Environmental Engineering Reference
In-Depth Information
7.1.5 French Prototypes
The
rst French magnetocaloric prototype was presented in 2003 by Grenoble
Electrical Engineering Laboratory in the article of Clot et al. [
23
]. They designed a
reciprocating device with a 0.8-T permanent-magnet Halbach assembly. The AMR
was made of 1-mm Gd plates with a spacing of 0.15 mm. The total mass of the
AMR was 223 g. The heat-transfer
uid was water. The operating frequency of the
device was approximately 0.42 Hz. The maximum no-load temperature span
obtained with this device was 7 K. The speci
fl
c cooling power was 39.5 W kg
−
1
at
4 K of temperature span.
Based on experience from the 2003 device [
23
] researchers from the Grenoble
Electrical Engineering Laboratory built a second experimental device (Table
7.5
).
This was presented in 2009 by Dupuis et al. [
24
]. The Nd
Fe
B Halbach magnet
-
-
assembly provided a magnetic
eld of 0.8 T by moving over the static AMR. The
static AMR consisted of 1-mm Gd plates. The device allowed operating frequencies
up to 1 Hz. The maximum no-load temperature span achieved was approximately
7.8 K.
Another experimental study was conducted on the described testing device. In
2014, Legait et al. [
25
] presented the results of an extensive study on six different
magnetocaloric materials. Three single-material AMRs were made of Gd,
Pr
0.65
Sr
0.35
MnO
3
and La
Fe
Co
Si (T
c
= 293 K), respectively. The fourth AMR
-
-
-
was layered with four different La
Si materials (Curie temperatures of 283,
288, 293 and 298 K). The total mass of the Gd-based AMR was 190 g, for the
Pr
0.65
Sr
0.35
MnO
3
-based AMR it was 91 g, and the mass of both AMRs based on
La
Fe
Co
-
-
-
Si was 150 g. All the plates were 1 mm thick, with Gd having a spacing
of 0.3 mm, and in the AMRs with the other materials, the spacing for the
-
Fe
-
Co
-
ow
was 1 mm. The highest no-load temperature span obtained by the Gd AMR was
11.5 K, and with the layered La
fl
uid
fl
Si AMR, a 10.5 K temperature span was
obtained. In the AMRs with a single material, the temperature span was the lowest,
i.e. 8 K in theLa
-
Fe
-
Co
-
Si-based AMR and 5 K in the AMR consisting of
Pr
0.65
Sr
0.35
MnO
3
material.
In 2009 another French group, a company called CoolTech Applications, pre-
sented their
-
Fe
-
Co
-
rst magnetic reciprocating device, which was presented in the article
of Bour et al. [
26
]. The experimental device consisted of a Halbach permanent-
magnet assembly providing a magnetic
eld of 1.1 T. The AMR was made of
0.6-mm Gd plates with a spacing of 0.1 mm. The heat-transfer
uid used in the
device was a freezing depressant, because of its good corrosion protection. With
such an experimental device, the highest no-load temperature span achieved was
approximately 16.1 K.
Based on the experience from the
fl
rst prototype, CoolTech Applications built
their second reciprocating prototype in 2011. Operating characteristics are pre-
sented in Table
7.6
.
Search WWH ::
Custom Search