In the article, the author decided to share homemade, which can help reduce heating costs, this homemade product is called a solar air collector. A corrugated aluminum pipe is used here as the basis for such a collector. The advantage of the coil from it is that its external area per unit length is greater than that of a conventional pipe. In this regard, the absorber works more efficiently and warms up the air better. In addition, due to irregularities, air turbulence is created on the inside of the pipe, which allows cold and warm layers to mix better and warm up better. Well, and that aluminum has an excellent degree of thermal conductivity, no one needs to say.
Materials and tools for manufacturing:
- corrugated aluminum duct (diameter 80 mm, length 10 meters);
- a box measuring 90X90 cm (you can make it yourself from the boards);
- foil polystyrene foam (thickness 25 mm);
- wire;
- black heat-resistant paint (paint for painting silencers);
- newspaper;
- glass;
- 12V channel fan (cooler from a computer is suitable);
- solar battery (optional);
- minimal set of tools.
The process of manufacturing a solar collector:
Step one. Create a box and stack the absorber
First of all, you need to make a box, it can be made from a board. To do this, you need a saw, a hammer and nails. As the bottom, you can use a fiberboard sheet or plywood. When the box is assembled, it must be insulated; for these purposes, foil polystyrene foam 25 mm thick is used. They need to glue the inside of the box to increase collector performance.Also, the bottom of the box will need to be insulated, for this you need to cut out a whole piece of polystyrene foam, you need shapes and sizes and stick it to the bottom of the box.
Next, you can lay the absorber. To do this, take the corrugated duct and lay it with a snake, as indicated in the photo. To make this convenient, the coil can be fixed with copper or aluminum wire to the side wall of the box.
Among other things, in the box you will need to cut two holes, and insert the ends of the duct into them. Cold air will enter the absorber through one hole, and warm air will come out through the other.
Step Two Absorber painting
In order for the absorber to heat up, it must be painted with a matte black paint, otherwise the sun's rays will be reflected from the coil and the collector will not work. For these purposes, paint is suitable with which car mufflers are painted, it withstands high temperatures.
Before painting, the side walls of the box must be covered with a newspaper, they do not need to be painted. The fact is that they are coated with foil and, according to the author, the sun's rays will be reflected from them and then fall on the absorber. In principle, it makes a big difference if they are not painted, since in this case the walls will heat up, and as a result, the air temperature inside the collector will increase.
Step Three Forced Manifold Ventilation
In principle, if the collector is positioned with the outlet up and the inlet down, natural air circulation will occur in it, therefore, an air pump for this system is not needed as such. But if there is a desire to increase productivity, the collector can be equipped with a cooler or fan. The author used a 12 Volt fan in combination with a solar battery. That is, when the sun shines, the fan will start itself and improve the air circulation in the collector. The fan is installed at the inlet to the collector and runs on "blowing", if you do the opposite, it will quickly become worthless from overheating.
During testing, the air temperature in the street was 17 degrees, after half an hour of work an indicator of 39.5 degrees was reached. For a collector with an area of only 0.81 square meters, this is a pretty good figure. If the task is to heat the room in winter, then the collector area must be increased at least 4 times. In addition, it is necessary to make sure that the collector takes cold air not from the street, but directly from the room where it works, since it does not have to warm the icy air from the street.