Optimization of viscosity of diamond and boron nitride based nanofluids for enhanced thermal management and pumping efficiency

Abstract. The present study investigates optimizing the viscosity of hybrid nanofluids composed of diamond and boron nitride in thermal oil for high-temperature heat transfer applications. Recognizing that higher viscosity equates to increased pumping costs, the study seeks to minimize this critical parameter to enhance the overall efficiency of thermal systems. Employing Response Surface Methodology (RSM) and a desirability function approach, explored the effect of temperature (25°C to 65°C), concentration (0.2 wt.% to 0.6 wt.%), and shear rate (1 to 1000 1/s) on the viscosity of nanofluids. The optimization process pinpointed conditions that yield the minimum viscosity with the highest desirability score, signifying the most advantageous operating scenario. The results showed an optimal balance at a higher temperature and mid-range concentration, culminating in a nanofluid demonstrating Newtonian behavior at low shear rates and shear-thinning attributes at elevated temperatures and shear rates. These findings explain the potential of tailored nanofluids to substantially cut pumping costs while maintaining excellent heat transfer properties, making them ideal candidates for advanced cooling systems in demanding thermal management settings.