ENHANCING COOLING PERFORMANCE OF A HEAT EXCHANGER DRIVEN BY WATER/ALUMINA-SILICA HYBRID NANOFLUID: EXPERIMENTAL RESULTS

Abstract

The application of nanofluids in heat exchangers has been established to be beneficial in augmenting heat transfer performance. This study presents an experimental investigation of the performance of a heat exchanger using a water/Al<sub>2</sub>O<sub>3</sub>-SiO<sub>2</sub> nanofluid under constant heat flux condition. The nanofluid, consisting of well-stabilized nanoparticles, was applied at concentrations ranging from 0.01 to 0.025 vol.%. By systematically varying the Reynold's number from 6,000 to 24,000, the effects of the Reynold's number and concentration on the average Nusselt numbers and friction factor were analyzed. The results indicate that the addition of nanoparticles significantly enhances both the average Nusselt number and friction factor. At a Reynolds number of 24,000, the hybrid nanofluid with a concentration of 0.025 vol.% exhibited a maximum increase of 13.57% in the average Nusselt number and a 10.08% increase in the friction factor compared to using water alone. Sensitivity analysis revealed that concentration had a more pronounced impact on the average Nusselt number and friction factor than Reynold's number. Various figures of merits determined the thermal performance of the heated tube. The study proposes new correlations with high accuracies (R<sup>2</sup> > 99%) to predict these parameters. Based on the findings, the use of hybrid nanofluid is recommended for enhancing heat transfer applications. However, it is important to consider the potential increase in pumping power requirements associated with nanoparticles.