DIY - Solar air heater - Heating without power!

 

Thermal application space heating - Solar Heater
With the construction that will show here, can heat a room in winter (the days can be cold but sunny weather, even partial). The modules are not suitable for heating a space, for the conversion of solar energy into electricity and then again converted into electrical energy by thermal means huge losses, making the solution of photovoltaic inefficient. Here instead, we will convert solar energy directly into heat, warming the air.

The solar air heater (solar heater) is very easy to build and very cheap! Me cost me about 30 Euros in materials and two hours of my time! This you see here is very small and because of the small surface area is only suitable for a small space such as a small store a small caravan etc. (If you put two such collectors). Fabricating but in a larger format (and / or putting more) can heat and proportionately larger areas.
For example, here is the tray is 50cm wide and 100cm in height, that has a surface of 0.5 mA room eg 10 sq.m. takes 1/5 of the surface of a collector, i.e. 2 m solar collectors as the heater it.So for an area of ​​10 sq.m. they will make a solar air heater (collector) with a surface area four times larger than 0.5 m, ie a manifold with dimensions of 2 meters height for 1 meter wide (2 m).For an area of ​​20 sq.m. they will make two panels with 2 meters high by 1 meter in width each.
The construction
As shown in the figure above, we construct (or order ready a carpenter) a frame in the dimensions we want depending on the area they want to heat (see above). On the front put a mosque (we stick around with transparent silicone).The distance from the timber back to the glass front, should be about 7 cm for every 1 meter of the collector. There will be heated air out of the sun.The ratio of height to width of the collector should be about 2:1.
On the back there should be two openings, one down and one up. Underneath it enters the wind and cold will be coming from the top opening warm (hot air is lighter than cold, so it rises and will be leaving the top open).
In the next photo shows the exposures. I did at the beginning of the cycle to experiment but it is preferable to be rectangular as shown below:
The height of the slit inlet and outlet flow is approximately 6 cm for each meter of the collector. If for example the height of the collector is 2 meters, then each slit should have a height of about 12 cm and a width nearly the width of the collector.
As we said, the hot air will be coming out with pressure alone, without the use of fans, from the top outlet as shown in the representation on paper towels that I made in the next picture.The collector placed outside the wall of the space we want to heat. Open a hole in the wall which communicates with the lower opening of the collector and insulates gaps to prevent leaks.Or joined with a tube thus creating an air duct. From here it enters the cold air of the room.Do the same for the top opening of the collector and the wall of our space. From there it returns the warm air again in most indoor-heated.
Designed to prevent the reverse process at night and cools the space, hang a thin plastic sheet on the top exit. Because it is light, the pressure of the hot air in the outlet and thus pushes the path is not interrupted air. In the evening there is no air movement, the plastic visor disappears and closes the exit.
Computers (with several complex calculations that are not present) that this construction achieves almost 1.000 BTU per square meter of collector. I.e. with a collector surface 2 m earn each day (from 10:00 to 16:00) over 10.000 BTU heating in free! 4 m wins over 20.000 BTU. Not bad ... And then the benefit is even greater if we consider that when you leave the sun and light a heater, stove or electric heater, they should just keep an already warm cozy space and not to heat from 13 degrees at 19 (this implies a significant fuel economy or power).The solar heater can not reach an area of ​​13 to 14 degrees Celsius to 19 to 20 ° C in two hours.
The first tests
The first test came in January, a day not exactly sunny but with enough sun. The outdoor temperature was a little over 15 degrees Celsius (the digital thermometer behind the collector shows 18.4 because there the air is affected by the temperature of the collector itself).
The collector left for 30 minutes in the sun. With a digital thermometer (and this DIY job) measured the temperature at the inlet cold air and it was 18.4.Immediately after measured the temperature at the exit of hot air was 50.4 degrees Celsius! The solar air heater raised the temperature of the air in his whole by 32 degrees within a few seconds!
So works and very efficiently. His performance certainly went up a bit, after I hung and stretched a black metal screen (like the one we put in windows for insects) within the frame and in half the distance from the back to the window. Because it is black and metallic, heated very quickly and transmits its heat to the air passing over and beside her as he climbs up to find the exit onto the frame.
Applications
The applications are numerous: a small scale can heat a small space such as a camper, a small workshop or garage etc.On a large scale, we can imagine the entire south side of a house "dressed" with such panels will give 100.000 BTU each day indoors, warming day and saving fuel in the afternoon (since when you get into the heater, the space will is already at room temperature).Because construction costs are low, the damping becomes very quickly. In terms of aesthetics, if done right job, the result is beautiful. What appears is a black glass surface, where else would seem the wall behind the glass panels.There are ways to store heat provided by the solar collector. But add in complexity and will not linger here. Illustrative only: the convection of hot air can be directed onto a large diameter column containing water. The water will warm up much, but it slowly releases that heat till late in the evening, after sunset.Below you will find other articles that interest you, divided into three sections ...