氧化石墨烯改性相变胶囊壳材的潜热型纳米流体光热转换性能研究

Non-renewable fossil fuels and the growing shortage is a major problem facing our country and the world. Speeding up the development of solar energy and other renewable energy technology is the effective way to alleviate the energy crisis and environment problems caused by the consumption of fossil energy. As a key component of solar thermal utilization system, the properties of collector and its heat transmitted medium determine the solar energy utilization efficiency. According to the low conversion efficiency of solar collectors, instability and low thermal conductivity of the media, the project proposes an innovative plan to simultaneously introduce the concept of nanofluid and functional latent heat fluid into the development of new heat transmitted media, and explore the thermal physical process of heat absorption of solar radiation, thermal energy storage and transfer of thermal energy occurred in direct absorption solar collector (DASC). Graphene oxide is introduced to the capsule shell of phase change energy storage in the preparation of nano-encapsulated phase change particles to synthesize the new functional latent heat nanofluid with three excellent properties of heat collection, heat storage and heat transfer, which can provide DSAC with high performance heat collection nanofluid, possessing the advantages of high solar heat capture rate, good thermal stability, high thermal conductivity and large specific heat capacity. This project also studies the radiation characteristics, thermal physical properties, heat transfer properties and solar thermal conversion property of the new nanofluid, and reveals its light-trapping mechanism and solar-thermal conversion principle.

化石能源的不可再生和日益短缺，是我国乃至全世界面临的重大问题。加快发展太阳能等可再生能源技术，是缓解化石能源消耗引起的能源危机以及环境问题的有效途径。作为太阳能光热利用系统关键部件的集热器及其集热介质性能决定了太阳能利用的效率。本项目针对太阳能集热器转换效率低、介质不稳定和导热系数低等缺陷，提出将纳米流体和潜热型功能热流体的概念同时引入到新型集热介质的开发中，研究直接吸收式太阳能集热器（DASC）中发生的吸收太阳辐射热、热能储存以及传递热能等热物理过程，在制备纳米胶囊相变粒子流体的基础上，将氧化石墨烯引入相变储热胶囊壳材中，制备出兼具集热、储热和传热三种优良特性的新型潜热型纳米功能热流体，以期为DASC提供太阳辐射热捕获率高、热稳定性好以及导热系数和比热容较大的高性能集热纳米流体，并研究这类新型纳米流体的辐射特性、热物性、传热特性以及光热转化性能，揭示其光捕获机制和光热转化原理。

随着全球经济的高速发展，化石能源短缺和环境污染问题日益突出。太阳能等可再生能源的开发可以减轻经济增长对能源和环境造成的负担。相变储能技术是利用太阳能热的有效方式，通过相变材料在相变过程中吸热和放热来实现能量的存储和释放。相变材料在直接使用过程中存在易流动及易腐蚀等问题，常通过微胶囊化封装来得以解决。理想的相变微胶囊应具有储能密度大、传热性能好、性能稳定等优点。本论文致力于制备具有高储热、高导热等优异性能的相变微胶囊。在合成具有高储能密度正十二醇@密胺树脂相变微胶囊的基础上，引入氧化石墨烯及碳纳米管等高导热填料来提高其导热性；为了制备导热性能更优异的相变微胶囊，选用具有更高储能密度和导热系数的无机水合盐十二水合磷酸氢二钠作相变材料，分别用有机聚脲和无机二氧化硅对其进行封装制成相变微胶囊；分析比较两种相变微胶囊的综合性能，选用储热性和导热性更好的二氧化硅封装的相变微胶囊进行导热增强，然后将导热增强无机水合盐/二氧化硅相变微胶囊分散到基体液中制得潜热型功能流体，探究其光热转换性能。