Stability Optimization of Al2O3/SiO2 Hybrid Nanofluids and a New Correlation for Thermal Conductivity: An AI-Supported Approach

Abstract

Due to their high thermal conductivity compared to traditional coolants, nanofluids are preferred; however, their high thermal conductivity alone is meaningless without ensuring their stability. Therefore, when determining the appropriate mixing ratio (hybrid ratio) for hybrid nanofluids, which are starting to replace mono nanofluids today, the primary factor to consider should be stability. In this study, sedimentation and zeta potential measurements, which are methods for evaluating stability, were used to assess the stabilities of mono Al2O3/water and SiO2/water nanofluids with mass fractions of 1 %, 2 %, and 3 %, as well as hybrid Al2O3/SiO2/water (2 % to 1 %, 1 % to 2 %) nanofluids together for the first time in the literature, and the optimum Al2O3/SiO2 hybrid ratio was determined in terms of stability. The results showed that the optimal hybrid ratios for the stability of Al2O3-SiO2/water nanofluids are 1 and 0.714. Furthermore, the thermal conductivities of stable mono and hybrid nanofluids were measured between 25 and 60 degrees C, and a new correlation valid for both mono and hybrid nanofluids was proposed by modeling with artificial neural networks (MSE = 8.2175E-5 and R2 = 0.99958), with a maximum deviation ratio of 3.839 % (for mono SiO2/water) from the experimental measurements.