PCM in Water Emulsions: Supercooling Reduction Effects of Nano-Additives, Viscosity Effects of Surfactants and Stability

• Published in: Advanced engineering materials 2015-02, Vol.17 (2), p.181-188
• Main Authors: Zhang, Xiyao, Niu, Jianlei, Zhang, Shuo, Wu, Jian-Yong
• Format: Article
• Language: English
• Subjects: Carbon; Emulsions; Hexadecane; Nanostructure; Stability; Supercooling; Surfactants; Thermal analysis
• ISSN: 1438-1656; 1527-2648
• DOI: 10.1002/adem.201300575

This study aims to develop a paraffin‐based phase change material (PCM) for water emulsions with a low degree of supercooling, high fluidity and stability, which can be applied in thermal energy storage (TES) systems to improve the cooling efficiency. A hexadecane/water emulsion was prepared and chemically modified multi‐wall carbon nano‐tube (MWCNT) particles were dispersed in the emulsion as a nucleating agent to reduce supercooling. Three surfactants were also tested on the properties of the hexadecane/water emulsions. Thermal analysis by differential scanning calorimeter (DSC) indicated that the degree of supercooling of the emulsion was significantly decreased by the nucleating agent. The effective nucleating agent concentrations required for the PCM liquid were found to be low, which agrees with the previous finding, but for the emulsion there appeared to be a minimum effective concentration to reduce the supercooling. The rheology characters and the stability of the emulsions were also observed and discussed. A hexadecane‐water emulsion is prepared and chemically‐modified multi‐wall carbon nano‐tube (MWCNT) particles are dispersed in the emulsion as a nucleating agent to reduce supercooling. Thermal analysis by differential scanning calorimeter (DSC) indicates that the degree of supercooling is significantly decreased. Three surfactants are also tested on the rheology characters and stability of the PCM‐water emulsions.