Molecular Dynamics Predictions of Thermal Conductivity in Graphene for Phase Change Energy Storage Applications

2011 ◽  
Author(s):  
Masoud H. Khadem ◽  
Aaron P. Wemhoff
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Energy Storage ◽  
Phase Change ◽  
Md Simulations ◽  
Heat Diffusion ◽  
Graphene Sheets ◽  
Covalent Bonds ◽  
Energy Storage Applications ◽  
Change Material

Additives of highly-conducting nanoparticles such as graphene to a phase change material (PCM) improves PCM heat diffusion, which in turn produces better energy storage than pure PCM. Equilibrium Molecular Dynamics (EMD) simulations with Green-Kubo relations are used to predict the thermal conductivity of graphene sheets of various sizes and using different ensemble formulations. The Tersoff potential function has been implemented to model the covalent bonds between carbon atoms. The MD simulations predict an increase in thermal conductivity with graphene sheet size, and the predictions for the canonical (NVT) ensemble are consistently larger than those using the microcanonical (NVE) ensemble. The autocorrelation functions for the NVT simulations converge to zero for large sampling periods, which is not the case for NVE simulations.

scholarly journals Enhancement of the Thermal Energy Storage Using Heat-Pipe-Assisted Phase Change Material

Energies ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 6176 ◽  
Author(s):  
Hamidreza Behi ◽  
Mohammadreza Behi ◽  
Ali Ghanbarpour ◽  
Danial Karimi ◽  
Aryan Azad ◽  
...  
Keyword(s):  
Energy Storage ◽  
Phase Change ◽  
Heat Pipe ◽  
Latent Heat ◽  
Thermal Energy ◽  
Thermal Energy Storage ◽  
Phase Change Materials ◽  
Liquid Fraction ◽  
Energy Storage Applications ◽  
Change Material

Usage of phase change materials’ (PCMs) latent heat has been investigated as a promising method for thermal energy storage applications. However, one of the most common disadvantages of using latent heat thermal energy storage (LHTES) is the low thermal conductivity of PCMs. This issue affects the rate of energy storage (charging/discharging) in PCMs. Many researchers have proposed different methods to cope with this problem in thermal energy storage. In this paper, a tubular heat pipe as a super heat conductor to increase the charging/discharging rate was investigated. The temperature of PCM, liquid fraction observations, and charging and discharging rates are reported. Heat pipe effectiveness was defined and used to quantify the relative performance of heat pipe-assisted PCM storage systems. Both experimental and numerical investigations were performed to determine the efficiency of the system in thermal storage enhancement. The proposed system in the charging/discharging process significantly improved the energy transfer between a water bath and the PCM in the working temperature range of 50 °C to 70 °C.

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