The author of this air collector set the main goal of saving on heating a house in the spring and autumn. Considering that if you focus on the combination of the collector with the exterior of the house and make it small in size, as in the previous article, then there will not be much sense from it, it’s only enough to heat the room. Therefore, he decided to make the largest solar air collector possible.
Materials that the author used to build a large air solar collector:
1) boards 30-40 mm thick
2) moisture resistant plywood 10 mm
3) OSB plate
4) aluminum drainpipes
5) mineral wool
6) polystyrene
7) wooden blocks
8) transparent slate
9) matte black heat resistant paint
Consider the main points of the construction of this model of a solar air collector, as well as the scheme of its operation.
As in the past case, the collector was decided to make the maximum length equal to the length of the house, but also higher. Since the dimensions of the future collector, based on the considerations of the author, were impressive, the materials for its manufacture were selected suitable. A board with a thickness of 30-40 mm was used as the main frame. The back wall of the box in which the absorber will be placed was decided to be made of moisture-resistant plywood 10 mm thick.
Below is a diagram of the solar air collector, which shows its basic principle of operation and general view:
Since aluminum is one of the metals that conducts heat well and is not very expensive at the same time, the author decided to use rectangular drainpipes made of aluminum as an absorber for this solar collector. Although it is also allowed to use conventional pipes made of sheet metal of circular cross-section, simply the efficiency of the air manifold will directly depend on this.
Since efficiency was in the first place for the author, he decided to additionally insulate the back wall of the box with mineral wool.The author decided to also insulate the side walls of the box in which the pipes will be placed, but with the help of expanded polystyrene. In addition, in order to maximize the efficiency of the solar collector, the author put an aluminum sheet on the mineral wool, which will also heat under the sun and transmit heat to the pipes. Further, rectangular pipes were attached to this sheet.
Since the entrance and exit of the solar collector is on the one hand, the author decided to divide this part of the collector using a partition. which he made of wood, and then, like the back wall, sheathed with aluminum.
Thanks to this partition, two air flows of 3 pipes each are created in the collector.
The collector is quite large and for the most part made of wood and metal, which is why it turned out to be quite heavy. Therefore, the author recommends doing it already at the installation site using tripods, otherwise you will have to ask friends for help to pull out and install the collector, since it is too hard to lift such a structure.
Since the basement of the house is low, and the air manifold turned out to be quite high, the author decided to install it at a certain distance from the house and make it tilted. The tilt will not only put the absorber under the direct rays of the sun, but also allow you not to block the windows from sunlight. To fix the solar collector on the street and keep it at an angle, the author used a three-part construction. The holders were made of thick wooden beams and were aligned to the same height, as can be seen from the following photo:
To carry out the supply of air ducts to the house, the author dug a small trench from the house to the side of the air inlet and outlet from the solar collector. Pipes were laid in this trench along which air masses will move from the house to the collector and vice versa. Then he insulated these pipes with foam.
Since the base of the house is low, and the air manifold is high, it will have to be installed at a distance at an angle so as not to block the windows. To supply the air ducts, a trench was dug and the air ducts were laid in it, previously everything was thoroughly insulated with polystyrene foam.
After completing the assembly and connecting the solar collector, the author painted it black with heat-resistant matte paint.
In order to protect the pipes from wind, dust, dirt and other external conditions that could affect the efficiency of the collector, the author closed the box with pipes using transparent pieces of slate.
To ensure the movement of air masses inside the solar collector, the author installed a duct fan at the entrance to one of the pipes of the solar collector system.
The author took the main measurements of the work in December. The temperature in the street in sunny weather was about minus 10 degrees, and the temperature of the intake air into the solar collector system was about plus 14 degrees.
As a result, the air temperature after heating in this model of the solar collector was 65 degrees at the exit at 12 noon. However, since the days are rather short in winter, this collector could only work from 9 a.m. to 3 p.m., so it can only be used as support for basic heating.
Regarding the operation of the collector in summer, the author notes that if there is no need for heating the air, then the solar collector can be obscured, thereby reducing the effect of temperature on the collector.