A numerical study on the unsteady heat transfer in active regenerator with multi-layer refrigerants of rotary magnetic refrigerator near room temperature

摘要

As the temperature span(Delta T) of a refrigerator with an active magnetic regenerator(AMR) of single magneto-caloric material is limited, in the current investigation, the multi-layer AMR consisting of Gd and Gd0.73Tb0.27 is studied to improve the refrigeration performance at a larger Delta T with the numerical method, where the experimental magneto-caloric properties are adopted for a better precision. Effects of Gd0.73Tb0.27 content (phi) and fluid flowrate (q(v)) on refrigeration capacity (q(yef),(v)) and coefficient of performance (COP), together with those of hot and cold reservoir temperatures (T-c and T-h), are investigated. Besides, temperature contours of fluid and solid matrix are presented for discussions. The present study demonstrates that compared with AMR of pure Gd, the multi-layer AMR improves the q(ref,v) and COP by similar to 167% and 57% at Delta T = 28K, respectively. Moreover, it is observed that grew of multi layer AMR has a convex variation tendency with phi, and the maximum at T-c of 268K equals 874.7 kW/m(3). As a contrast, COP has two peaks, and the optimal (phi) is almost independent of Tc, while it decreases with a rising Th. In addition, current investigation indicates that q(ref,v) takes a lager value at a larger qv, while a smaller qv facilitates a good COP. (C) 2016 Elsevier Ltd and IIR. All rights reserved.