In-depth molecular dynamics analysis of the thermal energy storage and transfer enhancement mechanism within carbonate nanofluid system

To further improve the efficiency of the next-generation solar thermal power generation systems, higher temperature requirements were imposed on heat transfer materials. Ternary carbonates had a wider operating temperature range, meeting the requirements of the next generation of solar thermal power generation systems. Meanwhile, adding SiO₂ to the ternary carbonates can improve their heat transfer and storage performance. This study explored the mechanism of nanoparticle enhanced thermal and physical properties of the ternary carbonates, and provided a more comprehensive analysis of the mechanism by which nanoparticles improve the thermal conductivity (TC) and specific heat capacity (SHC) of the carbonates. including Brownian motion, micro-convection, solid-liquid interfacial layers, and particle agglomeration, the key factors for enhancing the SHC and TC of the ternary carbonates with nanoparticles were revealed. The result demonstrated that the micro-convection effect previously proposed in literature as a mechanism for enhancing heat transfer efficiency be unable to elucidate the observed TC improvement in nanofluids. The enhancement in TC can be ascribed to the Brownian motion occurring between particles, the presence of 0.3 nm solid-liquid interfacial layers around nanoparticles, and nanoparticles agglomeration. Investigations into heat storage mechanism revealed that semi-solid layers, the high SHC of nanoparticles, and the good dispersibility contribute to increase SHC of the carbonates. While validating existing theories, this study identified Brownian motion as an additional factor enhanced TC, systematically validating the mechanism behind thermophysical property reinforcement in the ternary carbonates. These findings serve as reference framework for informing the selection and design processes of nanocomposite materials in subsequent investigations.