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Fig. 10.17 Pyroelectric
Ericsson thermodynamic
cycle. The red line represents
electric displacement versus
electric eld at T
low
and the
blue line the electric
displacement versus electric
eld at T
high
of an arbitrary
pyroelectric material
changed to the low value (E
low
)(4
1). The pyroelectric material is now, thermo-
dynamically speaking, in the same state as at the beginning of the cycle. However,
the pyroelectric material had done some work, which is equivalent to the surface
area of the enclosed path presented in the
-
˃
-
E diagram (Fig.
10.17
).
eld of pyroelectric energy harvesting by
Olsen et al. [
67
]. For this reason, in the literature, the pyroelectric Ericsson cycle is
often simply referred to as the Olsen cycle [
72
Such a cycle was
rst introduced to the
74
]. However, it was already Olsen
and his coworkers [
67
] who concluded that such a device working under the basic
Ericsson cycle is energy inef
-
cient. Namely, the heat in such a cycle has to be
supplied to the pyroelectric material during the process of iso
eld polarization (3
4)
-
as well as during the process of isothermal depolarization (4
1). However, a portion
-
of the heat supplied to the process of iso
eld polarization could be obtained from
the process of iso
eld depolarization. The last process regards regeneration, which
should be employed to increase the ef
ciency of the cycle [
75
]. The concept of a
pyroelectric energy conversion system that employs regeneration was
rst descri-
bed by Olsen et al. [
75
] and is schematically presented in Fig.
10.18
. According to
Fig.
10.18
, the pyroelectric material is initially in thermal contact with the heat
source and the heat is transferred from the heat source to the pyroelectric material.
Then as the pyroelectric material is moved towards the heat sink, the heat is
transferred from the pyroelectric material to the heat regenerator. As the pyro-
electric material reaches the heat sink most of the heat has already been transferred
to the heat regenerator and only a small portion of the heat is transferred to the heat
sink. An analogue process occurs as the pyroelectric material is moved back to the
heat source and the heat that was transferred from the pyroelectric material to the
regenerator in the previous step can now be used to heat up the pyroelectric
material. In this case, the temperature variation of the pyroelectric material is the
same as if no regeneration process was employed and therefore the pyroelectric
material performs the same amount of work.
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