On anisotropic thermoelectric materials figure of merit increase
- PDF / 728,329 Bytes
- 6 Pages / 417.6 x 639 pts Page_size
- 48 Downloads / 247 Views
On anisotropic thermoelectric materis-x figure of merit Increase
Luk~gen I.Rnotyjchuk and rllg J.
The
thermoelemernts
anisotropy
thormoelements of
based
homogeneous
in
and
haterogeneous
thormoelement
have
The
of
simplest
Lust.
on
media
thermopiles
using
materials
1[1
been this
known Seebeck
Some
patented kind
the
are
Seebeck as
effact
our
as in
classical
the
variants
particularly
thermoelements
coefficlent
well
in
the
called
circuit
of
such
USA
[2,3L
anisotropic
is
represented in figtl. The voltage produced by the thermoelement To+AT
TO a Fig.l.
Anisotropic
thermoelement
The top and bottom *Ldowe o4a. therxmetabttrLzd at dWfferent tempercature., as % reeuLt of anteotroptc thermal e. m.f., the thermoetement procjcea a vottLge between the Left and the right sLte.
is
determined according to the expression A
A
a
T
U2 vhere
a
A
compownmts, height
is A
of
peculiarity
the T is
the is
the
difference
temperature
b
of
thermoelectric
difference,
thermoelement.
The
dependence
of
a
and
power
I
are
anisotropic
the
tensor
length
and
thermoelement
produced
voltage
on
the
dimensions
and
geometrical dimensions ratio a/b. The
essentially
temperature which
are
greater
differences also
patented
are
voltages
at
develops
M31 The
scheme
the by of
some helix
such
thermoelements, thermoelement
Mat. Res. Soc. Symp. Proc. Vol. 234. @1991Materials Research Society
is
80
shown in fig.2- The thermoelement
developed voltage is a-n
AaAT U-
NH 2
b
a
on
It
It -d
Fig.2-
thermoelement
Helix
M IX - heeater;the surfaceby temeaos thermosttLc. The trenrm•oLement current externaa Le conveyed of conta.ctso vhtch
where
N
ate dIsptacod
is
the
on the hettx onds.
of
number
helix
turns.Efficiency
thermoelements at small temperature differences
Carnot efficiency, Tav
this
1
S-? where Tc is
of
is
Za
is
CA a)
Tz "
,
mean working temperature,
2
a
Za x
a
and
electrical The absence
X
attractive of
thermoelement The
are
the
values
effective
of
the
specific
and thermal conductivity. of
such
regulation
are
thermoelements of
voltage
by
evident:
choice
of
geometry and configuration.
main
determination
features
junctions,
of
problem the
of
suitable
anisotropic anisotropic
thermoelement material.
usage
is
Parameters
of
81
the known anisotropic thermoelectric materials are represented
in
the table. Parameters of anisotropic thermoelectric
Table
Temperature.
Material
IT E M F Electrical anisetropy,
conductivity,
materials
Thermal conductivity,
Z a'
K
-1
a 0,08
9,9.10
54
0,9.10 -4
Bi
350
Sb
300
2,6
2,9.10
Cd
300
3,2
1,4.10
Zn
300
1,74
1,8.10
CdSb
400
BiGGSbz
3W50
280 25
CrSi.
800
s0
300
26
4.10
0,11
6,2.10
300
55
490
9,6.10
300
130
4,0
3,8.10 -z 2,9.10
CrSi. MnSi
1
,7
To
4
BizTea
400
40
ZnSb
400
140
400
145
ZnI
5 C0dasSbio
5
-5
O•18
2,7.10
0,92
3,3,8.10
5
4.10 4 15.10
1,13
-7 -7
1,2.10-.e
-s
1,2.10 -a 3,3.1
Data Loading...
