Magnetocaloric Fluids - Magnetocaloric Energy Conversion: From Theory to Applications - page 192

eld is
not applicable to ferrohydrodynamic Bernoulli equation, since the assumption of
the isothermal

As denoted by Rosensweig [ 7 ], the part of the tube inside the magnetic

eld is inherent and its derivation does not hold there. However,
by neglecting the acceleration of the

fl ow

uid, friction and gravity Rosensweig [ 7 ]
shows the following relationship inside the solenoid:

fl

p þ l 0 M

¼ r r ð 5 : 72 Þ

0 H

where Rosensweig [ 7 ] denotes the pressure p* to be the composite pressure. Since
the magnetic eld is considered to be uniform, it follows that p 2 *=p 3 *. The

pressure differences between stations 4 and 1 in Fig. 5.5 b can now be de ned

according to Rosensweig [ 7 ]as

D p ¼ p 4 p 1 ¼ l 0 H M ð T 1 Þ M ð T 4 Þ ¼ l 0 H D M ð 5 : 73 Þ

The pressure difference in Eq. ( 5.73 ) can actually be considered as the basis for
the propulsion of the magnetocaloric

uid.
The propulsion of the magnetocaloric

fl

uid may not be (with regard to the present
knowledge in this domain) interesting for power generation (see the Chap. 8 ) , but
results in the development of the heat-driven pumping system, especially for the
thermal management of electronic devices, seem to be some good directions for
near-future market applications.
A comprehensive research project was performed by Love et al. [ 162 ] in 2003,
where they developed and experimentally investigated a magnetocaloric pump (see
also Love et al. [ 163 ]). Soon after in 2004, Yamaguchi et al. [ 164 ] performed a
study of the characteristics of a thermomagnetic motor based on magnetic

fl

fl uids.

Fig. 5.5 a An element of magnetic uid in the gradient of a magnetic eld, b the magnetocaloric

pump principle (see also Rosensweig [ 7 ])

fl