Nucleation and Supercooling Mitigation in Fatty Alcohol Phase Change Material Emulsions for Heat Transport and Storage

Abstract

Organic phase change slurries (PCS) exhibit significant supercooling in small particles, which diminishes their advantages over sensible heat storage systems by reducing energy efficiency and reliability. While the mechanisms of supercooling in alkanes have been extensively studied, investigations of emulsions containing fatty alcohols are limited. This study examines the impact of nucleating agents on reducing supercooling in oil-in-water (O/W) emulsions of 1-docosanol, a fatty alcohol used as a phase change material (PCM). Emulsions with platykurtic particle size distributions were produced using rotor-stator emulsification. Various material combinations were explored to identify nucleation promoters compatible with 1-docosanol. Thermal analysis revealed that long-chain polymers effectively mitigate supercooling, particularly during rotator phase transitions, as confirmed by crystal structure analysis. On average, supercooling was reduced by 9 K; however, seed deactivation observed over multiple thermal cycles led to a gradual return of supercooling. Similar to alkanes, particle size influences the nucleation rate, surfactants affect the availability of heterogeneous nucleation sites, and nucleating agents can decrease the nucleation barrier. The findings indicate that high structural similarity between emulsion components is beneficial for minimizing supercooling in PCS, enhancing their potential for thermal energy storage applications.