Eventos Anais de eventos
COBEM 2023
27th International Congress of Mechanical Engineering
Numerical analysis of the magnetic flux density profile impact on the total power produced by a linear thermomagnetic motor
Submission Author:
Clara Silva , MG
Co-Authors:
Clara Silva, Paulo Vinicius Trevizoli
Presenter: Clara Silva
doi://10.26678/ABCM.COBEM2023.COB2023-0251
Abstract
Thermomagnetic motors can be applied to convert low grade thermal energy waste into usable mechanical energy, by directly producing force or torque. The present work proposes a mathematical model to simulate the operation of a linear thermomagnetic motor designed and built by researchers at Universidade Estadual do Maringá (UEM). The device consists of a double-C shape permanent magnet magnetic circuit, that generates two high field regions, and two heat exchangers filled with spherical particles of Gadolinium (Gd) magnetocaloric material in a packed-bed porous media. Two blows, one warm and the other cold, flows through the porous media along different periods of the cycle. This way, the Gd experiences a periodic change of its magnetic phase (ferro <=> paramagnetic) establishing a non-balance between the magnetic forces acting on each heat exchanger, which results in a linear motion. The mathematical model, numerically implemented using the finite volume method, solves the energy equation to a porous media coupled to the thermomagnetic properties of Gd. The model is used to investigate the influence of the magnetic flux density profile in the motor performance. Four different profiles, in addition to the original, are investigated. The maximum and minimal flux density values of each profile are the same as the original one, allowing a more reliable analysis. The output results are the cycle period, the maximum displacement and the power produced by the motor. The results showed that the profile with a constant flux density gradient profile is the ideal case for the thermomagnetic motor, producing a power of 8.298 W, which is, approximately, 127.5% higher than the power produced by original profile. Furthermore, higher flux density gradients showed to be more important than larger total displacements and lower cycle periods. Lastly, profiles with high flux density gradients at the center of the magnetic field region and low gradients at the edges do not generate motion.
Keywords
Thermomagnetic motor, Numerical analysis, Heat transfer in porous media
