同时无节制地开发资源更会造成严重的生态破坏和环境污染问题，解决这些问题的关键方法有发展新能源、节能减排以及提高能源效率等。

热管可以快速将热能由一段传输到另一段，几乎没有热损耗，这对于解决能源问题提供了新的思路。多数热管由金属制成并且是封闭回路，使得研究者对其内部的两相流动机理研究产生了困难，因为无法准确获得热管内部工质流动状态的信息，对热管传热性能的工作条件进行预测也产生影响，所以本课题旨在通过一种“内窥式”的可视化方法，更好地对充液率、冷凝段倾角、输入热量等工作条件改变下的热管传热性能进行研究。

1.2两相环路热虹吸管（TPLT）工作原理

两相环路热虹吸管作为一种高效的传热元件，其结构（如图1-1）主要由蒸发段、蒸汽上升管段、冷凝段、冷凝液下降管段四部分组成。工作原理为：工质在蒸发器受热达到饱和温度而变成蒸汽，蒸汽通过上升管进入冷凝段冷凝，而冷凝液又通过下降管回到蒸发段，完成一个循环过程，整个过程的驱动力由气液两相的密度差提供。它具有结构简单、无需外加动力就可以实现远距离的热量传输、传热效率高的特点，已经广泛应用于电子元器件散热、太阳能集热和余热回收等领域，在节能减排和提高能源利用率方面起到大有可观的作用^[1-3]。

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