Thermoelectric cooling

Last updated March 12, 2024

Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler (TEC) and occasionally a thermoelectric battery. It can be used either for heating or for cooling,^[1] although in practice the main application is cooling^{[ citation needed ]}. It can also be used as a temperature controller that either heats or cools.

This technology is far less commonly applied to refrigeration than vapor-compression refrigeration is. The primary advantages of a Peltier cooler compared to a vapor-compression refrigerator are its lack of moving parts or circulating liquid, very long life, invulnerability to leaks, small size, and flexible shape. Its main disadvantages are high cost for a given cooling capacity and poor power efficiency (a low coefficient of performance or COP). Many researchers and companies are trying to develop Peltier coolers that are cheap and efficient. (See Thermoelectric materials.)

A Peltier cooler can also be used as a thermoelectric generator. When operated as a cooler, a voltage is applied across the device, and as a result, a difference in temperature will build up between the two sides. When operated as a generator, one side of the device is heated to a temperature greater than the other side, and as a result, a difference in voltage will build up between the two sides (the Seebeck effect). However, a well-designed Peltier cooler will be a mediocre thermoelectric generator and vice versa, due to different design and packaging requirements.

Operating principle

Peltier element schematic. Thermoelectric legs are thermally in parallel and electrically in series. Peltierelement.png — Peltier element schematic. Thermoelectric legs are thermally in parallel and electrically in series.

Video from thermal camera of peltier element

Thermoelectric coolers operate by the Peltier effect (one of three phenomena that make up the thermoelectric effect).^[2] A thermoelectric module is made from three components; the conductors, legs, and the substrate, and many of these modules are connected electrically in series, but thermally in parallel.^[2] When a DC electric current flows through the device, it brings heat from one side to the other, so that one side gets cooler while the other gets hotter.

The "hot" side is attached to a heat sink so that it remains at ambient temperature, while the cool side goes below room temperature. In special applications, multiple coolers can be cascaded or staged together for lower temperature, but overall efficiency (COP) drops significantly. The maximum COP of any refrigeration cycle is ultimately limited by the difference between the desired (cold side) and ambient (hot side) temperature (the temperature of the heat sink). The higher the temperature difference (delta), the lower the maximum theoretical COP.

Construction

Design

Two unique semiconductors, one n-type and one p-type, are used because they need to have different electron densities. The alternating p & n-type semiconductor pillars are placed thermally in parallel to each other and electrically in series and then joined with a thermally conducting plate on each side, usually ceramic, removing the need for a separate insulator. When a voltage is applied to the free ends of the two semiconductors there is a flow of DC current across the junction of the semiconductors, causing a temperature difference. The side with the cooling plate absorbs heat which is then transported by the semiconductor to the other side of the device.

The cooling ability of the total unit is then proportional to the total cross section of all the pillars, which are often connected in series electrically to reduce the current needed to practical levels. The length of the pillars is a balance between longer pillars, which will have a greater thermal resistance between the sides and allow a lower temperature to be reached but produce more resistive heating, and shorter pillars, which will have a greater electrical efficiency but let more heat leak from the hot to cold side by thermal conduction. For large temperature differences, longer pillars are far less efficient than stacking separate, progressively larger modules; the modules get larger as each layer must remove both the heat moved by the above layer and the waste heat of the layer.

Materials

Requirements for thermoelectric materials:^[4]

Narrow band-gap semiconductors because of room-temperature operation;
High electrical conductivity (to reduce electrical resistance, a source of waste heat);
Low thermal conductivity (so that heat doesn't come back from the hot side to the cool side); this usually translates to heavy elements
Large unit cell, complex structure;
Highly anisotropic or highly symmetric;
Complex compositions.

Materials suitable for high efficiency TEC systems must have a combination of low thermal conductivity and high electrical conductivity. The combined effect of different material combinations is commonly compared using a figure of merit known as ZT, a measure of the system's efficiency. The equation for ZT is given below, where $\alpha$ is the Seebeck coefficient, $\sigma$ is the electrical conductivity and $\kappa$ is the thermal conductivity.^[5]

\mathbb {Z} \mathrm {T} =(\alpha ^{2}\sigma \mathrm {T} )/\kappa

There are few materials that are suitable for TEC applications since the relationship between thermal and electrical conductivity is usually a positive correlation. Improvements in reduced thermal transport with increased electrical conductivity are an active area of material science research. Common thermoelectric materials used as semiconductors include bismuth telluride, lead telluride, silicon–germanium, and bismuth antimonide alloys. Of these, bismuth telluride is the most commonly used. New high-performance materials for thermoelectric cooling are being actively researched.^[6]

For decades, narrow bandgap semiconductors, such as bismuth, tellurium and their compounds, have been used as materials of thermocouples.

Identification and characteristics

The vast majority of thermoelectric coolers have an ID printed on the cooled side.^[7]

These universal IDs clearly indicate the size, number of stages, number of couples, and current rating in amps, as seen in the adjacent diagram.^[8]

Very common Tec1-12706, square of 40 mm size and 3–4 mm high, are found for a few dollars, and sold as able to move around 60 W or generate a 60 °C temperature difference with a 6 A current. Their electrical resistance will be of 1–2 ohm magnitude.

Strengths and weaknesses

There are many factors motivating further research on TEC including lower carbon emissions and ease of manufacturing. However, several challenges have arisen.

Benefits

A significant benefit of TEC systems is that they have no moving parts. This lack of mechanical wear and reduced instances of failure due to fatigue and fracture from mechanical vibration and stress increases the lifespan of the system and lowers the maintenance requirements. Current technologies show the mean time between failures (MTBF) to exceed 100,000 hours at ambient temperatures.^[9]

The fact that TEC systems are current-controlled leads to another series of benefits. Because the flow of heat is directly proportional to the applied DC current, heat may be added or removed with accurate control of the direction and amount of electric current. In contrast to methods that use resistive heating or cooling methods that involve gases, TEC allows for an equal degree of control over the flow of heat (both in and out of a system under control). Because of this precise bidirectional heat flow control, temperatures of controlled systems can be precise to fractions of a degree, often reaching precision of milli Kelvin (mK) in laboratory settings.^[10]

TEC devices are also more flexible in shape than their more traditional counterparts. They can be used in environments with less space or more severe conditions than a conventional refrigerator. The ability to tailor their geometry allows for the delivery of precise cooling to very small areas. These factors make them a common choice in scientific and engineering applications with demanding requirements where cost and absolute energy efficiency are not primary concerns.

Another benefit of TEC is that it does not use refrigerants in its operation. Prior to their phaseout some early refrigerants, such as chlorofluorocarbons (CFCs), contributed significantly to ozone depletion. Many refrigerants used today also have significant environmental impact with global warming potential ^[11] or carry other safety risks with them.^[12]

Disadvantages

TEC systems have a number of notable disadvantages. Foremost is their limited energy efficiency compared to conventional vapor-compression systems and the constraints on the total heat flux (heat flow) that they are able to generate per unit area.^[10] This topic is further discussed in the performance section below.

Performance

Peltier (thermoelectric) performance is a function of ambient temperature, hot and cold side heat exchanger (heat sink) performance, thermal load, Peltier module (thermopile) geometry, and Peltier electrical parameters.^[7]

The amount of heat that can be moved is proportional to the current and time.

Q=PIt

, where P is the Peltier coefficient, I is the current, and t is the time. The Peltier coefficient depends on temperature and the materials the cooler is made of. Magnitude of 10 watt per ampere are common, but this is offset by two phenomena:

According to Ohm's law, a Peltier module will produce waste heat itself,

Q_{waste}=RI^{2}t

, where R is the resistance.

Heat will also move from the hot side to the cool side by thermal conduction inside the module itself, an effect which grows stronger as the temperature difference grows.

The result is that the heat effectively moved drops as the temperature difference grows, and the module becomes less efficient. There comes a temperature difference when the waste heat and heat moving back overcomes the moved heat, and the module starts to heat the cool side instead of cooling it further. A single-stage thermoelectric cooler will typically produce a maximal temperature difference of 70 °C between its hot and cold sides.^[13]

Another issue with performance is a direct consequence of one of their advantages: being small. This means that:

the hot side and the cool side will be very close to each other (a few millimeters away), making it easier for the heat to go back to the cool side, and harder to insulate the hot and cool side from each other
a common 40 mm × 40 mm can generate 60 W or more—that is, 4 W/cm² or more—requiring a powerful radiator to move the heat away

In refrigeration applications, thermoelectric junctions have about 1/4 the efficiency compared to conventional means (vapor compression refrigeration): they offer around 10–15% efficiency (COP of 1.0–1.5) of the ideal Carnot cycle refrigerator, compared with 40–60% achieved by conventional compression-cycle systems (reverse Rankine systems using compression/expansion).^[14] Due to this lower efficiency, thermoelectric cooling is generally only used in environments where the solid-state nature (no moving parts), low maintenance, compact size, and orientation insensitivity outweighs pure efficiency.

While lower than conventional means, efficiency can be good enough, provided:

temperature difference is kept as small as possible, and,
the current is kept low, because the ratio of moved heat over waste heat (for same temperature on the hot and cool side) will be ${\frac {Q}{Q_{waste}}}={\frac {P}{RI}}$ .

However, since low current also means a low amount of moved heat, for all practical purposes the coefficient of performance will be low.

Uses

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. TEC elements have limited life time. Their health strength can be measured by the change of their AC resistance (ACR). As a cooler element wears out, the ACR will increase.^{[ citation needed ]}

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.^[15]^[16]

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.^[17] 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.^[18]

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,^[19] 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.^{[ citation needed ]}

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.^[20] 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,^[21] 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").^{[ citation needed ]}

They are used in Energy Dispersive Spectrometers to cool the sensor crystals, eliminating the necessity of large liquid nitrogen dewars.

Related Research Articles

A semiconductor is a material that has an electrical conductivity value falling between that of a conductor, such as copper, and an insulator, such as glass. Its resistivity generally falls as its temperature rises; metals behave in the opposite way. In many cases their conducting properties may be altered in useful ways by introducing impurities ("doping") into the crystal structure. When two differently doped regions exist in the same crystal, a semiconductor junction is created. The behavior of charge carriers, which include electrons, ions, and electron holes, at these junctions is the basis of diodes, transistors, and most modern electronics. Some examples of semiconductors are silicon, germanium, gallium arsenide, and elements near the so-called "metalloid staircase" on the periodic table. After silicon, gallium arsenide is the second-most common semiconductor and is used in laser diodes, solar cells, microwave-frequency integrated circuits, and others. Silicon is a critical element for fabricating most electronic circuits.

A heat sink is a passive heat exchanger that transfers the heat generated by an electronic or a mechanical device to a fluid medium, often air or a liquid coolant, where it is dissipated away from the device, thereby allowing regulation of the device's temperature. In computers, heat sinks are used to cool CPUs, GPUs, and some chipsets and RAM modules. Heat sinks are used with other high-power semiconductor devices such as power transistors and optoelectronics such as lasers and light-emitting diodes (LEDs), where the heat dissipation ability of the component itself is insufficient to moderate its temperature.

The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa via a thermocouple. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, heat is transferred from one side to the other, creating a temperature difference. At the atomic scale, an applied temperature gradient causes charge carriers in the material to diffuse from the hot side to the cold side.

Thermoelectric materials show the thermoelectric effect in a strong or convenient form.

The term "thermal diode" can refer to:

A thermopile is an electronic device that converts thermal energy into electrical energy. It is composed of several thermocouples connected usually in series or, less commonly, in parallel. Such a device works on the principle of the thermoelectric effect, i.e., generating a voltage when its dissimilar metals (thermocouples) are exposed to a temperature difference.

Computer cooling is required to remove the waste heat produced by computer components, to keep components within permissible operating temperature limits. Components that are susceptible to temporary malfunction or permanent failure if overheated include integrated circuits such as central processing units (CPUs), chipsets, graphics cards, hard disk drives, and solid state drives.

Jean Charles Athanase Peltier was a French physicist. He was originally a watch dealer, but at the age of 30 began experiments and observations in physics.

An atomic battery, nuclear battery, radioisotope battery or radioisotope generator is a device which uses energy from the decay of a radioactive isotope to generate electricity. Like nuclear reactors, they generate electricity from nuclear energy, but differ in that they do not use a chain reaction. Although commonly called batteries, they are technically not electrochemical and cannot be charged or recharged. They are very costly, but have an extremely long life and high energy density, and so they are typically used as power sources for equipment that must operate unattended for long periods of time, such as spacecraft, pacemakers, underwater systems and automated scientific stations in remote parts of the world.

Bismuth telluride is a gray powder that is a compound of bismuth and tellurium also known as bismuth(III) telluride. It is a semiconductor, which, when alloyed with antimony or selenium, is an efficient thermoelectric material for refrigeration or portable power generation. Bi₂Te₃ is a topological insulator, and thus exhibits thickness-dependent physical properties.

<span class="mw-page-title-main">Thermal management (electronics)</span> Regulation of the temperature of electronic circuitry to prevent inefficiency or failure

All electronic devices and circuitry generate excess heat and thus require thermal management to improve reliability and prevent premature failure. The amount of heat output is equal to the power input, if there are no other energy interactions. There are several techniques for cooling including various styles of heat sinks, thermoelectric coolers, forced air systems and fans, heat pipes, and others. In cases of extreme low environmental temperatures, it may actually be necessary to heat the electronic components to achieve satisfactory operation.

A thermoelectric generator (TEG), also called a Seebeck generator, is a solid state device that converts heat directly into electrical energy through a phenomenon called the Seebeck effect. Thermoelectric generators function like heat engines, but are less bulky and have no moving parts. However, TEGs are typically more expensive and less efficient.

An automotive thermoelectric generator (ATEG) is a device that converts some of the waste heat of an internal combustion engine (IC) into electricity using the Seebeck Effect. A typical ATEG consists of four main elements: A hot-side heat exchanger, a cold-side heat exchanger, thermoelectric materials, and a compression assembly system. ATEGs can convert waste heat from an engine's coolant or exhaust into electricity. By reclaiming this otherwise lost energy, ATEGs decrease fuel consumed by the electric generator load on the engine. However, the cost of the unit and the extra fuel consumed due to its weight must be also considered.

High power light-emitting diodes (LEDs) can use 350 milliwatts or more in a single LED. Most of the electricity in an LED becomes heat rather than light. If this heat is not removed, the LEDs run at high temperatures, which not only lowers their efficiency, but also makes the LED less reliable. Thus, thermal management of high power LEDs is a crucial area of research and development. It is necessary to limit both the junction and the phosphor particles temperatures to a value that will guarantee the desired LED lifetime.

<span class="mw-page-title-main">Heat spreader</span> Device that tends to equalize temperature over its surface

A heat spreader transfers energy as heat from a hotter source to a colder heat sink or heat exchanger. There are two thermodynamic types, passive and active. The most common sort of passive heat spreader is a plate or block of material having high thermal conductivity, such as copper, aluminum, or diamond. An active heat spreader speeds up heat transfer with expenditure of energy as work supplied by an external source.

<span class="mw-page-title-main">Thermal copper pillar bump</span>

The thermal copper pillar bump, also known as the "thermal bump", is a thermoelectric device made from thin-film thermoelectric material embedded in flip chip interconnects for use in electronics and optoelectronic packaging, including: flip chip packaging of CPU and GPU integrated circuits (chips), laser diodes, and semiconductor optical amplifiers (SOA). Unlike conventional solder bumps that provide an electrical path and a mechanical connection to the package, thermal bumps act as solid-state heat pumps and add thermal management functionality locally on the surface of a chip or to another electrical component. The diameter of a thermal bump is 238 μm and 60 μm high.

Electronics cooling encompasses thermal design, analysis and experimental characterization of electronic systems as a discrete discipline with the product creation process for an electronics product, or an electronics sub-system within a product. On-line sources of information are available and a number of books have been published on this topic.

Bismuth antimonides, Bismuth-antimonys, or Bismuth-antimony alloys, (Bi_1−xSb_x) are binary alloys of bismuth and antimony in various ratios.

Thermoelectric acclimatization depends on the possibility of a Peltier cell of absorbing heat on one side and rejecting heat on the other side. Consequently, it is possible to use them for heating on one side and cooling on the other and as a temperature control system.

A cascade refrigeration cycle is a multi-stage thermodynamic cycle. An example two-stage process is shown at right. The cascade cycle is often employed for devices such as ULT freezers.

References

↑ Taylor, R.A.; Solbrekken, G.L. (2008). "Comprehensive system-level optimization of thermoelectric devices for electronic cooling applications". IEEE Transactions on Components and Packaging Technologies. 31: 23–31. doi:10.1109/TCAPT.2007.906333. S2CID 39137848.
1 2 Lundgaard, Christian (2019). Design of segmented thermoelectric Peltier coolers by topology optimization. OXFORD: Elsevier Ltd. p. 1.
↑ DiSalvo, Francis (July 1999). "Thermoelectric Cooling and Power Generation". Science. 285 (5428): 703–6. doi:10.1126/science.285.5428.703. PMID 10426986.
↑ Goldsmid, H. Julian (2016). Introduction to Thermoelectricity. Springer Series in Materials Science. Vol. 121. Berlin, Heidelberg: Springer Berlin Heidelberg. Bibcode:2016inh..book.....G. doi:10.1007/978-3-662-49256-7. ISBN 978-3-662-49255-0.
↑ Poudel, Bed (May 2008). "High-Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys". Science. 320 (5876): 634–8. Bibcode:2008Sci...320..634P. doi:10.1126/science.1156446. PMID 18356488. S2CID 206512197.
↑ Snyder, G.J.; Toberer, E.S. (2008). "Complex Thermoelectric Materials". Nature Materials. 7 (2): 105–114. Bibcode:2008NatMa...7..105S. doi:10.1038/nmat2090. PMID 18219332.
1 2 "PCB Heaven – Peltier Elements Explained". PCB Heaven. Retrieved 1 May 2013.
↑ Versteeg, Owen. "Peltier Element Identification". Archived from the original on 30 April 2019. Retrieved 14 October 2013.
↑ Ghoshal, Uttam (2001-07-31). "Highly reliable thermoelectric cooling apparatus and method". patents.google.com. Retrieved 2019-03-12.
1 2 Zhao, Dongliang (May 2014). "A review of thermoelectric cooling: Materials, modeling and applications". Applied Thermal Engineering. 66 (1–2): 15–24. doi:10.1016/j.applthermaleng.2014.01.074.
↑ University of California (April 18, 2017). "Chlorofluorocarbons and Ozone Depletion". American Chemical Society. Retrieved 2019-03-11.
↑ "Module 99: Propane as a refrigerant for use in chillers for air conditioning applications". CIBSE Journal. September 2016. Retrieved 2020-01-22.
↑ "The Heatsink Guide" . Retrieved 3 May 2013.
↑ Brown, D. R.; N. Fernandez; J. A. Dirks; T. B. Stout (March 2010). "The Prospects of Alternatives to Vapor Compression Technology for Space Cooling and Food Refrigeration Applications" (PDF). Pacific Northwest National Laboratory (PNL). U.S. Department of Energy. Retrieved 16 March 2013.
↑ Hsu, Jeremy (2011-06-14). "Cold? Put this jacket on. Hot? Put this jacket on Climate-controlled coat goes from zero to 100 degrees C 'in the flip of a button'". NBC News. NBC. Retrieved 16 March 2013.
↑ Ferro, Shaunacy (2013-03-15). "How Winter Woes Inspired A Nanotech Fix For Everything From Cold Necks To Knee Pain". Popular Mechanics. Bonnier Corp. Retrieved 16 March 2013.
↑ Fylladitakis, E. (September 26, 2016) anandtech.com The Phononic HEX 2.0 TEC CPU Cooler Review. Retrieved on 2018-10-31.
↑ "Overview of Intel Cryo cooling technology" . Retrieved 20 November 2022.
↑ Using Peltier modules for thermal management of electronic systems. Electronics Weekly, 4 October 2017
↑ Kotlyarov, Evgeny; Peter de Crom; Raoul Voeten (2006). "Some Aspects of Peltier-Cooler Optimization Applied for the Glove Box Air Temperature Control". SAE International. SAE Technical Paper Series. 1: 1. doi:10.4271/2006-01-2043.
↑ Vollmer, Michael; Möllmann, Klaus-Peter (20 February 2018). Infrared Thermal Imaging: Fundamentals, Research and Applications. John Wiley & Sons. ISBN 9783527413515.

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[1] Taylor, R.A.; Solbrekken, G.L. (2008). "Comprehensive system-level optimization of thermoelectric devices for electronic cooling applications". IEEE Transactions on Components and Packaging Technologies. 31: 23–31. doi:10.1109/TCAPT.2007.906333. S2CID 39137848.

[:2-2] 1 2 Lundgaard, Christian (2019). Design of segmented thermoelectric Peltier coolers by topology optimization. OXFORD: Elsevier Ltd. p. 1.

[3] DiSalvo, Francis (July 1999). "Thermoelectric Cooling and Power Generation". Science. 285 (5428): 703–6. doi:10.1126/science.285.5428.703. PMID 10426986.

[4] Goldsmid, H. Julian (2016). Introduction to Thermoelectricity. Springer Series in Materials Science. Vol. 121. Berlin, Heidelberg: Springer Berlin Heidelberg. Bibcode:2016inh..book.....G. doi:10.1007/978-3-662-49256-7. ISBN 978-3-662-49255-0.

[:0-5] Poudel, Bed (May 2008). "High-Thermoelectric Performance of Nanostructured Bismuth Antimony Telluride Bulk Alloys". Science. 320 (5876): 634–8. Bibcode:2008Sci...320..634P. doi:10.1126/science.1156446. PMID 18356488. S2CID 206512197.

[6] Snyder, G.J.; Toberer, E.S. (2008). "Complex Thermoelectric Materials". Nature Materials. 7 (2): 105–114. Bibcode:2008NatMa...7..105S. doi:10.1038/nmat2090. PMID 18219332.

[PCB_Heaven-7] 1 2 "PCB Heaven – Peltier Elements Explained". PCB Heaven. Retrieved 1 May 2013.

[blog.owenversteeg.com-8] Versteeg, Owen. "Peltier Element Identification". Archived from the original on 30 April 2019. Retrieved 14 October 2013.

[9] Ghoshal, Uttam (2001-07-31). "Highly reliable thermoelectric cooling apparatus and method". patents.google.com. Retrieved 2019-03-12.

[:1-10] 1 2 Zhao, Dongliang (May 2014). "A review of thermoelectric cooling: Materials, modeling and applications". Applied Thermal Engineering. 66 (1–2): 15–24. doi:10.1016/j.applthermaleng.2014.01.074.

[11] University of California (April 18, 2017). "Chlorofluorocarbons and Ozone Depletion". American Chemical Society. Retrieved 2019-03-11.

[12] "Module 99: Propane as a refrigerant for use in chillers for air conditioning applications". CIBSE Journal. September 2016. Retrieved 2020-01-22.

[HSG-13] "The Heatsink Guide" . Retrieved 3 May 2013.

[PNL-14] Brown, D. R.; N. Fernandez; J. A. Dirks; T. B. Stout (March 2010). "The Prospects of Alternatives to Vapor Compression Technology for Space Cooling and Food Refrigeration Applications" (PDF). Pacific Northwest National Laboratory (PNL). U.S. Department of Energy. Retrieved 16 March 2013.

[Hsu-15] Hsu, Jeremy (2011-06-14). "Cold? Put this jacket on. Hot? Put this jacket on Climate-controlled coat goes from zero to 100 degrees C 'in the flip of a button'". NBC News. NBC. Retrieved 16 March 2013.

[Ferro-16] Ferro, Shaunacy (2013-03-15). "How Winter Woes Inspired A Nanotech Fix For Everything From Cold Necks To Knee Pain". Popular Mechanics. Bonnier Corp. Retrieved 16 March 2013.

[17] Fylladitakis, E. (September 26, 2016) anandtech.com The Phononic HEX 2.0 TEC CPU Cooler Review. Retrieved on 2018-10-31.

[18] "Overview of Intel Cryo cooling technology" . Retrieved 20 November 2022.

[19] Using Peltier modules for thermal management of electronic systems. Electronics Weekly, 4 October 2017

[gloveboxtemps-20] Kotlyarov, Evgeny; Peter de Crom; Raoul Voeten (2006). "Some Aspects of Peltier-Cooler Optimization Applied for the Glove Box Air Temperature Control". SAE International. SAE Technical Paper Series. 1: 1. doi:10.4271/2006-01-2043.

[21] Vollmer, Michael; Möllmann, Klaus-Peter (20 February 2018). Infrared Thermal Imaging: Fundamentals, Research and Applications. John Wiley & Sons. ISBN 9783527413515.

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