Abstract
The excellent properties of graphene phase change nanocomposite made it have potential application value in the field of heat storage materials, which was expected to achieve the integration of heat transfer and storage. In order to enhance the thermal performance of paraffin in energy storage, the structure models of n-octadecane and three kinds of graphene/n-octadecane composites were established. Molecular dynamics method was used to study the variation of thermophysical properties. It is found that the strong interaction between graphene and noctadecane restricts the diffusion intensity of n-octadecane molecules, which reflects in the decreasing trend of the self-diffusion coefficient. In addition, the thermal conductivity of each system in the solid state is higher than that of liquid, and abruptly drops near the melting point. The thermal conductivity of the composite PCM always higher than the pure noctadecane and increases with the amount of graphene.
Highlights
Nowadays, limited reserves of fossil fuels and excessive emissions of greenhouse gases make efficient use of energy a key problem to be solved
We proposed a nanostructure of the three-dimensional graphene/paraffin nanocomposites, which consist of three-dimensional porous graphene networks and energy storage material paraffin
To rigorously characterize structural changes associated with the melting process and better demonstrate the phase change of n-octadecane and graphene/paraffin nanocomposites, we calculate mean square displacement (MSD) of atoms, which can be expressed as:
Summary
Nowadays, limited reserves of fossil fuels and excessive emissions of greenhouse gases make efficient use of energy a key problem to be solved. Using phase change materials (PCMs) for thermal energy storage, can reduce the mismatch between supply and demand, and improve the performance and reliability of energy distribution networks [1,2]. Phase change materials (PCMs) can solve the problem of discontinuity and instability in solar energy supply in time and realize the efficient and rational use of energy, so as to solve the energy and environment crisis [3,4,5]. Among numerous PCMs, paraffin (saturated hydrocarbons with CnH2n+2 formula), has proved to be desirable for thermal energy storage due to its rich latent heat, low cost, thermal and chemical stability, non-toxic and non-corrosive. The thermal properties of the three-dimensional nanoporous graphene/paraffin nanocomposites during phase transition are investigated systematically via MD simulations. This work will be beneficial to the development of PCM at thermal energy storage in the future
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