Numerical analysis of the effect of configurations of double rotating cylinders on heat transfer enhancement hybrid nanofluid flow in a vented cavity

In this paper, the effect of configurations of rotating cylinders in vented cavity with inlet and outlet port on the flow field and heat transfer enhancement of Al2O3/Cu-water hybrid nanofluid flow in the laminar regime is numerically investigated. Finite volume method is used to solve governing equations of flow and energy with assumptions of 2D, steady-state, and single phase. In this study, the influence of parameters as configurations of cylinders (A, B, C, and D), as well as the rotational velocity of cylinders, Reynolds number, and the volume fraction of nanoparticles on the flow field and heat transfer are studied. Also, to evaluate the simultaneous of heat transfer enhancement and pressure drop, the Performance Evaluation Index (η) is calculated. The results indicated that in presence of rotating cylinders, the η is higher than 1 for all cases, and it is clear that the presence of rotating cylinders is effective on the thermal efficiency of the cavity. Results indicate that the average Nusselt number and the η for configuration D are higher than other configurations. Also, it is obvious that by increasing the rotational velocity of cylinders, Reynolds number, and the volume fraction of nanoparticles, the η increases. The results show that Al2O3/Cu-water hybrid nanofluid causes heat transfer enhancement compared to the Cu-water nanofluid and it increases Performance Evaluation Index compared to the Al2O3-water nanofluid.