Special Heat Transfer Mechanisms: Active and Passive Thermal Diodes - Magnetocaloric Energy Conversion: From Theory to Applications - page 251

Fig. 6.30 Four phases of operation in the perpendicular direction to the fluid flow of the

magnetocaloric device with passive thermal diodes

In Fig. 6.30 b the passive thermal diode 1 becomes operational. Since it is passive,
its thermal properties are in

uenced in a manner that they result in a higher effective
thermal conductivity. The thermal diode 1 (Fig. 6.30 b) has a higher thermal con-
ductivity than the non-operational thermal diode 2. This, as an example in the

fl

gure, will lead to linear temperature distribution of thermal diode 1. Meanwhile,
thermal diode 2, which is at this moment inactive, responds as a non-perfect thermal
insulator between the MC material and the cold

fl uid. Therefore, most of the heat

fl uid. Figure 6.30 c presents

the process of the demagnetization. The temperature of the MC material decreases
due to the MC effect. Both thermal diodes are, in this phase, again inactive,
with low thermal conductivities (act as non-perfect insulators), and thus slowly

ux will be transported from the MC material to the hot fl