Ultrasonically regenerable nano-phase change emulsions with low supercooling and high shear stability

Abstract

An on-line regeneration method for nano-phase change emulsions enabling effective recovery of enthalpy and particle size to levels comparable to freshly prepared samples.Nano-phase change emulsions (NPCEs) are attractive thermal fluids for applications such as cold-chain logistics, vaccine storage, and low-temperature energy systems operating in the 0–20 °C range. However, their deployment is hindered by significant supercooling and poor stability under shear. Here, we report a formulation strategy combining surfactant and nucleating agent optimization to prepare NPCEs with suppressed supercooling (<0.5 °C) and high dispersion stability. The NPCEs maintain structural integrity after 24 h of continuous shear at 5 °C, with droplet size variation within 20 nm. Rheological and microscopic analyses elucidate the interfacial disruption mechanism under low-temperature shear, and a nucleating agent selection principle is established based on molecular conformation and crystallization compatibility. To address performance degradation, we develop a high-energy ultrasonic on-line regeneration method that rapidly restores thermal functionality without system downtime. The NPCEs achieve >99.5% latent heat recovery and maintain stable performance over 60 days of thermal and mechanical cycling. This work demonstrates a regenerable NPCE system featuring ultra-low supercooling and long-term operational stability. The findings offer a practical pathway for scalable deployment of advanced thermal fluids in energy-efficient industrial applications.