Solid State Cooling:
are still other useful methods of refrigeration. A Peltier cooler
can transform electrical energy into that of thermal energy. The
Peltier Effect can be explained through electron motion. As
current is applied to a peltier cooler, the following occurs:
increase or decrease their velocity based on the contact potential
difference of the material they are traveling though.
the electrons speed up in the material, kinetic energy increases
and this energy is converted to heat. For the slowdown of electrons,
the opposite occurs.
is an example of how a peltier cooler works: Cooling is created
through the combination of a current source, two pieces of highly
conductive wire (like copper), and a piece of bismuth or iron wire.
When the conducting wires are connected to the bismuth and the battery,
a sever difference in temperatures between the two conducting wires
junction where current flows from the conducting wire to the bismuth
will be very hot, and the wire from the bismuth to the conducting
wire will be very cold. One
can now see how this technology may be useful for refrigeration.
If the cold side is placed inside the refrigerator, and the hot
side is placed on the outside, zonal cooling will take place.
(Courtsey of Peltier
above diagram shows an example of an N-P type, semi-conducting peltier
cooler. From p to n junctions, conductivity is high and electrons
move quickly. The opposite is the case for n to p junctions). This
explains the difference in temperatures of the copper plates. This
method can be used to make refrigerators by simply facing the cold
end on the side of the refrigerator, and placing the hot end on
the outside (Peltier Coolers 1).
are also commonly used as cooling devices for computer processors,
as they are extremely effective at cooling these units.
(Courtsey of Peltier
A common problem with this method of cooling CPUs is the dissipation
of the heat produced by the hot side of the peltier. Sometimes even
with a heat sink (radiator) and a fan, one still may not be able
to dissipate the heat quick enough to make the peltier cooler effective
that we know how to cool the inside of a refrigerator through several
different means, we will examine how to best retain this lower temperature.