The effect of cooling during the passage of current. Peltier module: technical specifications. Drinking water production with the Peltier module

Definition 1

An article about temperature anomalies that are observed at the boundaries of two different conductors when an electric current flows through them was published Peltier in 1834. Peltier himself did not understand the essence of the phenomenon, it was explained by Lenz in 1838. Lenz conducted the following experiment. In the recess at the junction of the rods of bismuth and antimony, he placed a drop of water. If the current was passed in one direction, the water would freeze, if the current flowed in the opposite direction, the resulting ice would melt. So it was found that when passing through the contact of two conductors electric current, in addition to the Joule heat, additional heat is released or absorbed (depending on the direction of the current). This heat is called the Peltier heat. The process of release (absorption) of additional heat in the contact of two conductors is called "Peltier phenomenon". The Peltier heat is proportional to the first power of the current, and changes sign when the direction of the current changes. It has been empirically obtained that the Peltier heat ($Q_P$) can be expressed using the formula:

where $q$ is the charge, $P$ is the Peltier coefficient, which depends on the contacting materials and their temperature. $Q_P>0$ if it is allocated.

Explanation of the Peltier effect in classical theory

The classical electronic theory of conduction interpreted the Peltier phenomenon as follows: electrons that are transferred by current from one metal to another are accelerated or slowed down under the influence of an internal contact potential difference between the metals. In one case, the kinetic energy of the electrons increases and then is released as heat. In another case, the kinetic energy decreases, and this decrease is replenished by thermal vibrations of atoms, resulting in cooling.

One would expect that the coefficient of the Peltier effect would be equal to the contact potential difference, but this is not the case. In accordance with the classical theory, the average kinetic energy of the thermal motion of electrons in contacting metals is considered to be the same, but this is not so. The point is that the positions of the Fermi levels in different metals are different. The classical theory takes into account only the difference in potential energies on different sides of the metal interface, while it considers that the kinetic energies of electrons are the same. However, one should take into account the change in the total energy of an electron during its transfer from one metal to another.

For most pairs of conductors, the Peltier coefficient has a value of the order of $(10)^(-2)-\ (10)^(-3)V$ (volts).

Peltier effect for semiconductors

The Peltier effect, like all other thermionic phenomena, is especially pronounced in circuits of electronic and hole semiconductors.

Let us assume that there is a contact between a hole semiconductor and an electronic one, and the current flows from the hole conductor to the electronic one. In this case, holes in a hole semiconductor and electrons in electronic semiconductor will move towards each other. Electrons, having passed the interface from the free zones of the electronic semiconductor, fall into the filled zone of the hole semiconductor and annihilate with the hole there. As a consequence of this recombination, energy is released, which is released in the form of heat in the contact of semiconductors.

Consider the case when the current flows from an electronic semiconductor to a hole one. In this case, electrons in an electronic semiconductor and holes in a hole semiconductor move in opposite directions. Holes moving from the semiconductor interface are replenished as a result of the formation of new pairs during the transition of electrons from the filled zone of the hole semiconductor to the free zone. The formation of such pairs requires energy, which is provided by thermal vibrations of lattice atoms. Under the influence of an electric field, the emerging electrons and holes move in opposite directions. The continuous creation of new pairs goes on as long as the current flows through the contact. As a result of this process, heat is absorbed.

Note 1

The Peltier phenomenon in semiconductors is used in cooling devices.

Joule-Lenz heat and Peltier heat

It should be noted that between the Peltier phenomenon and the release of heat Joule -- Lenz there are significant differences. The amount of heat that is released in accordance with the Joule-Lenz law ($Q\sim I^2$) does not depend on the direction of the current. The heat that is released (or absorbed) as a result of the Peltier effect is proportional to the first power of the current ($Q_P\sim I$) and changes sign when the current direction changes. In addition, the Joule-Lenz heat depends on the resistance of the conductor, the Peltier heat does not depend on it.

Usually, the Peltier heat is substantially less than the Joule-Lenz heat. In order to reveal the effect of the Peltier phenomenon, it is necessary to reduce the Joule-Lenz heat as much as possible, using thick conductors with minimal resistance.

Example 1

The number of electrons (N) that passes through a unit area perpendicular to the current direction in $1 s$ is:

where $j$ is the current density, $q_e\ $ is the electron charge.

The energy of an electron is equal to the sum of its kinetic ($E_k$) and potential energies ($E_p=-q_e\varphi $). If $\left\langle E_k\right\rangle $ denotes the average energy for N electrons, then the energy flux ($P$) is:

where $\left\langle E_k\right\rangle \ne \frac(3)(2)$ kT-- is not equal to the average kinetic energy of an equilibrium electron gas, which is explained by the fact that in the case of a degenerate gas, not all electrons can be accelerated electric field.

Consider conductors 1 and 2 at the same temperature. Energy $P_1$ is supplied to each unit of the contact surface in conductor 1 per unit time, and energy equal to $P_2$ is removed in conductor 2. The potential values on both sides of the contact plane are equal to $(\varphi )_1$ and $(\varphi )_2$. And $(\varphi )_1$ $\ne $ $(\varphi )_2$. In addition, in the general case, we have that:

\[\left\langle E_(k1)\right\rangle \ne \left\langle E_(k2)\right\rangle \left(1.3\right).\]

To maintain the contact temperature unchanged from each unit of surface per unit time, it is necessary to remove (or supply) energy equal to $P_1-P_2.\ $From expression (1.3) it follows that:

This means that Peltier heat ($Q_p$) is released (or absorbed). In the event that $S$ is the area of contacting surfaces, then the Peltier heat is equal to:

\It\left(1.5\right),\]

where $I=jS$ is the current strength. We know that Peltier heat is expressed as:

Or for our case, from expression (1.7) we can write:

Let us compare expression (1.7) and formula (1.5), we obtain the expression for the Peltier coefficient:

\[П_(12)=\frac(1)(q_e)\left[\left(\left\langle E_(k2)\right\rangle -\left\langle E_(k1)\right\rangle \right)- q_e\left((\varphi )_1-\ (\varphi )_2\right)\right]\left(1.8\right).\]

Since we are interested in the heat in the contact, and we do not consider the Joule-Lenz heat in the volume, then in formula (1.5) one should understand by $P_1\ and\P_2$ their values near the contact plane itself. So the expression $(\varphi )_1-\ (\varphi )_2=U_(i12)$ is the contact potential jump.

If the electron gas in conductors is non-degenerate, then all electrons are accelerated by the field. The momentum distribution is described by Maxwell's law, and it depends only on temperature, then $\left\langle E_(k2)\right\rangle =\left\langle E_(k1)\right\rangle $, therefore:

\[P_(12)=u_1-\ u_2=U_(i12).\ \]

In this case, the Peltier coefficient is equal to the contact potential jump, while the Peltier heat is equal to the work done by the current due to the voltage drop.

Which is what needed to be shown.

Example 2

Quest: What is equal to the coefficient Peltier at T=0 K (case of strongly degenerate electron gas)?

In a state of strong degeneracy (T=0 K), all quantum states in the conduction band with an energy that is less than the Fermi level are completely occupied by electrons. In this case, only electrons that have energies equal to the Fermi energy can be accelerated by the field (in the first approximation, the Fermi energy will be taken equal to the chemical potential $\mu $). Therefore, in the formula for the Peltier coefficient, which we obtained in the previous example:

\[П_(12)=\frac(1)(q_e)\left[\left(\left\langle E_(k2)\right\rangle -\left\langle E_(k1)\right\rangle \right)- q_e\left((\varphi )_1-\ (\varphi )_2\right)\right]\left(2.1\right)\]

under $\left\langle E_(k2)\right\rangle \ and\ \left\langle E_(k1)\right\rangle $ one should understand the maximum kinetic energies of electrons and accept that:

\[\left\langle E_(k2)\right\rangle =(\mu )_2,\ \left\langle E_(k1)\right\rangle (=\mu )_1\left(2.2\right).\]

On the other hand, we know that:

We substitute expressions (2.3) and (2.2)

into formula (2.1), we obtain:

\[P_(12)=\frac(1)(q_e)\left[\left(m_2-m_1\right)-\left(m_1-m_2\right)\right]=0.\]

Answer: For $T$=0 $K$, $P_(12)=0\ V.$

Early 19th century. The golden age of physics and electrical engineering. In 1834, the French watchmaker and naturalist Jean-Charles Peltier placed a drop of water between bismuth and antimony electrodes and then passed an electric current through the circuit. To his amazement, he saw that the drop had suddenly frozen solid.

The thermal effect of electric current on conductors was known, but the reverse effect was akin to magic. One can understand Peltier's feelings: this phenomenon at the junction of two different areas of physics - thermodynamics and electricity evokes a feeling of a miracle even today.

The problem of cooling then was not as acute as it is today. Therefore, the Peltier effect was only addressed almost two centuries later, when electronic devices appeared that required miniature cooling systems to operate. Dignity Peltier cooling elements are small dimensions, the absence of moving parts, the possibility of cascade connection to obtain large temperature differences.

In addition, the Peltier effect is reversible: when the polarity of the current through the module is reversed, cooling is replaced by heating, so it is easy to implement precise temperature control systems - thermostats. The disadvantage of Peltier elements (modules) is the low efficiency, which requires the supply of large current values in order to obtain a noticeable temperature difference. The heat removal from the plate opposite to the cooled plane is also difficult.

But first things first. First, let's try to consider physical processes responsible for the observed phenomenon. Without plunging into the abyss of mathematical calculations, we will simply try to understand the nature of this interesting physical phenomenon on the “fingers”.

Insofar as we are talking about temperature phenomena, physicists, for the convenience of mathematical description, replace the vibrations of the atomic lattice of the material with a certain gas, consisting of, as it were, particles - phonons.

The temperature of the phonon gas depends on the temperature environment and properties of the metal. Then any metal is a mixture of electron and phonon gases in thermodynamic equilibrium. When two different metals come into contact in the absence external field a more “hot” electron gas penetrates into a zone of a “colderer” one, creating a contact potential difference known to all.

When applying a potential difference to the transition, i.e. When current flows through the interface between two metals, electrons take energy from the phonons of one metal and transfer it to the phonon gas of the other. When the polarity is reversed, the energy transfer, and hence heating and cooling, change sign.

In semiconductors, electrons and “holes” are responsible for energy transfer, but the mechanism of heat transfer and the appearance of a temperature difference is preserved. The temperature difference increases until the high-energy electrons are depleted. There is a temperature equilibrium. This is the modern picture of description Peltier effect.

It is clear from it that efficiency of the Peltier element depends on the selection of a pair of materials, the current strength and the rate of heat removal from the hot zone. For modern materials (as a rule, these are semiconductors), the efficiency is 5-8%.

And now about practical application the Peltier effect. To increase it, individual thermocouples (junctions of two different materials) are assembled into groups consisting of tens and hundreds of elements. The main purpose of such modules is the cooling of small objects or microcircuits.

Thermoelectric Cooling Module

Peltier effect modules are widely used in night vision devices with a matrix of infrared receivers. Charge-coupled microcircuits (CCDs), which are also used in digital cameras today, require deep cooling to capture images in the infrared region. Peltier modules cool infrared detectors in telescopes, active elements of lasers for radiation frequency stabilization, in precision time systems. But these are all military and special applications.

Recently, Peltier modules have found application in household products. Mainly in automotive technology: air conditioners, portable refrigerators, water coolers.

An example of the practical use of the Peltier effect

The most interesting and promising application of modules is computer technology. High performance microprocessor processors and video card chips generate a lot of heat. For their cooling, high-speed fans are used, which create significant acoustic noise. The use of Peltier modules as part of combined cooling systems eliminates noise with significant heat extraction.

Compact USB -refrigerator using Peltier modules

And, finally, a logical question: will Peltier modules replace the usual cooling systems in compression household refrigerators? Today it is unprofitable in terms of efficiency (low efficiency) and price. The cost of powerful modules is still quite high.

But technology and materials science do not stand still. It is impossible to exclude the possibility of the appearance of new, cheaper materials with high efficiency and high Peltier coefficients. Already today there are reports from research laboratories about the amazing properties of nano-carbon materials, which can radically change the situation with efficient cooling systems.

There have been reports of a high thermoelectric efficiency of clastrates - solid solutions similar in structure to hydrates. When these materials leave the research labs, completely silent refrigerators with an unlimited lifespan will replace our familiar home models.

P.S. One of the most interesting features thermoelectric technology is that it can not only use electrical energy to receive heat and cold, but also thanks to it you can but start the reverse process, and, for example, get electrical energy from heat.

An example of how you can get electricity from heat using a thermoelectric module () look at this video:

What do you think about this? I look forward to your comments!

Andrey Povny

If an electric current is passed through the boundary region between two different metals in contact, then the electrons passing through this region will, depending on the direction of the current, either be accelerated by the contact field indicated above or decelerated by it. In the first case in boundary layer heat is released (electrons that have received kinetic energy will transfer energy to metal atoms during collisions); in the second case, heat absorption (electrons that have lost speed will

in collisions with atoms, to receive energy from them, i.e., to cool the metal). If, for example, an electric current is passed through a thermoelement (Fig. II 1.37), then the temperatures of the contacts will begin to change, since in one of them the field does positive work, and in the other - negative. The release or absorption of heat during the passage of current through the boundary region, due to the work of the contact electric field, is called the Peltier effect; amount of heat per time at constant current

where is, as mentioned above, the potential difference, due to the field, the amount of electricity passed, and the constant of the thermoelectromotive force.

So, when an electric current passes through the boundary region between two metals, the following phenomena occur:

1) the release of a certain amount of heat according to the Lenz-Joule law: where is the resistance of the boundary region. This heat is independent of the direction of the current and is proportional to the square of the current strength;

2) the release or absorption of heat caused by the positive or negative work of the contact electric field (Peltier effect). This heat is proportional to the first power of the current. At low currents, the heat may be greater than

3) the transfer of energy from one metal to another, together with the electrons that have passed through the boundary region. The average kinetic energies of electrons in different metals (at the same temperature) can be different, so electrons that have passed from one metal to another will carry energy with them

Note that the indicated release and absorption of heat in the contacts also occurs in the case when an electric current flows in the thermoelement circuit, caused not by an external current source, but by the thermoelectromotive force itself (at ); in this case, in contact with a high temperature, heat is absorbed, and in contact with a low temperature, heat is released. Thus, the Peltier effect is aimed at equalizing the temperature difference in the contacts. If the creation of a temperature difference between the contacts is considered as an external effect on the thermoelement, then the Peltier effect is the counteracting reaction of this element.

The thermoelement at can be considered as physical system where heat is directly converted into electrical energy. Let us assume that in the thermoelement circuit the current strength is equal to The work performed by the thermoelectromotive force

(see formula (2.34)) for the time

However, the heat absorbed (according to the Peltier effect) in contact with a high temperature, the heat released in contact with a low temperature; the difference between them is converted into electrical energy. Therefore, the efficiency of the thermoelement

Thus, in full agreement with the second sign of thermodynamics, in a thermoelement, heat is received from a body with a high temperature, a certain amount of heat is transferred to a body with a low temperature, and the difference is converted into another form of energy. However, in the case of a thermoelement made of metals, a significant part of the heat transfers from a hot contact to a cold one by thermal conduction, so the amount of heat converted into electrical energy, even with a large temperature difference between the contacts, is only a very small part (fractions of a percent) of the total amount of heat transferred from the hot cold contact. When using, at the suggestion of A.F. Ioffe, semiconductor materials with low thermal conductivity, it is possible to bring the efficiency of a thermoelectric heat engine closer to its ideal value.

Above, only metallic conductors (conductors of the first kind) were considered, in which the appearance of a contact potential difference and the passage of an electric current are not accompanied by any chemical changes. However, the contact potential difference is also found in the system of any conductors, including, for example, electrolytes (conductors of the second kind), in which the excitation of the potential difference and the passage of current is accompanied by chemical reactions (galvanic cells, batteries). Unlike metal conductors, in a system containing electrolytes, charges (electrons, ions) are affected by special forces of “chemical” origin. Due to the presence of these external forces in a closed system of conductors containing electrolytes, there is a continuous one-way transfer of charges, i.e., there is an electric current.

Peltier effect Peltier effect

the release or absorption of heat when current passes through a contact (junction) of two different conductors. The amount of heat is proportional to the strength of the current. Used in refrigeration units. Opened in 1834 by J. Pelletier.

PELTIER EFFECT

PELTIER EFFECT, for thermoelectric phenomena (cm. THERMOELECTRIC PHENOMENA), consists in the release or absorption of heat during the passage of electric current through the contact (junction) of two different conductors. The Peltier effect is the inverse of the Seebeck effect. (cm. SEEBECK EFFECT).
Opened in 1834 by J. Pelletier (cm. PELTIER Jean Charles Athanaz), who discovered that when current passes through a junction of two different conductors, the temperature of the junction changes. In 1838 E. H. Lenz (cm. LENTS Emil Khristianovich) showed that with a sufficiently large current strength, one can either freeze or bring to a boil a drop of water deposited on a junction by changing the direction of the current.
The essence of the Peltier effect is that when an electric current passes through the contact of two metals or semiconductors in the area of their contact, in addition to the usual Joule heat, an additional amount of heat is released or absorbed, called the Peltier heat Q p. In contrast to the Joule heat, which is proportional to the square current strength, the value of Q p is proportional to the first power of the current.
Q p \u003d P. I. t.
t - current passage time,
I - current strength.
P - Peltier coefficient, proportionality factor, depending on the nature of the materials that form the contact. Theoretical concepts make it possible to express the Peltier coefficient in terms of the microscopic characteristics of conduction electrons.
Peltier coefficient P = T Da, where T is the absolute temperature, and Da is the difference in the thermoelectric coefficients of the conductors. The direction of the current determines whether Peltier heat is released or absorbed.
The reason for the effect is that in the case of contact between metals or semiconductors, an internal contact potential difference arises at the interface. This leads to potential energy carriers on both sides of the contact becomes different, since the average energy of current carriers depends on their energy spectrum, concentration and mechanisms of their scattering and is different in different conductors. Since the average energy of the electrons involved in the transfer of current differs in different conductors, in the process of collisions with lattice ions, carriers give off excess kinetic energy to the lattice, and heat is released. If during the transition through the contact the potential energy of the carriers decreases, then their kinetic energy increases and the electrons, colliding with the ions of the lattice, increase their energy to the average value, while the Peltier heat is absorbed. Thus, when electrons pass through a contact, electrons either transfer excess energy to atoms or replenish it at their expense.
During the transition of electrons from a semiconductor to a metal, the energy of the conduction electrons of the semiconductor is much higher than the Fermi level (see Fermi energy (cm. FERMI-ENERGY)) of the metal, and the electrons give up their excess energy. The Peltier effect is especially strong in semiconductors, which is used to create cooling and heating semiconductor devices, including the creation of micro-refrigerators in refrigeration units.

encyclopedic Dictionary. 2009 .

See what the "Peltier effect" is in other dictionaries:

The release or absorption of heat during the passage of electric. current I through the contact of two decomp. conductors. The release of heat is replaced by absorption when the direction of the current changes. French opened. physicist J. Peltier in 1834. The amount of heat ... ... Physical Encyclopedia

The Peltier effect is the process of generating or absorbing heat when an electric current passes through the contact of two dissimilar conductors. The amount of heat released and its sign depend on the type of contacting substances, current strength and travel time ... ... Wikipedia

The release or absorption of heat when current passes through a contact (junction) of two different conductors. The amount of heat is proportional to the strength of the current. Used in refrigeration units. Opened in 1834 by J. Peltier ... Big Encyclopedic Dictionary

The release or absorption of heat when an electric current passes through a contact (junction) of two different conductors. The release of heat is replaced by absorption when the direction of the current changes. Discovered by J. Peltier in 1834. The amount of allocated or ... Great Soviet Encyclopedia

The Peltier effect is a thermoelectric phenomenon in which heat is released or absorbed when an electric current passes at the point of contact (junction) of two dissimilar conductors. The amount of heat released and its sign depend on the type ... Wikipedia

The thermal converter (Peltier module) works on the principle opposite to the action of a thermocouple - the appearance of a temperature difference when an electric current flows.

How does the Peltier element work?

It is quite simple to use the Peltier module, the principle of which is to release or absorb heat at the moment of contact of different materials when the energy flow of electrons passes through it before and after the contact is different. If it is less at the outlet, it means that heat is released there. When electrons in contact are decelerated by an electric field, they transfer kinetic energy to the crystal lattice, heating it up. If they accelerate, the heat is absorbed. This is due to the fact that part of the energy is taken from the crystal lattice and its cooling occurs.

To a large extent, this phenomenon is inherent in semiconductors, which is explained by big difference charges.

The Peltier module, the application of which is the topic of our review, is used in the creation of thermoelectric cooling devices (TEM). The simplest of them consists of two p- and n-type semiconductors connected in series through copper contacts.

If the electrons move from semiconductor "p" to "n", at the first transition with a metal jumper they recombine with the release of energy. The next transition from the semiconductor "p" to the copper conductor is accompanied by the "pulling" of electrons through the contact by the electric field. This process leads to energy absorption and cooling of the area around the contact. Similarly, processes occur at the next transitions.

When the heated and cooled contacts are located in different parallel planes get a practical implementation of the method. Semiconductors are made from selenium, bismuth, antimony or tellurium. The Peltier module accommodates a large number of thermocouples placed between nitride or aluminum oxide ceramic plates.

Factors affecting the efficiency of TEM

Current strength.
Number of thermocouples (up to several hundred).
Types of semiconductors.
cooling rate.

It has not yet been possible to achieve large values due to low efficiency (5-8%) and high cost. In order for the TEM to work successfully, it is necessary to ensure efficient heat removal from the heated side. This creates difficulties in the practical implementation of the method. If the polarity is reversed, the cold and hot sides reverse with each other.

Advantages and disadvantages of modules

The need for TEM appeared with the advent of electronic devices requiring miniature cooling systems. The advantages of the modules are as follows:

compactness;
lack of mobile connections;
the Peltier module has a reversible principle of operation when changing polarity;
ease of cascading connections for increased power.

The main disadvantage of the module is its low efficiency. This manifests itself in high power consumption when achieving the desired cooling effect. In addition, it has a high cost.

Application of TEM

The Peltier module is mainly used for cooling microcircuits and small parts. A start was made to cool elements of military equipment:

microcircuits;
infrared detectors;
elements of lasers;
quartz generators.

The Peltier thermoelectric module gradually began to be used in household appliances: to create refrigerators, air conditioners, generators, temperature controllers. Its main purpose is to cool small objects.

CPU Cooling

The main components of computers are constantly being improved, which leads to an increase in heat dissipation. Together with them, cooling systems are developing with the use of innovative technologies, with modern means of control. The Peltier module has found application in this area primarily in the cooling of microcircuits and other radio components. Traditional coolers can no longer cope with forced overclocking modes of microprocessors. And increasing the frequency of the processors makes it possible to increase their performance.

Increasing the fan speed results in significant noise. It is eliminated by using a Peltier module in a combined cooling system. In this way, advanced firms quickly mastered the production of efficient cooling systems, which began to be in great demand.

Heat is usually removed from processors by coolers. The air flow can be sucked in from outside or come from inside the system unit. The main problem is that the air temperature is sometimes insufficient for heat removal. Therefore, TEMs began to be used to cool the air flow entering the system unit, thereby increasing the efficiency of heat transfer. Thus, the built-in air conditioner is an assistant to the traditional computer cooling system.

Aluminum radiators are mounted on both sides of the module. From the side of the cold plate, air is forced to cool the processor. After it picks up the heat, it is blown out by another fan through the module's hot plate heatsink.

A modern TEM is controlled by an electronic device with a temperature sensor, where the degree of cooling is proportional to the temperature of the processor.

Activating processor cooling also creates some problems.

Simple Peltier cooling modules are designed for continuous operation. Lower power consumption also reduces heat dissipation, which can cause the die to overcool and subsequently freeze the processor.
If the operation of the cooler and refrigerator is not properly coordinated, the latter may go into heating mode instead of cooling. The source of additional heat will cause the processor to overheat.

Thus, modern processors require advanced cooling technologies with control over the operation of the modules themselves. Such changes in operating modes do not occur with video cards, which also require intensive cooling. Therefore, TEM is ideal for them.

Do-it-yourself auto-refrigerator

In the middle of the last century, the domestic industry tried to master the production of small-sized refrigerators based on the Peltier effect. Existing technologies At that time they were not allowed to do so. Right now, the high price is predominantly a deterrent, but efforts are ongoing and progress has already been made.

The wide production of thermoelectric devices allows you to create a small refrigerator that is convenient for use in cars. Its basis is a "sandwich", which is made as follows.

A layer of heat-conducting paste of the KPT-8 type is applied to the upper radiator and the Peltier module is glued on one side of the ceramic surface.
Similarly, another radiator is attached to it from the bottom side, designed to be placed in the refrigerator chamber.
The whole device is tightly compressed and dried for 4-5 hours.
Coolers are installed on both radiators: the top one will remove heat, and the bottom one will equalize the temperature in the refrigerator chamber.

The body of the refrigerator is made with a heat-insulating gasket inside. It is important that it closes tightly. To do this, you can use a regular plastic tool box.

12V power is supplied from the vehicle system. It can also be made from a 220 V network. alternating current, with power supply. The circuit for converting AC to DC is the simplest. It contains a rectifier bridge and a ripple-smoothing capacitor. At the same time, it is important that at the output they do not exceed the value of 5% of nominal value otherwise the performance of the device will be reduced. The module has two outputs from colored wires. "Plus" is always connected to red, "minus" to black.

The power of the TEM must correspond to the volume of the box. The first 3 digits of the marking indicate the number of pairs of semiconductor microelements inside the module (49-127 or more). expressed by the last two digits of the marking (from 3 to 15 A). If the power is not enough, you need to glue another module on the radiators.

Note! If the current exceeds the power of the element, it will heat up on both sides and quickly fail.

Peltier module: electrical energy generator

TEM can be used to generate electricity. To do this, it is necessary to create a temperature difference between the plates, and the thermocouples located between them will generate an electric current.

For practical use, you need a TEM with at least 5 V. Then it can be used to charge mobile phone. Due to the low efficiency of the Peltier module, a DC boost converter will be required. To assemble the generator you will need:

2 Peltier modules TES1-12705 with plate size 40x40 mm;
converter EK-1674;
aluminum plates 3 mm thick;
pot for water;
heat resistant adhesive.

Two modules are placed between the plates with glue, and then the whole structure is fixed at the bottom of the pan. If you fill it with water and put it on fire, you get the necessary temperature difference that generates an EMF of about 1.5 V. By connecting the modules to a boost converter, you can increase the voltage to 5 V, which is necessary to charge the phone battery.

The greater the temperature difference between the water and the lower heated plate, the more efficient the generator will be. Therefore, it is necessary to try to reduce the heating of water different ways: make it flowable, replace it with fresh one more often, etc. An effective means of increasing the temperature difference is the cascading of modules when they are superimposed in layers one on top of the other. Increasing the overall dimensions of the device allows you to place more elements between the plates and thereby increase the overall power.

The performance of the generator will be enough to charge small batteries, operate LED lamps or a radio. Note! To create thermogenerators, you will need modules capable of operating at 300-400 0 C! The rest are only suitable for trial tests.

Unlike other means of alternative energy generation, they can work while driving, if you create something like a catalytic heater.

Domestic Peltier modules

TEMs of their own production appeared on the market not so long ago. They are highly reliable and have good performance. The Peltier module, which is in great demand, has dimensions of 40x40 mm. It is rated for a maximum current of 6 A and a voltage of up to 15 V.

You can buy a domestic Peltier module for a small price. At 85 W, it creates a temperature difference of 60 0 C. Together with a cooler, it is able to protect a processor with a power dissipation of 40 W from overheating.

Characteristics of modules of leading companies

Foreign devices are presented on the market in a greater variety. To protect the processors of leading companies, a Peltier module is used as a PAX56B refrigerator, the price of which, complete with a fan, is $35.

With dimensions of 30x30 mm, it maintains a processor temperature of no higher than 63 0 C with an allocated power of 25 watts. For power supply, a voltage of 5 V is sufficient, and the current does not exceed 1.5 A.

The Peltier RA6EXB module is well suited for processor cooling, providing normal temperature conditions with a dissipation power of 40 watts. The area of its module is 40x40 mm, and the current consumption is up to 8 A. In addition to its impressive size - 60x60x52.5 mm (together with a fan), the device requires free space around it. Its price is $65.

When a Peltier module is used, its specifications must match the needs of the devices to be cooled. It is unacceptable that they have too low a temperature. This can lead to moisture condensation, which is detrimental to electronics.

Modules for the manufacture of generators, such as are more powerful - 72 W and 108 W, respectively. They are distinguished by the marking, always applied to the hot side. The maximum allowable temperature of the hot side they have is 150-160 0 C. The greater the temperature difference between the plates, the higher the output voltage. The device operates at a maximum temperature difference of 600 0 C.

You can buy a Peltier module inexpensively - about $ 10 or less per piece, if you search well. Quite often, sellers significantly inflate prices, but you can find several times cheaper if you buy at a sale.

Conclusion

The Peltier effect has now found application in the creation of small refrigerators needed modern technology. The reversibility of the process makes it possible to manufacture microelectric power plants that are in demand for charging batteries of electronic devices.

Unlike other means of alternative power generation, they can operate while driving if a catalytic heater is installed.