Overview of Existing Magnetocaloric Prototype Devices - Magnetocaloric Energy Conversion: From Theory to Applications - page 273

The researchers from Nanjing University presented experimental results from
their rst AMR testing device in 2005 in Lu et al. [ 17 ]. In the device, two AMRs

were applied. These were moving in and out of the 1.4 T magnetic

eld provided by

a Halbach permanent-magnet assembly. The heat-transfer uid was water. The

experiments were conducted using three different magnetocaloric materials: Gd,
Gd

fl

Ga, respectively. The AMRs consisted of spherical
particles with a diameter of 0.2 mm (the masses were not reported). The performance
of the two AMRs (Gd

Si Ge and Gd Si Ge

- - - - -

Ga) was similar to the gadolinium-
based AMR. In all three cases, a maximum no-load temperature span of 23 K was
obtained. For a cooling power of 40 W the temperature span decreased to 5 K.
In 2006, the Technical Institute of Physics and Chemistry from Beijing presented
an experimental device in the article of Yao et al. [ 19 ]. This experimental device had
two AMR beds (each consisting of 583.7 g of gadolinium particles), and two per-
manent-magnet assemblies with 1.5 T of magnetic

Si Ge and Gd Si Ge

- - - - -

eld. The movement of the AMRs
was alternating, i.e. when one AMR was magnetized, the other AMR was demag-
netized. Helium was used as the heat-transfer uid. The maximum no-load temper-

ature span achieved was approximately 42 K. The device produced 43.9 W kg − 1 of
speci

fl

c cooling power at 18.2 K of temperature span, at a frequency of 1 Hz.
The Batou Research Institute of Rare Earths presented the results of a mag-
netocaloric testing device in the article by Huang et al. [ 20 ]. They designed a device
with a 1.5-T Nd - Fe - B Halbach permanent-magnet assembly. This was moved back
and forth over two, three-layered AMR beds at an operating frequency of 0.178 Hz.
The particle size of the magnetocaloric material in layers, i.e. Gd, LaFe 10.82-
Co 0.78 Si 1.1 B 0.3 and LaFe 11.12 Co 0.12 Si 1.1 , varied between 0.2 and 0.5 mm. The three
materials were layered along each AMR with respect to their Curie temperatures.
The total mass of the two beds together was 950 g. This device was capable of
achieving a maximum temperature span of 18 K. When speci c cooling powers of

13.3 and 21 W kg − 1 were applied, the temperature spans decreased to 10 and 5 K,
respectively. The rst reciprocating magnetocaloric prototype from the Baotou

Research Institute of Rare Earths is presented in Table 7.4 .
The

fth Chinese reciprocating prototype was developed by the South China
University of Technology in 2009 and was presented by Zheng et al. [ 21 ]. The
design of the device was similar to that of Huang et al. [ 19 ]. In this case, a single
1.5-T Nd B permanent-magnet assembly was moving between two AMRs

packed with Gd grains. This device was designed to perform an AMR Ericsson-like
thermodynamic cycle. Other operating characteristics and the performance of this
device were not reported.
In 2013, the Batou Research Institute of Rare Earths presented their second
reciprocating magnetic refrigeration testing device in the article of Cheng et al. [ 22 ].
This was de

Fe

- -

nitely an improved version of the 2006 prototype [ 20 ]. The general
design remained the same, with one 1.5-T Nd

B permanent-magnet assembly
moving over two AMR beds. However, the operating frequency was increased to
0.9 Hz. They tested three AMRs with three different magnetocaloric materials [Gd,
LaFe 11.0 Co 0.9 Si 1.1 B 0.25 (T c = 291 K) and LaFe 11.08 Co 0.82 Si 1.1 B 0.25 (T c = 279 K)].
The AMRs consisted of packed beds, with the particle diameters between 0.42 and

- Fe -