know more about theroelectric effect

1. Major Assignment on
Refrigration & Air conditioning
Thermoelectric effect
Submitted by submitted to
Sagar Bhardwaj Mr. Aditya
K10692 (Asst. prof. ME dept)

2. 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

3. 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

4. Why does this Effect Occur?
Charge Carrier Diffusion and Phonon Drag
Seebeck Effect Peltier Effect

5. Thermoelectric Module

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.

8. Applications
• Thermoelectric generator
• Cooling Computers
• Drink Coolers
• Recharging Devices
• Space Probes
• Solar Power
• Clothing
• Useful, Quiet, no Moving Parts
• It is less efficient (10%) and more expensive

9. 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?

10. . Principle, construction and working of
Thermoelectric power generator
Heat input
Hot junction
Cold junction
P-type N-type
Heat ejection
Power output
Thermoelectric power generator
based on the principle of Seebeck
effect that when the junctions of
two different metals are maintained
at different temperature, the emf is
produced in the circuit

11. • The figure shows the construction of thermoelectric
power generator.
• There is a burner in which the propane fuel is used as
heating source in one side.
• The exhaust is used to transmit a burnt fuel.
• On the other side, a cold junction is kept.
• The thermoelectric module (TE) (consist of number of
P- type and N-type semiconductor pellets connected in
series or parallel depending on the served load)) is kept in
between the hot and cold junction.
• The electrical out (load) is taken from the TE module.

12. Working
When the two sides of semiconductor are maintained with
different temperature, the emf is flows across the output
circuit
N-type
V
Cold side Hot side
Heat flow
Electron flow

13. • As the heat moves from hot side to cold side, the charge
carrier moves in the semiconductor materials and hence
the potential deference is created.
• The electrons are the charge carriers in the case of N-
type semiconductor and Hole are in P-type
semiconductors.
• In a stack, number of P-type and N-type
semiconductors is connected.
• A single PN connection can produce a Seebeck voltage
of 40 mV.
• The heat source such as natural gas or propane are
used for remote power generation

14. 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)