2. WHAT IS IT?
The thermoelectric effect is the
direct conversion of
temperature differences to
electric voltage or vice-versa.
The direction of heat flow can
be controlled by changing
polarity of the voltage source
3. HISTORY
In the 1820’s Thomas Seebeck
(Germany) discovered that if two metals
at different temperatures were touching
you could create an electric current
Jean Peltier discovered that the opposite
was also true. By sending a current
through two metals you could create
differences in temperature
4. WHY DOES THIS EFFECT OCCUR?
Charge Carrier Diffusion and Phonon Drag
Seebeck Effect Peltier Effect
6. THE ZEROTH LAW OF
THERMODYNAMICS
Pairs of P and N type conductors are
both it contact with a copper plate.
There will thermo power until the system
is at equilibrium. (All three materials are
at the same temperature)
7. SEMICONDUCTORS
Semiconductors have an electrical
conductivity between materials like copper
and glass
They possess and interesting property
where its conductivity increases with added
temperature
P and N type (thermocouples)
semiconductors are created by doping.
11. TEST FOR UNDERSTANDING
The USB Coffee cup warmer is an
example of the Seebeck Effect or the
Peltier Effect?
Before the P and N type Semiconductors
what material were used instead as
thermal couples for thermoelectric
modules?
What are the advantages of using
thermoelectric generators over, for
example heat engines?
12. REFERENCES
Rockwood, Alan L. (1984). "Relationship of thermoelectricity
to electronic entropy". Phys. Rev. A 30 (5): 2843–4. Bibcode
1984PhRvA..30.2843R. doi:10.1103/PhysRevA.30.2843
G. Jeffrey Snyder and Eric S. Toberer "Complex
Thermoelectric Materials" Nature Materials 7, 105-114
(2008).
CRC Handbook of Thermoelectrics, Introduction, Edited by
D.M. Rowe, CRC Press, 1995.
G. Jeffrey Snyder, Tristan Ursell. "Thermoelectric efficiency
and compatibility" Physical Review Letters, Vol 91 p. 148301
(2003)
Notes de l'éditeur
Change in electrons
Charge carrier diffusion if electrons move from hot to cold, then a positive immobile nucleus is left at hot side to conserve charge. So this gives rise to a voltage. Phonon Drag: Similar, P has holes while N has excess by running current the incoming electrons distort nearby electrons thus causing a degradation in mobility and thus a lower temperature.
Thermo Couples used to be only two different metals but now you have p and n type Used to be metal not p and n semiconductors2000 degress Celsiusseries
P type has a deficiency of charge carriers and n types have an excess