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Abstract: Thermal energy storage (TES) is incredibly important to expanding the field of renewable energy. In this study, the authors look at the potential of composite phase change materials (PCMs) for use in this application. A ball milling method was used to exfoliate expanded graphite in nanosheets that could be added to eicosane to create composite materials. Composites with nanosheets of various sizes were created, and the effect of cooling rate on their thermal conductivity was studied. As the cooling rate was raised, the thermal conductivity of pure eicosane slightly decreased. However, for a composite containing 1 wt% graphite, the thermal conductivity decreased by 25%, indicating that the composites were much more sensitive. Thermal conductivity measurements on the composites themselves showed that larger graphite sheets had a bigger impact on the thermal conductivity enhancement, the highest value recorded with 1.57 W/mK in a composite with 5 wt% loading of larger nanosheets. A percolation threshold was observed around 1 wt% in all samples, otherwise the thermal conductivity increased linearly with filler loading. Upon completion of this research the authors concluded that composite PCMs are a solution for extensive TES applications

Reference: Energy Conversion and Management 103 (2015) 251-258

DOI: 10.1016/j.enconman.2015.06.062