Suppression of supercooling and phase change hysteresis of Al-25mass%Si Micro-Encapsulated Phase Change Material (MEPCM) synthesized via novel dry synthesis method

Latent heat thermal energy storage (LHTES) via metals and alloy-based phase change materials (PCMs) is an effective means to recover waste heat from energy sources, store renewable energy and convert it into a constant temperature heat source. Al-Si PCMs are intriguing thermo-responsive materials with great potential for latent heat thermal energy storage for diverse applications. However, practical uses are militated by existential supercooling and particularly, phase change hysteresis (PCH), which is often neglected in thermal energy storage studies using PCMs. Thus far, suppression of supercooling and PCH of metal alloy PCMs is rarely reported despite their inherent large heat storage density per unit volume, large specific surface area, low vapor pressure, high thermal conductivity, and exceptional thermal stability for practical applications. Hence, this study to investigate the effect of Ti-doping on the PCH and supercooling of Al-25mass%Si MEPCMs for efficient thermal energy storage and utilization. TiO2 additive was introduced to Al-25mass%Si PCMs via high-speed impact blending method. Following heat oxidation treatment and characterization, the addition of 3 wt% TiO2 produced the best hysteresis suppression effect (97 % reduction), while 1 wt% addition led to the best supercooling suppression effect, yielding about 73 % reduction. The results demonstrate the development of highly durable Ti-doped Al25mass%Si MEPCMs with large latent heat capacity and an excellent suppression of hysteresis and supercooling, paving way for efficient practical uses as well as the utilization of this novel approach to suppress the PCH and supercooling of other metals and alloy based PCMs for a rich array of practical applications.