Environmental Engineering Reference
In-Depth Information
Chapter 10
Alternative Caloric Energy Conversions
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In this chapter, some alternative,
, solid-state energy conversion technolo-
gies are presented. These are the electrocaloric (pyroelectric), the barocaloric and the
elastocaloric energy conversions. In their nature, they are analogous to magnetoc-
aloric energy conversion; however, different external in
ferroic
uences are needed to ini-
tialize the caloric effect. In the case of electrocaloric energy conversion, this is
related to a change in the electric
fl
eld; in the case of barocalorics, to a change in the
hydrostatic pressure and in the case of elastocaloric energy conversion, to a change
in the mechanical stress. Each group, to some extent, possesses possible advantages
as well as some disadvantages in comparison with magnetocaloric energy conver-
sion. However, since all three alternative solid-state energy conversion technologies
are at an early stage of development, it is not yet reasonable to compare them with
magnetocaloric energy conversion. It is only time and further research that will show
the full potential of these alternative solid-state energy conversion technologies.
This chapter is divided into three sections. In each section, the physical principle
behind the discussed ferroic effect will be presented and an overview of existing
materials with their physical properties will be made. Furthermore, different pos-
sibilities for designing an energy conversion device using these materials will be
reviewed (especially for electrocalorics). However, since the technology based on
these three effects is at an early stage of development, only a few prototypes of
energy conversion devices have been presented.
10.1 Electrocaloric and Pyroelectric Energy Conversion
In this subsection, the electrocaloric and pyroelectric energy conversions are pre-
sented and discussed. In general, the electrocaloric energy conversion stands for the
heat pumping processes (or refrigeration), whereas the pyroelectric energy con-
version stands for the power generation.
The underlying mechanism of the electrocaloric energy conversion is the
so-called electrocaloric effect. The electrocaloric effect is expressed as the tem-
perature change of dielectric materials subjected to a varying electric
eld. To
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