The author of the “Cars and Upgrade” channel does not have air conditioning in the car. Therefore, he decided to make an air conditioner, or a cooler with a fan, for his car based on 3 peltier elements. Read about the principles of Peltier's work and where they sell it cheaply. To at least create cool air in the cabin. He did not have high hopes for the successful outcome of his project, but decided to conduct at least an experimental test of the idea. Used a radiator from water cooling computers. Made a metal container for water.
Peltier elements 6 amps each. Coolers and radiators. The pump pumps water, distills in a circle, cools the radiator. He had to stand in the cabin, where the air filter. It would seem that everything should work. Peltier thermoelements do not cope. There are some water cooling, at 10-15 degrees. The air doesn't cool as much. And for a small room inside the house, this is not bad, but the effect of coolness will not be felt in the car. 30 amp power supply. He's already warmed up. 6 amps takes one peltier element. Multiply by 3 will be 18 amps. Plus a cooler. So the load on the generator will be very large. It's inefficient.
The experiment is carried out at home. If the room temperature is 28 degrees, the air is blown out of the air conditioner at least 15 degrees. It blows cool air, but it's still not enough. If the entire structure is installed under the hood of the car, since heating occurs, anyway, there is not enough power to ensure comfort in the car.
The author of the video has already watched some videos and listened to the comments of the masters who have already made air conditioners for their cars. Some of them say they didn't succeed. Others claim that the Peltier air conditioner works fine in the car. But experience shows that even 4 peltier elements do not give the desired mode. Not enough power and too much consumption. The master assumes that there are 10-12 elements to be installed using this system, there may be some kind of cooling effect on the car. Well, you may have to change the design, changing the generator or other parts. This is due to the high energy consumption for their operation. The master assumes that it will be cheaper and more efficient to install a normal machine air conditioner.
Next, watch a video about a device powered by two Peltiers.
Another cooling unit, which the author called the prototype of the air conditioner on 2 peltier elements. The video was filmed on the Hurrygun Tank channel. Specifications to be considered in the manufacture of such devices. One peltier element consumes 5 amperes. Supply voltage 12 volts. Accordingly, two elements will take 10 amperes. In this case, the temperature difference that can be obtained in the car is 4 degrees Celsius. So the experience of the author of the video showed. It can be concluded that it is not advisable to use Peltier thermoelements to create portable air conditioners for cars.
The Peltier element is a thermoelectric type converter. It uses the Peltier effect, which consists in the fact that the passing current leads to different temperatures on different sides of the element.
The Peltier element uses two plates of semiconductor materials, the difference of which is in the energy levels of the electrons. The passage of current leads to the fact that one of them becomes colder, and the second heats up.
Among the advantages of Peltier elements, noiseless operation (there are moving parts in them), the absence of liquids and gases in the design are distinguished. But they have low efficiency, which limits their use.
On the basis of Peltier elements, mini-refrigerators are made for, for example, cars, in which there is little space for conventional appliances. They are in the designs of digital cameras, infrared spectra, diode lasers.
Using Peltier elements, it is easy to make your own air conditioner. True, their use for these purposes is rather controversial due to their high energy consumption, which is incomparable with the amount of cold that is generated.
But if the question is not about energy saving, but about the desire to get acquainted with the design and principle of operation of the element, the ability to make useful crafts, then you can proceed. They go to the radio store and buy Peltier elements in the amount of 4 ... 8 pieces.
Returning home, their “hot” sides are determined and they are attached to a radiator that will remove heat. It is better if it is aluminum and has a large number of fins that increase heat transfer. Landing is done on hot melt adhesive, which improves heat transfer.
The resulting device is placed in the window window with the radiator installed outward. In this position, it will be cooled by colder outside air.
The “cold” side of the Peltier elements is placed in the direction of the room in which they want to cool the air. A fan is attached to it, for example, taken from a computer, where it cools the processor. Place it so that the room air is directed by the compressor to the converter plate.
Peltier elements can cool the air in the room, but this will consume a lot of electricity. The fact is that in devices almost half of it is wasted, being converted into heat dissipated in the atmosphere.
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 junctions (depending on polarity). Contacts p-n are heated, n-p are cooled (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 the 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 heat source with a power of 100-170 W (corresponding to most modern CPU models), 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 it to absorb the moisture contained in the air passing through the unit. 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, it is necessary to apply constant voltage to the output wires, its value is indicated 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.
Probably, once the air conditioner in the car will become the most perfect norm, regardless of the cost and configuration. However, there are still millions of cars “running” on our roads that do not have this useful option, and new ones, also devoid of air conditioning, are still being produced. And, therefore, every summer, the heads of car drivers without air conditioning, hot from the sun, visit nervous thoughts about ways to cool the “gas chamber” of a sun-heated interior using alternative and “asymmetric” methods.
The first thing that the sufferer finds on the Internet for the queries “cool the interior of the car without air conditioning”, “escape from the heat without air conditioning”, etc. is a suggestion to use PET bottles with ice. This idea has been wandering from site to site for years and offhand even looks workable.
Confidence is added by numerous descriptions of garage designs of automotive surrogate "air conditioners" made on the knee and using the same frozen water in soda or beer bottles as a "coolant". They are a variety of boxes and boxes, covered with foil inside to prevent cold loss, and with installed fans to blow air through the ice. In principle, this is a logical direction of development aimed at increasing the efficiency of technology, although the main thing is lost behind engineering - attractive simplicity. In any design, you need to take into account the factor of human laziness - no matter how effective the development is, sooner or later it will be thrown onto a dusty shelf, even by the developer himself, if it requires a complex sequence of actions or difficult preparatory work ... Freeze, and then take a couple of bottles with you before the trip - anyone can do it, but fencing boxes with fans is already, according to the majority, too much ...
One way or another, the idea hovers among the masses, but there are very few of those who have tested the technology in practice. Therefore, our task is to destroy or confirm the myth with a thermometer in hand. To check, having received conclusions in dry numbers, and not in subjective sensations, the simplest basic option - can “one and a half” with ice, placed on the dashboard under a stream of air from a fan, make staying in a car without an “air conditioner” at least somewhat more comfortable? And thus understand whether it is expedient in principle to apply further creativity, hands and strength in this direction?
The experiment will look like this. We take two identical cars of the same color, put them side by side in the sun for several hours. After warming up the salons with sunlight in one car, we simply turn on the cabin fan to blow it with outside air, and in the other, we start recirculation and let the air flow onto the glass, blowing several liters of ice frozen in PET bottles lying on the dashboard. After 15 minutes, we look at the result - how much will it be possible to lower the temperature? So let's go!
The temperature in the car interior after three hours spent in the sun is 38 degrees Celsius:
We put ice bottles in one machine, turn on the fans in both, note the time - 15 minutes ...
The result is depressing ... In a car in which the fan worked to purge the cabin with outside air, the temperature dropped to 33 degrees, and in a car in which recirculation was turned on and the air was chasing in a circle, blowing over bottles of ice - only up to 35.5 degrees ... Banal blowing even without open windows turned out to be more effective than blowing ice in a confined space!
The bottle-cooling myth persists, and although the outcome was predictable, it was still worth checking. At the same time, it is still worth noting that six liters of ice are capable of more, but not in this form!
For any device that works on heat transfer, whether it is an air conditioner or a heater, the most important characteristic is the area of \u200b\u200bthe working surface. For bottles on the dashboard, it is extremely small, plus blowing them is organized inefficiently. If we put the same six liters of ice in a flat ribbed container, similar to a car radiator, placed it in the car and started blowing air through it, the effect would be much more noticeable. But the accompanying difficulties make such an event meaningless a little more than completely ...
Other dead-end ideas of "alternative air conditioners"
What other ideas are visited by car owners without air conditioning with enviable regularity with the onset of summer? You can, of course, install a non-standard universal air conditioner - in principle, it will not differ in any way from the standard one - except that the controls on the panel will stand out a little in the overall style of the interior. But the cost of installing a "kondeya" on a budget passenger car with components and turnkey work today is approximately 60,000 rubles. Expensive in general...
Therefore, such a decision is quickly discarded and "creative kroilovo" begins. And here, of course, in second place after frozen PET bottles comes the idea of using a mobile or window air conditioner in the car, the cost of which starts from more or less affordable 10,000 rubles even now, during the hot season.
It seems to many that if you put a monoblock household air conditioner in the back seat, power it through a 12-220 volt inverter and stick the hot air hose out the window, you can enjoy the coolness! However, none of these dreamers has yet achieved real success... Why is the idea not viable?
The fact is that even the weakest window air conditioner consumes about one and a half kilowatts of power in the cooling mode from the 220 volt network. The inverter efficiency of 12/220 is clearly not 100%, but for ease of demonstration on the fingers, we will take it as one hundred. Accordingly, from the on-board network of 14 volts, such an air conditioner will consume 1,500 watts / 14 volts = 107 amperes through the inverter. The current is crazy, the wiring will be a finger thick + for many generators, even the maximum current output limit is less. We are not talking about the fact that the inverter should be designed for long-term operation with a power of at least a couple of kilowatts - such inverters, as a rule, belong to expensive and specific professional equipment, are extremely rare on sale and cost crazy money ...
The third place idea is the use of Peltier elements. A semiconductor wafer, when current is applied to it, heats up on one side and cools on the other. Buying items is easy, they are not so expensive. On such plates, automobile portable refrigerator-boxes work well, and it seems to many that an air conditioner can be created on the same principle - inexpensive, silent, without a compressor, refrigerant, pipes and evaporators.
Alas, you won’t be able to find a single really working “auto-conde” design on Peltier modules, although there are a lot of projects on various automotive blogs and forums, many even with intermediate reports on the stages of work, demonstrating the fair efforts of DIY enthusiasts. Why? Yes, for the same reason that ice bottles do not work either ... Too small a “cold transfer” surface of the cold side and the difficulty of organizing effective heat removal from the hot side. To ensure at the very least cooling of the passenger compartment, a Peltier module in a passenger car must have a roof ...
***
So, whatever one may say, there is no alternative to the traditional car compressor air conditioner yet and is not expected in the near future. Indeed, even in hybrids and electric vehicles that are at the forefront of progress, it has a classic design that has not changed fundamentally since the first air-conditioned cars - Packards and Caddylacs of the early 40s of the twentieth century.
Does your car have air conditioning?
In this tutorial, we'll show you how to make a simple air conditioner from improvised materials. This air conditioner does not have any compressors and other similar parts, we will get cold from electricity, or rather, using. They are now not very expensive, and finding them should not be difficult.
As for other nodes, we will need fans and coolers from the computer, they will serve to cool one side of the elements and heat the other. That is, some fans will drive cold air to us, while others will cool the elements so that they do not overheat.
Of course, if you put such an air conditioner just indoors, there will be little sense from it, since they heat the air more than they cool it. But if you take the hot side outside and turn the cold side inside the room, in the end we get quite a good air conditioner, but its effectiveness will greatly depend on the thermal insulation of the room. One way or another, you will be pleased to be near such an air conditioner in hot weather, as a stream of cold air will come from it. The device is assembled quite simply. So, let's take a closer look at how to assemble such an air conditioner!
Materials and tools used
List of materials:
- Peltier elements ();
- 4 coolers from the computer (fans with radiators);
- 4 fans from the computer;
- power supply for 12V/30A;
- wires;
- thermal paste;
- switch;
- large aluminum radiator;
- plywood, sheet plastic or something similar for the body.
List of tools:
- stationery knife;
- glue gun;
- drill;
- soldering iron;
- screwdriver.
Air conditioner manufacturing process:
Step one. We prepare the basis
We need a base on which we will fix all the important organs of the air conditioner. You can use plastic, plywood or other similar material. To begin with, we take measurements and cut out four windows for Peltier elements. Do not forget to make grooves for the wires. The author cuts out these windows with a clerical knife, since the material used is soft.
Step two. Installation of Peltier elements
Now you can install Peltier elements. To do this, first fasten the radiator, which will be cooled in the process. The author simply fastens it with self-tapping screws. Well, then you can install Peltier elements, for this we need thermal paste. Thanks to this paste, there will be a good thermal bond between the radiators. We install all the elements with the cold side to the large radiator, for the author these are the sides with inscriptions.
Step three. Coolers
In order for the Peltier elements to work effectively, heat must be removed from them. To do this, we need four coolers from the computer. Again, thoroughly lubricate the elements with thermal paste and fasten the coolers. At the end, you will have to connect all the coolers in parallel and you can try to turn it on.
Step four. Assembling the body
To make a case from a similar material, the walls are cut out. Next, we fasten these walls using corners and a rivet gun. We seal all joints thoroughly with a glue gun. In addition to sealing, glue also strengthens the structure.
Step five. Cover with fans
A cover is installed over a large radiator, in which 4 fans are installed. They are designed to blow the radiator and as a result we will have cold air at the outlet. Fans are put on blowing. We drill holes for the fans with a bat and screw them into place. In the case on both sides, the author drills rows of holes, through which air from the room will enter. We glue the stops on the hot glue and fasten the lid with screws.
Step six. The final stage of assembly
As a completion, we solder all the necessary wires and install the switch. The author uses a fairly powerful power supply, as much as 30A at a voltage of 12V. As for the other, hot side, it is also recommended to install a protective grid here. That's all, our air conditioner is ready, you can test it! Unfortunately, the author did not provide an overview of the tests of his device.