Design Issues and Future Perspectives for Magnetocaloric Energy Conversion - Magnetocaloric Energy Conversion: From Theory to Applications - page 335

Fig. 8.7 An example of the operating principle of an axial rotary magnetocaloric device,
classi cation no: R20(3)0(5)(6)011112

ows continuously through the two interconnected and oppositely
positioned AMRs, since these operate at the same temperature level. The warm
working

The fl uid fl

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

fl

fl ows to the fl uid distri-

bution valve (not shown), which divides ow III and guides it to the AMRs in

the demagnetized state. Note that the entering of the working

fl uid fl

uid into the AMRs in
the magnetized state and the demagnetized state has to be provided on opposite
sides of the coaxial AMR ring (to provide a counter-

fl

fl ow direction). The working

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

valve system VII, which directs the fl uid fl ow to both magnetized AMRs. In these

AMRs the working fl uid absorbs heat VIII and fl ows towards the CHEX.

eld source in axial rotating devices can be very different. For
instance, in Fig. 8.8 , two different cases are presented in which the magnet
assembly does not necessarily cover the whole region of the AMR

The magnetic

' s coaxial ring.

Therefore, we refer to it as the opened magnet assembly.
In Fig. 8.8 a, the coaxial ring consists of eight separate AMRs, which can con-
tinuously or discontinuously rotate through the magnetic eld. A discontinuous

rotation in this case would require fast rotation for 180 (note that in the case of

Fig. 8.7 , a discontinuous rotation of 90 ° would be required). The fast rotation is
desired to provide the adiabatic conditions, as are, for instance, required for the
AMR Brayton-like cycle.
Continuous rotation, however, is also possible, but this can increase the com-
plexity of the valve-distribution system. This holds especially for the case when
separate AMRs are rotating and when the AMR passes from the low to high
magnetic

°

eld region and vice versa.
This can be partially solved by applying other thermodynamic cycles than the
AMR Brayton-like one. Whereas in Fig. 8.8 a the magnetic

fl ux direction is