Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
On the influence of asymmetric configurations of a magnetic field in the thermo-magnetic convection in a ferrofluid cavity An experimental investigation
Submission Author:
Bruno Silveira de Lima , SP
Co-Authors:
Bruno Silveira de Lima, Arthur França Martins, Flávio Bannwart
Presenter: Flávio Bannwart
doi://10.26678/ABCM.COBEM2023.COB2023-1633
Abstract
This study aims to quantify the influence of the position of a steady-state magnetic field provided by a neodimyum magnet at different vertical asymmetric configurations with respect to a rectangular ferrofluid cavity in its convective regimes. Depending on the asymmetry orientation and temperature gradient, the resulting combination between the magnetic and gravitational fields affects differently the ferrofluid convection in the regions closer to the magnet and, consenquently, on the heat transfer rates in the system. In the context of a better efficiency in the heat change process a lot of research has been conducted to improve it. Our preliminary study reveals a very strong influence of the magnetic field in the process of thermomagnetic convection. Our system consists in a closed rectangular cavity in the vertical orientation filled with ferrofluid and delimited by two vertical plates at different temperatures, to provide an arbitrary nonuniform temperature gradient. These plates have their average temperatures controlled and maintained by two water reservoirs designed to set them nearly constant, after the time transition till the steady-state regime. The magnetic field is provided by a previously characterized neodymium magnet positioned at various positions next to the lateral of the hotter plate. All processes are monitored by a set of sensors that provides the temperature at specific positions on the plates, of the external atmospheric environment, and of the water inlet and outlet every second. As a result of the experimental investigation, an extensive database is recorded and processed by a Python code dedicated to obtain the Nusselt number and heat flux for each configuration and arbitrary regime, allowing both qualitative and quantitative analysis of heat transfer efficiency modification. Our results indicate a systematic effect due to the magnet positioning towards an increase or a decrease on the heat transfer rates, depending on whether it is located on top or below at the vertical asymmetry direction. Such a behavior suggests that the asymmetry can be better managed taking this effect into account.
Keywords
magnetic field, thermo-magnetic, Convection, convection heat transfer., ferrofluid, asymmetric
