solar heater made from cans beer soda etc

[billi]

some interesting testing of air collectors  i found , if someone has the passion to read through ,

i was surprised that the air to water changer  heated water upto 80°

 http://130.226.56.153/rispubl/solenergi/sec-r-29.pdf

same guys  their absorber is perforated so the air flows on both sides of the absorber and through the absorber

http://www.solenergi.dk/rapporter/sec-r-22medbilag.pdf

I thought of tar /asphalt as the absorber covering 30mm-50 mm inch pipe , i think 1 ton of Asphalt is about 60 Euro so that should be enough to built a 5-8 m2 Absorber  (50mm -80mm thick) , built on a frame in the garden  and use polytunnel plastic first  as a tryout (can be replaced with glass if needed ) . I guess the mass of the asphalt could be a good buffer . I have to try a m2 to find out , if the asphalt melts and start to flow or will the tunnel plastic melt  


Billi

[dhaslam]

as a black fiol that is heat resistant ther is a product they use in film lighting  called black wrap,  they use it to control light  wrap it ourond to create effects some of it infact most of there lights are very hot 200w upto 20k plus.. it is mat black and great as it disappears as it it as stated mat  black hears a link
http://www.filmandvideolighting.com/blstforo12.html

actually looking at it  closer is made from aluminum and is 12in by 50 ft 21 dollar very heat resistant have a look could be useful. it is really easy to shape about 6 times as thick as baking foil holds its shape even  with  heat  black both sides.

i have some ends  of rolls in the shed could test any quick ideas?
 

[/color]

It would work out a little expensive on a large area. On ebay it is about £6 per square metre.    Metal roof sheeting is about the same price and it may be possible to find some recycled  sheeting. 

To test it you would need to put it in a box with plastic cover and blow air through it with a fan and measure the difference in air temperature.  For a measurement in kw the speed  volume  and velocity of the air movement would be needed but for comparison  only the temperature difference is needed.     

The biggest disadvantage  of a makeshift  collector is that efficiency would be low on dull days  but  a big area would make up for this on sunny days.       This assumes that the  heat can be stored in some way.   

I think that the tar system  would be  a bit messy.  Even in Ireland the tar melts on roads on a sunny day.   If probably would mean that the collector couldn't be mounted at a steep angle or it it would all  go to the bottom.    For  air heating  rather than water there isn't the same problem of concentrating  the heat into the  smaller water pipes.     I  am planning on using air to warm the heat store (using clay  as the storage medium)  but use  water pipes to extract the heat because it would be difficult to transfer warm air  over a distance.    The other advantage of hot air for the collector is that  there is no worry about overheating,  freezing, leaks  etc.   
   

[djh]

The thing that always gets me about air heaters is how to clean them?

Over time they're going to collect a lot of dust for sure and unless you're both very careful and lucky they're going to collect a fair few dead insects. So the question for me is how to design the thing so all the air passages are easily accessible?

[Chanireland]

yeh metal sheeting quick and easy. also could give it a wipe down if need  after taking the  glass or whatever off...
Billi intersting link yeh needs a bit of a reading  much info  but pushing air through sheet of  metal or cloth is diferent method alogether but seems to work for them and that  was 2002 so not such an old experiment. crazy the cloth absorber works aswel...
wonder about simple sheets of metal roofing (ie corigated area is littered  with the stuff..) holes drilled  through it. only diferance is there absorber is flat son not sure  how this would afect it.
they have some very detailed diagrams of how the madse  them in mm no less...

not sure about the sun to air to water to many transfers for loosing heat. pro better keep it simple

[daftlad]

The thing that always gets me about air heaters is how to clean them?

Over time they're going to collect a lot of dust for sure and unless you're both very careful and lucky they're going to collect a fair few dead insects. So the question for me is how to design the thing so all the air passages are easily accessible?

Especially when they are fitted with those diffuser things, maybe that is where the flat bits of foil would come in, maybe this is one time flat plates are better than tubes? 
ta ta

[Baz]

That special foil mentioned by Chanireland sounds good if thicker and already blackened.
I think double glazing is probably not cost affectve as the hot air will be taken off the rear / inside of the aluminium element. The air between the aluminium and glass will warm up and provide a buffer - but fit crosspieces to stop convection.

A quick and easy test would be to choose a wall or use a large piece of ply, cover with one inch of expanded polystyrene sheet, attach vertical laths 1 inch thick at spacing equal to width of foil, glue on foil, more spacer laths, then stretch over clear plasic sheet or even cover with bubblewrap. Seal it up a bit against rain with duct tape.
Just see how hot the back chamber can get before going to the trouble of piping it in.

[justsomeguy]

The thing that always gets me about air heaters is how to clean them?

Over time they're going to collect a lot of dust for sure and unless you're both very careful and lucky they're going to collect a fair few dead insects. So the question for me is how to design the thing so all the air passages are easily accessible?

Why not use a small heat exchanger and then you can keep the same air in the panels, becomes a sealed system no room for dust and insects,
could even combine it with a Air Source Heat Pump ? then the lack of double glazing could be a bonus when overcast.