Natural convection heat transfer enhancement of hybrid nanofluids in snowflake-inspired heat sink structures

With the continuous growth of energy demand and the increasing urgency of environmental protection, enhancing energy conversion efficiency and reducing energy consumption have become particularly important. Nanotechnology, especially nanofluids, has shown great potential in improving thermal conductivity and heat transfer performance. This study investigates the enhancement of natural convection heat transfer using multi-walled carbon nanotube-Fe3O4/water hybrid nanofluids in different radiator structures through numerical simulations. The study considers various radiator geometries (circular and snowflake-shaped), nanoparticle volume fractions (0, 0.001, and 0.003), and Rayleigh numbers (Ra = 103–106). The results indicate that the introduction of nanoparticles enhances the average Nusselt number by up to 13% at the highest nanoparticle volume fraction compared to the base fluid. The dense-branch snowflake-shaped radiator (DB case) demonstrates superior heat transfer performance, achieving a 23% higher Nusselt number than the circular design at high Ra number. Furthermore, as the Ra increases, convective heat transfer is significantly enhanced. The study highlights the combined influence of nanofluids and geometric optimization in improving heat transfer and provides quantitative insights for designing efficient thermal management systems.