Electrically driven nucleation for enhanced control of salt hydrate hydrogel heat release in long-term thermal storage applications

Abstract

Sodium acetate trihydrate (SAT) is a well-known salt hydrate phase change material (PCM) with large energy density and a high degree of supercooling, making it suitable for long-term thermal storage. However, effectively discharging heat from the supercooled SAT remains a challenge. This study delves into optimizing the electrical nucleation process in an SAT-based PCM, beginning with the validation of electrode pre-treatment and concluding with initiation under various conditions. The research identifies the optimal voltage and electrode spacing for nucleation. The crucial role of diffusion field interactions from growing crystals at different sites is highlighted, noting that their convergence creates a complex concentration gradient profile that hampers crystallization efficiency. Additionally, an increase in electrode pairs correlates with a more uniform heat distribution. Findings revealed that through material modification and nucleation strategy optimization, the theoretical crystallization time for SAT-based PCMs can vary significantly, ranging from 44 to 252 s. This variability, offering up to a 472.73 % extension in discharge time, underscores the PCM's adaptability for customized applications, especially in fields requiring variable discharge rates, such as residential heating and electronic thermal management.