论文总字数：22429字

摘 要

二十一世纪以来，电子设备正朝着微型化、高速化、高集成度、大功耗、功能种类多的方向发展，微电子设备的单位面积热流密度逐步升高，关键在于寻找一种更高效的传热装置。平板热管是一种相变传热装置，具有高导热性、优良等温性、热流密度可变性等特性，显现出极大的优势，被越来越广泛地认知和研究。

吸液芯的性能是影响热管性能的重要因素，传统的沟槽芯、丝网芯和烧结芯已遇到“瓶颈”。泡沫金属作为一种新型的多功能材料，在满足这些要求的同时，制备成本低廉，能在工业生产中大规模使用，是吸液芯的优选材料。

本文设计了一种新型泡沫金属吸液芯平板热管，以紫铜为管壳，泡沫铜为吸液芯、水为工质。然而一般的泡沫金属孔密度较低，传热性能较差，因此本文采用磁控溅射的方法制备泡沫金属铜，强化过的泡沫金属能够提高吸液芯的传质传热性能。该泡沫金属吸液芯平板热管具有良好的延展性、较轻的质量和廉价的成本，在提高设备的空间利用率和散热能力方面具有较大的优势。本文主要研究三个方面内容：

1. 设计了一种泡沫金属吸液芯平板热管，该热管的长、宽、高分别为300mm、30mm、8mm，管壁厚1.2mm，吸液芯厚0.8mm，吸液芯烧结于上下铜底板上，中间为蒸汽腔。采用磁控溅射法强化后的泡沫金属孔隙率为ppi150。
2. 根据设计数据，计算了泡沫金属吸液芯平板热管在工作温度为85℃时的传热极限。其粘性极限、声速极限、携带极限、毛细极限、沸腾极限分别为3.7757×10⁴W 、1.9423×10⁵W、4632.8W、196.79W、269.17W，这些极限均大于热管在该条件下的传热热流密度。对比可知，热管的最大传热能力主要取决于毛细极限和沸腾极限。
3. 计算了热管的理论热阻。总热阻为0.1335K/W，其中盖板热阻占0.52%，吸液芯热阻占14.47%，相变及两相流动热阻占85.01%，主要热阻发生在蒸发和冷凝部位。

关键词：泡沫金属 吸液芯 平板热管 传热极限 传热性能

Abstract

Since the 21st century, electronic equipments are developing toward miniaturization, high speed, high integration, large power consumption, and multiple functions. The heat flux density per unit area of microelectronic devices is gradually increasing. The key is to find a new and efficient transmission thermal device. Flat heat pipe shows great advantages as a heat transfer device .Because of its high thermal conductivity, excellent isothermal property, and heat flux variability, it is recognized and studied more and more widely.

The performance of the wick is an important factor to affect the performance of the heat pipe.Traditional cores,such as groove core, wire mesh core and sintered core, have encountered "bottleneck".As a new multifunctional material, foam metal meets these requirements .At the same time,it is cheap to prepare and can be used on a large scale in industrial production. It is the preferred material for the wick.

This paper designs a new type of foam metal wick flat heat pipe,which uses copper as the shell, foam copper as the wick and water as the working fluid.However, the general foam metal has a low cell density and poor heat transfer performance. Therefore, in this paper, the magnetron sputtering method is used to prepare copper foam metal. The mass and heat transfer performance are improved by strengthing foam metal .The foam metal wick flat heat pipe has better ductility, lighter quality and cheaper cost, and has greater advantages in improving the space utilization rate and heat dissipation capacity of devices.This article mainly studies three aspects:

1. A flat metal heat pipe with foam metal wick is designed. The length, width and height of the heat pipe are 300mm, 30mm and 8mm, the wall thickness is 1.2mm, the wick thickness is 0.8mm, and the wick is sintered on the upper and lower cover plates.There is a steam cavity in the middle. The porosity of the foam metal strengthened by magnetron sputtering method is ppi150.
2. According to datas, the heat transfer limits of the foamed metal wick flat heat pipe is calculated, which are under the conditions of operating temperature 85 ℃ . The viscosity limit, sound speed limit, carrying limit, capillary limit, and boiling limit are 3.7757 × 10⁴W, 1.9423 × 10⁵W, 4632.8W, 196.79W, and 269.17W.These limis are greater than the heat transfer density of the heat pipe . It can be seen from the comparison that the maximum heat transfer capability is mainly affected by the capillary limit and the boiling limit .
3. Calculates the theoretical thermal resistance of the heat pipe. The total thermal resistance is 0.1335K/W. The thermal resistance of the cover plates ccount for 0.52%, the

thermal resistance of the wicks account for 14.47%, the thermal resistance of phase change and two-phase flow accounts for 85.01%.It is the evaporation and condensation parts where the main thermal resistance take place.

Key Words: Foam metal ;Capillary Wick ;Plate heat pipe;Heat transfer limit;Heat transfer performance

目 录

摘要 I

Abstract II

第一章 绪论 1

1.1 课题研究背景及意义 1

1.2 热管在电子散热领域的研究现状 1

1.2.1 热管原理及类型 1

1.2.2 吸液芯类型 2

1.3 多孔泡沫金属的研究进展 4

1.3.1 泡沫金属的研究现状 4

1.3.2 泡沫金属的制备方法 6

1.4 热管传热极限的研究进展 6

1.5 本文的研究内容 7

第二章 泡沫金属吸液芯平板热管的设计 9

2.1 热管工质及材料选择 9

2.1.1 工质选择 9

2.1.2 管壳材料选择 10

2.1.3 吸液芯选择 11

2.2 吸液芯平板热管结构设计 12

2.3 制造工艺 13

2.3.1 清洗 14

2.3.2 吸液芯制备 15

2.3.3 检漏 15

2.3.4 充液 16

2.3.5 二次除气 16

2.3.6 封口焊接 16

2.3.7 性能检测 16

第三章 泡沫金属吸液芯平板热管的传热性能 18

3.1 粘性极限 18

3.2 声速极限 19

3.3 携带极限 19

3.4 毛细极限 20

3.5 沸腾极限 21

3.6 冷凝极限 22

3.7 冷凝启动极限 22

3.8 连续流动极限 22

3.9 热管热阻 23

第四章 结论与展望 25

4.1 结论 25

4.2 展望 25

参考文献 27

致谢 30

第一章 绪论

1.1 课题研究背景及意义

近年来，电子设备的发展表现为微型化、集成化的趋势，一方面，电子元器件内部的散热容积非常狭小，其内部单位面积热流密度和发热功率大幅度上升，势必造成温度和热应力的上升。如：台式电脑、服务器等所需要散热的功率可达80~120W^[1]。另一方面，一般的电子设备的最佳工作温度为零下5~70℃，设备的损坏率与工作温度呈正相关，研究表明，工作温度上升10℃导致设备的可靠性大约降低50%。

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