Thermal and electrical properties of palmitic acid/expanded graphite composite phase change materials for thermal energy storage

Abstract

Expanded graphite (EG) based phase change material (PCM) has attracted significant concern in thermal management systems. In this paper, a series of composite PCMs composing of EG with different sizes (50, 80, and 100 mesh) as the substrate, and palmitic acid (PA) as the PCM, were prepared by vacuum impregnation method. The results shown that the size of EG particles effect the adsorption capacity of PA. The mass fraction of PA in PA/EG-50 reached 83.6% and the enthalpy of melting and solidification of PA/EG-50 are 160.13 J/g and 159.75 J/g, respectively. The thermal conductivity decreased slightly as the particle size of EG increased, and the thermal conductivity of PA/EG-100 is the highest of 4.86 W/(m·K). The TGA results show that all composite PCMs present good thermal stability below 200 °C. The electro-thermal conversion efficiency increased with the particle size of EG increasing, and the electro-thermal conversion efficiency of PA/EG-100 reached up to 91.39% under low-voltage conditions (1.9 V). These results throw light on the potential application of EG-based composite PCM, especially for the electro-thermal conversion.

Keywords:

• Expanded graphite
• phase change material
• thermal conductivity
• electro-thermal conversion

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the Scientific Research Program of Shaanxi Provincial Education Department (22JK0417), the Scientific Research Program of Shaanxi Provincial Science and Technology Department (2024JC-YBQN-0592) and the Natural Science Foundation of Xi’an Technological University (Grant No. 302020552).