How thermoelectric power generation work

August 24, 2020
August 24, 2020 Longchang Chemical

1. Today, the environment is deteriorating and energy is becoming more and more tense. Researchers have been looking for green and pollution-free clean energy applications. Among them, solar energy, wind energy, and tidal energy are familiar to everyone. Also in some science fiction novels will also imagine the future life of people, more or less will mention energy, and once the temperature difference power generation frequency is not low. For example, in a fairy tale by Zheng Yuanjie, a device resembling a turtle shell appeared, and people carried it on their backs, using the heat generated by the human body to generate electricity for daily use. The only drawback of this device is its ugly appearance, but the electricity generated is enough to allow everyone to carry this “turtle shell”. Although Zheng Yuanjie used to satire social phenomena, in principle, this device is possible. Although there are not enough products in real life, some researchers have made model products under experimental conditions. . The realization of thermoelectric power generation began as early as the 1940s. The initial thermoelectric material conversion efficiency was low, the cost was high, and the life was short. It has been limited to the military and aerospace fields, and it has not been rapidly developed in the civil field until recently. New hotspot.

2. The principle of temperature difference power generation is that because the surface temperature of the human body is slightly higher than the daily ambient temperature, this temperature difference can be directly converted into electrical energy with special temperature difference materials. The use of temperature difference is not only this way, but also the thermal expansion and contraction of the air chamber can be used to tighten the spring through mechanical design, or the medium is heated to evaporate to drive the generator blades, but in theory this is not directly converted into The efficiency of electrical energy is high. Thermoelectric power generation is a power generation technology developed based on the Seebeck effect of thermoelectric materials. It uses two different types of semiconductor thermoelectric materials, P-type and N-type (P-type is a hole-rich material and N-type is an electron-rich material. ) One end is connected to form a PN junction, as shown in Figure 1a, placed in a high temperature state, and the other end is placed in a low temperature, and there must be a certain temperature difference between the two ends. Due to thermal excitation, the concentration of holes (electrons) at the high temperature end of the P(N) type material is higher than that at the low temperature end, so under the driving of this concentration gradient, holes and electrons begin to diffuse toward the low temperature end, thus forming an electromotive force The thermoelectric material completes the process of directly converting the thermal energy input at the high temperature end into electrical energy through the temperature difference between the high and low temperature ends. The same device, if it is powered, can realize active cooling, which is an efficient application method of electric cooling, and can be applied in small and micro-cooling equipment.

3. In the process of making a device, due to the limitation of materials and temperature difference, a single PN junction can form a small electromotive force and a relatively small current. If many such PN junctions are connected in series, a sufficiently high voltage can be obtained to become an effective thermoelectric generator. The integration method shown in the figure below is very common in device fabrication.

4. In addition to the use of solar energy for thermoelectric power generation, all other sources of thermoelectric difference are generated by other energy consumption. Even if it is used on the human body surface, it also uses the biomass energy generated by human beings. Since the energy dissipated in the form of thermal energy is considerable, and both solar energy and ocean energy storage are very large, thermoelectric power generation has great development prospects.

This article was written by Longchang Chemical R&D Department. If you need to copy and reprint, please indicate the source.

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