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The thermoelectric effect is the direct conversion of
temperature Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer. Thermometers are calibrated in various temperature scales that historically have relied o ...
differences to electric
voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
and vice versa via a
thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the ...
. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it,
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...
is transferred from one side to the other, creating a temperature difference. At the atomic scale, an applied temperature
gradient In vector calculus, the gradient of a scalar-valued differentiable function of several variables is the vector field (or vector-valued function) \nabla f whose value at a point p is the "direction and rate of fastest increase". If the gradi ...
causes
charge carrier In physics, a charge carrier is a particle or quasiparticle that is free to move, carrying an electric charge, especially the particles that carry electric charges in electrical conductors. Examples are electrons, ions and holes. The term is used ...
s in the material to diffuse from the hot side to the cold side. This effect can be used to generate electricity, measure temperature or change the temperature of objects. Because the direction of heating and cooling is affected by the applied voltage, thermoelectric devices can be used as temperature controllers. The term "thermoelectric effect" encompasses three separately identified effects: the Seebeck effect, Peltier effect, and Thomson effect. The Seebeck and Peltier effects are different manifestations of the same physical process; textbooks may refer to this process as the Peltier–Seebeck effect (the separation derives from the independent discoveries by French physicist
Jean Charles Athanase Peltier Jean Charles Athanase Peltier (; ; 22 February 1785 – 27 October 1845) was a French physicist. He was originally a watch dealer, but at the age of 30 began experiments and observations in physics. Peltier was the author of numerous papers in d ...
and
Baltic German Baltic Germans (german: Deutsch-Balten or , later ) were ethnic German inhabitants of the eastern shores of the Baltic Sea, in what today are Estonia and Latvia. Since their coerced resettlement in 1939, Baltic Germans have markedly declined ...
physicist
Thomas Johann Seebeck Thomas Johann Seebeck (; 9 April 1770 – 10 December 1831) was a Baltic German physicist, who, in 1822, observed a relationship between heat and magnetism. Later, in 1823, Ørsted called this phenomenon thermoelectric effect. Seebeck was bor ...
). The Thomson effect is an extension of the Peltier–Seebeck model and is credited to
Lord Kelvin William Thomson, 1st Baron Kelvin, (26 June 182417 December 1907) was a British mathematician, Mathematical physics, mathematical physicist and engineer born in Belfast. Professor of Natural Philosophy (Glasgow), Professor of Natural Philoso ...
.
Joule heating Joule heating, also known as resistive, resistance, or Ohmic heating, is the process by which the passage of an electric current through a conductor (material), conductor produces heat. Joule's first law (also just Joule's law), also known in c ...
, the heat that is generated whenever a current is passed through a
conductive In physics and electrical engineering, a conductor is an object or type of material that allows the flow of charge (electric current) in one or more directions. Materials made of metal are common electrical conductors. Electric current is gener ...
material, is not generally termed a thermoelectric effect. The Peltier–Seebeck and Thomson effects are thermodynamically reversible, whereas Joule heating is not.


Seebeck effect

The Seebeck effect is the electromotive force (emf) that develops across two points of an electrically conducting material when there is a temperature difference between them. The emf is called the Seebeck emf (or thermo/thermal/thermoelectric emf). The ratio between the emf and temperature difference is the Seebeck coefficient. A
thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the ...
measures the difference in potential across a hot and cold end for two dissimilar materials. This potential difference is proportional to the temperature difference between the hot and cold ends. First discovered in 1794 by Italian scientist
Alessandro Volta Alessandro Giuseppe Antonio Anastasio Volta (, ; 18 February 1745 – 5 March 1827) was an Italian physicist, chemist and lay Catholic who was a pioneer of electricity and power who is credited as the inventor of the electric battery and the ...
,In 1794, Volta found that if a temperature difference existed between the ends of an iron rod, then it could excite spasms of a frog's leg. His apparatus consisted of two glasses of water. Dipped in each glass was a wire that was connected to one or the other hind leg of a frog. An iron rod was bent into a bow and one end was heated in boiling water. When the ends of the iron bow were dipped into the two glasses, a thermoelectric current passed through the frog's legs and caused them to twitch. See: *
see p. 139.
* Reprinted in: Volta, Alessandro (1816) ''Collezione dell'Opere del Cavaliere Conte Alessandro Volta'' … ollection of the works of Count Alessandro Volta … (in Italian) Florence (Firenze), (Italy): Guglielmo Piatti. vol. 2, part 1.
''"Nuova memoria sull'elettricità animale, divisa in tre lettere, dirette al Signor Abate Anton Maria Vassalli … Lettera Prima"''
(New memoir on animal electricity, divided into three letters, addressed to Abbot Antonio Maria Vassalli … First letter), pp. 197–206
see p. 202.
From (Volta, 1794), p. 139: ''" … tuffava nell'acqua bollente un capo di tal arco per qualche mezzo minuto, … inetto de tutto ad eccitare le convulsioni dell'animale."'' ( … I dipped into boiling water one end of such an arc f iron rodfor about half a minute, then I took it out and without giving it time to cool, resumed the experiment with the two glasses of cool water; and
t was T, or t, is the twentieth letter in the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''tee'' (pronounced ), plural ''tees''. It is deri ...
at this point that the frog in the bath convulsed; and this appenedeven two, three, four times, ponrepeating the experiment; until, avingcooled – by such dips
hat were A hat is a head covering which is worn for various reasons, including protection against weather conditions, ceremonial reasons such as university graduation, religious reasons, safety, or as a fashion accessory. Hats which incorporate mecha ...
more or less long and repeated, or by a longer exposure to the air – the end of the iron od that had beendipped earlier into the hot water, this arc returned o beingcompletely incapable of exciting convulsions of the animal.)
it is named after the
Baltic German Baltic Germans (german: Deutsch-Balten or , later ) were ethnic German inhabitants of the eastern shores of the Baltic Sea, in what today are Estonia and Latvia. Since their coerced resettlement in 1939, Baltic Germans have markedly declined ...
physicist
Thomas Johann Seebeck Thomas Johann Seebeck (; 9 April 1770 – 10 December 1831) was a Baltic German physicist, who, in 1822, observed a relationship between heat and magnetism. Later, in 1823, Ørsted called this phenomenon thermoelectric effect. Seebeck was bor ...
, who in 1821 independently rediscovered it. It was observed that a compass needle would be deflected by a closed loop formed by two different metals joined in two places, with an applied temperature difference between the joints. This was because the electron energy levels shifted differently in the different metals, creating a
potential difference Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
between the junctions which in turn created an electrical current through the wires, and therefore a
magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...
around the wires. Seebeck did not recognize that an electric current was involved, so he called the phenomenon "thermomagnetic effect". Danish physicist
Hans Christian Ørsted Hans Christian Ørsted ( , ; often rendered Oersted in English; 14 August 17779 March 1851) was a Danish physicist and chemist who discovered that electric currents create magnetic fields, which was the first connection found between electricity ...
rectified the oversight and coined the term "thermoelectricity". The Seebeck effect is a classic example of an
electromotive force In electromagnetism and electronics, electromotive force (also electromotance, abbreviated emf, denoted \mathcal or ) is an energy transfer to an electric circuit per unit of electric charge, measured in volts. Devices called electrical ''transd ...
(EMF) and leads to measurable currents or voltages in the same way as any other EMF. The local
current density In electromagnetism, current density is the amount of charge per unit time that flows through a unit area of a chosen cross section. The current density vector is defined as a vector whose magnitude is the electric current per cross-sectional ar ...
is given by :\mathbf J = \sigma (-\nabla V + \mathbf E_\text), where V is the local
voltage Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to m ...
, and \sigma is the local
conductivity Conductivity may refer to: *Electrical conductivity, a measure of a material's ability to conduct an electric current **Conductivity (electrolytic), the electrical conductivity of an electrolyte in solution ** Ionic conductivity (solid state), ele ...
. In general, the Seebeck effect is described locally by the creation of an electromotive field :\mathbf E_\text = -S \nabla T, where S is the
Seebeck coefficient The Seebeck coefficient (also known as thermopower, thermoelectric power, and thermoelectric sensitivity) of a material is a measure of the magnitude of an induced thermoelectric voltage in response to a temperature difference across that material ...
(also known as thermopower), a property of the local material, and \nabla T is the temperature gradient. The Seebeck coefficients generally vary as function of temperature and depend strongly on the composition of the conductor. For ordinary materials at room temperature, the Seebeck coefficient may range in value from −100 μV/K to +1,000 μV/K (see
Seebeck coefficient The Seebeck coefficient (also known as thermopower, thermoelectric power, and thermoelectric sensitivity) of a material is a measure of the magnitude of an induced thermoelectric voltage in response to a temperature difference across that material ...
article for more information). If the system reaches a steady state, where \mathbf J = 0, then the voltage gradient is given simply by the emf: \nabla V = -S \nabla T. This simple relationship, which does not depend on conductivity, is used in the
thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the ...
to measure a temperature difference; an absolute temperature may be found by performing the voltage measurement at a known reference temperature. A metal of unknown composition can be classified by its thermoelectric effect if a metallic probe of known composition is kept at a constant temperature and held in contact with the unknown sample that is locally heated to the probe temperature. It is used commercially to identify metal alloys. Thermocouples in series form a
thermopile 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 thermoele ...
.
Thermoelectric generator A thermoelectric generator (TEG), also called a Seebeck generator, is a solid state device that converts heat flux (temperature differences) directly into electrical energy through a phenomenon called the ''Seebeck effect'' (a form of thermoele ...
s are used for creating power from heat differentials.


Peltier effect

When an electric current is passed through a circuit of a
thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the ...
, heat is generated at one junction and absorbed at the other junction. This is known as the Peltier effect: the presence of heating or cooling at an electrified junction of two different conductors. The effect is named after French physicist
Jean Charles Athanase Peltier Jean Charles Athanase Peltier (; ; 22 February 1785 – 27 October 1845) was a French physicist. He was originally a watch dealer, but at the age of 30 began experiments and observations in physics. Peltier was the author of numerous papers in d ...
, who discovered it in 1834. When a current is made to flow through a junction between two conductors, A and B, heat may be generated or removed at the junction. The Peltier heat generated at the junction per unit time is :\dot = (\Pi_\text - \Pi_\text) I, where \Pi_\text and \Pi_\text are the Peltier coefficients of conductors A and B, and I is the electric current (from A to B). The total heat generated is not determined by the Peltier effect alone, as it may also be influenced by Joule heating and thermal-gradient effects (see below). The Peltier coefficients represent how much heat is carried per unit charge. Since charge current must be continuous across a junction, the associated heat flow will develop a discontinuity if \Pi_\text and \Pi_\text are different. The Peltier effect can be considered as the back-action counterpart to the Seebeck effect (analogous to the back-EMF in magnetic induction): if a simple thermoelectric circuit is closed, then the Seebeck effect will drive a current, which in turn (by the Peltier effect) will always transfer heat from the hot to the cold junction. The close relationship between Peltier and Seebeck effects can be seen in the direct connection between their coefficients: \Pi = T S (see below). A typical Peltier
heat pump A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
involves multiple junctions in series, through which a current is driven. Some of the junctions lose heat due to the Peltier effect, while others gain heat. Thermoelectric heat pumps exploit this phenomenon, as do
thermoelectric cooling 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 o ...
devices found in refrigerators.


Thomson effect

In different materials, the Seebeck coefficient is not constant in temperature, and so a spatial gradient in temperature can result in a gradient in the Seebeck coefficient. If a current is driven through this gradient, then a continuous version of the Peltier effect will occur. This Thomson effect was predicted and later observed in 1851 by
Lord Kelvin William Thomson, 1st Baron Kelvin, (26 June 182417 December 1907) was a British mathematician, Mathematical physics, mathematical physicist and engineer born in Belfast. Professor of Natural Philosophy (Glasgow), Professor of Natural Philoso ...
(William Thomson). It describes the heating or cooling of a current-carrying conductor with a temperature gradient. If a current density \mathbf J is passed through a homogeneous conductor, the Thomson effect predicts a heat production rate per unit volume :\dot q = -\mathcal K \mathbf J \cdot \nabla T, where \nabla T is the temperature gradient, and \mathcal K is the Thomson coefficient. The Thomson coefficient is related to the Seebeck coefficient as \mathcal K = T \tfrac (see below). This equation, however, neglects Joule heating and ordinary thermal conductivity (see full equations below).


Full thermoelectric equations

Often, more than one of the above effects is involved in the operation of a real thermoelectric device. The Seebeck effect, Peltier effect, and Thomson effect can be gathered together in a consistent and rigorous way, described here; this also includes the effects of
Joule heating Joule heating, also known as resistive, resistance, or Ohmic heating, is the process by which the passage of an electric current through a conductor (material), conductor produces heat. Joule's first law (also just Joule's law), also known in c ...
and ordinary heat conduction. As stated above, the Seebeck effect generates an electromotive force, leading to the current equation :\mathbf J = \sigma (-\boldsymbol \nabla V - S \nabla T). To describe the Peltier and Thomson effects, we must consider the flow of energy. If temperature and charge change with time, the full thermoelectric equation for the energy accumulation, \dot e, is :\dot e = \nabla \cdot (\kappa \nabla T) - \nabla \cdot (V + \Pi) \mathbf J + \dot q_\text, where \kappa is the
thermal conductivity The thermal conductivity of a material is a measure of its ability to conduct heat. It is commonly denoted by k, \lambda, or \kappa. Heat transfer occurs at a lower rate in materials of low thermal conductivity than in materials of high thermal ...
. The first term is the Fourier's heat conduction law, and the second term shows the energy carried by currents. The third term, \dot q_\text, is the heat added from an external source (if applicable). If the material has reached a steady state, the charge and temperature distributions are stable, so \dot e = 0 and \nabla \cdot \mathbf J = 0. Using these facts and the second Thomson relation (see below), the heat equation can be simplified to :-\dot q_\text = \nabla \cdot (\kappa \nabla T) + \mathbf J \cdot \left(\sigma^ \mathbf J\right) - T \mathbf J \cdot \nabla S. The middle term is the Joule heating, and the last term includes both Peltier (\nabla S at junction) and Thomson (\nabla S in thermal gradient) effects. Combined with the Seebeck equation for \mathbf J, this can be used to solve for the steady-state voltage and temperature profiles in a complicated system. If the material is not in a steady state, a complete description needs to include dynamic effects such as relating to electrical
capacitance Capacitance is the capability of a material object or device to store electric charge. It is measured by the change in charge in response to a difference in electric potential, expressed as the ratio of those quantities. Commonly recognized are ...
,
inductance Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of the ...
and
heat capacity Heat capacity or thermal capacity is a physical property of matter, defined as the amount of heat to be supplied to an object to produce a unit change in its temperature. The SI unit of heat capacity is joule per kelvin (J/K). Heat capacity i ...
. The thermoelectric effects lie beyond the scope of equilibrium thermodynamics. They necessarily involve continuing flows of energy. At least, they involve three bodies or thermodynamic subsystems, arranged in a particular way, along with a special arrangement of the surroundings. The three bodies are the two different metals and their junction region. The junction region is an inhomogeneous body, assumed to be stable, not suffering amalgamation by diffusion of matter. The surroundings are arranged to maintain two temperature reservoirs and two electric reservoirs. For an imagined, but not actually possible, thermodynamic equilibrium,
heat In thermodynamics, heat is defined as the form of energy crossing the boundary of a thermodynamic system by virtue of a temperature difference across the boundary. A thermodynamic system does not ''contain'' heat. Nevertheless, the term is al ...
transfer from the hot reservoir to the cold reservoir would need to be prevented by a specifically matching voltage difference maintained by the electric reservoirs, and the electric current would need to be zero. In fact, for a steady state, there must be at least some heat transfer or some non-zero electric current. The two modes of energy transfer, as heat and by electric current, can be distinguished when there are three distinct bodies and a distinct arrangement of surroundings. But in the case of continuous variation in the media, heat transfer and
thermodynamic work In thermodynamics, work is one of the principal processes by which a thermodynamic system can interact with its surroundings and exchange energy. An exchange of energy is facilitated by a mechanism through which the system can spontaneously exer ...
cannot be uniquely distinguished. This is more complicated than the often considered thermodynamic processes, in which just two respectively homogeneous subsystems are connected.


Thomson relations

In 1854, Lord Kelvin found relationships between the three coefficients, implying that the Thomson, Peltier, and Seebeck effects are different manifestations of one effect (uniquely characterized by the Seebeck coefficient). The first Thomson relation is :\mathcal K \equiv \frac - S, where T is the absolute temperature, \mathcal K is the Thomson coefficient, \Pi is the Peltier coefficient, and S is the Seebeck coefficient. This relationship is easily shown given that the Thomson effect is a continuous version of the Peltier effect. The second Thomson relation is :\Pi = TS. This relation expresses a subtle and fundamental connection between the Peltier and Seebeck effects. It was not satisfactorily proven until the advent of the
Onsager relations In thermodynamics, the Onsager reciprocal relations express the equality of certain ratios between flows and forces in thermodynamic systems out of equilibrium, but where a notion of local equilibrium exists. "Reciprocal relations" occur betw ...
, and it is worth noting that this second Thomson relation is only guaranteed for a time-reversal symmetric material; if the material is placed in a magnetic field or is itself magnetically ordered (
ferromagnetic Ferromagnetism is a property of certain materials (such as iron) which results in a large observed magnetic permeability, and in many cases a large magnetic coercivity allowing the material to form a permanent magnet. Ferromagnetic materials ...
,
antiferromagnetic In materials that exhibit antiferromagnetism, the magnetic moments of atoms or molecules, usually related to the spins of electrons, align in a regular pattern with neighboring spins (on different sublattices) pointing in opposite directions. ...
, etc.), then the second Thomson relation does not take the simple form shown here. Now, using the second relation, the first Thomson relation becomes :\mathcal K = T \tfrac The Thomson coefficient is unique among the three main thermoelectric coefficients because it is the only one directly measurable for individual materials. The Peltier and Seebeck coefficients can only be easily determined for pairs of materials; hence, it is difficult to find values of absolute Seebeck or Peltier coefficients for an individual material. If the Thomson coefficient of a material is measured over a wide temperature range, it can be integrated using the Thomson relations to determine the absolute values for the Peltier and Seebeck coefficients. This needs to be done only for one material, since the other values can be determined by measuring pairwise Seebeck coefficients in thermocouples containing the reference material and then adding back the absolute Seebeck coefficient of the reference material. For more details on absolute Seebeck coefficient determination, see
Seebeck coefficient The Seebeck coefficient (also known as thermopower, thermoelectric power, and thermoelectric sensitivity) of a material is a measure of the magnitude of an induced thermoelectric voltage in response to a temperature difference across that material ...
.


Applications


Thermoelectric generators

The Seebeck effect is used in thermoelectric generators, which function like
heat engine In thermodynamics and engineering, a heat engine is a system that converts heat to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state ...
s, but are less bulky, have no moving parts, and are typically more expensive and less efficient. They have a use in power plants for converting
waste heat Waste heat is heat that is produced by a machine, or other process that uses energy, as a byproduct of doing work. All such processes give off some waste heat as a fundamental result of the laws of thermodynamics. Waste heat has lower utility ...
into additional electrical power (a form of
energy recycling Energy recycling is the energy recovery process of utilizing energy that would normally be wasted, usually by converting it into electricity or thermal energy. Undertaken at manufacturing facilities, power plants, and large institutions such as ho ...
) and in automobiles as
automotive thermoelectric generator 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 exchan ...
s (ATGs) for increasing
fuel efficiency Fuel efficiency is a form of thermal efficiency, meaning the ratio of effort to result of a process that converts chemical potential energy contained in a carrier (fuel) into kinetic energy or work. Overall fuel efficiency may vary per device, wh ...
. Space probes often use
radioisotope thermoelectric generator A radioisotope thermoelectric generator (RTG, RITEG), sometimes referred to as a radioisotope power system (RPS), is a type of nuclear battery that uses an array of thermocouples to convert the heat released by the decay of a suitable radioacti ...
s with the same mechanism but using radioisotopes to generate the required heat difference. Recent uses include stove fans, lighting powered by body heat and a smartwatch powered by body heat.


Peltier effect

The Peltier effect can be used to create a
refrigerator A refrigerator, colloquially fridge, is a commercial and home appliance consisting of a thermally insulated compartment and a heat pump (mechanical, electronic or chemical) that transfers heat from its inside to its external environment so th ...
that is compact and has no circulating fluid or moving parts. Such refrigerators are useful in applications where their advantages outweigh the disadvantage of their very low efficiency. The Peltier effect is also used by many
thermal cyclers The thermal cycler (also known as a thermocycler, PCR machine or DNA amplifier) is a laboratory apparatus most commonly used to amplify segments of DNA via the polymerase chain reaction (PCR). Thermal cyclers may also be used in laboratories to fa ...
, laboratory devices used to amplify DNA by the
polymerase chain reaction The polymerase chain reaction (PCR) is a method widely used to rapidly make millions to billions of copies (complete or partial) of a specific DNA sample, allowing scientists to take a very small sample of DNA and amplify it (or a part of it) t ...
(PCR). PCR requires the cyclic heating and cooling of samples to specified temperatures. The inclusion of many thermocouples in a small space enables many samples to be amplified in parallel.


Temperature measurement

Thermocouple A thermocouple, also known as a "thermoelectrical thermometer", is an electrical device consisting of two dissimilar electrical conductors forming an electrical junction. A thermocouple produces a temperature-dependent voltage as a result of the ...
s and
thermopile 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 thermoele ...
s are devices that use the Seebeck effect to measure the temperature difference between two objects. Thermocouples are often used to measure high temperatures, holding the temperature of one junction constant or measuring it independently ( cold junction compensation). Thermopiles use many thermocouples electrically connected in series, for sensitive measurements of very small temperature difference.


Dehumidifiers

Peltier dehumidifiers work by forcing damp air across a cold heat sink. As the air passes over the cold surface, it cools and the water vapor contained in it condenses onto the heat sink. The water then drips down into a water tank. The dry air may be forced over another heat sink to cool the hot side of the Peltier cell before being released back into the room.


See also

* Barocaloric material *
Nernst effect In physics and chemistry, the Nernst effect (also termed first Nernst–Ettingshausen effect, after Walther Nernst and Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon observed when a sample allowing electrical conduct ...
– a thermoelectric phenomenon when a sample allowing electrical conduction in a magnetic field and a temperature gradient normal (perpendicular) to each other *
Ettingshausen effect The Ettingshausen effect (named for Albert von Ettingshausen) is a thermoelectric (or thermomagnetic) phenomenon that affects the electric current in a conductor when a magnetic field is present. Ettingshausen and his PhD student Walther Nernst w ...
– thermoelectric phenomenon affecting current in a conductor in a magnetic field *
Pyroelectricity Pyroelectricity (from the two Greek words ''pyr'' meaning fire, and electricity) is a property of certain crystals which are naturally electrically polarized and as a result contain large electric fields. Pyroelectricity can be described as the a ...
– the creation of an electric polarization in a crystal after heating/cooling, an effect distinct from thermoelectricity *
Thermogalvanic cell In electrochemistry, a thermogalvanic cell is a kind of galvanic cell in which heat is employed to provide electrical power directly. These cells are electrochemical cells in which the two electrodes are deliberately maintained at different tempe ...
- the production of electrical power from a galvanic cell with electrodes at different temperatures *
Thermophotovoltaic Thermophotovoltaic (TPV) energy conversion is a direct conversion process from heat to electricity via photons. A basic thermophotovoltaic system consists of a hot object emitting thermal radiation and a photovoltaic cell similar to a solar cell b ...
- production of electrical power from thermal energy using the photovoltaic effect


References


Notes


Further reading

* * P.M. Jack (2003).
Physical Space as a Quaternion Structure I: Maxwell Equations. A Brief Note.
. Toronto, Canada * * *


External links


''International Thermoelectric Society''
*

{{DEFAULTSORT:Thermoelectric Effect Physical phenomena Energy conversion Thermoelectricity