Environmental Engineering Reference
In-Depth Information
Table 9.1 The growth of
Nd
-
Fe
-
B magnet market
production [
7
]
Production by Country/Region
Metric
tons
×
1000
2012
2015
China
50
65
EU
1
1
Japan
10
8
USA
0
2
Others
2
2
Total
63
78
global Nd
B magnet production will be in China in 2015 (see also Table
9.1
).
In other words, the market for Nd will be very dependent on this fact (unless the
production of magnets is based in China). Since each country tries to be energy
independent, material source dependence should be avoided as much as possible.
Any restriction in terms of quotas or a variation in prices can drastically in
Fe
-
-
uence
not only the magnetic refrigeration technology, but also many new, renewable-
energy-related technologies based on permanent magnets (see also Bradsher [
2
] and
Qi [
3
]).
In 2013, the average global price for sintered Nd
fl
B material (52 MGOe) was
about 30 eurokg
−
1
, whereas in 2011 the price of the same material was about twice
as high [
4
]. A rapid decrease in Chinese prices (which differ from global prices) for
Nd
Fe
-
-
B magnets in 2012 and 2013 can be seen in Fig.
9.1
(note that these are of
course lower than export-related prices).
The following example is used to address how important it is to minimize the
costs of magnets or magnet assemblies. For this purpose an example of a magnet
assembly, which our laboratory ordered from a commercial supplier in 2010, is
shown in Fig.
9.2
[
8
]. This magnet was designed in our laboratory. The cost of
2,085 euro were related only to the European industry manufacturing costs and the
costs of materials (soft
Fe
-
-
iron + Nd
-
Fe
-
B 52 MGOe). The ratio
Λ
cool
/P
eld
is
approximately 0.15, which is actually a rather good magnet con
guration. Of
course, the price of 2,085 euro for a single magnet assembly is too high to be
considered in a real economic evaluation.
Let us now consider the application of two different AMRs, consisting of
magnetocaloric materials, Gd and La
Si (Table
9.2
). For these we assume
approximately the same Curie temperature of T = 292 K. This will be taken into
consideration as the refrigeration temperature T
R
. We assume that the magnetic
Fe
Co
-
-
-
eld
change corresponds to 1 T. We also assume a perfect AMR geometry (e.g. with a
very
ne order tiny structure) as well as that AMR occupies all the available volume
in the high magnetic
eld region. The average porosity of such an AMR can be
considered 30 %, therefore, the volume of each AMR will be 84 cm
3
. The maxi-
mum refrigeration capacity of each material is de
nition
cooling power that corresponds to the different frequencies of operation (the
number of thermodynamic cycles per unit of time) is shown. For this we do not
ned according to the de
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