Evaluation of thermal/morphological performance of SSPCM based nanoclay: Influence of the interlayer microstructure of hydrophilic and hydrophobic

• Published in: Solar energy materials and solar cells 2022-01, Vol.235, p.111479, Article 111479
• Main Authors: Nam, Jihee, Yang, Sungwoong, Yun, Beom Yeol, Kim, Sumin
• Format: Article
• Language: English
• Subjects: Bentonite; Cation exchange; Cation exchanging; Cations; Compatibility; COVID-19; Crystal structure; Energy conservation; Energy consumption; Energy efficiency; Energy storage; Hydrophilicity; Hydrophobicity; Impregnation; Interlayers; Latent heat; Morphological Property; Nanoclay; Occupancy; Pandemics; Paraffin; Paraffins; Performance evaluation; Phase Change Material; Phase change materials; Sodium; Thermal conductivity; Thermal energy; Thermal Performance; Thermal Storage; Time lag
• ISSN: 0927-0248; 1879-3398
• DOI: 10.1016/j.solmat.2021.111479

The COVID-19 pandemic has led to an increase in construction energy consumption and indoor occupancy; this, in turn, has increased the demand for energy efficiency. Thermal energy storage is an effective method for energy saving and improving efficiency. In this study, improved shape-stabilized phase change materials (SSPCMs) for enhancing the energy efficiency of buildings were manufactured and evaluated. These SSPCMs were prepared via the vacuum impregnation of n-octadecane into bentonite nanoclay. Bentonite exhibits a layered tetrahedral and octahedral crystal structure with Na+ cations (which feature high cation exchange capacity) in the interlayer space. The Na+ ion is a hydrophilic ion that affects the properties of the interlayer. However, paraffin-PCMs are hydrophobic and have poor compatibility with water. Therefore, hydrophobicity is induced in the organic nanoclay by using an organic modifier as the PCM container. Cloisite Na+, Cloisite 15, Cloisite 20, and Cloisite 93 were used to fabricate the SSPCMs. This study compares the amount of PCM impregnated depending on the compatibility of different PCMs between hydrophilic/hydrophobic nanoclays and also evaluates the thermal performance. The observed reduction in peak temperature and the time lag effect of the PCMs confirmed that the organically modified nanoclay and the PCM composites significantly improved the amount of PCM impregnated, thermal conductivity, and latent heat characteristics. The latent heat of the hydrophobic organic nanoclay was 209% higher than that of the SSPCM-based hydrophilic nanoclay. •Composites using paraffin PCM and nanoclay were fabricated and analyzed.•Hydrophobic nanoclay showed 124% higher PCM impregnation than hydrophilic nanoclay.•It was observed that PCM impregnation was affected by the microstructure.•SSPCMs showed up to 84% improved thermal conductivity than pure PCM.•The overall thermal performance in the SSPCM based hydrophobic nanoclay were high.