Concentrating sunlight to creat different extream temperatures

[douglasg14b]

I am wondering of a way to concentrate sunlight to an extent to create high temperatures that vary depending on how many mirrors, lenses...etc i use and so on...it is an idea i have for a physics project any suggestions on how i might go about this would be muchly appreciated.

 

[Loren Booda]

In the 1970's I bought a plastic, 12" x 12" x .2" Fresnel lens from Edmund Scientific Company for $6. I would guess that in full sunlight it generated over 1500^o F. Paper would catch fire in a couple of seconds; in general, organic material would easily vaporize. It would take out not just an ant, but the whole anthill. I believe I melted lead with it; I have heard said that it could melt a penny. It seemed to ablate concrete. I probably have some eye damage thanks to my youthful nonchalance.

 

[robphy]

For really high temperatures, check out "nonimaging optics".
http://findarticles.com/p/articles/mi_m1200/is_n22_v135/ai_7344688

 

[douglasg14b]

using non-imaging optics to concentrate sunlight

how might i go about using mirrors and a large lens or 2 to concenrate sunlight enough to attain 3500-8500k or the closest i can within limited funds [physics project] and also how i might measure the temp.

 

[Captain Barbosa]

I probably have some eye damage thanks to my youthful nonchalance.

*tsk tsk* They're called welding goggles my friend... The biggest lens I have is a 8.5"x11" fresnel page magnifier. Douglas, your question might be easier to answer if we had a general ballpark on your budget.

 

[douglasg14b]

*tsk tsk* They're called welding goggles my friend... The biggest lens I have is a 8.5"x11" fresnel page magnifier. Douglas, your question might be easier to answer if we had a general ballpark on your budget.

can you expand on that...if you are saying i need space i live on a farm so i have abundant space. and would concentrating light on a large lens using mirrors increase the concentration of sunlight on the other side of the lens thus increasing the temperature?

 

[Captain Barbosa]

and would concentrating light on a large lens using mirrors increase the concentration of sunlight on the other side of the lens thus increasing the temperature?

Assuming the lens could survive the already concentrated energy, I don't see why not.

For the budget thing, how can we keep a limited budget in mind if we have no idea what that budget is? Are we talking tens, hundreds, or thousands of dollars here?

 

[douglasg14b]

Assuming the lens could survive the already concentrated energy, I don't see why not.

For the budget thing, how can we keep a limited budget in mind if we have no idea what that budget is? Are we talking tens, hundreds, or thousands of dollars here?

we are speaking the budget that one would use or a advanced high school physics project[year long] like 100 to150$ I am not going to spend allot on a grade.

 

[berkeman]

I googled solar mirror array, and got lots of good hits:

Make-it-yourself solar furnace with a mirror array -- http://amasci.com/amateur/mirror.html

Solar power tower fed by a large area mirror array -- http://en.wikipedia.org/wiki/Solar_power_tower

Private (medium size) heliostat array -- http://www.redrok.com/helio.htm


EDIT -- This is a better page at RedRock: http://www.redrok.com/main.htm

 

[AlephZero]

This might not sound as much fun as a solar furnace, but you can easily heat up small objects to 1000C in a few minutes, using the light from a a 12V halogen car headlight bulb instead of sunlight.

We had a test rig for doing high temp experiments on objects about 1mm cube that used that method for heating, with a feedback loop and a controller to vary the lamp output once the object had got up to the working temperature.

The bulbs already contain a parabolic reflector, so you don't need any fancy optics to make this work.

 

[berkeman]

This might not sound as much fun as a solar furnace, but you can easily heat up small objects to 1000C in a few minutes, using the light from a a 12V halogen car headlight bulb instead of sunlight.

We had a test rig for doing high temp experiments on objects about 1mm cube that used that method for heating, with a feedback loop and a controller to vary the lamp output once the object had got up to the working temperature.

The bulbs already contain a parabolic reflector, so you don't need any fancy optics to make this work.

So did you use a 2nd (no bulb) headlight to concentrate the light from the source headlight?

 

[Captain Barbosa]

Here is a 20.5" x 36" fresnel I just found that you can buy for 80 bucks plus shipping. http://www.alltronics.com/cgi-bin/item/24L021/32/20%2E5%22%2DX%2D36%22%2DGiant%2DFresnel%2DLens

Some of them are a bit out of your price range, but here are some more to choose from if you want. http://www.edmundoptics.com/onlinecatalog/displayproduct.cfm?productid=2040