Evaluation of Dispersion Behavior and Practicality of PGPR@ZnO Nano-Hyperdispersant in DEHC.

To achieve stable dispersion of ZnO nanoparticles in the base fluid and enhance thermal conductivity (λ), a PGPR@ZnO nano-hyperdispersant was synthesized using polyglycerol polyricinoleate (PGPR) and ZnO. FT-IR and DSC confirmed the bonding interaction between PGPR and ZnO, and zeta potential analysis verified the steric hindrance effect that effectively inhibits particle agglomeration. The PGPR@ZnO was dispersed into di(2-ethylhexyl) carbonate (DEHC) by ultrasonication and stirring, yielding a stable DEHC-PGPR@ZnO nanofluid. This nanofluid achieved a 16.2% increase in λ while retaining the low viscosity and low pour point of the base fluid. Stability assessments showed consistent particle size main peaks before and after static and dynamic tests, with no obvious agglomeration peaks, average particle size variation below 6%, PDI below 0.3, and negligible zeta potential fluctuation. Following static and dynamic stability tests, the thermal conductivity decreased by 0.85% and 7.98%, respectively. These results indicate excellent dispersion stability and provide a valuable reference for evaluating the operational adaptability of the coolant. The nanofluid meets the basic standards for immersion coolants and exhibits a figure of merit (FOM) superior to most oil-based coolants. Compared with PAO2, it offers advantages in raw material availability and resistance to hydrolysis and acidification, providing research and practical foundation for the development of high-performance immersion coolants.