Inducing and controlling supercooling in industrial-grade sodium acetate trihydrate for long-term PCM based thermal energy storage system

Phase change material (PCM) based energy storage systems are a promising solution to ensure a continuous energy supply from intermittent renewable sources for long-term applications. This study explores the potential of economical, industrial-grade sodium acetate trihydrate (SAT) for thermal energy storage, as pure SAT is expensive. Unlike conventional approaches to mitigate supercooling, this research induces controlled supercooling for long-term usage of latent heat activation. Composites, including Tween 80, coconut oil, and ethylene glycol, were incorporated into industrial-grade SAT to analyze their effects on supercooling behavior. The morphological and thermophysical properties of composite PCMs (CPCMs) were analyzed. PCM samples with 30g were heated to 65 degrees C, 80 degrees C, and 95 degrees C, then cooled naturally, with crystallization triggered using a heterogeneous seeding technique. The influence of composites at varying concentrations, with mass ratios of 1/2 and 1/3, was evaluated for their effects on the crystallization temperature and supercooling degree. Additionally, the behavior of copper particles submerged in supercooled SAT and air-surface interactions was examined. The experimental results revealed that Tween 80-based CPCMs exhibited the highest degree of supercooling across all conditions, while coconut oil-based CPCMs showed an interesting trend at higher initial temperatures of 95 degrees C, where the degree of supercooling increased, a behavior not observed at lower temperatures. Conversely, ethylene glycol-based CPCMs exhibited poor crystallization kinetics, tailoring the maximum heat release temperature from 58 degrees C to 40 degrees C, which makes them suitable for specific thermal applications. In all CPCMs, higher composite concentrations increased supercooling, highlighting the need to optimize composite levels for desired thermal performance.