Eventos Anais de eventos
ENCIT 2016
16th Brazilian Congress of Thermal Sciences and Engineering
OPTIMIZATION OF MULTILAYER ACTIVE MAGNETIC REGENERATORS
Submission Author:
Jean Eduardo Cararo , SC
Co-Authors:
Jaime Lozano, Paulo Vinicius Trevizoli, Jader Riso Barbosa Jr., Andrew Rowe, Reed Teyber
Presenter: Jean Eduardo Cararo
doi://10.26678/ABCM.ENCIT2016.CIT2016-0320
Abstract
Magnetic refrigeration harvests the magnetocaloric effect (MCE) in regenerative thermodynamic cycles by means of magnetic work on an active magnetic regenerator (AMR). Since the MCE of typical materials is large only over a narrow temperature range, layered regenerators can improve the AMR temperature span and thermal performance by using materials with different transition (Curie) temperatures (TC) to enhance the MCE along the regenerator bed [1,2]. In this work, a numerical model [3] is used to simulate layered AMRs. Experimental magnetocaloric properties of Gd spheres are employed to simulate three different Gd1-xYx alloys with TC = 277 K (x=0.075), TC = 283 K (x=0.05), TC = 286 K (x=0.025) and TC = 290 K (x=0) [4]. Layered AMRs with two to four layers have been studied by varying the layer length and the Gd1-xYx alloy type. Different operating conditions are simulated, in which the mass flow rate ranges from 25 to 200 kg/h, the operating frequency goes from 0.5 to 2.0 Hz and system temperature spans of 15 and 20 K are considered. The hot reservoir and the ambient temperatures are fixed at 298 K and 293 K, respectively. The packed bed matrix is composed of spheres with average diameter of 0.45 mm, porosity of 0.36, and a total bed length of 130 mm [4]. Optimized layered AMRs, for each operating condition, are found when a given proportional layer length combination returns the highest cooling capacity and coefficient of performance, for a fixed temperature span. To perform a more meaningful optimization analysis, heat leaks or gain are included in the simulations. Finally, the optimized layered AMRs are tested in the Permanent Magnet Magnetic Refrigerator (PMMR II) experimental apparatus [4,5], and the numerical and experimental results are compared. [1] J. A. Barclay & W. A. Steyert Jr. Active magnetic regenerator. 1982. U. S. Patent No. 4,332,135. [2] B. Monfared and B. Palm. Int. J. of Refrig. 57, 103-111 (2015). [3] P.V. Trevizoli. PhD Thesis (2015). Available in: www.polo.ufsc.br/portal/en/publicacoes. [4] R. Teyber et al. Performance evaluation of two-layer active magnetic regenerators with different second-order magnetocaloric materials. Submitted to Appl. Thermal Eng. (2016). [5] D. Arnold et al. Int. J. of Refrig. 37, 99-105 (2014).
Keywords
magnetic refrigeration, magnetocaloric effect, active magnetic regenerator, multilayer, magnetic refrigeration, magnetocaloric effect, active magnetic regenerator, multilayer
