Design Issues and Future Perspectives for Magnetocaloric Energy Conversion - Magnetocaloric Energy Conversion: From Theory to Applications - page 339

case a closed arrangement can also be constructed. According to Fig. 8.12 , the
magnet assembly has to provide the magnetic ux in the direction of the observer of

the system (direction of the central rotating axis of the coaxial ring with AMRs).
The

fl

ow is therefore usually directed from the central axis in a radial direction
through the AMRs or vice versa, from the outer diameter towards the centre of the
device. Similar as in the case of Fig. 8.7 , we can describe the operation of such an
architecture.
According to Fig. 8.12 , the

fl uid fl

ows continuously through two, oppositely
positioned and interconnected AMRs, since these operate at the same temperature
level. Note, also, in this case that the entering of the working

fl uid fl

uid in the AMRs in
the magnetized state and demagnetized state has to be provided on opposite sides of
the coaxial AMR ring in the radial direction. The warm working

fl

uid that is leaving
the AMRs in the magnetized state enters the HHEX at position I. There it rejects
heat II to the environment and

fl

fl ows to the fl uid distribution valve (not shown),

which divides ow III and guides it in a radial direction through the AMRs in

the demagnetized state. The working

fl uid fl

fl uid cools down in both demagnetized AMRs

and fl ows to the valve system ( fl ow divider) IV, which directs the fl uid fl ow to the

CHEX V. In the CHEX the working fl uid heats VI since it absorbs heat from the

cooled environment and fl ows back to the valve system VII, which directs the fl uid

fl ow in the radial direction to both magnetized AMRs. In those AMRs, the working

fluid absorbs the heat VIII and flows towards the CHEX. Also, in this case, the
rotation of the coaxial structure with the AMRs can be continuous or discontinuous.
Figure 8.13 shows two ways of applying the magnetic fl ux direction through the

AMR. In the rst case (Fig. 8.13 a), the parallel plates of the AMR have to be

arranged in the direction of the magnetic fl ux, i.e. in the radial direction. In the case

of Fig. 8.13 b, ux direction is parallel to the axis of rotation.

Therefore, the parallel plates in the AMR have to be arranged in the same direction
with the magnetic

the magnetic fl

ux.
As can be seen in this case, the length of the AMR is more restricted in radial
devices than in axial ones. Because of this the difference between the outer and
inner diameters of such a ring has to be suf

fl

ciently long (e.g. from about 50 to

Fig. 8.12 An opened magnet assembly of the rotary magnetocaloric device with the radial fl uid

fl ow through AMRs, classication no: R20(3)0(5)(6)01111(12)