Thermoelectric coolers are used for applications that require heat removal ranging from milliwatts to several thousand watts. They can be made for applications as small as a beverage cooler or as large as a submarine or railroad car.
Consumer products Peltier elements are commonly used in consumer products. For example, they are used in
camping, portable coolers, cooling electronic components, mattress pad sleeping systems and small instruments. They can also be used to extract water from the air in
dehumidifiers. A camping/car type (12 V) electric
cooler can typically reduce the temperature by up to 20 °C (36 °F) below the ambient temperature, which is 25 °C if the car reaches 45 °C under the sun. Climate-controlled jackets are beginning to use Peltier elements. Thermoelectric coolers can be used to
cool computer components to keep temperatures within design limits or to maintain stable functioning when
overclocking. A Peltier cooler with a
heat sink or
waterblock can cool a chip to well below ambient temperature. Some
Intel Core CPUs from the 10th generation and onwards are capable of using the Intel Cryo technology, which uses a combination of thermoelectric cooling and a liquid heat exchanger to deliver a much greater cooling performance than normally possible with
standard liquid cooling. Local environment conditions are electronically monitored to prevent shorting from condensation.
Acclimatization Thermoelectric heat pumps can be easily used for both local
acclimatization for removing local
discomfort situations. For example, thermoelectric ceilings are today in an advanced research stage with the aim of increasing indoor
comfort conditions according to Fanger, such as the ones that may appear in presence of large glassed surfaces, and for small building acclimatization if coupled with solar systems. Those systems have the key importance in the direction of new
zero emissions passive building because of a very high COP value and the following high performances by an accurate
exergy optimization of the system. At industrial level thermoelectric acclimatization appliances are actually under development
Industrial Thermoelectric coolers are used in many fields of industrial manufacturing and require a thorough performance analysis as they face the test of running thousands of cycles before these industrial products are launched to the market. Some of the applications include laser equipment, thermoelectric air conditioners or coolers, industrial electronics and telecommunications, automotive, mini refrigerators or incubators, military cabinets, IT enclosures, and more. In
fiber-optic applications, where the wavelength of a laser or a component is highly dependent on temperature, Peltier coolers are used along with a
thermistor in a feedback loop to maintain a constant temperature and thereby stabilize the wavelength of the device. Some electronic equipment intended for military use in the field is thermoelectrically cooled.
Science and imaging Peltier elements are used in scientific devices. They are a common component in
thermal cyclers, used for the synthesis of DNA by polymerase chain reaction (
PCR), a common molecular biological technique, which requires the rapid heating and cooling of the reaction mixture for denaturation, primer annealing, and enzymatic synthesis cycles. With feedback circuitry, Peltier elements can be used to implement highly stable temperature controllers that keep desired temperature within ±0.01 °C. Such stability may be used in precise laser applications to avoid laser wavelength drifting as environment temperature changes. The effect is used in
satellites and
spacecraft to reduce temperature differences caused by direct
sunlight on one side of a craft by dissipating the heat over the cold shaded side, where it is dissipated as
thermal radiation to space. Since 1961, some uncrewed spacecraft (including the
Curiosity Mars rover) utilize
radioisotope thermoelectric generators (RTGs) that convert thermal energy into electrical energy using the Seebeck effect. The devices can last several decades, as they are fueled by the decay of high-energy radioactive materials. Peltier elements are also used to make
cloud chambers to visualize
ionizing radiation. Just by passing an electric current, they can cool vapors below −26 °C without
dry ice or moving parts, making cloud chambers easy to make and use. Photon detectors such as
CCDs in astronomical
telescopes,
spectrometers, or very high-end
digital cameras are often cooled by Peltier elements that may be arranged in a multi-stage,
cascade refrigeration configuration.This reduces dark counts due to
thermal noise. A dark count occurs when a pixel registers an electron caused by thermal fluctuation rather than a photon. On digital photos taken at low light these occur as speckles (or "pixel noise"). They are also used in
energy-dispersive spectrometers to cool the sensor crystals, eliminating the necessity of large liquid nitrogen dewars.
Thermodynamic parameters The efficiency can be determined by the following relation: \eta= \frac{T_C - T_H}{T_C} where T_C is the temperature of the cooling surface and T_H is the temperature of the heating surface. The key energy phenomena and the reason of defining a specific use of thermoelectric elements (Figure 1) as heat pump resides in the energy fluxes that those elements allow realizing: • Conductive power \dot{Q}_L: \dot{Q}_L= \frac{L}{d}S(T_H-T_C) • Heat flux on the cold side \dot{Q}_C: \dot{Q}_C=\alpha I T_C - \frac{I^2 R}{2} - \frac{k}{d}A \Delta T • Heat flux on the hot side \dot{Q}_H: \dot{Q}_H=\alpha I T_C + \frac{I^2 R}{2} - \frac{k}{d}A \Delta T • Electric power \dot{E}_{EL}: \dot{E}_{EL}=\alpha I T_C + I^2 R Where the following terms are used: \Delta T = T_H-T_C, I
electric current;
α Seebeck coefficient;
R electric resistance,
A surface area,
d cell thickness, and
k thermal conductivity. The efficiencies of the system are: • Cooling efficiency: \eta _C = \frac{\dot{Q _C}}{\dot{E}_{EL}} • Heating efficiency: \eta _H = \frac{\dot{Q _H}}{\dot{E}_{EL}} COP can be calculated according to Cannistraro.
Experimental Around 1955,
RCA Laboratories built a refrigerator and a small room that was air conditioned using the Peltier effect. These were research demonstrations and did not result in products. The air conditioner was one of the "birthday presents" asked for by CEO
David Sarnoff to challenge the researchers. One of the lead researchers was
Nils E. Lindenblad. ==See also==