Magnetic field influence on heat transfer in inclined laminar ferronanofluid flow

Understanding the interaction of the magnetic field with the inclined ferronanofluid flow on heat transfer is an important element in the industrial applications of these fluids. Inclined flow is unavoidable and constitutes a large part of technical solutions. In order to intentionally design devices employing ferronanofluids, especially those with switchable performance under the influence of a magnetic field, it is necessary to explore the phenomena behind heat and mass transfer in the flow. The purpose of this work is to determine the effect of the upward ferronanofluid flow on the heat transfer parameters and the possibility of influencing it with a magnetic field. For this purpose, upward inclined flow was studied for 30°, 60° and 90° angles and Reynolds numbers of 106, 185, 264, and 397 subjected to two configurations of magnetic field generated by a static magnet. The main conclusions of the analysis indicate that the flow inclination, with respect to the horizontal position, for low Reynolds numbers (Re = 106 and 185) leads to a deterioration of the heat transfer parameters in the ferronanofluid flow. As the relative magnitude of the inertia forces in the flow increases, the negative effect on heat transfer decreases. The possibility of improving the heat transfer in inclined flow by a permanent magnet is limited. The effect of the magnetic field on the heat transfer process must be determined in relation to the mixed convection in the fluid. The direction agreement of the flow and gravity does not prevent fluid mixing, and it is noticeable in the heat transfer parameters. However, the change in averaged Nusselt number is independent of the tested magnetic field configurations, suggesting that the flow retains a symmetrical character, as evidenced by a similar improvement in the Nusselt number. Additionally, the analysis indicates that mixed convection occurred in each of the flow conditions studied. However, flow regime maps available in the literature are not sufficient to clearly determine these flow conditions and therefore need to be updated with new data.