While I was building a country house, I couldn’t help but think of another way to use extruded polystyrene foam. Today this is one of the most effective insulation materials with a huge number of advantages and a very affordable price. The first thing I realized was that for grocery shopping trips to the hypermarket it is very useful to have a thermos container in which you can safely transport frozen food. To make such a box it took 160 rubles and half an hour of free time. But I decided to go further and modify the design in order to use it as a stand-alone refrigerator.
Let's start making!
2. So, let's start with a thermos container. We will need one sheet of polystyrene foam with dimensions 1200x600 mm, thickness 50 mm, a stationery knife and a tape measure. The cost of such a sheet in any hardware store is 160 rubles. We cut the sheet according to the template, take the polyurethane foam and glue together such a container.
3. Here is a diagram for cutting the sheet. The sheet has sides 20 mm thick; they need to be cut off on all sides except the bottom. The sheets are glued together with polyurethane foam. The technology is simple. Apply a little foam to the gluing area, wait 1 minute, press the sheets tightly against each other and then manually control for 5 minutes so that they do not move due to the expansion of the foam. The main thing is not to leave it unattended. Only a small piece of polystyrene foam will be left over, marked in gray in the diagram.
4. Pay attention to the design of the cover; I cut one of the large sheets from the diagram above into 3 parts in place when gluing it together to ensure a tight fit. After this, the outside of the box can be painted. The paint slightly corrodes the polystyrene foam, so it is better to paint in two stages. The resulting container weighs 820 grams and has incredible heat loss performance. You can put several kilograms of frozen food in such a box and transport it for several hours without any problems. The main thing is not to mix frozen and chilled foods. You can supplement the design with a cold accumulator.
5. Or you can modify the design to get a full-fledged refrigerator. For these purposes, we will use a Peltier element - a thermoelectric converter, the operating principle of which is based on the occurrence of a temperature difference when an electric current flows. These are the elements that are used in serial car refrigerators, as well as ventilated car seats.
The cost of one Pelte element with a maximum power of 60 W on aliexpress is 130-150 rubles. Model TEC1-12706. During operation, one side of the element heats up, the other cools. To prevent the element from burning, it is necessary to intensively remove heat from the hot side. To do this, we need a processor cooler with a radiator from a computer store, costing 250 rubles. To improve air circulation inside the refrigerator compartment and prevent the radiator from freezing, I decided to install fans on both sides. We will also need a thermostat with an external temperature sensor and a relay, costing 170 rubles, which will allow us to control the set temperature inside the container. Well, an extension cable with a connector for a car cigarette lighter for 100 rubles.
So, let's start assembling.
6. We install the Peltier element using thermal paste (included with the cooler) between two aluminum radiators. It is worth noting here that the temperature gradient of the installation can be increased by assembling 2 or 3 Peltier elements installed in series. Thus, so that one Peltier element cools the other. In this option, it is possible to get a negative temperature of up to -18 degrees Celsius in the container. We lay a piece of foam thermal insulation along the perimeter between the element.
7. We connect the radiators to each other with standard mounting plates to the motherboard, connecting them using plastic clamps. This also allows the cold and hot sides to be thermally isolated from each other. Test run of installation. The more intensely we cool the hot side, the lower the temperature on the cold side will be. Here the fans are aimed at supplying air to the radiators; this is less efficient than if they are turned over to blow them out. In the improvised box, we managed to achieve a temperature of -3 degrees, at an ambient temperature of +26. The photo clearly shows the model of the coolers; their advantage is the large area of the radiator support area. And as a thermal insulation pad, I used a piece of thermal insulation for round pipes.
8. Now let's integrate the thermoelectric converter into the new container lid. For the convenience of placing the entire structure, we will increase the thickness of the cover to 100 mm (2 sheets of polystyrene foam). This photo clearly shows the perimeter gasket between the two radiators.
9. Artistic cutting on polystyrene foam and sandpaper processing. Let's paint again. After painting, the outer shell of polystyrene foam becomes stronger.
10. Coat the seams with sealant, turn both fans over to blow out. Among the potential improvements, it might be worth reducing the fan speed on the cold side (currently both fans operate at maximum speed).
11. We install the thermostat board next to the case and fix the power wire in this simple way. First we press the plate using self-tapping screws, then fix it with sealant.
12. Container assembled. The weight of the container without a lid is 800 grams; the lid with the assembled thermoelectric converter weighs the same. Total expenses - 1000 rubles and a couple of hours of time. Tests with cooled products in the trunk of a car showed the system’s ability to maintain the temperature at the bottom (!) of the container within +5 degrees Celsius, at an ambient temperature of +29 degrees (yes, it is much warmer in the trunk, even with the air conditioner running) and current consumption - 3 Ampere. I think this is an excellent result.
I plan to make the next container from 3 Peltier elements installed in series to get a full-fledged freezer.
A great craft for the summer is to make a miniature refrigerator with low-voltage power. A variety of supply voltages (220 V, 12 V, 5 V) makes it possible to use such a refrigerator almost anywhere: in the car, office, home, etc. This is a great thing to cool drinks on a hot summer day.
Will need
Manufacturing a miniature refrigerator using a Peltier element
The case was made of arbitrary dimensions, taking into account the placement of the cooling unit, power supply and beverage chamber. It will consist of two sections: one for the technical part, the other for cooling products.We make the body. We mark a piece of hardboard using a pencil and ruler.
We cut out all the elements with a hacksaw.
All body parts are ready.
From the middle part dividing the refrigerator into two parts, we cut out a window for a radiator with a Peltier module.
We apply the cooling unit to the side of the case.
And we drill a lot of holes on both sides. That is, the air flow will enter from one side through the holes in the side. Pass through the radiator, picking up heat and exiting through the holes on the other side.
We paint all parts of the refrigerator body with aerosol paint from a can.
Let's start assembling.
Glue the separating part of the cooling block with hot glue.
We glue all parts of the body on both sides.
The cooling unit rests on a piece of wood that is glued to the base.
For illumination you will need two sections of 12 V LED strip. One color is white, the other is colored.
Screw on the small fan.
We divide the technical part of the refrigerator into two parts. The power source will be located at the top. The dividing wall is placed on square pieces of wooden slats glued to the sides.
Installing the back wall.
We will make the door from a piece of acrylic glass. Mark with a ruler and pencil.
You can buy miniature loops or make your own. Glue them on with instant glue.
We cover the sides of the acrylic glass with black self-adhesive tape.
Glue the handle to the door.
We will organize lighting. Solder the contacts to the mini limit switch.
Solder the wires to the pieces of LED strip. We glue the pieces themselves onto a mini shelf made from the same acrylic.
We connect the backlight, fans, Peltier element.
Install the switch on the side.
We isolate all open twists.
Close the compartment with the cooling unit. This must be done to prevent hot air from rising and heating the power source.
Drill a hole for the 220 V power cable.
To prevent the refrigerator door from opening, we will install small neodymium magnets from a broken sidir on the side.
We close the top cover, but before that we cut in the power switch and solder the wires. Now the refrigerator can be turned off with the button on top.
Close the lid and secure with glue.
For proper thermal insulation, we cover the inside of the refrigerator with thin foam plastic. We place the cut out foam panels on hot glue.
And finally, the result of the work is such that in thirty minutes the temperature inside the chamber dropped from 42 to 16 degrees Celsius. The drinks were cooled to a temperature of 20 degrees Celsius. And all this in 30 minutes!
Of course, the efficiency of such a refrigerator is much lower than that of a compressor, but it also has its advantages, one of which is low-voltage power supply, which can be not only 12 V but also 5 V! Naturally, it is quite possible to power it from a computer’s USB port, although the output will be lower than when powered by a voltage of 12 V.
The total power consumption when powered from a 220 V network is about 100 W. More detailed assembly instructions are in the video below.
Those who are planning to go to the sea this summer should know that it is better to store food and drinks in a cool place so that they do not spoil. And there is no better place than a refrigerator.
Not everyone wants to buy a car refrigerator for four thousand rubles. Therefore, many people who want to relax by the sea decide to create a new car refrigerator with their own hands, which contains “cold accumulators”, which are frozen one and a half liter bottles with coolant “water”. Even a refrigerator made from packaging cardboard can last a considerable number of trips to southern resorts. You can read about how to make a car refrigerator with your own hands in this article.
To create such a solution, we select refrigerator dimensions in the area of 40x40x30 cm, which, however, can be varied depending on the dimensions of the car trunk. For average cars, this size is better, since a refrigerator that is too large would take up a lot of space, and there would be no place to put things.
Insulation, namely thermal insulation using foam insulation with foil on one side, should have a thickness of ten millimeters. Width 1.2 meter, length 1 meter. The price tag is currently 90 rubles per meter. The body materials used are furniture waste, or, to be more precise, ten-millimeter fiberboard. Buy two aluminum corners 1.5×1.5 mm for 120 rubles. Blind rivets of the 4×16 type are purchased “one hundred pieces for 50 rubles” and a pair of furniture hinges for 30 rubles each. Total expenses can be about 300 rubles.
Tools and other equipment will also be useful in manufacturing.
We cut off the corners in place and without stress we begin to make the frame of the future box.
The result of titanic work should be a quite presentable box. A lock with a latch and a folding wire handle can be placed on the lid of the box. Thus, the finished unit with packaged food can be carried in your hand with peace of mind. Being filled with liquid and food, it becomes very, very weighty!
Now it’s time to start covering the object of the article with insulation. The bottom and lid, as an option, can be pasted over in two layers, and the walls in one layer. To do this, you can resort to liquid nails. Spread the workpiece with this product, stick it to the walls and then press it with a weight. All this should stick without any problems and quite successfully, you can later try to tear off the material a little, but it will be very, very good. As a result, after three days in your free time, a rather nice unit will come out, equipped with a hinged top cover with a latch.
Four 1.5 liters will be attached or placed in the corners or at the bottom. bottles of liquid, or from six to eight 0.5 each, previously stored in the freezer. You can also resort to cool mineral water, including carbonated water, which will come in handy on a hot summer day. Mineral water is best suited for 0.5 liters, such volumes are the most practical. Containers with water are not filled completely, otherwise, after the water freezes, the ice will damage the bottle due to expansion, and the food will have to float in the defrosted water. You can save space in the unit by purchasing branded “cold accumulators” from the store. They come in the form of special bags or flat boxes with water inside, which take the place of bottles. Such boxes can be purchased from 120 rubles.
But in the case of vessels with spring water, everything is much more profitable. Even if the liquid in them thaws “usually after 24 hours,” it can be used to wash your face or simply drink.
Using the cardboard refrigerator described above, all contents not eaten or drunk along the way will reach the resort cold.
This unit can be used even as a stool. You should not rush to paint the unit, because if something happens to the wood fiber board, “for example, it will warp from the liquid.”
The refrigerator is able to fully justify the hours spent on it and the small investment in production. The benefits of such a decision will be very great.
To create another option, you need to buy a box for children's toys for three hundred and fifty rubles. You should also choose a couple of sheets of polystyrene foam for a total of one hundred rubles, a couple of rolls of metallized adhesive tape, universal glue for eighty, you will also have to resort to mounting foam for 120 rubles. All the necessary material is unlikely to exceed the amount of 900 rubles.
The entire work will take two and a half hours of your time.
Any of the elements must be placed on the lid, since installation will proceed much easier and the cold will drop.
Elements - the more there are, the better, since they affect cooling.
Either alligator clips or T-type sockets are used. In this case, the cigarette lighter will not provide the required area. You can use a monoblock radiator.
It is thinner, but at the same time it is characterized by greater width, and in some cases you can take options with copper.
The author needed a small refrigerator that could be used in the car. Having gone shopping and found out the prices for such devices, he was struck by the idea that perhaps creating a homemade mini refrigerator would be much preferable to buying a branded device. Therefore, having assessed the materials he had that could be useful for creating a homemade car refrigerator, he decided to start assembling such a device.
Materials:
- water cooler that is out of order
- Peltier element
- thermal conductive paste KPT-8
- radiator
- fan
- computer power supply
- polyurethane foam
- metal fastenings with bolts
- foil
- switch and additional wires.
- fan thermostat
Description of making a car refrigerator with your own hands.
Step one: choosing the refrigerator body.
As the main part of the body of the future refrigerator, the author decided to take his existing body from a non-working cooler, or rather its lower part.
Here's a photo of the cooler in its entirety:
This part of the cooler will be used to make a car refrigerator:
This is his front view, and this is what he looks like from the back:
Step two: modification of the refrigerator body.
Having chosen the body for the future refrigerator, the author began to modernize it to suit his needs. To begin with, the cooler was disassembled. The top part of the plastic shell was removed. Since the standard door fastenings were located exactly there, he had to make his own fastenings. To do this, several bolts and a couple of metal plates were used. As a result, we got these kind of hinges that hold the refrigerator door in place.
Step three: selection and installation of the cooling element.
The author decided to use a Peltier element as a cooling device for the refrigerator chamber. In general, almost all modern models of refrigerators for use in cars operate on exactly this principle.
Step four: creating a cooling system for the element.
It is very important to attach the Peltier element to the cooling radiator as tightly as possible. To better transfer the heat generated by the back side of the Peltier element to the radiator, the use of heat-conducting paste can help; he used KPT-8 paste. Moreover, I attached both the upper and lower parts, for more gentle operation of the element.
Step five: connect power to the refrigerator.
As power for this device, I used a computer power supply, or rather a laptop power supply, since it is quite convenient and can be brought outside. The main thing is that this power supply is capable of supplying a voltage of 12 V, as well as a current of 5 A.
During operation, the power supply can get quite hot, so the author considered that it would be more expedient to move the power supply outside from the chamber of the future refrigerator to maintain the cold in the chamber.
Step six: work on thermal insulation.
In order to minimize the transfer of heat from the body of the device into its refrigerating chamber, I decided to fill the back wall of the refrigerator with polyurethane foam.
And also, in order to preserve the cold environment inside the refrigerator chamber as much as possible and avoid heat transfer from the outer walls, I covered the inner walls of the chamber with foil.
Step seven: installing a fan and creating a thermostat for its operation.
A fan was installed on top of the radiator to which the Peltier element was attached. In this way, active cooling of the radiator and the element itself will be carried out, respectively. And in order to regulate the speed of the fan, the author found a circuit for a thermostat, which, depending on the temperature of the radiator, can reduce or increase its rotation speed.
Thermostat circuit for controlling fan operation:
In order to make a car refrigerator with your own hands, there is no need to purchase expensive materials and come up with complex assembly schemes. In this article we will look at a simple and effective way to make a car refrigerator with minimal time and money.
1 Homemade refrigerator - assembling the body
The body of the future refrigerator can be assembled from various materials, but it is best to use a building material, namely extruded polystyrene foam. This material has many advantages and is inexpensive. Expanded polystyrene is actively used for insulation of various structures and buildings; it has excellent thermal insulation properties and resistance to external influences.
To model the body of a future refrigerator, you will need one or two sheets of polystyrene foam of standard sizes and widths (1200x600 and 50 mm), the cost of one sheet in a hardware store does not exceed 450 rubles. To glue the container, you will also need several cylinders of polyurethane foam. To work, you will also need a tape measure for measurements and a stationery knife, with which you need to cut a sheet of polystyrene foam according to a pre-prepared template.
It is best to make the walls of the container double by gluing the sheets together with polyurethane foam. To do this, apply a little foam to the surface, connect the sheets and wait 5-10 minutes until completely dry, making sure that the sheets do not move due to the expansion of the foam. The size template can be taken as an example of a regular wooden box, only in our case, insulation material is used instead of wood.
Once the container is created, the outside can be painted any color using regular paint. It is better to paint in several stages, as the paint eats up the polystyrene a little. As for the lid, it is necessary to cut a piece of material so that it fits as tightly as possible to the surface and closes tightly. Even without electrical elements, such a box is capable of storing very frozen foods for several hours, since the material has low heat loss rates.
To get a full-fledged refrigerator, you need to connect a Peltier element to the body. The operating principle of a thermoelectric conversion device is based on the occurrence of a temperature difference depending on the flow of electric current. This device is also used in the industrial production of car refrigerators, and you can purchase it at a hardware store.
2 Connection of electrical elements
To make a full-fledged homemade refrigerator, and not just a thermal container, in addition to the Peltier element, you also need to purchase a computer cooler (in any specialized store). A cooler is necessary to actively remove heat from one of the parts of the refrigerator, since during operation one side will heat up and the other will cool, due to this a certain temperature will be maintained inside the box. To control this temperature, you also need a thermostat with a special sensor, and to connect the refrigerator to the car's on-board network, you need an extension cord with a cigarette lighter connector.
First you need to install a Peltier element between two aluminum radiators. At this stage, you can use thermal paste for the cooler, and lay a small piece of thermal insulation material around the perimeter between the element and the radiators (pipe insulation is suitable). Radiators can be connected with plates that are attached to the motherboard, and the plates can be connected with plastic clamps.
Thus, the more intensely the hot side of the container is cooled, the lower the temperature on the cold side will be. With one Peltier element and a cooler, if installed correctly, you can achieve a temperature of minus 2 degrees inside the box. To lower the temperature inside, you can use several Peltier elements, so that one cools the other, etc.
3 Installation of the structure in the lid of a homemade refrigerator
If the design is assembled correctly and the test run produces the required temperature, you should begin installing a cooler with a Peltier element in the lid. For better heat dissipation, it is recommended to double the thickness of the lid, that is, place another piece of polystyrene foam on the foam to fit the size of the lid. To fit the size of the structure, you should cut a hole in the insulation (use a utility knife), then use sandpaper to level the surface and, if desired, . In this case, paint allows not only to improve the aesthetic appearance, but also gives strength to the outer shell of polystyrene foam.
Next, you need to install the fans and coat the seams with sealant. The fan speed can be adjusted, but it is best to leave the maximum blow speed to ensure the lowest possible temperature. You need to connect a thermostat sensor to the fan, and secure the board itself to the cover using self-tapping screws. The power cord to the cigarette lighter is also installed in the cover; you can use a plate and self-tapping screws, and seal the plate body with sealant.
Thus, at the end you will get a high-quality homemade refrigerator. The weight of the box will be approximately 800–900 grams, and the lid with an integrated fan and thermostat will weigh the same.
When using such a refrigerator in summer weather, provided that the fan is always blowing at maximum speed, the temperature at the bottom will remain stable at +5 ... +7 degrees. In this case, the entire structure will consume no more than 4 amperes of current.
For a more powerful result, as we have already noted, it is necessary to integrate two or three Peltier elements installed in series, but this will already be a freezer, and not a simple refrigerator. And to create such temperatures, it will be necessary to use an additional radiator and antifreeze, similar to the principle of a car air conditioner, and this is much more difficult to do. There are several more ways to make a car refrigerator with your own hands, but the presented method is the most effective and simple, in addition, the cost of all parts does not exceed 3,500 rubles, and the result is quite enough for transporting various products over long distances.