Design Issues and Future Perspectives for Magnetocaloric Energy Conversion - Magnetocaloric Energy Conversion: From Theory to Applications - page 328

(4) magnetic eld application (0 by immersion of magnetocaloric material, 1 by

elds composition of moving magnets, 2 by switching on/off electromagnets),
(5) number of layers in magnetocaloric regenerators (number of different mag-
netocaloric material layers with different Curie temperatures),
(6) magnetocaloric regenerators structure (0 for ordered: calibrated spheres,
plates, wires, sheets, honeycomb; 1 for disordered: random spheres, powder,

uid, particle sus-
pension; 3 for magnetocaloric material with thermal diodes),
(7) working

bres, porous matrix; 2 for magnetocaloric fl uid: ferro fl

fl uid (0 for liquid, 1 for gas, 2 for any phase-change fl uid),

(8) pumping system (0 for bi-directional; 1 for uni-directional),
(9) relative motion between the magnetocaloric material and magnet (0 for no
motion, 1 for motion),
(10) relative motion between the magnetocaloric material and magnet (0 for static
magnetocaloric material, 1 for moving magnetocaloric material),
(11) relative motion between the magnetocaloric material and magnet (0 for
linear, 1 for rotational, 2 for static device) and
(12) relative motion between the magnetocaloric material and magnet (0 for
discontinuous bi-directional, 1 for discontinuous uni-directional; 2 for
continuous).
We also propose to use the following characters in front of the number of the
classication, as follows: R for refrigerators, freezers, chillers; H for heat pumps;
AC for air conditioners and P for magnetocaloric power generators. In the fol-
lowing text we use the classi

cation mentioned above for all types of refrigeration
magnetocaloric devices. In cases that all or at least two options of a certain clas-
si cation can be used, we simply leave the brackets and the number of such a

classi cation.

8.1 Linear AMR Magnetocaloric Devices

In this chapter we do not focus on the principles where a single AMR is used,
because this, especially at low frequencies of operation, does not provide a con-
tinuous cooling process and requires higher work input. This is especially the case
because the two forces on the magnetocaloric material during the magnetization or
demagnetization process are not counter-balanced.
In Fig. 8.1 , a linear system is shown in which the magnet assembly is moved
over the two AMRs, so all the time one AMR is magnetized and the other is
demagnetized. Of course, this only holds for the case when we neglect the time
required for the movement of a magnet. In this particular case the linear device
means that the linear movement of the magnet assembly will be provided over the

rst AMR shown in Fig. 8.1 a. Since the magnetocaloric material will heat due to
the positive change of the magnetic eld, by using the AMR principle, the fl uid will

fl ow from the CHEX (heat source heat exchanger) through the AMR to the HHEX

(heat sink heat exchanger). The fl uid fl ow in this case is driven by a bi-directional