Turbulent nanofluid flow over periodic rib-grooved channels

In this paper, the effects of using different rib-groove shapes of triangular, square and arc, different geometrical parameters and also different types of nanofluids including Al₂ O₃, CuO, ZnO and SiO₂ on the thermal and hydraulic behavior of flow in a horizontal rib-grooved channel are numerically investigated. The finite volume method (FVM) is applied to solve the two dimensional governing and energy equations. Constant heat flux was imposed on the channel walls. The effects of nanoparticle diameter in the range of 30–70nm, nanoparticle volume concentration in the range of 1–4%, and also Reynolds numbers varying from 30,000 to 50,000 were examined in this study. The performance of rib-grooved channel was evaluated in terms of average Nusselt number, friction coefficient and performance index. The results revealed that rectangular rib- rectangular groove shows the best performance having the highest performance evaluation criterion (PEC). The results also indicated that using nanofluid flow in grooved channels could provide a significant increase in heat transfer and thermal performance with negligible increase in friction. The SiO2-water nanofluid provides highest Nusselt number among all types studied. It is also observed that increasing the nanoparticles volume fraction and Reynolds number enhanced the Nusselt number while increasing nanoparticles diameter decreased it.