Special Heat Transfer Mechanisms: Active and Passive Thermal Diodes - Magnetocaloric Energy Conversion: From Theory to Applications - page 257

6.6.3 Active Magnetic Regeneration with Thermal Diodes

In the previous subsections single-stage and cascade operations with thermal diodes
were presented. However, when considering different designs of magnetocaloric
devices with thermal diodes, we can also apply the active magnetic regeneration
process to such a device. In this case the operation and the design of the active
magnetic regenerator with thermal diodes are different from the classic AMR.
Figure 6.35 shows a basic design concept for such a device.
A long and thin magnetocaloric plate is stacked between two sets of thermal
diodes on each side. The thermal diodes denoted by number 1 face a hot heat
exchanger, while thermal diodes denoted by number 2 face a cold heat exchanger.
From Fig. 6.35 this looks similar to the basic single-stage device, only with a longer
MC material.
However, from Fig. 6.36 it is clear that only one heat-transfer

uid is used in the
AMR device with thermal diodes, suggesting the counter-current

fl

ow as in the
classic AMR. The difference between the classic AMR and the AMR with thermal
diodes is in the asymmetrical counter-current

fl

ow of the AMR with thermal diodes.
This means that in the case of the AMR with thermal diodes, the

fl

ows from
the heat source to the heat sink on the side of the thermal diodes 1, as well as it
fl

fl uid fl

ows from the heat sink to the heat source on the side of thermal diodes 2. The
classic AMR requires periodic fl ow, whereas in the case of AMR the fl uid fl ow may

be continuous, without the need for fl uid-switching valves.

Fig. 6.35 Design concept of an active magnetic regenerator with thermal diodes