With the help of simple devices, heat losses from heating air or liquids can be used. In this article, we will tell you how to use the waste energy of furnaces, boilers and open fires, converting it into a constant electricity little strength.
Any chemical process takes place with the release of various kinds of energy. Such a powerful source as combustion has been used at all times. It can be called the primary source of heat and light. Almost all substances on Earth burn, releasing heat and light in different quantities. Converting thermal energy into electrical energy is not difficult if you have a working steam turbine at hand, similar to those installed at a thermal power plant. This is a bulky and complex device, which is unlikely to find a place in the boiler room of a country house. We will try to benefit from the release of heat during stove heating or water heating.
The Peltier effect is a phenomenon of temperature difference during the interaction of thermocouples of two various types conductors (p-type and n-type) when passing through them direct current. The Seebeck effect is a consequence of the Peltier effect, when an electric current is generated when one of the thermocouples is heated. We will not describe in detail the thermodynamics of the process - this difficult-to-understand information can be easily found in the reference literature. We are interested in the result and options for its practical use.
Thermoelectric module design
A thermoelectric module (TEM) consists of many thermocouples interconnected by a copper plate. The thermocouple field is glued between two ceramic plates. It is possible to assemble such a module only in the factory. But it will be possible to assemble several TEMs for your own needs at home. Peltier-Seebeck elements are available for free sale in specialized stores (and websites) for the sale of technological equipment.
We collect TEM for 5 V
What you need:
- Peltier module TEC1-12705 (40x40) — 2 pcs.;
- step-up DC voltage converter EK-1674;
- sheet of duralumin 3 mm thick;
- a water tank with a perfectly flat bottom (bucket);
- hot glue;
- soldering iron.
We cut out two identical plates from a sheet of duralumin, a little more than two modules in size, lying side by side. We strengthen the plates on the modules on both sides with hot glue. We fix (with hot glue) the resulting “sandwich” to the bottom of the bucket. Such a design can already be put on fire, but we will get useless 1.5 V at the output. To improve performance, we need a boost converter, which we solder into the circuit. It will increase the voltage to 5 V, which is already enough to charge a mobile phone.
Attention! The converter has dimensions of 1.5x1.5 cm. In the absence of professional skills, entrust the soldering to a specialist.
The temperature difference in our design is obtained by heating one side (from the furnace or flame) and cooling the other (water in the ladle). Of course, the greater the difference, the work more efficiently module. Therefore, to work in the microgenerator mode, you will need a relatively low temperature of water in the ladle (it is better to replace it periodically). To generate the cherished 5 V, it is enough to put the design on a glass with a burning candle.
By proportionally combining more modules, we get a more efficient power generation system. Accordingly, increasing the design, we proportionally increase the heat exchanger. In this case, the surface to be cooled must be completely covered with a container of water (the easiest and most affordable option).
Everything is so simple that immediately there is a desire to collect more modules into one system and generate 220 V from a fire. And then connect an oil heater or air conditioner. Such a simple system has its drawbacks, and the main one is low efficiency. Usually this figure does not exceed 5%. This causes a relatively low current strength of 0.5 - 0.8 A and very low power - up to 4 watts.
For a pump or an incandescent lamp, this is negligible, but quite enough for:
- charging batteries up to motorcycle (in options proportional to requirements);
- work of light-emitting diode (LED) lamps;
- radio receiver.
In winter, a system placed on a heat source located outside will work as efficiently as possible.
The cost of materials for the assembly of a thermoelectric microgenerator for 5 V:
*- this model item was chosen for price reasons. The range of TEMs from supplier companies is quite wide, which allows you to choose more productive (up to 8 V) models (they are significantly more expensive).
Factory products of a similar design are just beginning to appear on sale. Serial production is carried out in small batches, and the range is small. The cost of such a "ladle" starts from 2500 rubles.
The factory thermogenerator is a device based on the Peltier-Seebeck effect, which can be mounted directly on a heated surface. From the design described above, it is distinguished by the factory design (and therefore reliability), the absence of a liquid heat exchanger (instead of it - fins for air cooling) and a higher price.
The standard "camping" thermogenerator has the following characteristics:
As can be seen from the table, factory reliability and utility are not cheap. At the same time, it cannot be said that it is functionally superior to the home-made version with a bucket. An impressive 13.5 V will speed up the charging of the mobile phone, but for this you will need to carry 2 kg of weight with you on a hike, and this is an unaffordable luxury (given the size of the device). And, of course, the price makes you think. For this amount, you can no longer collect a “thermal ladle”, but a “thermal saucepan” and calmly charge a laptop. And one more nuance - the device still requires fixing on a metal plate in case of using an open flame.
In general, this is a pleasant and convenient addition for those who do not have problems with money and free space in the trunk.
Energy furnace
To date, the energy furnace is the apotheosis of the use of TEM in everyday life. This is a factory product, in fact, a “potbelly stove”, for any type of solid fuel with an integrated thermoelectric module. An ideal option for hunting lodges, dachas, remote winterings and in general any kind of life away from civilization. Designed for autonomous use (without peripheral heat sinks), it has only a hearth and a chimney. Includes food preparation. The most powerful Peltier-Seebeck elements are installed on this furnace.
Characteristics of energy furnaces:
Although the oven is portable, it is certainly the “heavy weight category” among household appliances. However, the range of tasks for an energy stove is quite wide - it can even charge car batteries, illuminate entire rooms with LED lamps. She will find a place in the expedition wagon train and in the hunting all-terrain vehicle, in the technical room and in the country. In other words, in this case, we always have a heat source with us, it remains to find fuel.
In its niche, the energy furnace is indispensable, although the service life declared by the manufacturer is a little alarming - 10 years. It should be noted that, as in a thermogenerator, there is the possibility of preventive (or emergency) replacement of all parts up to the housing.
Thermoelectric modules are extremely interesting objects. In addition to the applications described, they are also used for water and air conditioning. In this case, the same element is fed D.C. and it works "in the opposite direction" - it cools the air. This technology has been successfully used in automotive air conditioners and water coolers, in the automotive industry and in microprocessor manufacturing. We will describe these devices in the next article.
Vitaly Dolbinov, rmnt.ru
> Generators > Thermoelectric generator
A huge number of electronic devices absorb electrical energy, which must be constantly renewed. While on the road, you have to carry chemical current sources with you or generate electricity from mechanical energy using complex and bulky devices.
Type of thermoelectric generator
Even earlier, Seebeck discovered the occurrence of thermo-EMF in a circuit of dissimilar conductors while maintaining different temperatures at the contact point.
Based on thermoelectric effects, the so-called Peltier element or module was created, which is 2 ceramic plates with a bimetal located between them.
When an electric current is applied through them, one side of the plate heats up and the other cools, which makes it possible to create refrigerators from them. The figure below shows modules of different sizes used in engineering.
Peltier modules in different sizes
The process is reversible: if a temperature difference is maintained on the elements on both sides, an electric current will be generated in them, which allows the device to be used as a thermoelectric generator to generate a small amount of electricity.
The Peltier effect is the release of heat at the point of contact of dissimilar conductors when an electric current flows through them.
The principle of operation of the modules
At the contact of dissimilar conductors, heat is released or absorbed, depending on the direction of the electric current. The flow of electrons has potential and kinetic energy. The current density in the contacting conductors is the same, but the energy flux densities are different.
If the energy flowing into the contact is greater than the energy flowing out of it, this means that the electrons slow down at the point of transition from one area to another and heat up the crystal lattice (the electric field slows down their movement). When the direction of the current changes, the reverse process of electron acceleration occurs, when the energy is taken from the crystal lattice and it is cooled (the directions of the electric field and the movement of electrons coincide).
The energy charge difference at the boundary of semiconductors is the highest and the effect is most pronounced in them.
Peltier module
The most common thermoelectric module (TEM), which is p- and n-type semiconductors, interconnected through copper conductors.
Scheme of the principle of operation of the module
In one element, there are 4 transitions between metal and semiconductors. With a closed circuit, the flow of electrons moves from the negative pole of the battery to the positive, sequentially passing through each transition.
Near the first copper-p-type semiconductor transition, heat is released in the semiconductor zone, as the electrons pass into a state with a lower energy.
Near the next boundary with the metal in the semiconductor, heat is absorbed due to the “sucking out” of electrons from the p-conduction band under the action of an electric field.
At the third transition, the electrons enter the n-type semiconductor, where they have more energy than in the metal. In this case, energy is absorbed and the semiconductor is cooled near the transition boundary.
The last transition is accompanied by the reverse process of heat release in the n-semiconductor due to the transition of electrons to a zone with a lower energy.
Since the heating and cooling transitions are in different planes, the Peltier element will cool from above and heat up from below.
In practice, each element contains a large number of heating and cooling transitions, which leads to the formation of a noticeable temperature difference, which makes it possible to create a thermoelectric generator.
What does the module structure look like?
The Peltier element contains a large number of semiconductor parallelepipeds of p- and n-types, connected in series with metal jumpers - thermal contacts, with the other side in contact with the ceramic plate.
Bismuth telluride and silicon germanide are used as semiconductors.
Advantages and disadvantages of TEM
The advantages of a thermoelectric module (TEM) include:
- small size;
- the ability to work as coolers and heaters;
- reversibility of the process when changing the polarity, which allows maintaining the exact temperature value;
- lack of moving parts that usually wear out.
Disadvantages of modules:
- low efficiency (2-3%);
- the need to create a source that provides a temperature difference;
- significant electricity consumption;
- high price.
Despite the disadvantages, TEMs are used where high energy costs do not matter:
- cooling of chips, parts of digital cameras, diode lasers, quartz oscillators, infrared detectors;
- the use of TEM cascades, allowing to achieve a low temperature;
- creation of compact refrigerators, for example, for cars;
- thermoelectric generator for charging mobile devices.
With a low productivity of TEG, it is advisable to use it in field conditions, where it is necessary to obtain electricity for charging. cell phone or led light bulb. The simplicity of the design allows you to make an electric generator with your own hands.
Alternative sources are also solar panels or wind turbine. For the first, special conditions are required - the presence of sunlight, which may not always be. Another source is large and requires wind. Another disadvantage they have is the presence of moving parts that reduce reliability and are heavy.
Thermal generators for industrial production
BioLite has developed a new hiking model that allows you to cook in a compact portable wood-burning stove and simultaneously charge your mobile device from the built-in TEG.
Compact portable wood burning stove
The device is useful everywhere: fishing, camping, in the country. Anything that burns can be used as fuel.
During combustion in the fuel furnace, heat is transferred through the wall to the module, which generates electricity.
At a voltage of 5V, the output power is 2-4W, which is enough to charge many types of mobile devices and operate LED lighting.
The red arrow shows the direction of heat movement, the blue one - cold air into the furnace, the yellow arrow - the supply of electricity to rotate the air suction fan and to the generator output via USB.
Scheme of operation of BioLite TEG on wood
The furnace-generator "Indigirka", developed by the St. Petersburg enterprise Krioterm, has the following characteristics:
- thermal power - 6 kW;
- weight - 56 kg;
- dimensions - 500x530x650 mm;
- email power at a voltage of 5V - 60 watts.
The furnace is an ordinary heating and cooking furnace, where thermoelectric generators are fixed on both sides.
What does the furnace-thermoelectric generator "Indigirka" look like?
The device is quite convenient, but the price is impressive - 50 thousand rubles. Although the stove is designed for field conditions, it will obviously not be affordable for ordinary hunters and fishermen. As a heating system, it is no better than conventional and cheaper models.
If you attach a TEG to a simple furnace, a do-it-yourself device will work perfectly.
DIY TEG
To assemble a thermoelectric generator with your own hands, you need the following elements:
- Module. Not all modules can be used to generate electric current, but only those that can withstand heating up to 300-4000C. The presence of a margin for heating is necessary, since even with a slight overheating, the element fails. The most common models of the TEC1-12712 type are in the form of square plates with a side size of 40, 50 or 60 mm.
If you take the maximum size, it is enough to use one element in a do-it-yourself design. The first 3 digits of the marking - 127 mean how many elements are contained in 1 plate. The last digits show the maximum allowable current, which is 12 A.
- boost converter. It is necessary to obtain a constant voltage of 5V. The generator may produce a lower voltage, which must be increased. Devices are produced by foreign (types 5V NCP1402 and MAX 756) and domestic (3.3V / 5V EK-1674). To charge your mobile phone, you need to choose a device with a USB connector.
- Heater. The simplest options are a fire, a candle, homemade lamp Or a mini oven.
- cooler. The easiest way is to use water or in winter - snow.
- Connecting elements. Equipment is needed to create the highest possible temperature difference between the two sides of the plate. Here the choice is up to the craftsmen, they most often use 2 mugs or pans of different sizes, in which the handles are sawn off and where one is inserted inside the other. A module is placed between them and attached to the thermal paste. 2 wires are soldered to it and connected to a voltage converter.
To increase the efficiency of the generator, the bottoms of the metal surfaces of mugs or pans in contact with the generator plate should be polished. In addition, a heat-resistant sealant is applied to the places between the bottoms of the smaller and larger mugs. Then the heat from heating will be localized at the location of the module.
The wires between the module and the converter are protected by heat-resistant insulation and sealant.
Water is poured into the inner mug, and the whole structure is put on fire. After a few minutes, you can check the output voltage with a multimeter.
In order to assemble a thermoelectric generator yourself, you will need materials:
- the Peltier element";
- case from an old computer power supply for making a mini-firebox;
- voltage converter with USB output to 5V with input 1-5V;
- radiator with a cooler from the processor;
- thermal paste.
The costs here are small and the device is quite capable of charging mobile phone. The do-it-yourself generator is an analogue of the foreign model of BioLite. If you assemble it carefully, the device will work reliably. long time, since there is nothing to break here. It is only important not to overheat the Peltier element, which can cause it to fail.
When using a cooler to cool the radiator, it should be connected to the generator, after which part of the generated energy will be spent on cooling.
Despite the additional energy costs, the efficiency of the installation will increase. If the radiator becomes very hot during operation, it is necessary to take measures to cool it. Otherwise, the efficiency of the generator will be low.
The characteristics of the generator are as follows:
- output voltage - 5V;
- load power - 0.5A;
- output type - USB;
- fuel - any.
The device is made as follows:
- disassemble the power supply, leaving the case;
- glue the Peltier module to the radiator with thermal paste. It is necessary to glue the cold side where the marking is applied;
- clean and polish the outer side surface of the power supply housing and glue the element to it with the other side (together with the radiator);
- solder the wires from the input of the voltage converter to the terminals of the plate.
You can check the TEG by placing thin twigs inside the furnace and setting them on fire. After a few minutes, you can connect a phone, which requires a temperature difference of 1000C between the sides of the module to recharge. The figure below shows the generator in the assembly.
Do-it-yourself thermoelectric generator assembly
When using the TEG, it is necessary to observe the polarity of the modules connection.
. thermoelectric generator
The Peltier effect makes it possible to create small generators and refrigerators that operate without moving parts. Improving the quality of modules and reducing the power consumption of mobile devices makes it possible to create a do-it-yourself thermoelectric generator for charging batteries and supplying large quantity energy various devices, where efficiency does not matter much.
Source: https://elquanta.ru/generator/termoehlektricheskijj-generator.html
In order to get electricity, you need to find a potential difference and a conductor. People have always sought to save money, and in the era of ever-growing utility bills, this is not at all surprising.
Today, there are already ways by which a person can get free electricity for him.
As a rule, these are certain do-it-yourself installations, which are based on an electric generator.
A thermoelectric generator is a device that generates electrical energy from heat. This is an excellent steam source of electricity, however, with low efficiency.
As a device for the direct conversion of heat into electrical energy, thermoelectric generators are used, which use the principle of operation of conventional thermocouples.
In essence, thermoelectricity is the direct conversion of heat into electricity in liquid or solid conductors, and then the reverse process of heating and cooling the contact of various conductors using electric current.
Heat generator device:
- The heat generator has two semiconductors, each of which consists of a certain number of electrons;
- They are also interconnected by a conductor, above which there is a layer capable of conducting heat;
- A thermionic conductor is also attached to it for transferring contacts;
- Next comes the cooling layer, followed by the semiconductor whose contacts lead to the conductor.
Unfortunately, a heat and power generator is not always able to work with large capacities, therefore it is used mainly in everyday life, and not in production.
To date, the thermoelectric converter is almost never used. It “requests” a lot of resources, it also takes up space, but the voltage and current that it can generate and convert are very small, which is extremely unprofitable.
Solar thermal generator of electricity and radio waves
Sources of electrical energy can be very different. Today, the production of solar thermoelectric generators has begun to gain popularity. Such installations can be used on lighthouses, in space, cars, as well as other areas of life.
Solar thermal generators are a great way to save energy
RTG (stands for radionuclide thermoelectric generator) works by converting isotope energy into electrical energy. This is a very economical way to get almost free electricity and the possibility of lighting in the absence of electricity.
RITEG features:
- It is easier to obtain an energy source from isotope decays than, for example, to do the same by heating a burner or a kerosene lamp;
- The production of electricity and the decay of particles are possible in the presence of special isotopes, because the process of their decay can last for decades.
Using such an installation, you need to understand that when working with old models of equipment, there is a risk of getting a dose of radiation, and it is very difficult to dispose of such a device. If destroyed incorrectly, it can play the role of a radiation bomb.
When choosing a manufacturer of the installation, it is better to focus on companies that have already proven themselves. Such as Global, Altec (Altec), TGM (Tgm), Cryotherm, Termiona (Termiona).
By the way, another good way to get electricity for free is a generator for collecting radio waves. It consists of pairs of film and electrolytic capacitors, as well as low-power diodes. An insulated cable of about 10-20 meters is taken as an antenna and another ground wire is attached to a water or gas pipe.
How to make a Peltier element with your own hands
The usual Peltier element is a plate assembled from parts of various metals, with connectors for connecting to the network. Such a plate passes current through itself, heating up on one side (for example, up to 380 degrees) and working from cold on the other.
The Peltier element is a special thermoelectric converter that operates on the same principle of supplying electric current.
Such a thermogenerator has the opposite principle:
- One side may be heated by a burning fuel (for example, a wood fire or some other raw material);
- The other side, on the contrary, is cooled by a liquid or air heat exchanger;
- Thus, a current is generated on the wires, which can be used according to your needs.
True, the performance of the device is not very large, and the effect is not impressive, but, nevertheless, such a simple home-made module may well charge the phone or connect an LED flashlight.
This generator element has its advantages:
- Silent operation;
- The ability to use what is at hand;
- Light weight and mobility.
Such homemade stoves began to gain popularity among those who like to spend the night in the forest by the fire, using the gifts of the earth and who are not averse to getting electricity for free.
The Peltier module is also used to cool computer boards: the element is connected to the board and, as soon as the temperature rises above the permissible level, it starts to cool the circuits. On the one hand, the device enters the cold air space, on the other - hot. The 50X50X4mm (270w) model is popular. Such a device can be bought in a store or made by yourself.
By the way, connecting a stabilizer to such an element will allow you to get an excellent charger for household appliances, and not just a thermal module.
To make a Peltier element at home, you need to take:
- Bimetal conductors (about 12 pieces or more);
- Two ceramic plates;
- Cables;
- Soldering iron.
The manufacturing scheme is as follows: the conductors are soldered and placed between the plates, after which they are tightly fixed. In this case, you need to remember about the wires, which will then be attached to the current converter.
The scope of the use of such an element is very diverse. Since one of its sides tends to cool, with the help of this device you can make a small camping refrigerator, or, for example, an air conditioner.
But, like any device, this thermocouple has its pros and cons. The advantages include:
- Compact size;
- Ability to work with cooling or heating elements together or each separately;
- Quiet, almost silent operation.
Minuses:
- The need to control the temperature difference;
- Large energy consumption;
- Low level of efficiency at high cost.
A simple homemade generator
Despite the fact that these devices are not currently popular, on this moment there is nothing more practical than a thermogenerator unit, which is quite capable of replacing an electric stove, a lighting bulb during a trip, or helping out if the charging to a mobile phone is broken, powering the power window. Such electricity will also help at home in the event of a power outage. It can be obtained for nothing, one might say, on a ball.
So, to make a thermoelectric generator, you need to prepare:
- Voltage regulator;
- soldering iron;
- Any body;
- Radiators for cooling;
- thermal grease;
- Peltier heating elements.
Instrument assembly:
- First, the body of the device is made, which should be without a bottom, with holes at the bottom for air and at the top with a stand for the container (although this is not necessary, since the generator may not work on water);
- Next, a Peltier element is attached to the case, and a cooling radiator is attached to its cold side through thermal paste;
- Then you need to solder the stabilizer and the Peltier module, according to their poles;
- The stabilizer should be very well insulated so that moisture does not get there;
- It remains to check his work.
By the way, if it is not possible to get a radiator, you can use a computer cooler or a car generator instead. Nothing bad will happen from such a replacement.
The stabilizer can be bought with a diode indicator that will give a light signal when the voltage reaches the specified value.
Such a heat generator warms up for about 30 seconds, but at the same time, the voltage it consumes already reaches several volts. After a few minutes of warming up, the generator will be ready for operation.
Do-it-yourself thermocouple: process features
What is a thermocouple? A thermocouple is an electrical circuit consisting of two different elements with electrical contact.
The thermoelectric power of a thermocouple with a temperature difference of 100 degrees at its edges is about 1 mV. To make it higher, several thermocouples can be connected in series. A thermopile will be obtained, the thermoEMF of which will be equal to the total sum of the EMF of thermocouples included in it.
The thermocouple manufacturing process is as follows:
- A strong connection of two different materials is created;
- Take a voltage source (for example, car battery) and wires of different materials pre-twisted into a bundle are connected to one of its ends;
- At this time, you need to bring a lead connected to graphite to the other end (a regular pencil rod will do here).
By the way, for safety it is very important not to work under high voltage! The maximum figure in this regard is 40-50 volts. But it is better to start with small capacities from 3 to 5 kW, gradually increasing them.
There is also a "water" way to create a thermocouple. It consists in ensuring that the connected wires of the future structure are heated by an arc discharge that appears between them and a strong solution of water and salt.
In the process of such interaction, "water" vapors hold the materials together, after which the thermocouple can be considered finished. In this case, it matters what diameter the bundle of the product is.
It shouldn't be too big.
Do-it-yourself free electricity (video)
Getting free electricity is not as tricky as it seems. Thanks to various kinds of generators working with different sources, it is no longer scary to be left without electricity during a power outage. A little skill and you have your own mini-station for generating electricity.
Source: http://6watt.ru/elektrosnabzhenie/free-of-charge-elektrichestvo
Peltier module: technical specifications
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 current passes through it. The energy flux density of electrons before and after contact is different.
If it is less at the outlet, it means that heat is released there. When the electrons in the contact are decelerated electric field, they transfer kinetic energy to the crystal lattice, heating it. 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 a large charge difference.
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 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 an 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, a practical implementation of the method will be obtained. 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.
Large values have not yet been achieved 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 has gradually been used in household appliances: to create refrigerators, air conditioners, generators, thermostats. 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 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. The existing technologies of that time did not allow this. 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 AC network, with a 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 5% of the nominal value, otherwise the efficiency of the device is 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). The current strength is 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 will be possible to charge a mobile phone with it. 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, we must try to reduce the heating of water in various ways: make it flowing, replace it with fresh water more often, etc.
An effective means of increasing the temperature difference is the cascade connection 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 0C! 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. With a power consumption of 85 W, it creates a temperature difference of 60 0C. Together with the cooler, it is able to protect the 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 the processor temperature no higher than 63 0C with a power output 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 regime at a power dissipation 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 dimensions - 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 TEC1-12706, TEC1-12709, 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 is 150-160 0C. The greater the temperature difference between the plates, the higher the output voltage.
The device operates at a maximum temperature difference of 600 0C.
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 found application at the present time in the creation of small refrigerators required by 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.
A little bit of theory.
single element thermoelectric module (TEM) is a thermocouple consisting of two dissimilar elements with p- and n-type conductivity. The elements are interconnected by means of a connecting plate made of copper. Semiconductors based on bismuth, tellurium, antimony, and selenium are traditionally used as element materials.
Thermoelectric module (Peltier element) is a set of thermocouples electrically connected, usually in series. In a standard thermoelectric module, thermocouples are placed between two flat ceramic plates based on aluminum oxide or nitride. The number of thermocouples can vary over a wide range - from units to hundreds of pairs, which makes it possible to create TEMs of almost any refrigeration power - from tenths to hundreds of watts.
When direct electric current passes through the thermoelectric module, a temperature difference is formed between its sides - one side (cold) is cooled, and the other (hot) is heated. If efficient heat removal is ensured from the hot side of the TEM, for example, using a radiator, then on the cold side it is possible to obtain a temperature that will be tens of degrees lower than the ambient temperature. The degree of cooling will be proportional to the magnitude of the current. When the polarity of the current is reversed, the hot and cold sides are reversed.
Practice.
Pelte elements are widely used in cooling systems. But not many people know about their other property - to generate energy. This laboratory work is devoted to the study of their capabilities.
50*50 mm element installed between two aluminum bars. Their surfaces are preliminarily lapped and lubricated with KPT paste. Through holes are drilled in one of the bars, through which a copper tube is passed for water cooling. Here's what happened:
We connect water to the cooler to one side Peltier element, and put the other on the burner. We connect a 10W 6 volt light bulb to the output of the element. Result - our generator works!
Experience proves that the Peltier element generates electricity well. The light bulb burns brightly enough, the voltage is about 4.5 volts.
Heating up to 160 degrees was not optimal, at 120 degrees the result was only 10% worse.
The coolant temperature at the outlet is ten degrees, at the inlet it is one degree less. Judging by these results, water is not so necessary for cooling ...
With help Peltier elements you can get electricity on an expedition, on a camping trip, at a hunting lodge, in a word, in any place where it may be needed. Naturally, in the presence of firewood or bright sun, and, of course, ingenuity.
Use of thermoelectric module.
Such a thermoelectric generator is well remembered by those who remember Soviet state farms and collective farms. They say that during the war the Germans could not understand how the partisans could broadcast for a long time from the besieged forest.
Yes, as they say - if our scientists were paid money, they would have invented the iphone back in `85! :-)
thermoelectric refrigerator
Thermoelectric refrigerator (option 2)
Thermoelectric refrigerator (option 3)
Car cooler for canned drinks
Drinking water cooler
Thermoelectric air conditioner for KAMAZ cab
Water is poured into such a "ladle", put on fire and, please, recharge your mobile phone. The whole secret is in the bottom, Peltier is "buried" there
Let's take a closer look at this design.
There is currently a growing interest in the use of thermoelectric generator modules in home appliances. First of all, this concerns the possibility of supplying low-power consumers of electricity - radios, cellular and satellite phones, portable computers, automation devices, etc. from available heat sources. A thermoelectric generator, in which there are no rotating, rubbing or any other wear parts, allows you to directly receive electricity from any heat source: exhaust gases from internal combustion engines, hot water from geothermal sources, "waste" heat from thermal power plants, etc. Guided by the experience gained in the creation of industrial thermoelectric generators (TEG) of various power - from several watts to several kilowatts, IPF KRYOTHERM started mass production of domestic TEG with a nominal power of 8 W. Structurally, the generator is made in the form of an aluminum ladle with an internal volume of about 1 l in the bottom part of which generator modules manufactured by IPF Kryotherm are installed.
The temperature difference necessary for the operation of the generator is achieved when the ladle is heated, for example, by a fire flame. The water heated inside the ladle can be used for cooking or for other purposes. This generator is primarily intended for use in remote, hard-to-reach places for recharging batteries for personal communications and navigation, lighting, etc. It is indispensable for hunters, tourists, sailors, rescue and special services employees who are forced to stay away from central energy sources for a long time.
The advantage of the generator is its low weight and volume, high specific power generated, functionality and high reliability. The design of the generator excludes a possibility of its overheat at the correct use. As an additional option, the generator is offered with a step voltage regulator with ranges of 3V - 6V - 9V -12V and adapters for chargers.
HOUSEHOLD THERMOELECTRIC GENERATOR 1TG-8
Data sheet
Weight without liquid, kg, no more than 0.55
Overall dimensions, mm
without handle 250x130x110? 123, h=100
Many electricians are interested in one very popular question - how to get a small amount of electricity autonomously and for free. Very often, for example, when going out into nature or hiking, there is a catastrophic lack of an outlet to recharge the phone or turn on the lamp. In this case, a self-made thermoelectric module assembled on the basis of a Peltier element will help you. With the help of such a device, you can generate a current with a voltage of up to 5 volts, which is quite enough to charge the device and connect the lamp in an emergency. Next, we will tell you how to make a thermoelectric generator with your own hands, providing a simple master class in pictures and with video examples!
Briefly about the principle of action
So that in the future you understand why certain spare parts are needed when assembling a home-made thermoelectric generator, we will first talk about the design of the Peltier element and how it works. This module consists of semiconductors connected in series - pn junctions, located between ceramic plates, as shown in the picture below.
When an electric current passes through such a circuit, the so-called Peltier effect occurs - one side of the module heats up, and the other side cools down. Why do we need it? Everything is very simple, this effect also works in the opposite direction: if you heat one side of the plate and cool the other, you can get electricity of low voltage and current. Huge Advantage this method in that you can use any source of heat, be it a fire, or a hot mug of boiling water, a cooling stove, and so on. For cooling, you can use air or for more powerful options - ordinary water, which is sure to be found even in a hike. Next, we turn to master classes that will clearly show what and how to make a thermoelectric generator with your own hands.
Assembly master class
We have a very detailed and at the same time simple instructions for assembling a homemade power generator based on a mini-oven and a Peltier element. It will be useful to every traveler on a hike. To get started, you need to prepare the following materials:
- Directly the Peltier element itself with the parameters: maximum current 10 A, voltage 15 Volts, dimensions 40 * 40 * 3.4 mm. Marking - TEC 1-12710.
- An old non-working power supply from a computer (only a metal case is needed from it).
- Voltage stabilizer, with the following technical specifications: input voltage 1-5 Volts, output - 5 Volts. This instruction for assembling a thermoelectric generator uses a module with a USB output, which will simplify and make the process of recharging a modern phone or tablet safe. This part can be purchased from a radio parts store or online.
- Radiator. You can take it from the processor immediately with a cooler (fan), as shown in the photo.
- Thermal paste, sold at a computer store.
Having prepared all the materials, you can proceed to the manufacture of the device with your own hands. So, to make it clearer to you how to make a generator yourself, we provide a step-by-step master class with pictures and a detailed explanation:
The thermoelectric generator works as follows: you pour firewood, small chips into the oven, set fire to them and wait a few minutes until one of the sides of the thermoelement heats up. In parallel, you can boil water on the grate. To recharge the phone, it is necessary that the difference between the temperatures of different sides be about 100 ° C. If the cooling part (radiator) heats up, it will need to be cooled - carefully poured with water, put a mug of liquid, ice, etc. on it. It is better to mount the radiator so that its fins are vertical, this improves the heat transfer to the air.
And here is a video that clearly shows how a homemade wood-fired electric generator works:
Generating electricity from fire
You can also install a fan from the computer on the cold side of the device, which will slightly change its design. Let's look at this option in more detail: 
In this case, the cooler will consume a small fraction of the power of the generator set, but in the end the system will work with higher efficiency. In addition to telephone charging, the Peltier module can be used as a source of electricity for a flashlight, which is an equally useful option for using a generator. Another feature of this design is the ability to adjust the height above the fire. For this, the author uses a part from a CD-ROM (one of the photos clearly shows how you can make the design yourself).
If you make a thermoelectric generator with your own hands using this method, you can have up to 8 volts of voltage at the output, so to recharge the phone, you need to connect a step-down converter that will make a stable 5 V at the output.
Refrigeration equipment has become so firmly established in our lives that it is even hard to imagine how it was possible to do without it. But the classic refrigerant designs are not suitable for mobile use, for example, as a travel cooler bag.
For this purpose, installations are used in which the principle of operation is based on the Peltier effect. Let's briefly talk about this phenomenon.
What it is?
This term refers to a thermoelectric phenomenon discovered in 1834 by the French naturalist Jean-Charles Pelletier. The essence of the effect is the release or absorption of heat in the zone where dissimilar conductors come into contact, through which an electric current passes.
In accordance with the classical theory, there is the following explanation of the phenomenon: an electric current transfers electrons between metals, which can speed up or slow down their movement, depending on the contact potential difference in conductors made of different materials. Accordingly, with an increase in kinetic energy, it is converted into heat.
On the second conductor, the reverse process is observed, requiring replenishment of energy, in accordance with the fundamental law of physics. This is due to thermal fluctuation, which causes cooling of the metal from which the second conductor is made.
Modern technologies make it possible to manufacture semiconductor elements-modules with the maximum thermoelectric effect. It makes sense to briefly talk about their design.
Device and principle of operation
Modern modules are a structure consisting of two insulator plates (usually ceramic), with thermocouples connected in series between them. A simplified diagram of such an element can be found in the figure below.
Designations:
- A - contacts for connecting to a power source;
- B is the hot surface of the element;
- C - cold side;
- D - copper conductors;
- E is a p-junction based semiconductor;
- F is an n-type semiconductor.
The design is made in such a way that each side of the module contacts either p-n or n-p transitions(depending on polarity). p-n contacts heat up, n-p - cool down (see Fig. 3). Accordingly, a temperature difference (DT) occurs on the sides of the element. For an observer, this effect will look like a transfer of thermal energy between the sides of the module. It is noteworthy that a change in the polarity of the supply leads to a change in the hot and cold surfaces.
Rice. 3. A - hot side of thermocouple, B - cold side Specifications
The characteristics of thermoelectric modules are described by the following parameters:
- cooling capacity (Q max), this characteristic is determined on the basis of the maximum allowable current and the temperature difference between the sides of the module, measured in Watts;
- the maximum temperature difference between the sides of the element (DT max), the parameter is given for ideal conditions, the unit of measurement is degrees;
- allowable current strength required to ensure the maximum temperature difference - I max;
- the maximum voltage U max required for the current I max to reach the peak difference DT max ;
- the internal resistance of the module - Resistance, is indicated in Ohms;
- efficiency coefficient - COP (abbreviation from English - coefficient of performance), in fact, this is the efficiency of the device, showing the ratio of cooling to power consumption. For inexpensive elements, this parameter is in the range of 0.3-0.35, for more expensive models it approaches 0.5.
Marking
Consider how the typical marking of modules is deciphered using the example of Figure 4.
Fig 4. Peltier module marked TES1-12706 Marking is divided into three meaningful groups:
- Element designation. The first two letters are always unchanged (TE), indicating that this is a thermoelement. The next indicates the size, there may be letters "C" (standard) and "S" (small). The last digit indicates how many layers (cascades) are in the element.
- The number of thermocouples in the module shown in the photo is 127.
- The value of the rated current in Amperes, we have - 6 A.
The markings of other models of the TEC1 series are read in the same way, for example: 12703, 12705, 12710, etc.
Application
Despite the rather low efficiency, thermoelectric elements are widely used in measuring, computing, and household appliances. Modules are an important operating element of the following devices:
- mobile refrigeration units;
- small generators to generate electricity;
- cooling systems in personal computers;
- coolers for cooling and heating water;
- dehumidifiers, etc.
Let us give detailed examples of the use of thermoelectric modules.
Refrigerator on Peltier elements
Thermoelectric refrigeration units are significantly inferior in performance to compressor and absorption counterparts. But they have significant advantages, which makes their use expedient under certain conditions. These benefits include:
- simplicity of design;
- vibration resistance;
- lack of moving elements (with the exception of the fan blowing the radiator);
- low noise level;
- small dimensions;
- the ability to work in any position;
- long service life;
- small energy consumption.
These characteristics are ideal for mobile installations.
Peltier element as a generator of electricity
Thermoelectric modules can work as electricity generators if one of their sides is subjected to forced heating. The greater the temperature difference between the sides, the higher the current generated by the source. Unfortunately, the maximum temperature for the thermogenerator is limited; it cannot be higher than the melting point of the solder used in the module. Violation of this condition will lead to the failure of the element.
For serial production of thermogenerators, special modules with refractory solder are used; they can be heated to a temperature of 300°C. In ordinary elements, for example, TEC1 12715, the limit is 150 degrees.
Since the efficiency of such devices is low, they are used only in cases where it is not possible to use a more efficient source of electrical energy. Nevertheless, 5-10 W thermal generators are in demand among tourists, geologists and residents of remote areas. Large and powerful stationary installations operating on high-temperature fuel are used to power gas distribution units, meteorological station equipment, etc.
For CPU cooling
Relatively recently, these modules began to be used in cooling systems for the CPU of personal computers. Given the low efficiency of thermoelements, the benefits of such structures are rather doubtful. For example, to cool a 100-170W heat source (corresponds to most modern models CPU), you will need to spend 400-680 W, which requires the installation of a powerful power supply.
The second pitfall is that an unloaded processor will emit less thermal energy, and the module can cool it below the dew point. As a result, condensation will begin to form, which, guaranteed, will disable the electronics.
Those who decide to create such a system on their own will need to carry out a series of calculations to select the power of the module for a specific processor model.
Based on the foregoing, it is not profitable to use these modules as a CPU cooling system; in addition, they can cause computer equipment to fail.
The situation is quite different with hybrid devices, where thermal modules are used in conjunction with water or air cooling.
Hybrid cooling systems have proven to be effective, but the high cost limits their circle of admirers.
Air conditioner on Peltier elements
Theoretically, such a device will be structurally much simpler than classic climate control systems, but it all comes down to low performance. It is one thing to cool a small volume of a refrigerator, another thing is a room or a car interior. Air conditioners based on thermoelectric modules will consume more electricity (3-4 times) than equipment operating on a refrigerant.
As for the use as an automotive climate control system, the power of a standard generator will not be enough to operate such a device. Replacing it with more productive equipment will lead to significant fuel consumption, which is not cost-effective.
In thematic forums, discussions on this topic periodically arise and various home-made designs are considered, but a full-fledged working prototype has not yet been created (not counting the air conditioner for a hamster). It is quite possible that the situation will change when modules with more acceptable efficiency become widely available.
For cooling water
The thermoelectric element is often used as a cooler for water coolers. The design includes: a cooling module, a controller controlled by a thermostat and a heater. Such an implementation is much simpler and cheaper than the compressor circuit; in addition, it is more reliable and easier to operate. But there are also certain disadvantages:
- water is not cooled below 10-12°C;
- cooling takes longer than the compressor analogue, therefore, such a cooler is not suitable for an office with a large number of employees;
- the device is sensitive to external temperature, in a warm room the water will not cool to the minimum temperature;
- installation in dusty rooms is not recommended, as the fan may become clogged and the cooling module will fail.
Desktop water cooler using a Peltier element Air dryer on Peltier elements
Unlike an air conditioner, the implementation of an air dryer on thermoelectric elements is quite possible. The design is quite simple and inexpensive. The cooling module lowers the temperature of the heatsink below the dew point, causing the moisture contained in the air passing through the device to settle on it. The settled water is discharged into a special storage tank.
Despite the low efficiency, in this case the efficiency of the device is quite satisfactory.
How to connect?
There will be no problems with connecting the module; constant pressure, its value is specified in the datasheet of the element. The red wire must be connected to the positive, the black wire to the negative. Attention! Reversing the polarity swaps the cooled and heated surfaces.
How to check the Peltier element for performance?
The easiest and most reliable way is tactile. It is necessary to connect the module to an appropriate voltage source and touch its different sides. For a workable element, one of them will be warmer, the other colder.
If a suitable source is not at hand, you will need a multimeter and a lighter. The verification process is quite simple:
- connect the probes to the terminals of the module;
- bring a lit lighter to one of the sides;
- observe the readings of the instrument.
In the working module, when one of the sides is heated, an electric current is generated, which will be displayed on the instrument panel.
How to make a Peltier element with your own hands?
It is almost impossible to make a self-made module at home, all the more it makes no sense, given their relatively low cost (about $4-$10). But you can assemble a device that will be useful on a hike, for example, a thermoelectric generator.
To stabilize the voltage, you need to assemble a simple converter on the L6920 IC chip.
A voltage in the range of 0.8-5.5 V is applied to the input of such a converter, at the output it will produce a stable 5 V, which is quite enough to recharge most mobile devices. If a conventional Peltier element is used, the operating temperature range of the heated side must be limited to 150 °C. In order not to bother tracking, it is better to use a pot of boiling water as a heat source. In this case, the element is guaranteed not to heat up above 100 °C.
