Hybrid nanofluids possess synergistic effects capable of enhancing buoyancy-driven heat transfer in engineering systems that depend on natural convection. However, the relationship between nanoparticle composition, thermophysical properties, and cavity geometry is nonlinear. This makes it difficult to reliably predict thermal performance. This study investigated the properties of ternary hybrid nanofluids under natural convection conditions in a hexagonal cavity with a focus on the impact of nanoparticle composition and geometric parameters on heat transfer and fluid flow for passive thermal management applications. This study used a ternary nanofluid composed of Magnesium oxide (MgO), Copper oxide (CuO), and Silicon carbide (SiC) dispersed in a base fluid of ethylene glycol. A mixture-based Response Surface Methodology (RSM) implemented in Design-Expert (v13. 0) was used to generate five (5) optimal ternary compositions with nanoparticle volume fractions between 0–4% and base fluid content between 96–99%. The optimal ternary nanofluid composition consisted of 0. 58612% MgO, 0. 64405% CuO, 2. 58917% SiC, and 96. 18067% ethylene glycol. For each composition, effective thermophysical properties such as thermal conductivity ("), specific heat (!), and dynamic viscosity (%) were computed using established theoretical models. The average k, C", μ, and ρ were 0. 2742885 W/m·K, 2279. 17221 J/kg·K, 0. 0168881 Pa·s, and 1184. 22594 kg/m3, respectively. The laminar natural convection governing equations were expressed in dimensionless form and solved using the Finite Element Method (FEM) in COMSOL Multiphysics (v5. 6). The influence of inclination angle + was investigated over Rayleigh numbers, with a fixed aspect ratio (AR) of 0. 25. At, - = 10# the average Nusselt numbers (12) were 2. 760979, 2. 760986, 2. 767196, 2. 770342, and 2. 760979 for + = 0∘, 30∘, 45∘, 60∘, 90∘, respectively. At, - = 10%, the Nusselt numbers increased to 3. 147658, 3. 139457, 3. 140626, 3. 145446, and 3. 147658. At, - = 10&, the values were 4. 680454, 4. 689514, 4. 757156, 5. 035523, and 4. 680454. This indicates a sensitivity to inclination under convection conditions.
Moses (Thu,) studied this question.