Thermo-Hydraulic Characteristics of TiO₂-SiO₂ Hybrid Nanofluids Utilizing Wire Coil Inserts: A Numerical Study
Abstract
The enhancement of heat transfer device performance through the use of wire coil inserts and hybrid nanofluids can significantly improve convective heat transfer, though it also results in higher pumping power requirements. Therefore, a comprehensive investigation considering both heat transfer improvement and the effects of friction factor and pressure drop on pumping power is essential. In this study, the heat transfer characteristics of TiO₂-SiO₂ hybrid nanofluids dispersed in an EG/water mixture within tubes equipped with wire coil inserts under constant wall heat flux were analyzed using computational fluid dynamics (CFD). Simulations were conducted with TiO₂-SiO₂ nanofluids at volume concentrations of 1.0, 2.0, and 3.0%, combined with wire coil inserts of varying pitch-to-diameter (P/D) ratios ranging from 0.2 to 0.8. Results show that the friction factor at 1.0% volume concentration increases with decreasing P/D ratio and Reynolds number, while the Nusselt number rises at a lower pitch ratio of 0.2. Furthermore, the thermal performance factor (TPF) was observed to increase as the pitch ratio decreased, with a maximum value of 1.43 at a P/D ratio of 0.2 for the 1.0% volume concentration.