Peltier is a French watchmaker and scientist. In 1834, he discovered the thermoelectric effect (Peltier effect), that is, when the circuit composed of two conductors is powered on, heat absorption or release occurs at the node due to different current directions. Its physical mechanism is derived from the energy exchange caused by the energy level transition of the charge carrier between different materials[1]。
This effect is remarkable in semiconductor materials: when N-type and P-type semiconductors are powered on, the temperature at the junction rises and falls with the change of current direction. The semiconductor cooler based on this principle can reduce the temperature below room temperature, and has the characteristics of precise temperature control and noise free. It is used in electronic ice box, laser system temperature control and other fields[1]The application of bismuth telluride and other materials has improved the cooling efficiency.
Peltier was originally engaged in clock making and turned to scientific research at the age of 30.Its discovery was not applied in practice because of the weak metal semiconductor effect in the early stage. Until the 1990s, the Soviet scientist Yoffi developed a practical semiconductor cooler, which promoted the effect from theory to industrial application.
The Peltier effect was discovered by the French scientist Peltier in 1834. Therefore, when the name of Peltier is mentioned, it is easy to associate him with the Peltier effect and mistake him for a physicist. In fact, he is at most an amateur physicist.
Partier was born in FranceSommeHe used to be a clockmaker. At the age of 30, he gave up his profession and devoted himself to the field of experiment and scientific observation.In his numerous papers, most of them are about the observation of natural phenomena, such as natural electricity, tornadoesSky bluenessMeasurement and light polarization, water temperature of sphere, polar boiling point, etc. There are also a few papers on natural history.
Clockmaker makes scientific discoveries
In 1834, French watchmaker and scientist Peltier discovered the thermoelectric cooling and heating phenomenon - thermoelectric effect.A pair of thermocouples is composed of two materials. When the thermocouple is connected with DC current, the phenomenon of heat absorption and heat release will occur at the junction of the thermocouple due to the different direction of DC current. This phenomenon is calledPeltier effect。
Physical interpretation
Announce
edit
The physical explanation of the Peltier effect is that the charge carrier moves in the conductor to form a current.Because the charge carrier is in different energy levels in different materials, when it moves from the high energy level to the low energy level, it will release excess energy;On the contrary, when moving from low energy level to high energy level, energy is absorbed from the outside.Energy is absorbed or released in the form of heat at the interface of two materials.
In 1837, Lenz (1804-1865), a Russian physicist, found that the direction of the current determines whether heat is absorbed or generated. The amount of heat (cooling) is proportional to the size of the current, and the proportional coefficient is called the "Peltier coefficient".
Q=л·I=a·Tc·I，Where л=a · Tc
Where: Q - exothermic or endothermic power
π - proportional coefficient, called Peltier coefficient
The Peltier effect has not been applied in practice for more than 100 years since it was discovered, because the Peltier effect of metal semiconductors is very weak.Until the 1990s, Yo Fei, a former Soviet scientist, showed that compounds based on bismuth telluride were the best thermoelectric semiconductor materials, which led to the emergence of practical semiconductor electronic cooling elements——Thermoelectric coolerThermoElectric cooling (TEC for short).
Compared with air cooling and water cooling,Semiconductor refrigerantIt has the following advantages: (1) It can reduce the temperature below room temperature;(2) Precise temperature control (using closed-loop temperature control circuit, the accuracy can reach ± 0.1 ℃);(3) High reliability (cooling components are solid devices without moving parts, with a service life of more than 200000 hours and low failure rate);(4) No working noise.
