Phase change nanoemulsions developed by a modified phase inversion temperature method for low-temperature thermal energy storage.

Phase change nanoemulsions based on high-concentration ethylene glycol (EG) solutions have been developed for low-temperature thermal energy storage (TES). To address the challenge of poor nanoemulsion stability at high EG concentrations, a modified phase inversion temperature method was proposed. Through optimization of processing parameters and nanoemulsion formulation, nanoemulsions with improved stability were successfully achieved. Comprehensive stability tests confirmed their enhanced long-term storage stability. Thermal cycling tests performed over 300 cycles demonstrated that droplet sizes stabilized around 150 nm, with a polydispersity index <0.02. Notably, the sample containing 40 wt % EG demonstrated minor decreases in melting and freezing enthalpies of 2.7 % and 0.8 %, respectively, indicating its high thermal cycling  performance. Furthermore, the energy storage capacities of nanoemulsions with 30, 40, and 50 wt % EG significantly exceeded those of the base fluids by 94.60 %, 93.89 %, and 105.85 %, respectively. These results underscore the significant potential of these nanoemulsions for application in low-temperature TES systems.