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PRINCIPLES & APPLICATIONS OF THERMOELECTRIC MODULES
A thermoelectric cooling/heating module is a miniature solid state heat pump having either a cooling or a heating function. Its principle is a phenomenon called "Peltier Effect" discovered by Peltier in 1834. He discovered that when two metal wires of different materials were joined to form an electrical circuit and a direct electrical current was made to flow through the circuit, one junction became cold and the other junction became hot; when the current direction was reversed, the cold junction got hot while the hot junction got cold. Since then, there have been constant efforts to make use of this principle. Solid state heat pumps became commercially attractive only recently, however, when high performance semi-conductor materials had been developed by early 1960's and the manufacturing technologies of the thermoelectric modules using the materials well developed.
The semi-conductor materials currently widely used for making the thermoelectric modules are bismuth telluride, a quaternary alloy of bismuth, tellurium, selenium, and antimony-doped and reprocessed to yield oriented polycrystalline semiconductors with an-isotropic thermoelectric properties.
When low-voltage DC power is applied through the modules, heat will be moved from one side of the module to the other side. By reversing the polarity, the heat will be moved in the opposite direction. Thus, a thermoelectric module can either heat or cool. Many modules can be either connected in parallel, or in a series, in a single heat pump for generating a specific cooling or heating capacity. Cascading the modules thermally in series can increase the temperature differential. Each module can be also considered a special resistor.
Applications
Thermoelectric cooling/heating modules are used in an ever increasing range of applications from everyday consumer goods to high-tech laboratory, military, medical, scientific and telecommunications markets. Some of the applications are:
| Military/Aerospace Inetrial Guidiance System Night Vision Equipment "Smart" Munitions Electronic Equipment Cooling Cooled Personnel Garments Parametric Portable Refrigerators
Consumer Products Recreational Vehicle Refrigerator Mobile Home Refrigerators Portable Picnic Coolers Wine Coolers Beer Keg Coolers Motorcycle Helmet Refrigerators Insulin Coolers(Portable) Residential Water Coolers/Purifiers Beverage Can Coolers Cosmetics Refrigerators
Industrial-Temperature Control NEMA Enclosures Fine Temperature Control Harsh Environment Protection for Critical Components PC computer Microprocessors Microprocessors and PC's in Numerical Control and Robotics
Restaurant Equipment Cream Dispensers Whipped Cream Dispensers Buttler Dispensers Individual Portion Dispensers Cold plates
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Laboratory and Scientific Equipment Infrared Detectors Photomultipliers Tube Housing Coolers Lasers Diode Coolers Charge Coupled Device Coolers-(CCD) Charge Induced Device Coolers-(CID) Intergrated Circuit Coolers Laboratory Cold Plates Stir Coolers Cold Chambers Immersion Coolers Ice Point Reference Baths Microtome Stage Coolers Electrophoresis Cell Coolers Osmometers Dewpoint Hygrometers Air Pollution Control Analyzers Oil Pour Point Apparatus Constant Temperature Baths Thermostat Calibrating Baths Heat Density Measuring Laser Collimators
Medical Instruments Hypothermia Blankets Pharmaceutical Refrigerators-Portable and Stationary Blood Analyzers Tissue Preparation and Storage
Miscellaneous Hotel Room Refrigerators Automobile Mini-Refrigerators Automobile Seat Cooler Aircraft Drinking Water Coolers
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A thermoelectric power generating module is a miniature power generator producing a DC power . Its principle is a pheonomenon called "Seebeck Effect" discovered by Seebeck in 1922. He discovered that when a temperature difference was applied to the two junctions of the Peltier circuit, a direct current voltage was generated in the circuit. Therefore, any cooling/heating modules can become also power generating modules. Since both Peltier and Seebeck Effects are irreversible phenomena, however, electric power generating as a result of the temperature difference is much smaller than the power input to obtain the same temperature difference.
Modern thermoelectric power generating modules utilize still bismuth telluride up to themperature of about 250°C. Beyond 400°C, lead telluride are used.
HTRD has been collaborating with the foremost manufacturers in the world including those in the former Soviet Union for supplying thermoelectric modules (HT-series) which are the best in quality and yet most reasonable in price.