The cooling slice is also called thermoelectricSemiconductor refrigerationComponents, Peltier, etc., refer to a kind of patch that is divided into two sides, one side absorbs heat, the other side dissipates heat, and plays a role in heat conduction. It does not generate cold itself.
The Peltier effect is very simple - when the current passes through the thermocouple, one node dissipates heat and the other node absorbs heat. This phenomenon was discovered by the French physicist Jean Peltier in 1834.
2. P-type semiconductor
A form of semiconductor material in which the density of holes in the conduction band exceeds the density of electrons in the valence band.P-type materials are formed by increasing acceptor impurities, such as boron doping on silicon.
3. N-type semiconductor
A form of semiconductor materials. For semiconductors with electron density in the conduction band greater than the hole density in the valence band, N-type materials are obtained by adding donor impurities (dopants) such as arsenic or phosphorus into the crystal structure of silicon.
Application of Peltier Effect
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Semiconductor coolerIt is a cooling device composed of semiconductors, which only appeared around 1960. However, its theoretical basis Peltier effect can be traced back to the 19th century.A closed circuit composed of X and Y metal conductors.
After the power supply is connected, the heat at the cold end is moved to the hot end, resulting in a decrease in the temperature at the cold end and an increase in the temperature at the hot end. This is the famous Peltier effect.This phenomenon was first discovered by Thomas Seeback, a German scientist, in 1821. However, he made a wrong inference at that time and did not understand the real scientific principle behind it.In 1834, Jean Peltier, a French watchmaker and a physicist who also studied this phenomenon part-time, found the real reason behind this phenomenon. It was only with the development of semiconductors in modern times that this phenomenon was actually applied, that is, the invention of [refrigerators] (note that this kind of cooler is not calledSemiconductor cooler)。
3、 Principle and structure of semiconductor cooling method:
Semiconductor thermocouples are composed ofN-type semiconductorandP-type semiconductorform.N-type materials have excess electrons and negative thermoelectric potential.P-type material has insufficient electrons and positive thermoelectric potential;When electrons pass through the node from P type to N type, the temperature of the node decreases, and its energy will inevitably increase, and the increased energy is equivalent to the energy consumed by the node.On the contrary, when electrons flow from the N-type to the P-type material, the temperature of the node will rise.
Direct contactThermocouple circuitIt is not available in practical application, so the connection method is used instead. Experiments show that the introduction of the third material (copper connector and wire) in the temperature difference circuit will not change the characteristics of the circuit.
In this way, semiconductor components can meet the requirements of users with various connection methods.Connect a P-type semiconductor element and an N-type semiconductor element into a pair of thermocouples. After DC power is connected, temperature difference and heat transfer will occur at the joint.
At the above connector, the current direction is from N to P, the temperature drops and absorbs heat, which is the cold end;At the lower connector, the current direction is from P to N, the temperature rises and heat is released, so it is the hot end.
So it'sSemiconductor refrigerantIt is composed of many N-type and P-type semiconductor particles arranged with each other, and the N/P is connected with a general conductor to form a complete line, usually copper, aluminum or other metal conductors. Finally, two pieces of ceramic chips are clamped together like sandwiched biscuits. The ceramic chips must be insulated and have good heat conduction.
1. It does not need any refrigerant, and can work continuously. There is no pollution source, no rotating parts, and no rotating effect. No sliding parts are solid pieces. It has no vibration, noise, long service life, and is easy to install.
2. The semiconductor refrigeration chip has two functions, which can both cool and heat. The refrigeration efficiency is generally not high, but the heating efficiency is very high, always greater than 1.Therefore, using one chip can replace the separate heating system and cooling system.
3. The semiconductor refrigeration chip is a current converter chip. Through the control of input current, high-precision temperature control can be achieved. With temperature detection and control means, it is easy to realize remote control, program control, computer control, and easy to formautomatic control system。
4. The thermal inertia of the semiconductor cooling fin is very small, and the cooling and heating time is very fast. When the hot end has good heat dissipation and the cold end has no load, the cooling fin can reach the maximum temperature difference within one minute of power on.
5. The reverse use of semiconductor refrigeration chips is thermoelectric power generation, and semiconductor refrigeration chips are generally suitable for power generation in the middle and low temperature regions.
6. The power of the single refrigeration element pair of the semiconductor refrigeration chip is very small, but it can be combined into a stack. If the same type of stack is used in series and parallel to form a refrigeration system, the power can be very large, so the refrigeration power can reach a range of several milliwatts to tens of thousands of watts.
7. The temperature difference range of semiconductor refrigeration chip can be achieved from positive temperature 90 ℃ to negative temperature 130 ℃.
application area
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According to the above analysis, the application range of semiconductor thermoelectric devices includes: refrigeration, heating, power generation, refrigeration and heating applications are common, including the following aspects:
1. Military: infrared detection and guidance systems for missiles, radars, submarines, etc.
2. Medical treatment;Lengli, Lenghe, Cataract Extraction TabletsBlood analyzerEtc.
3. Laboratory devices: cold trap, cold box, cold bath, electronic low-temperature testing device, various constant temperature, high and low temperature experimental instruments.
4. Special devices: petroleum product low-temperature tester, biochemical product low-temperature tester, bacterial incubator, constant temperature developing tank, computer, etc.
5. Daily life: air conditioners, hot and cold boxes, water dispensers, electronic refrigerators, etc.In addition, there are other applications, which will not be mentioned here.
