论文总字数：54121字

摘 要

环路两相热虹吸管是重力热管中的一种，都通过管内介质的相变进行热量传递，并且由于没有吸液芯的存在，和普通的热管换热相比而言就更加的高效，快捷，结构也变的更加简单，在各种领域都有着广泛的应用，是一种性能优良的传热元件。本课题就针对环路两相热虹吸管的结构利用EES软件进行了数值模拟并优化分析，在总换热面积一定的条件下，以蒸发器和冷凝器的换热面积配比为变量，以最大总传热效率，即最小的系统总热阻作为目标参数进行优化分析，工质选用R134a，蒸发器采用微通道模式，冷凝器采用板式换热器，通过冷却水进行对工质的冷却。所得的模拟结果数据采用origin软件进行处理。模拟结果表明，在一定的工况下，总存在一个蒸发器和冷凝器换热面积配比x使得系统总热阻R_sys最小。例如，在给定换热量Q_e=400W，换热总面积A_total=1700cm²，充灌量为M_charge=250g的条件下，当换热面积配比x=0.09时，系统的总热阻R_sys达到最小值，R_sys=51.78K kW^-1，并且此时的蒸发器壁面温度t_wall,e也达到最小，t_wall,e=28.1^oC。模拟结果还表明在给定换热量，换热总面积，充灌量一定的条件下，改变冷凝器内冷却水的进口温度t_cwi，对系统的总热阻影响比较小并且对系统的最优面积配比，即最小系统总热阻所对应的总面积配比影响也比较小；在给定换热量，换热总面积，换热面积配比一定的条件下，改变充灌量，系统总热阻会随着充灌量的升高而升高。模拟结果充分表明了一个合理的蒸发器和冷凝器的换热面积配比对换热器能否达到最小的换热热阻有着重大的影响。这些理论结果对于环路两相热虹吸管的结构优化与发展有一定的借鉴意义。

关键词：环路两相热虹吸管 系统优化 热阻

Structural optimization for Two-phase thermosyphon loop

Abstract

The two-phase thermosyphon loop is a kind of the gravity heat pipe, which transfers heat through the phase change of the working medium in the pipe. And because of no wick, compared with the ordinary heat pipe, it is more efficient, faster and simpler. So that it can be used in various fields with excellent performance. In this paper, the EES software is used to optimize the structure of the two-phase thermosyphon loop. Under the condition that the total heat transfer area is fixed, the heat transfer area ratio of evaporator and condenser is variable, and the maximum total heat transfer efficiency or the minimum total heat resistance of the system is taken as the target parameter to optimize the analysis. R134a is selected to be the working medium, A microchannel mode is used as the evaporator, the plate heat exchanger is used as the condenser, and the refrigerant is cooled by cooling water. The analysis drawings are plotted by the origin based on the simulated results. The simulation results show that under certain working conditions, there is always a ratio of evaporator x to total heat transfer area which corresponds to the minimize the total heat resistance of the system R_sys. For example, at the condition that the heat transfer capacity Q_e=300W, the total heat transfer area A_total=1700cm² and the refrigerant charge M_charge=250g, when the heat transfer area ratio x=0.09, the total heat resistance of the system R_sys reaches the minimum, R_sys=51.78K kW^-1, and the evaporator wall temperature t_{wall, e} also reaches the minimum, t_{wall, e}=28.1^oC. The simulation results also show that the minimum total thermal resistance of the system and the optimal heat transfer ratio is slightly affected by the inlet temperature of cooling water in the condenser. Under the given heat transfer capacity and total heat transfer area, the total thermal resistance of the system will increase with the increase of the filling charge. The simulation results fully show that a reasonable ratio of heat transfer area between evaporator and condenser has a significant impact on the minimum total heat resistance of heat exchanger. These theoretical results provide the guideline for the structure optimization and development of the two-phase thermosyphon loop.

Keywords: two-phase thermosyphon Loop; system optimization; thermal resistance

目录

摘要 Ⅰ

ABSTRACT Ⅱ

第一章 绪论 1

1.1课题研究背景 1

1.2热虹吸管国内外研究现状 1

1.3研究的目的和意义 4

1.4研究思路和技术方法 4

第二章 环路两相热虹吸管数学模型 5

2.1系统描述与假设 5

2.2环路两相热虹吸管系统中的能量守恒 5

2.3环路两相热虹吸管系统中的动量守恒 6

2.4环路两相热虹吸管系统中的质量守恒 10

2.5蒸发器的传热系数 12

2.6冷凝器的传热系数 13

2.7系统总热阻的计算 15

2.8模拟方案 15

第三章 模拟结果与分析 17

3.1系统结构参数 17

3.2换热面积对系统性能的影响 17

3.3冷却水温对系统性能的影响 21

3.4充灌量对系统性能的影响 24

第四章 总结 28

参考文献 29

附录 32

致谢 55

1. 绪论

1.1课题研究背景

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