Solar air heater - Heating without electricity!
DIY Solar Heater: Solar space heating application - Solar Heater
The diy solar heater, can heat a room in winter (the days can be cold but should be sunny, albeit partial).
This Solar Heater page was translated automatically using a software. Sorry for the poor quality because of this...
Photovoltaic solar panels are not suitable for heating a space, because the conversion of solar energy into electricity and then converted back to heat means huge losses, making the solution of photovoltaic inefficient. Here however, we will convert solar energy directly into heat, by warming the air directly with solar energy.
The diy solar air heater is very easy to manufacture and very cheap! The cost is about 30 euros in materials and 2 hours of my time!
This specific diy solar air heater i build here is very small and because of this it is suitable only for a small space like a small caravan etc. (if you put two such panels).
But by constructing it larger (or placing more panels like this) it can heat larger spaces.
For example, this collector is 50cm wide and 100cm in height (has a surface that is 0.5 sqm).
We need the 1/5 of the rooms' surface as the surface area of the collector (i.e. to heat a 10 sqm room, we need 2 sqm of solar heater panels, for a 20 sqm room we need 2 panels with 2 meters high by 1 m wide each, etc).
As shown in the picture above, we construct a frame which we scale according to the square meter that we want to heat (see above).
The distance from the wood back to the front glas should be about 7 cm per 1 meter of the collector. There will be air heated by the sun. The ratio of height to width of the collector should be about 2:1.
Underneath the air enters cold and comes out of the upper opening hot (warm air is lighter than cold, so it will be up and leaving at the top).
The duct is preferable to be rectangular as in the following picture:
The amount of slit inlet and outlet flow is approximately 6 cm for each meter (hight) of the collector. For example, if the height of the collector is 2 meters, then each slot should have a height of about 12 inches and width approximately the width of the collector.
As we said, the hot air will come out with pressure alone, without the use of Fans, leave the top as shown in the animation I made with paper towels to the next image.
The collector is placed outside the wall of the space we want to heat. We are opening a hole in the wall which communicates with the lower opening of the collector and insulated the gaps that there are no leaks. Or joined with a tube thus creating an air duct. From here it gets cold air space.
The same for the upper opening of the collector. To avoid the reverse process at night (cooling therefore the space), hang a thin plastic sheet on the top exit. Because it is light, the pressure of hot air to exit has no problem. At night there is no air movement and the plastic windshield closes the exit.
With this type of diy solar air heater we achieve almost 900 BTU per square meter collector area. With a collector area of 2 meters, every day (from 10:00 to 16:00) about 9.000 BTU in free heating! With 4 meters, 18.000 BTU etc. Not bad ...
And then the benefit is larger if we consider that when you leave the sun and lit radiator, stove or electric heater, they should simply keep an already warm cozy and not the heat from 13 degrees to 19 (this material fuel economy or power). The solar air heater can heat from 14 degrees Celsius to 18 degrees Celsius in two hours.
The first tests
The first test was in January on a day not exactly sunny, but with enough sun. The outside temperature was just above 15 degrees Celsius (the digital thermometer behind the collector shows 18.4 Celcius because there the air temperature is affected by the collector itself).
I let the collector for 30 minutes in the sun. With a digital thermometer i measured the temperature at the entrance of cool air and it was 18.4. Immediately after I measured the temperature at the exit of hot air and it was 50.4 degrees Celsius!
The solar space heater raised the temperature of the air inside by 32 whole degrees Celsius within seconds!
So it works very efficient. His performance is good because i hang a black metal windows screen (like the one we put on windows), at half the distance from the back to the front glass.
Because it is black and metallic it heats very quickly and transmits its heat to the air passing over as he goes up to find the exit of the solar heater.
The applications are numerous: In a small scale can heat a small space like a caravan, a small workshop or garage, etc.
In large scale, we can imagine the entire south side of a house "dressed" with such collectors for 100.000 BTU per day in the internal space, warming the day and saving fuel for heating in the afternoon (because when the radiator starts, the room will be already at room temperature saving a lot of money).
In terms of aesthetics, if build properly, the result is beautiful. What appears is a nice black glass surface.
There are ways of storing the heat provided by solar panels. But it adds in complexity and i will not go in detail now. Just a hint: the hot air of the solar air heater can be directed onto a large diameter column containing water. The water will warm up much, but it slowly releases the heat it until late in the evening after sunset.
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