基于相变材料 的核救灾机器人电子件热防护研究

华东理工大学博士学位论文第I页基于相变材料的核救灾机器人电子器件热防护研究摘要核电站事故现场除了出现大量射线外，还会伴随高温、高湿、粉尘、酸性等恶劣条件，核救灾机器人是能代替人类进入事故现场实施紧急任务的唯一选择。

核救灾机器人除了要有极高的耐辐射性能，对热防护也提出了很高的要求。

机器人需要携带大量的电子器件，为了减轻本体重量，其内部空间极为紧凑，器件还会受到高温和金属辐照热效应的影响，导致电子器件温度过高使系统过早失效。

因此建立可靠有效的热防护系统是核救灾机器人进入现场开展工作的前提。

本论文针对核事故环境下的特殊温度条件，以伺服电机驱动器为例，提出一种基于相变材料被动吸热的核救灾机器人电子器件热防护方法，考察了基于相变材料的电子器件热防护系统中相变材料、系统相关尺寸、器件发热功率等参数，探讨了纳米掺杂对相变材料热物性的影响，分别针对常温和高温两种情况进行了系统防护方案的考察与评估。

论文主要研究内容与结论如下：（1）常温环境双驱动器热防护系统设计、实验与数值模拟研究针对双驱动器的热防护要求，设计了由金属支架和填装相变材料的散热器组成，采用滑槽式安装方式的热防护系统。

通过对相变温度、潜热、耐辐射性能的考察，确定选用44#相变材料作为实验用相变材料的方案。

对防护系统结构参数与热控时间关系的考察发现，与在散热器中添加翅片相比，基于相变材料的无翅片散热器在热防护过程中能使器件保持更低温度，保证器件在最佳工作温度范围保持最长时间（延长12倍工作时长）。

系统的热控时间随相变材料质量的增加基本呈线性增长趋势。

器件的安全工作时长与发热输出功率（5.57 W、6.28 W、7.04 W、7.85 W和8.7 W）呈线性递减关系。

通过热阻模型分析以及Fluent软件模拟相变系统固-液熔化过程，发现空气层的存在延缓了相变材料的熔化，阻碍了相变材料的吸热，通过相变材料导热增强可以弥补空气层的传热抑制作用。

（2）热防护系统导热增强对热控效果的研究对比三种孔隙率相似、孔密度不同（5 PPI、10 PPI、20 PPI）的铜泡沫金属的添加效果，发现在散热器中的泡沫金属强化了传热，并且泡沫金属孔密度越大传热增强效果越明显，但是热防护效果较差。

孔密度为5 PPI的泡沫金属系统拥有长于只有相变材料的散热器的温控时间，而20 PPI的泡沫金属系统温控时间短于相变材料散热器的温控时间。

此外，实验对比了多壁碳纳米管掺杂的复合相变材料（质量分数为0%、0.08%、2%和5%）对系统的热控效果，发现添加2%碳纳米管的相变材料热控结果最好，可使安全工作时间控制在97 min，比未添加碳纳米管的相变材料系统延长了30 min。

由于碳纳米管质量更轻，所占体积更小，因此，对于设计的双驱动器热防护系统，碳纳米掺杂的导热增强方式优于添加泡沫金属的方式。

第II页华东理工大学博士学位论文（3）高温环境热防护系统设计与实验研究针对高温环境下驱动器的热防护需求，以隔热和吸热双重防护的思路设计了驱动器的热防护系统，并对多驱动器温度均匀性、发热功率、环境温度等参数进行考察。

该热防护系统可以使驱动器的发热表面温差控制在1 o C以内，器件最佳工作时长和相变时长均随输入功率增加而呈下降趋势。

实验结果表明，相比单纯使用铝合金支撑架结构，实验环境温度为100 o C时，填装相变材料使双驱动器的工作时间有效延长了34 min，6驱动器的工作时间可达164.3 min。

当环境温度小于50 o C时，可以保证驱动器工作长达180 min以上。

热量评估计算发现，相变材料在180 min内在热防护系统中起决定性作用，可以吸收系统内总热量的56%。

而通过隔热层进入到系统内的热量会随着时间的增加逐渐积累，传入系统的热量达63%。

因此隔热层的绝热特性提升将使热控系统的温控效果更佳。

（4）多壁碳纳米管掺杂的复合相变材料性能研究采用两步法制备了不同质量分数（0.1%、0.2%、0.5%、1%、2%、5%）多壁碳纳米管复合的44#相变材料，沉降实验、DSC曲线和温度—时间曲线测试评定表明该多壁碳纳米管掺杂的复合相变材料热稳定性和热分散性良好。

不同的碳纳米管掺杂量对复合相变材料的相变温度影响不大，相变潜热值则随碳纳米管质量分数的增加而线性减小，在0.1%处出现潜热增强现象。

固体复合相变材料的导热系数随着掺杂量的提高而逐渐上升，较纯相变材料导热系数最多提高了61.7%。

复合相变材料的液态导热系数要低于固态时，但当温度在35 o C和45 o C时材料出现导热系数增高的现象，最高值相对固体导热系数分别增长了104.8%和49.0%。

（5）被动热防护系统的应用评估针对多驱动器高温热防护系统开展了应用评估。

针对隔热材料在高温环境下对热防护系统的重要性，从导热系数、使用温度、材料密度、抗辐照性等角度分析说明材料选用原则。

此外，由于重金属屏蔽层在伽马射线辐照条件下的热效应，确定将隔热材料安装在射线屏蔽层内部以减少对电子器件带来的额外的热负担。

根据常温下机器人各部分电子器件的实际发热规律，提出相应的整机热防护对策，并对6足机器人的被动热防护系统的质量和价格评估表明，热控制系统的相变材料和隔热材料重量轻，材料和加工费用低。

为了满足更长时间的任务需求，提出了恢复性任务方案和自适应环境方案两种增加被动热防护系统工作效率的策略。

本论文针对核灾变现场恶劣环境提出了由隔热和吸热结构组成的核救灾机器人的热防护方案，实现了高温（100o C）环境下多驱动器安全工作的目标，且该热防护系统可以在核环境和高温环境多场耦合的条件下实现热控功能。

除了针对在核救灾方面的应用，本研究还可以对核电站日常维护机器人、焊接机器人及消防救灾机器人实施热保护，为恶劣环境工作对象的温度防护研究提供了理论依据和解决方法。

关键词：核救灾机器人；电子器件；热防护；相变材料华东理工大学博士学位论文第III页Phase Change Material based Thermal Management for Electronic Deviceson Nuclear Rescue RobotAbstractThere are a plenty of radiation in the scene of the nuclear accident. Besides, high ambient temperature, high humidity, dust and boracic acid would also accompany with the disaster. The nuclear rescue robot is the only choice to replace the human being for entering the scene of the accident to execute disaster relief missions. Therefore, the robot should not only have a high radiation resistance, but also own a good heat – resistant quality. The inner space of the robot is generally compact for reducing body weight. The thermal problems, which were caused by high temperature environment and radiant heat effect of the metal, would lead to premature failure of electronic devices on nuclear rescue robot. Therefore, developing a reliable thermal protection system is the prerequisite of the normal operation of robot. In view of the special temperature condition in the nuclear accident environment, a thermal control design for electronics on nuclear rescue robot was proposed based on passive energy storage. The parameters of the thermal control system such as types of PCM, size of the heat sink, input power levels were studied. The effect of nanoparticle doping on the thermophysical property of the PCM was researched. Investigation and evaluation on the thermal management scheme were conducted in the cases of room temperature and elevated temperature environment. The main research contents and achieved results are stated as follows:(1) Design, experiments and numerical simulation for the thermal control system of double drivers in room temperatureFor the purpose of safe working, a thermal management system, which was composed of metal support and PCM based heat sink, was put forward. The system was packaged with a chute –form. 44# PCM was selected as the PCM used in experiments after investigating parameters like phase change temperature, latent heat and radiation resistance. It was found that, lower temperature would be acquired by PCM based heat sink without fins compared with the PCM based heat sink with fins, which resulted in extending the safe working time by 12 times. The operating time of electronics increased linearly with the growth of PCM weight, and was a linear decreasing function of input power. The melting process of the PCM system was investigated using thermal resistance model analysis combined with numerical simulation. It was found that the existence of the air layer in the system delayed the melting of the PCM and hindered the heat absorption. The enhancement of thermal conductivity could make up the defects of the air layer.(2) Study on the effect of thermal conductivity enhancement on thermal controlThree kinds of copper metal foams with similar porosity and different pore density of 5 PPI, 10 PPI and 20PPI were adopted to enhance the thermal conductivity of the PCM based heat sink. It can be concluded that better heat conduction would be obtained when a bigger pore density was chosen. However, good heat conduction in the heat sink resulted in a bad thermal protective effect. The metal foam system with copper metal foam of 5 PPI got a slightly better performance than the system used PCM only. The effect of the multi-walled carbon nanotubes (CNTs) doped composite PCMs (mass fraction of 0%, 0.08%, 2% and第IV页华东理工大学博士学位论文0.08%) on the thermal control system was also studied. The thermal control system with 2% CNTs doped PCM got the best results, and made the drivers safely work for 97 min, which was 30 min longer than the system without CNTs. Because the CNTs are much lighter and smaller than the metal foams, it was a better solution for the thermal control system of double drivers to employ CNTs in the thermal management system.(3) System design and experimental study for the thermal control system in high temperature environmentAccording to the idea of double insulation and heat absorption, a thermal management system was designed for high temperature application. The temperature uniformity, heating power and the ambient temperature were studied for an overall understand of the system. Results showed that the temperature difference among each driver could be controlled within 1 o C. The best working hours and phase transition time both got a downward trend with the increase of input power. Compared with the support frame of aluminium alloy, filling PCM in the fame could prolong operating time by 34 min for double drivers, and make six drivers safely work for 164.3 min in experimental environment of 100 o C. When the environment temperature was lower than 50 o C, the drivers were able to operate more than 180 min. According to the heat calculation of system, it can be seen that PCM absorbed 56% of total heat, and played an indispensable role in thermal control. Enhancing the heat-shielding performance is supposed to further improve the thermal control ability of the airtight thermal controller.(4) Performance study of multiwall CNTs doped composite PCMsMultiwall CNTs doped composite PCMs with different mass fraction (0.1%、0.2%、0.5%、1%、2%、5%) were prepared by two-step method. The thermal stability and dispersion of the composite PCMs were evaluated by sedimentation test, DSC measurement and temperature - time curve test. The amount of carbon nanotubes doped in 44# PCM had little influence on the phase change temperature of the composite materials. The latent heat value decreased linearly with the mass fraction increasing of carbon nanotubes. A latent heat enhancement phenomenon was found at the mass fraction of 0.1%. The heat conductivity coefficient of composite PCMs grew up gradually with the increase of doping amount. It increased by 61.7% when CNTs occupied 5% in composite PCMs. The thermal conductivity of liquid composite PCM was lower than the solid state. Higher heat conductivity coefficient appeared at 35 o C and 45 o C, which increased by 104.8% and 49.0% relative to the solid thermal conductivity.(5) The application evaluation of passive thermal protection systemThe application evaluation was conducted for high temperature thermal protection system of multiple drivers. The thermal insulation material was important to the system. Hence, the principles of material selection were stated from the points of heat conductivity coefficient, operating temperature and radiation resistance. In consideration of irradiation heating effect caused by heavy metal shielding layer, the insulation needs to install inside the heavy metal shielding box. The overall unit thermal protection scheme was put forward after a temperature test of the robot. Weight and price assessments were also conducted for a hexapod robot, which showed that the suggested scheme owed advantages of light weight and low cost. In order to meet the task requirements of longer operating time, a restorative solution and an adaptive environmental solution were proposed to enhance the work efficiency of the passive thermal protection system.A thermal management scheme for electronics on nuclear rescue robot was proposed华东理工大学博士学位论文第V页with the idea of combining heat insulation with heat absorption structure. It realized the thermal protection for multiple drivers in high temperature (100 o C) environment. The designed system could implement its thermal control function in multi –field coupling environment with nuclear and high temperature conditions. In addition to the nuclear disaster relief applications, the scheme can also protect the electronics on nuclear power plant maintenance robot, welding robot and fire –fighting robot. The achievement can be the theoretical basis and solutions to thermal management of electronics working in harsh environment.Keywords: Nuclear rescue robot; electronic devices; thermal control; phase change material第VI页华东理工大学博士学位论文目录摘要 (I)Abstract (III)目录 ..................................................................................................................... V I 第1章绪论. (1)1.1 课题背景 (1)1.1.1 课题来源 (1)1.1.2 研究背景与意义 (1)1.2 核救灾机器人工况 (2)1.3 电子器件的热防护 (3)1.3.1 电子器件的发展趋势 (3)1.3.2 电子器件的热安全与温度特性 (4)1.3.3 电子器件热防护国内外研究进展 (6)1.4 基于相变传热的热控技术 (14)1.4.1 相变材料及其表征 (14)1.4.2 有机相变材料导热增强 (17)1.4.3 相变材料的封装技术 (19)1.4.4 相变储能的应用 (20)1.5 机器人电子器件热防护研究 (20)1.6 论文主要研究内容 (21)第2章基于相变储能材料热防护系统设计与材料测试 (24)2.1 伺服电机驱动器发热情况 (25)2.2 驱动器热防护实验装置与实验流程 (27)2.2.1 单个驱动器热防护实验系统 (27)2.2.2 双驱动器热防护实验系统 (28)2.2.3 多驱动器热防护实验系统 (29)2.3 相变材料性能测试 (32)2.3.1 相变温度与潜热 (32)2.3.2 伽马射线辐照测试 (33)2.3.3 中子辐照测试 (35)2.4 本章小结 (36)华东理工大学博士学位论文第VII页第3章常温环境热防护研究 (37)3.1 单个驱动器常温环境热防护 (37)3.1.1 散热形式考察 (38)3.1.2 相变材料质量的影响 (40)3.1.3 热管对散热效果的影响 (40)3.2 双驱动器常温环境热防护 (44)3.2.1 基于相变材料的矩形散热器参数考察 (44)3.2.2 相变过程散热器内部温度与热量耗散考察 (50)3.2.3 泡沫金属增强传热研究 (53)3.3 热防护系统模型与数值分析 (55)3.3.1 模型建立 (55)3.3.2 系统传热与相变材料熔化分析 (56)3.4 多驱动器常温环境热防护 (58)3.5 本章小结 (59)第4章高温环境热防护实验研究 (61)4.1 双驱动器高温环境热防护 (61)4.2 六驱动器高温环境热防护 (64)4.2.1 系统的温度分布与隔热效果 (64)4.2.2 输入功率对热控时间的影响 (65)4.2.3 中高温环境下的热防护实验 (67)4.3 防护系统的热评估计算 (69)4.4 本章小结 (71)第5章相变材料改性研究 (73)5.1 碳纳米管掺杂复合相变材料的制备 (73)5.1.1 材料选用 (73)5.1.2 制备方法 (75)5.1.3 复合相变材料稳定性研究 (75)5.2 质量分数对相变材料改性的影响 (77)5.2.1 相变温度与潜热 (77)5.2.2 导热系数 (80)5.3 参比温度曲线法测量热物性 (82)5.3.1 参比温度曲线法介绍 (82)5.3.2 基于参比温度法对热物性计算结果 (84)5.4 复合相变材料的热防护系统实验 (85)第VIII页华东理工大学博士学位论文5.5 本章小结 (86)第6章热防护系统适用性评估 (87)6.1 隔热层设计考虑 (87)6.1.1 隔热材料基本参数 (87)6.1.2 隔热设计计算 (89)6.1.3 隔热安装设计 (91)6.2 系统使用评估 (92)6.2.1 循环使用评估 (92)6.2.2 工作时间评估 (93)6.2.3 质量与价格估算 (94)6.3 实际方案实施设计 (94)6.3.1 整机热防护对策 (94)6.3.2 恢复性任务方案 (97)6.3.3 自适应环境方案 (98)6.4 本章小结 (99)第7章结论与展望 (101)7.1 主要结论 (101)7.2 本文创新点 (102)7.3 展望 (103)参考文献 (104)致谢 (115)博士学位期间获得的成果 (116)第1章绪论1.1 课题背景1.1.1 课题来源本课题来源于国家重点基础研究计划（973计划）项目“核电站紧急救灾机器人的基础科学问题”（项目编号：2013CB035500）。