Thermal conductivity enhancement and predictive modeling of BNNP-paraffin nanofluids: synergistic effects of BNNP concentration and temperature.

In this study, we present some results on the preparation, dispersion stability, and thermal conductivity of boron nitride nanoplatelet (BNNP)-based nanofluids. BNNPs were successfully fabricated from bulk hBN via high-energy ball milling, resulting in nanosheets with reduced lateral size and a preserved layered structure. Surface functionalization with hydroxyl and oleic acid groups was confirmed by FTIR and Raman analyses, demonstrating improved interfacial compatibility and dispersion stability. UV-vis spectroscopy revealed that nanofluid stability strongly depends on BNNP concentrations, with a critical aggregation threshold observed at higher loadings. Thermal conductivity measurements showed a significant enhancement with increasing BNNP concentration and temperature, reaching up to ∼42% improvement at 60 °C and 0.1 vol%. This enhancement is attributed to the formation of thermally conductive pathways, improved interfacial heat transfer, and increased Brownian motion at elevated temperatures. A theoretical model was proposed, incorporating both BNNP concentration and temperature effects. The model parameters were found to vary linearly with temperature, enabling the development of a generalized correlation for predicting thermal conductivity. The proposed model exhibits excellent agreement with experimental data, confirming its high accuracy and practical applicability. This work provides new insights into the structure-property relationship of BNNP nanofluids and offers a reliable predictive tool for advanced thermal management systems.