Environmental Engineering Reference
In-Depth Information
Fig. 8.16 A magnetocaloric device with a rotary movement of the magnet assembly over two
static AMRs with the application of the bi-directional pump (a left AMR demagnetized, right
AMR magnetized; b left AMR magnetized, right AMR demagnetized), classication no: R20(3)1
(5)(6)00101(12)
Figure 8.17 shows the example of a rotary magnetic
eld source with the
application of a uni-directional pump. In this case the
ow through the CHEX
and HHEX will be provided, and always in the same direction. However, a valve
system has to be applied. This provides the switching and the distribution of the
fl
fl
uid
fl
uid
fl
ow. Let us
rst consider Fig. 8.17 a, in which different processes that relate to
the
uid enters
the CHEX at I, where it absorbs heat from the refrigerated environment II. Then it
passes to the valve system III, which directs the
fl
uid
fl
ow are denoted using the Roman numbers from I to XI. The
fl
uid to the AMR, which is in the
magnetized state IV. By passing through the magnetized AMR the working
fl
uid
warms V and leaves in the direction of another valve system VI. There it is directed
to the HHEX VII. By passing the HHEX, the working
fl
fl
uid rejects heat to the
environment and
ows back to the valve system, where it is directed towards
the AMR in the demagnetized state IX. By passing the demagnetized AMR the
working fluid cools down X and enters the valve system XI, from which it is
directed to the CHEX. Since the magnetic
fl
eld source is rotating, in the next phase,
the previously magnetized AMR will become demagnetized and the previously
demagnetized AMR will become magnetized, respectively (Fig. 8.17 b). Note that in
the case of the AMR Brayton-like cycle, the time that the system switches from the
case of Fig. 8.17 a to the case of Fig. 8.17 b should be as small as possible.
In the case of Fig. 8.17 b, the working
uid still enters the CHEX at the same
position as in the case of Fig. 8.17 a. However, now the valve system instead of the
bi-directional pump serves for switching of the directions of the
fl
fl
uid
fl
ow.
eld source can be provided by different archi-
tectures of the magnet assembly. For instance, the magnets can be arranged as
rotating bars (shown in Fig. 8.18 a) or the magnet can consist of the stationary part
The rotation of the magnetic
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