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COBEM 2023
27th International Congress of Mechanical Engineering
Numerical and experimental assessment of a hybrid active magnetic regenerator manufactured with Gd and La-Fe-Si alloys
Submission Author:
Paulo Vitor de faria , SC
Co-Authors:
Rogerio Sucaria, Paulo Vitor de faria, Bernardo Vieira, Hígor Feltrin Teza, Jaime Lozano, Jader Riso Barbosa Jr.
Presenter: Rogerio Sucaria
doi://10.26678/ABCM.COBEM2023.COB2023-2010
Abstract
Throughout the last few decades, the interest in new refrigeration technologies has increased substantially. These alternatives to the already established vapor compression systems aim to diminish the harm that it causes to the environment while also being capable of achieving a theoretical energy efficiency which surpasses the vapor compression technology. Within the alternatives, magnetic refrigeration has some characteristics that stand out when compared to conventional refrigeration, such as the absence of ozone depletion and greenhouse gases and the usage of a solid-state refrigerant which prevents leakage. Magnetocaloric refrigerators consist of many subsystems coupled together and among them is the active magnetic regenerator (AMR), the focus of this work, which is where the magnetocaloric material (MCM) is stored and the cooling power is generated during cyclic changes of the hydraulic and magnetic subsystems. The signature MCM for magnetic refrigeration is Gadolinium (Gd), although other materials like La-Fe-Si alloys have been extensively studied for near room magnetic cooling. The use of the MCM as a thermal regenerator is justified by the low magnitude of the magnetocaloric effect (MCE), which alone is not capable of achieving satisfactory cooling capacities. Another important characteristic of AMRs is that may consist of layers with different magnetocaloric properties, as to improve the maximum temperature span of the system. Each of these layers has a unique Curie temperature (Tc) organized in a way that guarantees that the regenerator temperature gradient follows the Tc of each layer to maximize the MCE. Because single material regenerators have been the focus of extensive research in the past decades, and although some regenerators with multiple materials were studied, the literature still lacks a more in-depth assessment of the cooling capacity vs temperature span relation of the latter. With this in mind, a hybrid regenerator consisting of one layer of Gd and ten layers of La-Fe-Si with a length of 120mm and a diameter of 24.2mm was assembled and experimentally characterized for cooling capacity with three different operational parameters: frequencies of 0.25, 0.5 and 0.75 Hz, blow fraction of 50% and 37.5% and the mass flow rate varying from 20 kg/h to 80kg/h. The measured results were then compared with the numerical results of an already validated numerical model for single material regenerators, which was modified as to simulate a multi material regenerator, being its validation one of the main objectives of this paper.
Keywords
magnetic refrigeration, active magnetic regenerator, Numerical Modeling, La-Fe-Si alloy, Gadolinium
