Thermoelectric Coolers
(TEC or Peltiers)
Posted : 10/4/99
Written by: Heat
What they are and how do they work?
Thermoelectric Coolers (AKA Peltiers or TEC for short) are solid state heat pumps, which
operate on the Peltier effect. The Peltier effect is a theory that there is a heating or
cooling effect when electric current passes through two conductors. The TEC is consists of
a number of p- and n- type semiconductor pairs (referred to as couples) connected
electrically in series and sandwiched between two ceramic plates)
Note: The Peltier Effect was discovered in 1822 by Jean Charles Athanase Peltier (1785 -
1845), and refers to the reversible heating , or cooling which occurs at a contact when
current flows from one connector to another.
A voltage is applied to two ends of the peltier. This
creates a difference in temperature between two dissimilar materials. With the temperature
difference, heat is moved from one end to the other. The absence of heat is simply cold.
The heat is absorbed from the environment and is carried through the cooler by electron
transport. It is released to the opposite side of the peltier (hot side) as the electrons
go from a high to low energy state. The capacity of the cooler is proportional to the
current and number of n- and p- type elements (couples)
So what do Imax, Vmax, dTmax and Qmax mean?
There is a limit where the heat generated breaks down the TECs ability to pump heat. This
is referred to as Qmax. Note that Qc or Qh means heat pumped at the cold side or hot side.
The current associated with Qmax is Imax (no not the theater) :^) The maximum voltage
across the cooler is Vmax. DTmax is the maximum temperature difference when the TEC is
completely insulated and isolated from its environment and running at Imax. The reason for
the insulation this is that the environment itself puts a load on the TEC. Simply because
the object is cooler than the surrounding environment. At Imax its not pumping heat at
all. When heat is applied to the cold side, the temperature difference is suppressed. The
temperature differential is 0 and the corresponding heat load is Qmax.
Next page: Simple test to make
sure your TEC works
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