Environmental Engineering Reference
In-Depth Information
In the 2004 Richard et al. [
8
] report on further experimental results. The
experimental set up was generally the same as in the previous case; however,
different compositions of AMRs were tested. First, two AMRs were packed with
180 g of 0.12
akes. The maximum no-load temperature span
achieved was 16 K. Cooling loads were also applied in this experiment. The device
produced 5.6 W kg
−
1
of speci
×
0.7
×
1mmGd
fl
c cooling power at a temperature span of 14 K and at
an operating frequency of 0.8 Hz. In the second experimental test, layered bed
AMRs were evaluated. Each AMR was
lled with 45 g of Gd and 40 g of
Gd
0.74
Tb
0.26
fl
akes (T
c
= 278 K). In this manner, the operating characteristics of the
device were enhanced. 20 K of no-load temperature span was achieved. The device
produced 11.8 W kg
−
1
of speci
c cooling power for the 14 K temperature span at
the operating frequency of 0.8 Hz.
In 2006, researchers from University of Victoria presented new experimental
results on the described experimental magnetocaloric device [
9
]. The investigation
was focused on the two AMRs layered with three different magnetocaloric materials
(Gd, Gd
0.74
Tb
0.26
and Gd
0.85
Er
0.15
, respectively). The mass of both AMRs together
was 270 g. The experiment was carried out at two different magnetic
elds (1.5 and
2 T). The maximum no-load temperature span at the lower magnetic
eld was 44 K
at the operating frequency of 1 Hz. At the higher magnetic
eld, a 50 K temperature
span was achieved at the operating frequency of 0.8 Hz. These results can de
nitely
be considered as a milestone in magnetic refrigeration research, showing the
potential of applying layered AMRs.
The most recent results of the Canadian reciprocating prototype were published
in 2011 by Arnold et al. [
10
]. In this case, each of the AMRs was constructed from
two magnetocaloric materials, i.e. 33 g of Gd and 35 g of Gd
0.85
Er
0.15
crushed
particles. The characteristics of the AMRs were tested in two magnetic
elds of 2
and 5 T, respectively. The frequency of the operation was 0.85 Hz. A lower
eld
maximum no-load temperature span of 33 K has been achieved. A maximum
speci
c cooling power of 110.3 W kg
−
1
was obtained for a zero temperature span.
In the high magnetic
eld, the maximum no-load temperature span was 59 K. The
c cooling power in this case for a zero temperature span was 274.1 W kg
−
1
.
The device produced speci
speci
c cooling powers of 95.6 and 257.4 W kg
−
1
at tem-
perature spans of 39 and 7 K, respectively.
7.1.3 Japanese Prototypes
The
rst reciprocating prototype from Japan was presented in 2002 by the Tokyo
Institute of Technology in collaboration with Chubu Electric Power Co. Inc. [
11
].
The two moving AMRs consisted of Gd spheres with diameter of 0.3 mm, and with
the total mass of spheres being 2.2 kg. A magnetic
eld of 4 T was induced by a
superconducting magnet. The heat-transfer
fl
uid was water. At frequency of
c cooling power of 45.5 W kg
−
1
0.167 Hz, the device produced a speci
at a
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