Numerical Investigation of the Effects of Using Nanofluid on Thermal Performance and Flow Properties in a Gyroid Structure Heat Exchanger

Recently, heat exchangers based on triply periodic minimal surface (TPMS) structures have attracted increasing interest in engineering applications due to their high surface-to-volume ratio, compact design, superior thermal performance, and the feasibility of manufacturing these complex geometries using additive manufacturing technologies. This study, the thermal performance and flow characteristics of a gyroid heat exchanger are numerically investigated using air-air and water-water based Al2O3 nanofluids as working fluids. Firstly, the numerical model for the air-air heat exchanger is validated against reference data from the literature for the hot fluid side, then thermal analysis was conducted for at different Recold numbers. As the Re increased, the heat transfer coefficient, heat transfer and Nusselt number increased. Subsequently, Al2O3 nanoparticles were added to the hot-side water base fluid at various volume concentrations (0%, 0.1%, 0.3%, 0.5%), and simulations were conducted under different Rehot-Recold combinations. It was observed that nanofluid concentration and Reynolds number affected the heat transfer coefficient, heat transfer rate, thermal efficiency and Nusselt number. In addition, a decrease in thermal efficiency was observed with the addition of 0-0.3% nanoparticles, followed by a slight increase between 0.3-0.5%. Studies examining the use of nanofluids in TPMS-gyroid structures are generally limited to heat sink applications; this study provides a contribution to the literature by investigating the effect of nanofluids in a compact cross-flow heat exchanger with simultaneous hot and cold fluid provided.