Molecular dynamics simulation of graphene/n-octadecane composite phase change material on Cu nano-surface
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摘要: 为了探究提高石蜡基相变材料热物理性能的途径与机制,通过引入Cu纳米表面建立了Cu纳米表面-无定型正十八烷复合体系以及Cu纳米表面-石墨烯/正十八烷复合体系,并采用分子动力学模拟的方法对两复合体系进行了模拟分析。结果表明,在体系中添加金属纳米颗粒来提高相变材料的热物理性能的微观机制在于不仅其本身具有极高的导热系数,而且金属纳米表面与烷烃分子的相互作用促使了烷烃分子在纳米表面的定向结晶。石墨烯作为一种性能优良的高导热碳纳米材料,可以进一步促进复合体系中烷烃分子的定向结晶,进而提高整个体系中复合相变材料的导热性能。Abstract: In order to explore the ways and mechanisms to improve the thermophysical properties of paraffin-based phase change materials, Cu nano-surface-amorphous n-octadecane composite system and Cu nano-surface-graphene/n-octadecane composite system were established by introducing Cu nano-surface. And molecular dynamics simulation method was used to simulate and analyze the two composite systems. The results show that the microscopic mechanism of adding metal nanoparticles to the system to improve the thermophysical properties of phase change materials lies in not only its very high thermal conductivity, but also the interaction between the metal nano surface and the alkane molecule promoting the alkane molecule on the nano-surface directional crystallization. Graphene, as a high thermal conductivity carbon nanomaterial with excellent performance, can further promote the oriented crystallization of alkane molecules in the composite system, thereby improving the thermal conductivity of the composite phase change material in the entire system.
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表 1 各复合体系的结构参数
Table 1. Structural parameters of each composite system
System Atoms Nn-octadecane Ngraphene Density/(g·cm−3) Tvacuum/nm Cu(100) 720 − − − − System A 3688 53 0 1.149 5 System B 2684 45 164 1.176 5 Notes:Nn-octadecane—Number of n-octadecane molecules; Ngraphene—Number of graphene atoms; Tvacuum—Thickness of vacuum layer. -
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