When two wire ends made of different metals are combined and a closed circuit is formed, if the temperatures are the same, no electric current will be generated in the circuit at the beginning. When one of the tips is heated, an electric current will flow into the circuit. This event was revealed in 1821 by an observation by Thomas Seebeck. This effect is now used for temperature measurements and power generation. In 1834, Jean Charles Athanese Peltier saw that the point of convergence was cooled when the two pieces of wire made from different materials flowed from their ends. This process, also called Peltier effect, is the basis of thermoelectric cooling.
Thermoelectric coolers are sometimes called thermoelectric modules or Peltier coolers.Thermoelectric coolers consist of semiconducting materials with infinitesimal resistance after this value, which does not allow the electric current running like a small heat pump to flow up to a certain value. Thanks to a small DC voltage from a DC source, the heat moves from one end of the module to the other. Thus, while one face of the module warms up, the other starts to cool simultaneously. This phenomenon can be reversed by shifting the positive and negative poles of the DC source. A thermoelectric module is used as a heater or cooler for the purpose of use. The thermoelectric cooling system and module are shown below.
Thermoelectric cooling and module (peltier effect)
It is not even the case that the thermoelectric cooling systems compete with the steam compression mechanical compression cooling system since the efficiency values are very low, about 0.1-0.2. However, in some special small-cap applications, they are used commercially for their simplicity, quiet operation and reliability. They usually operate with 12 volts direct current. So they are used in space vehicles with the energy provided by solar batteries. Food service vehicles are preferred because they can see cooler and heater function at the same time.
Mini refrigerators in automobiles perform cooling process by this method. It is also used as a coolant in the laboratory equipment, medicine, electronics and bio-technology fields. Especially thermoelectric cooling systems can be used where it is not enough to cool the electronic control panels with the normal fan. When the surface of the thermoelectric cooler inside the panel cools too much, condensation occurs and damages the electronic circuits. For this solution, the cooler side of the thermoelectric plant should be removed from the surface with the aid of the low-speed fan and precautions should be taken to prevent the temperature of the panel interior temperature from falling below the raw-point temperature. Positive and negative connections can be replaced to work like a heat pump. In order to remove the heat drawn from the cooled surface of the peltier coolers from the other heated surface, a fan must be used.