Carbon-based nanoadditives induced enhancement of phase change thermal properties of sugar alcohol and interfacial heat transport mechanisms

DL Feng and ZH Zhao and XX Zhang and YH Feng, COMPOSITES SCIENCE AND TECHNOLOGY, 243, 110258 (2023).

DOI: 10.1016/j.compscitech.2023.110258

Sugar alcohol phase change materials (SAPCMs) are gaining more attention in thermal storage due to their large energy storage density, wide melting temperature range, and excellent thermal cycling stability. However, the low thermal conductivity and high supercooling severely restrict their applications. In this study, two types of high thermal conductivity carbon-based nanoadditives (CBN), multi-walled carbon nanotubes (MWCNT) and graphene (Gra) were selected to improve the thermal properties of mannitol and erythritol. From the experimental aspect, carbon nanoadditives were uniformly mixed with SAPCMs, and the phase change thermal properties of the composite PCMs were tested. The results indicate that graphene and MWCNT not only enhance the thermal conductivity of the SAPCMs but also suppress undercooling and latent heat difference. Then, the underlying mechanisms behind these observed phenomena were revealed from a microscopic perspective via the molecular dynamics (MD) method. The results demonstrate that Gra and MWCNT exhibit enhanced heat transfer by better matching the atomic vibrations of SAPCMs within the frequency range of 0-70 THz. However, we found that the interfacial thermal resistance (ITR) between SAPCMs and carbon nanoadditives weakens the thermal enhancement effect of the nanoparticles, with the most pronounced impact observed in MWCNT. This negative influence of interfacial thermal resistance can be mitigated by modifying the tube length, diameter, and layer count. This study can provide guidance for the design and application of SAPCM-based phase change materials.

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