Magnetocaloric Fluids - Magnetocaloric Energy Conversion: From Theory to Applications - page 196

Based on previous subsections, we can now draw certain conclusions as well as
guidelines for the future development of magnetocaloric devices, based on magnet-
ocaloric

uids. As pointed out by Rosensweig (Sect. 5.4.2 ), the application of a mag-
netorheologic suspension is doubtful because of the drawbacks, which concern high
losses due to pumping. On the other hand, a high volume fraction of the solid mag-
netocaloric material in the carrier

fl

uid can provide good power density for a device.
Therefore, there is still an open question as to whether there exists a solution that could
make the application of magnetocaloric magnetorheologic suspensions feasible.
An important issue which needs to be addressed is also the thermal capacity of
the carrier or base liquid compared to that of the magnetocaloric material. Also, the
thermal conductivity of the carrier

fl

fl uid and the magnetocaloric material plays an

important role.
Another important issue regards the pumping system, which should operate with
high ef

ciency. This also concerns different magnetic eld sources, which may be

applied in applications with magnetocaloric uids.

Because of the above-mentioned problems, as well as other important design
issues, the text below discusses a particular problem or application.

fl

5.5.1 Applications of Magnetorheologic Fluids (Including
Magnetocaloric Suspensions)

Below we describe potential applications not only for magnetocaloric suspensions,
but also for other types of magnetic suspensions; applications that may be suc-
cessfully applied as part of the magnetocaloric energy-conversion system.

5.5.1.1 Magnetorheologic Fluids as Seals or Valves

This domain is already well applied in different applications. Since the magnetic

eld source in magnetocaloric devices is always present it makes sense to take this
advantage and apply magnetorheologic

uids for seals (especially in rotating
devices) or valve system, which would provide switching of the

fl

ow direc-
tion. Both the magnetorheological valve and the sealing concern applications of
magnetocaloric energy conversion, which is based on active magnetic regeneration
(AMR). Note that in devices with thermal diode mechanisms (see Chap. 6 ) , valves
or dynamic sealing are not actually required.

fl uid fl

5.5.1.2 Magnetorheologic Fluids as Thermal Diode Mechanisms

A whole chapter in this topic has been dedicated to special heat-transfer mecha-
nisms — thermal diodes. Therefore, the reader should read this rst to become