导热增强型相变微胶囊的制备与应用

发布时间：2018-03-17 14:04

  本文选题：改性碳纳米管　切入点：相变微胶囊　出处：《东南大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着工业化、城镇化、现代化的推进,我们对能源的需求越来越大,要求也越来越高,可是能源的储量日趋减少,利用率低,供给矛盾大,对环境污染严重,这些问题都给可持续发展带来了一定的影响,而相变储能技术作为一种新型技术手段,可以解决能量供求在时间和空间上不匹配的矛盾问题,有效提高能源利用率。石蜡作为相变材料的一种,存在着易泄露和导热低的缺点,为解决该问题,本课题采用绿色环保、稳定性、成膜性、封装效果好的甲基丙烯酸甲酯为壁材,采用3种不同乳化体系：Tween-80体系、SDBS/Span-80、Tween-80/Span-80,通过微胶囊化技术对石蜡进行封装,结果表明：采用Tween-80/Span-80乳化体系热焓值为91.76J/g,导热系数为01226 W/(m-k),微胶囊分散性好,粒径小且均匀,致密无自聚体粘附,并且有着规则的球形形貌。甲基丙烯酸甲酯的包覆可明显降低芯材的泄露率,但同时也存在着导热性能差、强度低、热稳定性差、易老化等缺点;无机壁材的导热优于有机壁材,其热稳定性、机械强度、化学稳定性等方面较有机壁材出色许多,为了进一步提高微胶囊的导热性能,本课题采用无机壁材SiO2进行二次包覆,结果表明：二次包覆制备的相变微胶囊球形形貌好,表面光滑致密,分散性好,粒度均匀,热焓为72.51J/g,导热系数较高,达到0.1724W/(m k),相比聚甲基丙烯酸甲酯/石蜡相变微胶囊的导热提高了40.62%。为了进一步提高相变微胶囊的导热性能,本课题采用改性碳纳米管作为导热添加剂,结果表明：PMMA-SiO2/P-C 18/CNTs-C 18微胶囊的导热系数相比石蜡,PMMA/Paraffin微胶囊,PMMA-SiO2/Paraffin微胶囊分别提高了56.25%,129.52%,63.22%,并达到0.2814 W/(m·k),加入 CNTs-COOH时,导热系数达到0.3024 W/(m·k)。将导热性能优异的相变微胶囊与电子控温装置结合,来解决电子芯片的散热问题,结果表明：当相变微胶囊的导热值分别提高15.97%,22.09%的时候,控温时间分别可提高40.11%,22.22%,故填充导热系数高的微胶囊,可以大大提高散热片的散热效果,涂覆金属漆后,由于散热面积与导热的提高,可以大大减缓温度的上升速度：从散热片的表面热红外图可以发现掺入相变金属漆的散热片,表面温度上升速率慢,在30min温度处于41℃左右,比未掺入相变微胶囊的温度低了4℃,这说明相变微胶囊可以被应用于电子控温领域。
[Abstract]:With the development of industrialization, urbanization and modernization, our demand for energy is increasing and our requirements are getting higher and higher. However, the reserves of energy are decreasing, the utilization ratio is low, the supply is contradictory, and the pollution to the environment is serious. These problems have a certain impact on sustainable development, and phase change energy storage technology, as a new technical means, can solve the contradiction between energy supply and demand in time and space. As a kind of phase change material, paraffin has the disadvantages of easy leakage and low thermal conductivity. In order to solve this problem, this subject adopts green environmental protection, stability, film forming, Methyl methacrylate (MMA) with good encapsulation effect was used as wall material, and three different emulsifying systems: Tween-80 / SDBS / Span-80 / Tween-80 / Span-80 were used to encapsulate paraffin wax by microencapsulation technology. The results showed that the enthalpy of Tween-80/Span-80 emulsified system was 91.76J / g and the thermal conductivity was 01226 W / m ~ (-1). The microcapsules had good dispersity, small and uniform particle size, and no self-polymer adhesion. The coating of methyl methacrylate can obviously reduce the leakage rate of the core material, but it also has some disadvantages such as poor thermal conductivity, low strength, poor thermal stability, easy aging and so on. The thermal conductivity of inorganic wall material is better than that of organic wall material, and the thermal stability, mechanical strength and chemical stability of inorganic wall material are much better than that of organic wall material. In order to further improve the thermal conductivity of microcapsule, the SiO2 of inorganic wall material is used for secondary coating. The results show that the phase change microcapsules prepared by secondary coating have good spherical morphology, smooth and compact surface, good dispersion, uniform particle size, high enthalpy of 72.51J / g and high thermal conductivity. In order to further improve the thermal conductivity of phase change microcapsules, modified carbon nanotubes (CNTs) were used as heat conduction additives, compared with that of polymethyl methacrylate / paraffin phase change microcapsules (PCMs). The results showed that the thermal conductivity of the microcapsules: PMMA-SiO _ 2 / P-C _ (18) / CNTs-C _ (18) was higher than that of the paraffin PMMA / Paraffin microcapsule PMMA-SiO _ 2 / Paraffin microcapsules by 56.25% 129.52%, and reached 0.2814 W / m 路kg ~ (-1). When CNTs-COOH was added, the thermal conductivity of the microcapsules was 0.3024 W/ / m 路KG. The phase change microcapsules with excellent thermal conductivity were combined with the electronic temperature control device. The results show that when the thermal conductivity of phase change microcapsules is increased by 15.97% or 22.09%, the temperature control time can be increased by 40.11% and 22.22%, respectively. Therefore, filling microcapsules with high thermal conductivity can greatly improve the heat dissipation effect of the radiator. After coating with metal paint, the rising rate of temperature can be slowed down greatly because of the increase of heat dissipation area and heat conduction. From the surface thermal infrared diagram of the heat sink, it can be found that the heat sink mixed with phase change metal paint has a slow rising rate of surface temperature. The temperature is about 41 鈩，

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