Can a home-made air cooler become an alternative to modern split systems? After all, refrigerators that create a comfortable microclimate in the house, stand together with the installation of a lot of money and are affordable not for everyone. Therefore, home craftsmen - craftsmen are trying to solve the problem cheaply and angrily, inventing all sorts of cooling units. Our goal is to consider all design options, choose the most viable and tell us how to make a working do-it-yourself air conditioner for your home or car. And in order to assess the complexity of the task, we suggest first to parse ...
The principle of operation of a household split system
Air conditioning is a complex household appliance that operates on the principle of transferring heat from one place to another: in summer - from an apartment to the street, in winter - from the environment to the house. An interesting substance is used to transfer heat - freon, which can boil and turn into gas at a negative temperature.
For reference. Freon circulating in the circuits of refrigerators is called a refrigerant or a working fluid. The key point is its evaporation and condensation, during which thermal energy is respectively absorbed and released in large quantities.
The home split system works according to the cyclic algorithm:
- First, the refrigerant in a liquid state enters the heat exchanger of the indoor unit of the air conditioner (evaporator), blown by a centrifugal fan. Here, the evaporation of freon occurs, due to which the flow of room air is sharply cooled.
- Further, the gas through a copper tube enters the compressor, raising its pressure to a certain value. The task is to make the working fluid condense on the street, where the air temperature is even higher than indoors.
- After the compressor, gaseous freon passes through the radiator of the external unit (condenser). A large axial fan drives a stream of air through its ribs, and the refrigerant again goes into the liquid phase, giving off room heat to the outside.
- At the last stage, the pressure of the liquid working fluid decreases due to passage through an expansion (throttle) valve. Now freon is again ready for the absorption of heat and moves into the indoor unit, the cycle repeats again.
Note. In the process of work, a lot of condensate appears on both heat exchangers and it needs to be taken to the street or to the sewer. In order for the split system to switch to heating the house, freon starts in the opposite direction, and the radiators are functionally swapped.
The electronic control unit (ECU), which receives signals from various sensors, is responsible for maintaining the room temperature and the refrigerant pressure in the system. The automobile air conditioner operates on the same principle, the evaporator is integrated into the passenger compartment ventilation system, and the condenser is installed near the standard radiator of the cooling system.
Now you understand that making an evaporative type air conditioner yourself at home is not as easy as it might seem. And for a car this is realized even more difficult, here you need to be a master - a refrigerator. As an example, we suggest watching a video where such a specialist installed a household split system in his VAZ 2104 car:
Next, let's take a look at the design of air conditioners invented by craftsmen and highlight the most workable devices that can be recommended for manufacture.
Simple homemade air conditioning
The principle of operation of such coolers is to blow room air through objects with a negative temperature.As such, ice or cold accumulators are usually used, designed for special bags used for the summer transportation of products.
- old car refrigerator with insulated walls;
- spacious plastic bottles for 5 l of water and more;
- boxes made of cardboard or plastic with lids;
- canisters made of polymer materials.
Note. Air supply is provided by any small-sized fan, for example, a computer cooler.
This mini air conditioner is also suitable for cooling the passenger compartment, you just need to connect the air supercharger to the onboard power supply correctly and stock up on the right amount of ice in advance.
Advantages and disadvantages of construction
It is noteworthy that such devices really drive cold air flow into the room. In addition, simple air conditioners are actually made from improvised materials, whose price tends to zero. The maximum that you have to spend money on is an axial fan, if it is not found in the household.
Unfortunately, the flaws cross out all the advantages of the cooler:
- No matter how much ice is put into the chamber, it will not be enough for a long time in the heat, so you need to constantly freeze new water.
- While you are cooling one room, the next is heated by a refrigerator, where ice is made. Plus increases energy consumption.
- The duration of the unit in the car depends on the supply of ice taken with you.
- The air passing through the ice is partially humidified. After some time, the room will become oversaturated with moisture, which makes you feel even worse than from the effects of heat.
Tip. Overmoistening can be avoided if instead of ice, accumulators of cold are used that do not melt and do not turn into water. And to control and maintain optimal moisture levels, there are other household appliances.
Conclusion. The self-made air conditioners described above can be considered efficient. They can help you out in a hopeless situation, but the operation of the cooler is rather troublesome.
How much ice is enough in the chamber
To answer this question, we calculate how much cold will release 1 kg of ice when heated from a freezing temperature of -6 ° С to +20 ° С. To do this, we use the formula for calculating heat depending on the specific heat.
You need to perform 4 actions:
- We consider the return of cold during ice melting: Q = 1 kg x 2.06 kJ / kg ° C x (0 ° C - 6 ° C) = –12.36 kJ.
- We find the reference value of the energy released during ice melting - 335 kJ.
- We calculate how much cold water will transfer when heated: Q = 1 kg x 4.187 kJ / kg ° C x (0 ° C - 20 ° C) = –83.74 kJ.
- Add the results and get -431.1 kJ or 119.75 watts.
Note. The results of calculations of cold in physics are also obtained with a minus sign, this is natural.
Even if you freeze ice to a temperature of minus 15 ° C, you are unlikely to get more than 150 W of cold with 1 kg. This means that for intensive cooling of a 3 x 3 m room with a heat of more than 30 degrees, you will have to add 1 kg of ice to your homemade air conditioner every 20-30 minutes and freeze the same amount. In practice, the flow rate will be lower if you are satisfied with a tolerable air temperature of 25–28 ° С.
How to assemble an air cooler
Mini air conditioning for home or car is made as follows:
- Cut a hole in the side of the tank that is equal in size to the working cross section of the fan.
- Screw the cooler with screws or put on small bolts.
- Make a second hole to exit the chilled stream. Another option is to put a corrugated plastic tube on the neck of the bottle or canister. The device is ready.
Tip. From the point of view of operation, it is better to use a box with a removable lid, since it is more convenient to load ice or cold storage batteries into it.
Water cooling unit
The idea is simple and effective at the same time: cold water is pumped through a heat exchanger with a fan located indoors. Since its temperature lies within 5-10 ° C, the air flow cools and the room becomes cooler. A well or a well serves as a water source, and a radiator from a car or an old air conditioner acts as a heat exchanger.
Important notice. Unlike other home-made units, the water installation operates on the principle of a heater and can not only cool the air in the house, but also heat it. It all depends on the temperature of the water supplied inside the radiator.
The flow cooling system consists of 3 elements:
- heat exchanger itself;
- submersible or borehole pump;
- insulated water supply and discharge pipelines.
Making a water conditioner
The assembly procedure for the cooler is as follows:
- Place and secure the car radiator in a convenient location.
- Route the supply and return pipes to it. Use adapters and clamps to connect to the branch pipes of the element.
- Mount the pump in a well or well and connect the coolant supply pipe to the heat exchanger to it.
- Insulate the feed pipe so that the water does not heat up ahead of time. It is not necessary to isolate the return line.
To make a water conditioner and start it successfully, you need to solve 2 problems: where to put water and how to regulate its flow rate, because the pump performance usually exceeds the need. We propose to solve the problem of water discharge in the following ways:
- collect in a storage tank, from where the garden is irrigated;
- transfer to another well, as a water-to-water heat pump does;
- organize a closed circulation loop with a second heat exchanger immersed at the bottom of the well.
For reference. Cultivated plants are not recommended to be watered with cold water. Therefore, you will kill two birds with one stone if you first heat well water in a radiator - an air cooler.
To reduce the performance of the pump, you need to control the engine speed, which is impossible without a frequency converter (otherwise, an inverter), which will cost you a pretty penny. Any autotransformers and other notions are not good - so you just "put" the electric motor of the pump unit. Without buying expensive equipment, the issue is resolved as follows:
- for a well up to 10 m deep, a circulation pump can be used to heat the appropriate capacity;
- it is possible to limit the flow of water to the radiator using the bypass valve, which dumps part of it back into the well. An example of a water conditioner is shown in the next video:
Pros and cons of the flow system
Briefly about the positive points:
- air conditioning is able to both heat and cool the room;
- the design is simple compared to the factory split system;
- even if you have to buy a pump and pipes, the manufacturing costs will be low.
We have already listed some of the negative aspects and ways of eliminating them - difficulties with regulating the supply and the problem of water discharge. There is another drawback: it is unrealistic to use the system in an apartment (there is no source of cold water) or in a car for obvious reasons.
For reference. The simplest version of the cooler can still be adapted in the apartment. It is a household fan, on whose grate there is a coil made of a copper tube through which water flows. The only question is where to get so cold water and how much to pay for it on the counter, if taken from a water tap.
Conclusion. A home-made air conditioner - a heater on the water - the design is quite viable. If you wish, you can make a decent cooler for a private house, provided that there is a well with groundwater at an acceptable temperature on the site.
Is it possible to make air conditioning from an old refrigerator
Absolutely utopian idea.All materials published on the Russian-language Internet describe the same video, where a person tries to build a freezer for mushrooms from two refrigerators. Moreover, the result of this action is unknown, because the video material is incomplete. Let's imagine what it should look like:
- Both heat exchangers are carefully cut out of the refrigerator without disconnecting from the compressor, otherwise freon will disappear and you will have to pay for refueling.
- A compressor with a condenser is taken out of the room, and an evaporator (former freezer) is installed in the room. You need to attach a fan to it for blowing.
- A full-time sensor and a control unit configured for a compressor shutdown temperature of minus 3-6 ° C will have to be discarded and replaced with other elements by connecting the units via a relay. Otherwise, the compressor will never stop and break after 100-200 hours of continuous operation.
Let's discard all the technical details (not this mode of operation, a different brand of freon, and so on) and imagine that you managed to assemble this circuit. The maximum refrigerating power of such units is not more than 400 W or 0.4 kW. A rough calculation shows that this is enough for a room of 4 m². This is in theory, but in practice it will be even less.
Conclusion. If you belong to a noble tribe of enthusiasts and experimenters, then you can try to make air conditioning out of the refrigerator. But you will spend much more labor than getting a cold.
Peltier cooling
The use of these parts for the assembly of a homemade air conditioner is a moot point. It's all about the energy consumption of Peltier elements (otherwise - thermoelectric converters), incomparable with the amount of produced cold. Outwardly they look like plates with 2 wires, when electricity is connected, one surface of the element generates heat, and the second - cold.
How do home craftsmen and car enthusiasts - enthusiasts who seek comfort:
- Buy from 4 to 8 Peltier elements and mount them with the “hot” side on a finned aluminum radiator.
- Install this radiator so that it is cooled by street air.
- A cooler from the computer is attached to the “cold” side of the converters so that it supplies room air to the plate.
Note. For better heat transfer, the element is coated with thermal paste (“hot” face) before being installed on the radiator.
Conclusion
Not all ideas, when implemented, give a positive result. Having made an air conditioner for a home or a car from improvised materials, you are unlikely to achieve efficiency comparable to splits. On the other hand, some designs are quite functional, although not very convenient in operation. They will be useful to you as a temporary solution to the problem, while there is no way to purchase and install a conventional air conditioning.