1. Jacob McKenzie, Ty Nowotny, Colin Neunuebel
The Peltier Effect
Jacob McKenzie, Ty Nowotny, Colin Neunuebel
SRJC Engr45 - Fall 2005

2. History of the Seebeck effect
Discovered by Thomas Johann Seebeck in 1821.
He accidentally found that a voltage existed between two ends of a metal bar when a temperature gradient existed within the bar.

3. where α is the Seebeck coefficient of the couple
The Seebeck Effect
A temperature difference causes diffusion of electrons from the hot side to the cold side of a conductor.
The motion of electrons creates an electrical current.
The voltage is proportional to the temperature difference as governed by: V=α(Th-Tc)
where α is the Seebeck coefficient of the couple

4. History of Peltier devices
The Peltier effect is named after Jean Charles Peltier ( ) who first observed it in 1834.
The Peltier effect had no practical use for over 100 years until dissimilar metal devices were replaced with semiconductor Peltiers which could produce much larger thermal gradients.

5. What is a Peltier Cooler?
Thermoelectric heat pumps that will produce a temperature gradient that is proportional to an applied current.

6. Peltier Effect With Dissimilar Metals
At the junction of two dissimilar metals the energy level of conducting electrons is forced to increase or decrease.
A decrease in the energy level emits thermal energy, while an increase will absorb thermal energy from its surroundings.
The temperature gradient for dissimilar metals is very small.
The figure of merit is a measure of
thermoelectric efficiency.

7. Semiconductor Peltier
Bismuth-Telluride n and p blocks
An electric current forces electrons in n type and holes in p type away from each other on the cold side and towards each other on the hot side.
The holes and electrons pull thermal energy from where they are heading away from each other and deliver it to where they meet.

8. Device Construction
Individual couples are connected in series electrically and in parallel thermally.
Couples are thermally connected by a ceramic that has high electrical resistivity and high thermal conductivity.

9. Our Peltier: Change in Temperature @ 12v

10. our peltier: Temperature Gradient
Carnot Efficiency
12v:
=1-Tc/Th
= /342.3
=17.1%

11. Radioisotopic Thermoelectric Generator (RTG)
Applications
Deep space probes
Microprocessor cooling
Laser diode temperature stabilization
Temperature regulated flight suits
Air conditioning in submarines
Portable DC refrigerators
Automotive seat cooling/heating
Radioisotopic Thermoelectric Generator (RTG)

12. Pros and Cons Pros Solid state (no moving parts) No maintenance
Long service lifetime
Cons
Large electrical power requirements
Inefficient compared to phase change cooling

13. References
Thermoelectric Materials
THE HEATSINK GUIDE: Peltier Guide, Part 1