Environmental Engineering Reference
In-Depth Information
of the permanent magnet material as well as that of the AMR, since these represent
the major contribution to the costs of a device. Table
9.7
presents the parameters
that have been applied in the analyses of Bj
ø
rk et al. [
38
] for AMRs based on
spheres and on parallel plates.
The
D
x in Table
9.7
represents the
fl
uid strokes length, which describes the
fraction of
fl
uid that is displaced with respect to all the volume of
fl
uid in the AMR.
The
s
rel
represents the relative cycle time, which is the ratio between the time used
for the magnetization or demagnetization of the AMR and the time used for the
fl
uid displacement.
The analysis was performed in such a manner that for each set of process
parameters the cooling power was de
ned. Based on this, the mass of magnetoc-
aloric material was de
ned as a function of the magnetic
fl
ux density for a desired
Table 9.7 Parameters used in the analysis of Bj
ø
rk et al. [
38
]
Spheres
Δ
x (%)
70
90
110
135
150
180
215
Frequency of operation (Hz)
1
2
4
10
˄
rel
(/)
0.1 0.25 0.5
Sphere diameter (mm)
0.1
0.25
0.5
Maximal magnetic
fl
ux density (T)
0.4
0.6
0.8
1
1.2
1.4
1.6
Temperature of the cold end of AMR T
cold
(K)
268
272
276
278
280
284
288
292
296
298
Parallel plates
Δ
x (%)
40
50
60
70
80
90
Frequency of operation (Hz)
0.167
0.33
1
2
4
˄
rel
(/)
0.25
0.5
Height of the fluid channel (mm)
0.1 0.25 0.5
Thickness of the plate (mm)
0.1
0.25
0.5
Maximal magnetic
fl
ux density (T)
0.4
0.6
0.8
1
1.2
1.4
1.6
Temperature of the cold end of AMR T
cold
(K)
268
272
276
278
280
284
288
292
296
298
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