Magnetic refrigerator development. Final report

Recent developments in magnetocaloric materials

“…[239] played an important role in the development of the AMR concept. The seminal paper [240] (and patent [241]) on the AMR cycle for MR was presented by Barclay at a NASA conference in 1983 [240]. He showed that one can get much larger temperature lifts than just the T ad of the magnetic refrigerant by using the magnetic material simultaneously as a regenerator and the active magnetic component.…”

“…In addition to Barclay's early work [240,241] on using the AMR cycle for subliquid N 2 temperature refrigeration, several papers dealing with the AMR cycle for hydrogen [243,246] and helium [243,247] liquefaction have been published. The basic refrigeration design and modelling for cooling to 4 K from 80 K, and experimental verification, was reported by DeGregoria et al [243].…”

Magnetic refrigeration: Single and multimaterial active magnetic regenerator experiments

“…Since the MCE is at a maximum near the transition temperature of magnetic materials, it has been suggested that a way to improve refrigerator performance would be to arrange different refrigerants in layers ordered according to transition temperature. 8 The governing differential equations that describe magnetic refrigeration cycles are highly nonlinear. Thus, analyti-a͒ Author to whom correspondence should be addressed; electronic mail: richardគchahine@uqtr.ca cal relationships are limited and numerical models often poorly duplicate experimental results.…”

Novel Design of La(Fe,Si)13 Alloys Towards High Magnetic Refrigeration Performance

“…A common feature of these transitions is the change of the exchange interaction during the transition and a concomitant volume and/or crystal symmetry change 10, 14. A substantial isotropic expansion (about 1% in La(Fe,Si) 13 , for example)15 or anisotropic change of the lattice constants (2.8% elongation along the c ‐axis and 1.5% contraction along the a ‐axis in (Mn,Fe) 2 (P,Ge))16 during the magnetic or (magneto)structural transition6 combined with a relatively high brittleness of the parent phase is a severe shortcoming for magnetic cooling applications, where the magnetic refrigerant is exposed to a cyclic application and removal of the magnetic field and cyclic temperature variation 1, 17. Moreover, materials exhibiting a first‐order phase transition usually possess magnetic and thermal hysteresis, which reduces the efficiency or even makes the refrigeration cycle impossible 8, 18…”