Solar air collector with own hands

To use inexhaustible and free solar energy humanity began a long time ago. For the its collection there are special devices - solar collectors. Each year their design becomes more and more perfect, but the high prices for them do not yet allow to use them widely and everywhere. Therefore, people who have an inquisitive mind and skillful hands, try to make solar collectors on their own. And they are ready to share their knowledge. In this article, you are invited to learn how to make a solar air collector with your own hands.

What is a solar collector

The task of the solar collector is to collect the thermal energy of the solar radiation and to transfer the to its to some substance that will then transmit the to its to the "destination".This substance is called a coolant and in the quality of which either liquids( most often water) or gases( almost always air) can act.

Water is a more efficient coolant, because its heat capacity is much higher than air, but its application is associated with certain difficulties: dumping excessive heat in the summer or protection from freezing in winter. Air can not transmit this amount of energy, but the design of air collectors is much simpler, they are much safer than and safer. Yes, and make a solar air collector with their own hands is much easier than water. By the way, it is air that is the first coolant that the person began to use. What are the advantages of air, like a coolant:

• The air is not subject to freezing and boiling.
• Air does not have toxicity.
• Air should not be given any special qualities( in water systems antifreeze is added), it is always available.

Air solar collectors are widely used in air heating systems for residential buildings, as well as cellars, garages, storage facilities. In which countries air solar power plants are used most widely, the diagram is very eloquent.

It is evident that the most economically developed countries do not neglect the solar heating capabilities of the Sun. And we, alas, are still among the many 4.3% of others.

The device and operation principle of the air solar

The solar air collector consists of several main parts:

• The entire collector design is housed in a rugged and sealed enclosure, which is surely equipped with thermal insulator. The heat that enters the collector should not "leak" outside.
• The main part of any collector is sun detector panel, which else is called absorber or absorber. The task of this panel is to take solar energy, and then transmit to its air, so it should be made of the material with the greatest thermal conductivity. Such properties available in everyday life are copper and aluminum, less often steel. For better heat dissipation, the bottom of the absorber is made as large as possible, therefore edges , wavy surface, perforation and other methods can be used. For better absorption of solar energy , the receiver part of the absorber is painted in dark matt color.
• The upper part of the collector is hermetically sealed with transparent insulation, which can be used tempered glass or plexiglass, or polycarbonate glass.

The solar collector is oriented to the south and gives the surface such a slope so that the maximum amount of solar energy gets to the surface. As experts say - for maximum insolation. The cold outside air naturally or forcedly enters the reception part, passes through of the edge of the absorber and leaves on the other part, equipped with a flange for docking with the duct leading to the heated room. It should be noted that there are masses of solar collector designs and the above described is only for example.

Air heating with solar collectors can not completely replace the main heating in our climate zone, but it will be a very good help even on frosty winter sunny days.

Solar air collector with your own hands

Determination of the installation site and available area

First of all, you need to determine the location of the solar air collector, as this can greatly affect its performance. Several factors should be taken into account:

• The air solar collector should be located as close as possible to the place where heated air will flow, since the losses in the ducts may become such that the use of the collector will not be practical.
• The collector should be located on the south side of the house or other structure and if possible under with the defined slope providing maximum insolation. If this is not available, then we must try to establish as close as possible to the south side. The dependence of the insolation on the azimuth and the angle of the installation of the display on the diagram.

• The surrounding objects, buildings and plants should not interfere with the natural lighting of the collector surface.

In the selected place, which corresponds to to all conditions, it is necessary to see what area the solar collector can accommodate. Obviously, the larger the collector area, the more productive it will be.

Selecting a collector absorber structure

Absorber( absorber) is the most important part of any solar collector and its performance will largely depend on its design. The factory models use parts from special alloys having a special highly selective coating, but this basically determines the high price. Our task is to find such material that is available and, nevertheless, it will be good to cope with its function - to capture solar heat and transfer it to air.

And such an available material is an ordinary aluminum can from Coca-Cola, beer or other beverages. How to assemble the right amount of empty containers, we will not describe, but rather focus on those remarkable properties that allow the use of aluminum cans as an absorber:

• First, the cans are made of aluminum( very rare steel), and it has a very high thermal conductivity.
• Secondly, all cans from under any drinks have the same dimensions: the bottom diameter is 66 mm, the upper diameter is 59 mm, the height of the can 0.5 l is 168 mm.
• Thirdly, the banks are made in such a way that in the package they are placed friend of over friend of , that is, they fit perfectly.
• Finally, the thin aluminum from which the cans are made can easily be processed with the tool .

As you accumulate the right amount of aluminum cans, they must be thoroughly washed with detergent and dried. Otherwise, in the future they will exude an unpleasant smell, which will be more difficult to cope with.

Manufacture of the collector body and its thermal insulation

Depending on the available area of ​​the collector, its overall dimensions are calculated. In this article, it is proposed to make a solar air collector with a size of 8 for 8 aluminum cans of 0.5 liters, which in terms of overall dimensions is approximately 1400 * 670 mm. One sheet of plywood with a thickness of 21 mm of a standard size of 1525 * 1525 mm is enough to manufacture the entire solar collector, and the thickness of the plywood will provide the necessary strength and rigidity design.

For the manufacture of the case it is necessary: ​​

Carefully mark the sheet of plywood. For the collector you will need:

• Rear wall size 1400 * 670 mm.
• Two side walls 1400 * 116 mm.
• Two end walls 630 * 116 mm.
• Two guides for cans 630 * 116 mm.

When marking it is worth considering that for further processing of edges of parts it is necessary to give an allowance of 3-5 mm on each side. To cut without an failure , it's better to draw a bright marker with a line.

Cutting plywood is best with a circular saw, with the smaller the teeth at the disc - the better. For a smoother cut , you can use the guide, which can be used as a sheet chipboard with the factory edge. The guide can be pulled to the sheet of plywood with clamps.

guide. If the cut goes across the fibers, then it is better to cut the top layer with a sharp knife using a metal ruler, so there will be less chipping. After cutting the sheet on the workpiece, if the edges are uneven, they can be machined by the milling machine according to the pattern to perfectly even and perpendicular.

It's time to build a frame. To do this:

• Attach the two side walls to the rear wall of the manifold. You can fix it with furniture screws 6,3 * 50 mm - their still is called by confirmers .Only before this, you must first walk through a drill with a diameter of 4 mm. For fixing, you can use both conventional screws and different angles. The collector must have a sealed housing, so it is advisable to lubricate the fastened surfaces with a silicone sealant.

• To the rear wall, and later to the side are attached end walls. After that, the correctness of assembly and dimensions is checked.

The rear and side walls of the collector must be insulated with heat and for this the extruded polystyrene foam( EPSS) thickness is 2 cm. Before sticking the insulation to the walls, it is necessary to treat the plywood with an antiseptic agent or simply paint, as in these places cancondensation of moisture.

EPS sheets can be glued to the surface of plywood with mounting foam, acrylic "liquid nails", glue "Master", glue "Moment" - in any case it will reliably to hold. The main thing that in the description of the adhesive foam is specified as one of the surfaces to be glued. During the gluing of the insulation, it is necessary to ensure that all joints are completely closed. If necessary, they can be "blown out" by mounting foam in the future.

After the entire internal surface of the collector has been insulated, its can be glued with reflective thermal insulation, which is a fiberglass or polyethylene foam base and aluminum foil. Very often, these materials have an adhesive base, which is very convenient, and if not, it can be glued to any suitable composition for this. Joints must be glued with aluminum tape.

Preparation of guides for the absorber

In order for the columns of aluminum cans to accurately hold their geometry, it is necessary to make guide rails for them. For this, two pieces of plywood 630 * 116 mm were cut previously, which should be marked and drilled as follows:

• From the top, retreat 53 mm and draw a line parallel to the long side.
• The resulting line is divided into 9 equal segments, that is, by 70 mm, to put marks. They will be the centers of the holes.
• A drill for wood with a cup-cup with a diameter of 57 mm must be drilled in the plywood. But before this, it is better to measure the diameter of the support ring of stability in the lower part of the can, since the dimensions can vary. If necessary, select another drill bit. The bank should fit into the hole fairly tightly. When working on a drill is not strongly pressed and periodically give him a break.

• plywood. Similar marking is done on the upper guide. The diameter of the head of the can is slightly larger( 57.4) than the rear support ring, so before drilling, it is better to measure it with a caliper and select the appropriate crown-cup, and then try on the top of the can.

Manufacture of absorbers

To prepare the cans for installation, perform a number of operations:

• All banks should be checked with a permanent magnet. Very rarely, but there are banks of steel that need to be sorted.
• In the upper part of the can with scissors for metal cuts from from the edges to the edges are made, and then these "tongues" are tucked inside. Work should be in gloves to avoid cuts from sharp edges of aluminum. Direct the sharp tongues inside the can and align the edges of the hole with a piece of polymer pipe clamped in a vice. Similarly, we process all 64 banks.

• It's time to tackle the bottom. To do this, three holes with a diameter of approximately 20 mm and placed at 120 ° to each other are drilled in the bottom in a conical metal drill in the bottom. In order not to crumple the jar, its should be placed in an elastic mandrel( for example, a piece of pipe insulation) and do not squeeze strongly with hands. So processed all the banks.

• For gluing cans, it is best to use high-temperature high-strength mortar adhesive based on silicate .It is used to seal furnaces, fireplaces, chimneys. Perhaps its fire resistance for the collector will be excessive, but "the pocket does not pull the reserve".

• absorber. In order for the jars to withstand the line during bonding, it is necessary to make a template of two flat boards, , fastened together with the at an angle of 90 °.To adhere the cans to the surface, the template is tilted and supported against the wall.

• Before bonding, degrease the cans with any available solvent( acetone, No. 646, 647).This work is better done on the street.
• Before the beginning of the next stage, you should put on your hands rubber gloves, and next to have tank with water. The glued surfaces are moistened, the gun is squeezed out with an even sausage sealant onto the bottom of the jar, and then it joins the top of the jar below.

• With a moistened , the finger in the glove is spread out with the squeezed adhesive so that the entire joint and the surface next to it are covered with glue. Then all these operations are repeated for all the cans of one column( 8 pieces).After that, all the banks are put in a pattern, aligned and pressed from above by the load.
• After the has hardened to , the column is removed and neatly laid on a horizontal surface. In the same way, other columns of cans are collected.

• . While the workpieces are completely dry, you can paint the rear wall of the solar collector and the can holders in the black matt. In good auto shops you can always find such paint, designed for silencers or brake drums.

• Side walls of the collector do not need to be painted, so they should be covered with newspapers, attached with paint tape. After degreasing the surfaces, the paint is applied in two layers.

Assembling the air solar collector

• It's time to begin the assembly of the absorber battery. To do this, each column is placed in the corresponding guide first from below, and then from above. Before docking, the cans are greased with sealant, and then the with the hydrated finger sealant is leveled. At this stage, you must be especially careful. Collect better on a horizontal surface. After assembling and checking all the connections, you can gently pull off the two guides with a rubber band and leave to dry.
• When the entire absorber design has dried its can be lifted gently and placed on top of the box so that the distances from above and below are the same. After that, the positioning of the guides is done, after all, for their mounting in the box, will have to cut out the groove in the heater so that they sit tight and the rests on the plywood sheet in the rear wall. After installation, the guide rails are attached from the ends through the side panels with furniture screws .After this, all joints are sealed with a sealant.

• For the entry and exit of air immediately it is necessary to provide the holes that are best made in the rear wall. The best way to do this is to use ready-made solutions in the system of plastic ventilation ducts, namely wall plates with a flange that can easily be mounted in the rear wall at the entrance and exit areas not occupied by the adsorber. To do this, in a plywood sheet and a heater, a rectangular hole is cut through the dimensions of the plate, and then it is fixed to the wall on the screws through the sealer layer.

• If you need to go to a circular air duct, mount a duct fan, make a turn, etc., then in the range of manufacturers there are any pipes and fittings that need to be adjusted already in place.
• The upper and lower face of the solar collector at the points of entry and exit of the ducts must be faced. For this purpose, a lining is very suitable, but its must first be cut to the exact size, and then cut the heater on the side and end walls of the collector exactly at the thickness of the lining. After that, it is glued to the sealant, it also handles all the joints.

• For painting, the collector is placed on the stops in a position close to vertical. Before painting, surfaces are degreased and dried. The paint is applied to several layers of until it covers the entire visible surface. Each layer is applied so that no streaks form. The surface should be saturated black and matte.

• After drying the paint, it's time to mount the front glass. For these purposes, acrylic plexiglass or polycarbonate glass is best. Firstly, if the is applied to the surface, its dimensions are outlined, and then it is already cut out. The edges immediately have to be processed with sandpaper and fit exactly to the size. Before installation, it must be thoroughly cleaned, especially the lower surface and placed in a compartment with an adsorber several bags of silica gel. It will prevent condensation on the inner surface of the glass.
• Before to , you need to replenish the glass, you need all the parts that are adjacent to it: the perimeter of the box and the guides are treated with sealant. And does not necessarily apply the sealant to the entire surface, it is sufficient only on the ends of the plywood sheets. To fasten it is better with screws with a press washer, preliminary having drilled before it apertures. It is advisable still and cover the edge of the glass with a special corner furniture profile.

• perfectly fits. To fix the air solar collector, you can fasten the brackets to the rear wall to it. This completes the assembly of the collector itself.

Connection of the solar air collector

The air solar collector can either integrate into the existing ventilation system or work completely separately. Even in the absence of forced ventilation, the inexorable physical laws of all will equally "promote" the heated air through the collector, but this process will go rather sluggishly, so a fan with a capacity of at least 150 cubic meters per hour is desirable.

Application of the fan reveals two important questions:

1. Where is the fan put: at the inlet or outlet of the collector? If the collector raises the outlet temperature to 60-70 ° C( and is it is quite possible ), then the fan standing there will not last long. On the other hand, a fan standing on the street is exposed to atmospheric influences and is more difficult to control. In most cases, its is still placed inside the room, and on hot days when the air is already heated - the fan simply does not turn on or connect it through a thermal relay.

1. The use of a fan makes certain skeptics doubt the feasibility of air heating. Is not it easier to direct the electricity spent on rotating the fan motor to heat the room? But practice shows that the collector design described above is all equally effective and profitable for the .The temperature difference between the outside air and the outlet from the collector can reach 35 ° C.

When operating the air collector, the still appears one reasonable question: at night, when there is no insolation of the collector, even if the fan is not working, cold air will enter the room. The solution to this question is quite simple. Among the components for ventilation systems, you can find special reverse valves , which open only under the pressure of the air flow. If the fan is not working, the valve will be closed. It is important only to install it correctly so that it does not block the air duct. There are also models of fans with a built-in valve, which should be noted.

For rapid warming up of the with warm air, you can think of a recirculation system when air from the room passes through the manifold and returns to the same room. In this case, it is justified to install a fan that will pump air into the manifold, rather than creating a vacuum in the .The disadvantage of recirculation is the lack of fresh air.

Operation and maintenance of the solar air collector

In order for the manifold to last long and trouble-free, two simple rules must be observed:

• Periodically it is necessary to clean and flush the front glass of the solar collector.
• In hot summer days, when there is no need for heating the air, it is better to cover the collector with a dense light cloth to avoid overheating of the absorber surface.
• To ensure that the fan does not run dry, periodically check the tightness of the duct connections and their integrity.

Conclusion

Summing up the article, it is worth paying attention to several points:

• The solar air collector model proposed in this article proved in practice its effectiveness and is successfully used all over the world.
• Optionally, you can make a more powerful solar collector or connect them in series.
• Air solar collectors can be used periodically. For example, for heating air in greenhouses in the early spring or for drying agricultural products in the fall.

Video: How to make an air solar collector( eng)

Video: Slideshow about manufacturing a solar collector from aluminum cans