三维纳米孔高导热石墨烯复合相变材料的传蓄热特性研究

Nanoporous graphene phase change composite was selected as a typical material of three dimensional nanoporous phase change composite with high thermal conductivity. The excellent properties of nanoporous graphene phase change composite made it have potential application value in the field of thermal storage materials, which was expected to achieve the integration of heat transfer and thermal storage. The project is aimed to grasp the heat storage properties and thermophysical effect of porous graphene composite phase change materials, and setup the relationship models between the structures and its’ thermophysical properties. The porous structure impact on the materials’ thermophysical properties, such as the thermal conductivity, the specific heat, the talent heat and the melting point, will be carefully studied. Based on the structure characterized, molecular dynamics and other methods were selected to explore the phase change properties of the material and the corresponding thermal physical properties; the physical mechanism of heat transfer phenomenon for porous grapheme composite phase change material at nanoscale will be illustrated to establish the thermophysical properties’ model of structure characterization parameters (pore diameter, bond energy, interfacial atomic distribution, porosity, etc.) as independent variables. The critical parameters and the influence principles which induced the bonding behavior will be explored and the structure-activity relationship of thermal transport in this kind of structure will be modified, which would provide a theoretical reference for the guidance of application of heat storage materials’ thermal design. Meanwhile, the measurement methods of heat storage characteristics of porous graphene composite will be explored, and the macroscale thermophysical properties of porous composites will be measured, which will be analyzed to relate the thermal transport model at nanoscale. Ultimately, a prediction method for thermophysical properties of three dimensional nanoporous phase change composite with high thermal conductivity, was expected to be formed.

本项目选定多孔石墨烯复合相变材料作为典型的三维纳米孔高导热复合相变材料，其优异的性能在蓄热领域具有潜在应用价值，有望实现传蓄热一体化。本项目以掌握多孔石墨烯复合材料的相变储热特性及其热物理效应，形成结构与热物理性质的关联关系模型为目标，主要研究结构等对材料热物理性质中的热导率、比热、潜热和熔点的影响。基于材料结构表征，采用分子动力学方法模拟材料的相变特性以及相应的热物理性质，阐明纳米尺度下复合相变材料热传递现象的物理机制，建立以结构特征表征参数（孔径、键能、界面原子分布、孔隙率等）为自变量的热物理性质描述模型，探究诱发成键行为的关键因素和影响规律，修正此类结构中热输运的构效关系；为指导蓄热材料热设计应用等提供理论参考。同时，探索测量多孔石墨烯复合材料储热特性的相关方法，建立宏观热性能与微观热物理性质之间的关联模型，形成三维纳米孔高导热复合相变材料热物理性质的预测研究体系。

本项目围绕石墨烯材料复合相变材料的制备与表征、热物理效应分析与测试、材料热设计的构效关系开展系统的研究。.材料设计与制备方面：采用两步法制备了纳米石墨烯片/正十八烷复合相变材料，成功通过化学修饰制备硬脂醇改性的石墨烯（简称改性石墨烯），将改性石墨烯与正十八烷通过物理混合的方式制成改性石墨烯/正十八烷复合相变材料。.传热机理与热性能方面：通过实验探究向正十八烷中添加石墨烯材料所造成的储热性能、相变温度、比热容及导热系数等性质的影响。建立了石墨烯材料复合相变材料热导率计算模型，从微观的角度研究复合相变材料体系在相变过程中密度、熔点、比热、导热系数等热物性参数的变化规律。.研究表明：将具有高导热系数的石墨烯材料加入到正十八烷中，可以有效提升其导热能力，且储热能力和相变温度等性质的改变可以忽略不记，主要原因是的石墨烯材料可以在相变材料中形成高导热空间网络结构，通过这些网络结构热量可以更有效率地传输。对石墨烯进行化学改性，利用相似相溶原理可以很大程度上提升石墨烯材料在相变材料正十八烷中的分散能力和循环稳定性，进而提升石墨烯材料的载入量，越高的载入量就意味着越密集的导热网络。