Preparation of nitrogen-doped graphene/palmitic acid shape stabilized composite phase change material with remarkable thermal properties for thermal energy storage

• Published in: Applied energy 2014-12, Vol.135, p.339-349
• Main Authors: Mehrali, Mohammad, Tahan Latibari, Sara, Mehrali, Mehdi, Mahlia, Teuku Meurah Indra, Sadeghinezhad, Emad, Metselaar, Hendrik Simon Cornelis
• Format: Article
• Language: English
• Subjects: Applied sciences; Composite materials; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Graphene; Heat transfer; Latent heat; Liquids; Palmitic acid; Phase change materials; Thermal conductivity; Thermal energy; Thermal energy storage; Thermal properties; Transport and storage of energy
• ISSN: 0306-2619; 1872-9118
• DOI: 10.1016/j.apenergy.2014.08.100

•Nitrogen-doped graphene (NDG)/palmitic acid (PA) composite shape stabilized PCMs were prepared.•The loading of PA in the composite PCMs with good form-stability could attain 97wt%.•The phase change enthalpy of the composite PCMs could attain 199.48J/g.•The thermal conductivity of the PCM containing 3wt% NDG is 3.5 times higher than that of PA. Palmitic acid (PA) is one of the main phase change materials (PCMs) for medium temperature thermal energy storage systems. In order to stabilize the shape and enhance the thermal conductivity of PA, the effects of adding nitrogen-doped graphene (NDG) as a carbon nanofiller were examined experimentally. NDG was dispersed in liquid PA at various mass fractions (1–5wt%) using high power ultrasonication. The dropping point test shows that there was clearly no liquid leakage through the phase change process at the operating temperature range of the composite PCMs. The thermal stability and thermal properties of composite PCM were investigated with a thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC), respectively. The thermal conductivity of the PA/NDG composite was determined by the laser flash method. The thermal conductivity at 35°C increased by more than 500% for the highest loading of NDG (5wt%). The electrical conductivity of composite PCMs was increased significantly by using NDG. The thermal cycling test proved that the PA/NDG composites PCMs had good thermal reliability and chemical durability after 1000 cycles of melting and freezing. The thermal effusivity of the PA/NDG composite PCMs was larger than that of pure PA, which is advantageous for latent heat thermal energy storage (LHTES).