Environmental Engineering Reference
In-Depth Information
Table 7.28 First rotary magnetic prototype from Sichuan University
Name and address of institute
School of Materials Science and Engineering, Sichuan
University, 24 South Section 1, Yihuan Road,
Chengdu 610065, China
Name of contact person/email
Yongbai Tang/tyb1973@163.com
Year of production
2002
Type
Rotary
Maximum frequency
0.2 Hz
Maximum cooling power
N/A
Maximum temperature span
6.2 K
Type of AMR
Parallel plates
MC material(s)
Gd plates
Type of magnets
Permanent, 0.78 T
He et al. [ 59 ]. This was a hybrid device, which employed active magnetic regen-
eration as well as Stirling gas regenerative refrigeration effect. The magnet
assembly was a concentric Halbach cylinder, where the inner cylinder rotated and
could induce a magnetic
eld of 1.5 T. The stationary AMR consisted of 1-mm-
thick Gd sheets with a total mass of 198 g. The Stirling part of the device consisted
of compression and expansion cylinders each
tted with a piston. The heat-transfer
fl
uid was helium. The prototype operated with a frequency of 1.5 Hz and the hot-
side temperature was set to 298 K. The main focus of the tests was to study the
optimal phase angle between the compression piston of the Stirling part and the
magnet position of the AMR part. The phase angle was given as a peak difference
between the compression volume and the magnetic
eld. It indicated the angular
relationship between the magnetic
eld and the compression volume. When the test
was carried out operating only Stirling gas refrigeration without the process of
active magnetic regeneration, the no-load temperature span achieved was 18.2 K.
When 30.3 W kg 1 of speci
c cooling load was applied the temperature span
decreased to 12 K. Then, also, the active magnetic regeneration was applied with
variations in the phase angle. At a phase angle of 0
°
the no-load temperature span
increased to 19 K. Applying 30.3 W kg 1 of speci
c cooling load also showed an
increase in the temperature span, increasing to 12.4 K (in comparison to Stirling
process). The highest no-load temperature span was achieved at a phase angle of
90
and it was 21.5 K. Applying 30.3 W kg 1 under the same conditions also
increased the temperature span to 14.9 K. Increasing the phase angle over 90
°
°
resulted in a lower performance of the device.
Tables 7.30 and 7.31 present four rotary prototypes from Baotou Research
Institute of Rare Earths. The
rst two prototypes (Table 7.30 ) were built in 2006
and 2010. Both prototypes were similar in their design. The magnet assembly
consisted of two stationary 1.25 T Nd
Fe
B magnets. The rotating AMR cylinder
-
-
consisted of eight compartments
0.6 mm in diameter.
The mass of each compartment was 180 g. The maximum speci
lled with Gd spheres of 0.4
-
c cooling power
was 34.7 W kg 1 , while the maximum temperature span was 18 K.
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