THERMOELECTRIC MODULES

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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 TEM's are mainly Bismuth Telluride doped with Selenium and Antimony 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 believe 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 (-50C) and the high temperature point being equal to 353 K (+80C)/ 423 K (+150C).
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 (25C) 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 10C, 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:
Improper operation and faulty mounting of TEM's leads to catastrophic electrical 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. This 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 150C. 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 supply 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

 


 

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