So I'm building a solar cooker for school. I need something on top of the cooker that has the capability of letting light in but doesn't let the infrared radiation out (much like a greenhouse). Since custom cut glass is relatively expensive, I was wondering if Plexiglass has this glass-like property. If so, what thickness should I use?
thanks broskis
[QUOTE=QuadCoreGman;22315164]So I'm building a solar cooker for school. I need something on top of the cooker that has the capability of letting light in but doesn't let the infrared radiation out (much like a greenhouse). Since custom cut glass is relatively expensive, I was wondering if Plexiglass has this glass-like property. If so, what thickness should I use?
thanks for doing my homework broskis[/QUOTE]
Maybe google it?
Might wanna try the Science sub-forum.
You could ask your local glass seller if they have any offcuts/scrap pieces of glass they could sell at a reduced price
[QUOTE=sonicrjk;22315210]Maybe google it?[/QUOTE]
I did, but I didn't really get a definite answer, much less an explanation of why or why not.
internet research time
Typically greenhouse glass will transmit solar radiation of wavelengths between 280 nm and 2500 nm and absorb infrared or thermal radiation in the 5000 nm to 35000 nm region. Plexiglass will let solar radiation up to 2800nm pass through and block infrared radiation up to 25000nm.
[url]http://www.school-for-champions.com/science/heating_greenhouse.htm[/url]
[url]http://en.wikipedia.org/wiki/Poly%28methyl_methacrylate%29#Properties[/url]
I'm no scientist but although plexiglass covers less infrared in the upper range they both seem to have generally overlapping infrared ranges and plexiglass seems to be a generally ok material
[url]http://www.hoophouse.com/greenhouse-glazing-options.html[/url]
aluminum foil as a solar cooker is effective as well, although I dunno if that's how you want to make your cooker
Large Fresnel lens, will cook FAST. I have used a 40 inch one before.
Will even melt coins.
Plastic is always better than glass.
Glass, it's naturally more thermally insulated. And cheaper.
Will it properly cook food or just warm it up?
One way glass?
[QUOTE=QuadCoreGman;22315164]So I'm building a solar cooker for school. I need something on top of the cooker that has the capability of letting light in but doesn't let the infrared radiation out (much like a greenhouse). Since custom cut glass is relatively expensive, I was wondering if Plexiglass has this glass-like property. If so, what thickness should I use?
thanks broskis[/QUOTE]
Plexiglass works fine, used it on cheap homemade greenhouses before and since you're trying to achieve the same effect, you should be alright.
[QUOTE=ExplodingGuy;22317134]Glass, it's naturally more thermally insulated. And cheaper.[/QUOTE]
No its not? Thats why it feels cold when you touch it.
[QUOTE=Maucer;22319568]No its not? Thats why it feels cold when you touch it.[/QUOTE]
Just because glass is at a different temperature to your skin does not make it a poor insulator, it is quite good, hence thermos flasks used to have (and some still do) glass inside them.
Infact, if what is on the other side of the glass is hot, and it feels cold to touch, does that not make it a good insulator?
It's not cheaper though.
[QUOTE=Maucer;22319568]No its not? Thats why it feels cold when you touch it.[/QUOTE]
You shouldn't associate insulation with only hot things.
Insulation is more to do with keeping a temperature stable. Insulation can be used to keep things both hot and cold.
alright, thanks
You can do this with a cardboard box. Cut the top flap so it functions as a lid on a pivot. Cover it in tin foil. Paint the inside of the box black. Stretch plastic wrap over the top and have the lid propped up at an angle the causes sunlight to be reflected into the box.
It's like magic!
pretty sure glass would be better, but harder to get and install. plexiglass would be easier to get, cheaper and easier to install. take your pic :P
Will post pictures of cooka when it's finished, along with temperatures.
[QUOTE=QuadCoreGman;22335970]Will post pictures of cooka when it's finished, along with temperatures.[/QUOTE]
I cant wait to see it :allears:
Thumbnail'd em cause they're so big.
[img_thumb]http://i298.photobucket.com/albums/mm243/irleethaxor/IMG_2032.jpg[/img_thumb]
[img_thumb]http://i298.photobucket.com/albums/mm243/irleethaxor/IMG_2031.jpg[/img_thumb]
Started cooking at around 8:00AM, sat in the sun for an hour and a half or so. Cup of chile got up to 134.6 degrees fahrenheit.
Thats a pretty awesome box there!
You plan to keep it?
Yup.
Use black for inside paper and it'll get hotter.
It is black, it just looks purple.
edit:
it is kind of purple :downs:
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