|
What is the Peltier Effect and
Thermoelectric Modules?
The basic concept behind thermoelectric modules (TEMs) is the
Peltier effect, which was discovered in 1834. The Peltier effect occurs
whenever current passes through the circuit of two dissimilar
conductors; depending on the current direction, the junction of the two
conductors will either absorb or release heat. The amount of heat pumped
is in direct proportion to the current supplied. The Peltier effect is
utilised to its maximum when thermocouples are made of material of
different conductivity. Today mainly Bismuth Telluride doped with
Selenium and Antimony are used as semiconductor material. Thoroughly
refined ingredients are alloyed together to result in polycrystalline
semiconductor material with anisotropic properties. Our vast experience
in this field allows us to obtain high-quality thermoelectric material,
which greatly contributes to our products reliability. Ingots are cut
into rectangular pellets with square cross-section. Two series-connected
pellets of different conductivity form a thermocouple. To make up a TEM,
thermocouples are connected electrically in series and thermally in
parallel and sandwiched between two ceramic substrates.
Advantages
Thermoelectric cooling devices and
systems are believed to be as good as compressor- or absorber based
refrigerators. However we suppose that thermoelectric cooling offers a
number of advantages over traditional refrigeration methods, namely:
- Solid state
heat pumps have no moving parts
- No freons or
other liquid or gaseous refrigerants required
- Noiseless
operation
- Compact size
and light weight makes TEMs well suited for miniature coolers
- High
reliability - We guarantee 200,000 hours of no failures
- Precise
temperature control
- Relatively
low cost and high effectiveness
- Operation in
any orientation
Technical Specification
Thermoelectric modules withstand potentially
detrimental environmental conditions operating without failure under the
low temperature point being equal to 213 K (-50°C) and the high
temperature point being equal to 353 K (+80°C)/ 423 K (+150°C).
Thermoelectric modules successfully meet the below specified conditions
without failure: sinusoidal vibration, 10-50 Hertz, with
vibro-acceleration amplitude up to 20 m/s2 (2g).
Unsealed thermoelectric modules withstand high humidity conditions with
the RH level up to 88 % and 298 ° K (25°C) without any failure in
operation. Thermoelectric modules withstand single mechanical shock with
the peak shock acceleration being equal to 20G (200 m/s2) amd 2-4
msec-Collision Momentum without any failure.
Insulation Resistance Requirements
Insulation resistance of thermoelectric
modules between the electrodes and outer surfaces of the ceramic plates
is no less 20 M Ohms at the test DC voltage of 100 Volts under such
standard climatic conditions as 25 ± 10°C, 45-80 % RH and 84-106,7
Kpascal atmospheric pressure.
Reliability
Reliability is one of the major criterions
of thermoelectric module (TEM) selection. TEMs are considered to be
highly reliable components due to their solid-state construction.
However premature TEM failure roots in soldered joints degradation which
is primarily caused by the following factors:
TEM improper operation and faulty mounting leads to its catastrophic, or
mechanical, failure;
Continuous exposure to an elevated temperature results in TEM's is
overheating.
It is important that the modules are
installed in full accordance with these general instructions to minimise
the possibility of premature TEM failure. If you choose the right TEM or
calculate/ design a thermoelectric cooling assembly, please take into
account TEM's operating temperature, which is TEM's hot side
temperature. It is highly important since if the TEM is exposed to the
higher temperature range, this will result in degradation changes in
semiconductor material parameters and subsequent TEM's failure. We
manufacture TEMs with the operating temperature of 80° C or 150°C. The
latter are marked with HT symbol.
According to the tests' results, the Mean Time Between Failures (MTBFs)
for TEMs is in excess of 200,000 hours at ambient room temperature. It
is recommended, however, to design thermoelectric cooling assemblies in
such a way as to provide the maximum heat dissipation from the TEM hot
side to minimise the possibility of premature TEM failure.
Products
We currently introduce over 150 types of
regular thermoelectric modules (TEMs) that serve a wide variety of
thermoelectric products applications. The TEM physical dimensions vary
from 3,4 x 3,4 mm to 62,0 mm x 62,0 mm with the cooling capacity values
of 0,1 Watts to 186 Watts respectively.
Working as a strategic partner with our clients, we run custom design
projects manufacturing TEMs with the cooling capacity within the range
of 0,1 - 250 Watts.
The TEMs are divided into the categories given below on the basis of
their physical dimensions and thermoelectric properties:
- Miniature
Single-Stage TEMs
- Standard
Single-Stage TEMs
- Improved
TEMs
- Special TEMs
- Hole TEMs
-
Multistage TEMs
|
download
catalog
