Environmental Engineering Reference
In-Depth Information
The advantage of the application of AMRs consisting of parallel plates can be
seen in Fig. 9.13 (bottom). Since the application of spheres leads to large heat
transfer surfaces, it could be expected that such geometry produces higher cooling
power than that of the parallel plates, which is actually true. Note that with regard to
Figs. 9.13 and 9.14 the masses of the evaluated packed-bed AMRs were signi
-
cantly smaller than those of the parallel-plate AMRs. However, for the same
coef
cient of performance COP the AMR with parallel plates enables greater
cooling power compared to the AMR with packed beds of spheres. The length of
the magnetocaloric regenerator also plays a crucial role. In the case of a packed bed
of spheres, the viscous losses, as well as the related heat generation inside the
structure, have a large impact on both the ef
ciency and the COP. This is especially
true for long regenerators. The impact of the AMR
'
s geometry is also explained in
Sect. 4.4 .
If the magnetic
eld change is increased to 3 T, this will increase the cooling
power and ef
ciency (Fig. 9.14 ).
By following the results on the characteristics of the operation of the AMR,
Kitanovski et al. [ 36 ] also performed an economic analysis. This was based on the
economic evaluation that was already presented in Egolf et al. [ 29 ]. The economic
analyses considered, besides the cost of the whole superconducting magnet system,
the cost of the magnetocaloric material. The production cost for a La(Fe,Si,H)
regenerator was estimated to be 60 eurokg 1 . Other costs were neglected.
The results in Figs. 9.15 and 9.16 show that the geometry of the AMR has an
important in
fl
uence on the cost of the magnetic chiller. Note that for the same COP
Fig. 9.14 The maximum
cooling power and the
corresponding COP as a
function of frequency for the
AMR with spheres (top) and
for the AMR with plates
(bottom) under a magnetic
eld change of
μ
H 0 =3
Δ
0
T[ 36 ]
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