What Is a Peltier Element?
A Peltier element is a device that uses the Peltier effect, in which heat is transferred at the junction when an electric current is applied to two different metals that have been intersected.
Efficient Peltier elements currently in practical use are not made of two metals but of three different materials: an n-type semiconductor, a metal, and a p-type semiconductor. They are usually used as cooling devices by utilizing heat transfer, but can also be used as heating devices since changing the direction of the electric current also changes the direction of heat transfer.
Unlike heat pumps, the Peltier element has the advantage of generating no noise or vibration, since the cooling effect is achieved simply by applying an electric current. In addition, since no refrigerant is required and no corrosive liquid is used, the Peltier element is a cooling device with low environmental impact.
Uses of Peltier Elements
Peltier elements are used in a wide range of fields as clean cooling elements.
1. Food Industry
Peltier elements are compact, clean, and safe. They are used in food showcases, small drink cases, milk coolers, hotel pans, etc.
2. Industrial Field
Industrial equipment is vulnerable to water without exception, but measures are taken to control temperature and supply cold air with minimal condensation, or to incorporate condensation drains. Applications include operation panel cooling, surveillance camera cooling, local cooling of internal control panel components, cooling of molding dies, and constant-temperature humidity air supply systems.
3. Optical Field
Peltier elements are often used to cool devices in limited space. Specifically, they are used for direct cooling of heat-generating sources, cooling of small relay boxes, temperature control of photodetectors, temperature control of laser diodes, cooling of CCD cameras, projectors, copiers, and surveillance cameras, and cooling water for lasers, etc.
4. Consumer Field
Peltier is used in commercial refrigerators for hospitals and hotel guest rooms, taking advantage of its advantages of no vibration and noise and the small size of the cooling mechanism. Peltier refrigerators are used in small refrigerators, cooler boxes, beer servers, wine cellars, aquarium water temperature control, computer CPU cooling, dehumidifiers, air purifiers, hair dryers, negative ion generators for facial care equipment, etc.
5. Other Fields
Peltier elements are also used for cooling and heating in the fields of measurement and analysis, semiconductors, and medical and physical chemistry.
Principle of Peltier Elements
Peltier elements currently use p-type and n-type semiconductors instead of metals. For electrons to be transferred from a p-type semiconductor with a low energy level to an n-type semiconductor with a high energy level, it is necessary to take in energy from the outside, which causes heat absorption and a decrease in temperature.
If the direction of the current flow is reversed, electrons are transferred from the higher energy to the lower energy side, resulting in heat generation to release the excess energy. Therefore, Peltier elements can be used as either a cooling or a heating device, depending on the direction of the current flow.
However, heat conversion using Peltier elements is not suitable for very large-scale cooling or heating because the efficiency is not high for power consumption. For efficient cooling, it is effective to use Peltier elements in combination with heat dissipation and exhaust mechanisms using fins and fans.
Other Information on Peltier Elements
1. Advantages of Electronic Cooling
Generally, a cooling system exchanges heat by using a cooling gas called a refrigerant. Since this refrigerant is one of the greenhouse gases that affect global warming in no small measure, its environmental impact cannot be ignored.
On the other hand, electronic cooling using Peltier elements is a cooling system with a low environmental impact because it does not require a refrigerant. In addition, cooling systems that use refrigerants require compressors, which inevitably generate noise and vibration, but electronic cooling does not have these concerns.
2. Cooling Function of Bertsche Element
The cooling function can be realized by utilizing the characteristics of the Peltier elements. When a DC current is applied to Peltier elements, heat absorption occurs at the low-temperature side, and heat generation occurs at the high-temperature side. The cooling function of the Peltier elements is based on this phenomenon.
Commercially available ones are capable of cooling down to negative temperatures. They are used in cooling boxes, cooling CPUs in PCs, etc.
3. Application to Wearable Devices
Wearable devices have been developed using the properties of Peltier elements. Among the wearable devices on the market are devices that can heat or cool the neck.
This device can feel warm or cold by controlling the temperature of a panel located where it touches the neck.