Increased Thermal Conductivity of Eicosane-Based Composite Phase Change Materials in the Presence of Graphene Nanoplatelets

Abstract

Alkanes and their mixtures (paraffins) have widely been used as phase change materials (PCMs) for low-tomedium temperature thermal energy storage. Among the various alkanes, eicosane, with a nominal melting temperature of 37 °C, has emerged in energy-storage-based passive thermal management technologies, for electronics for example. In an effort to increase the thermal conductivity of eicosane, the effect of adding graphene nanoplatelets (GNPs) as thermally conductive nanofillers was investigated experimentally. The composite PCM samples were prepared by dispersing GNPs in liquid eicosane at various loadings (0, 1, 2, 5, and 10 wt.%) without any surfactants. Thermal conductivity of the composite PCM samples in their solid phase was then measured by means of the transient plane source technique at elevated temperatures from 10 to 35 °C. Latent heat of fusion and melting point of the samples were also characterized using a differential scanning calorimeter. It was shown that for the highest loading examined (10 wt.%), the relative thermal conductivity enhancement is above 400% at 10 °C, indicating that the emerging GNPs have much better performance than the conventional nanofillers attempted in the available literature, such as metal/oxide nanoparticles and carbon nanotubes. Reduced thermal interface resistance, related to the unique two-dimensional planar morphology of GNPs, was interpreted to be responsible for their superior performance. The matrix/filler thermal interface resistance was estimated to range from 6 × 10 −9 to 9 × 10 −9 m 2 K/W. In contrast to the markedly increased thermal conductivity, however, the penalty of decrease in the energy storage capacity, caused by the presence of GNPs, was shown to be less significant.

Synergistically-Enhanced Thermal Conductivity of Shape-Stabilized Phase Change Materials by Expanded Graphite and Carbon Nanotube

“…In recent years, carbon based fillers, such as graphite, carbon nanofibers, carbon nanotubes, and graphene, were used to enhance the thermal conductivity of PCMs because of their excellent thermal conductivity and low density [15][16][17][18][19][20][21][22][23][24][25][26][27]. For example, Shi et al [15] prepared PCMs by mixing paraffin (Tm = 61.6 • C) with exfoliated graphite nanoplatelets (xGnP) or graphene in hot toluene, followed by solvent evaporation and vacuum drying.…”

Modeling and Simulation of Graphene Based Polymer Nanocomposites: Advances in the Last Decade

“…As there are strong π-π interactions between graphene-graphene, the TBR between graphene-graphene can be neglected. However, the TBR between graphene-PMMA must be considered and taken as 1.906 × 10 −8 m 2 K/W [172]. When graphene is oriented along the heat flux, higher K eff values are obtained due to efficient heat transfer channel provided by graphene.…”

The influence of three different intercalation techniques on the microstructure of exfoliated graphite

“…GNPs are mainly used as an additive to improve mechanical properties and to enhance thermal or electrical conductivity [11][12][13][14]. Specifically, this material is increasingly being used to enhance the thermal conductivity of thermal energy storage media [15,16] such as phase change materials (PCMs). In general the thermal conductivities of most PCMs are very low, leading to problems charging and discharging the storage units.…”