Performance Enhancement of Phase Change Materials Using Graphene and Carbon Nanomaterials

• Main Authors: Fan,Yang-Cheng, 范揚晟
• Other Authors: Liu,Yih-Ming
• Format: Others
• Language: zh-TW
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/tzstgy

碩士 === 國防大學理工學院 === 材料科學與工程碩士班 === 100 === In this study, different proportions of graphene, expanded graphite (EG) and exfoliated graphite nanoplatelets (xGnP) were used as filler materials in composite phase change materials (PCMs) in order to improve the performances. They were mixed with paraffin matrix using toluene solvent, ultrasonication, and magnet stirring. In the preliminary study of the composite PCMs, xGnP showed the best enhancement effect in thermal conductivity at all loading contents (1, 2, 5, and 10 wt.%). Due to the high aspect ratio of graphene, adding only 1 to 2 wt.% of graphene into paraffin PCM can drastically reduce the electrical resistivity. However, the thermal conductivity improvement by graphene is the lowest due to its small flake size, which increases the number of interfaces and results in large interfacial thermal resistance. In the drop point measurement, by adding 2 wt.% graphene into paraffin, the drop point temperature of paraffin PCM increased from 63.7 °C to 185.2 °C, and realized shape stabilization of the composite PCM. In the hot water flow tests at 52 and 90 °C, xGnP/paraffin composite PCM can quickly and effectively conduct heat energy from the central heat source to the outer part as compared to pure paraffin, and achieve the cooling effect. But xGnP cannot effectively enhance the drop point temperature of paraffin PCM. When the water flow temperature was increased above the drop point, the shape collapsed. But, by adding very small amount of graphene into the xGnP/paraffin composite PCM, the drop point temperature increased dramatically, and quickly achieved shape stabilization. Based on these results, adding a very small amount of graphene and some xGnP can significantly improve the thermal conductivity of paraffin and achieve shape stabilization. Other advantages include light weight and ease of shaping arbitrarily. In the future, there is a promising potential for the applications to the thermal management of electronic components.