Heating Water for Clam Shell Molds

parabolic mirrors

I taught in an "Education Otherwise" school in Ireland. We made parabolæ from papier maché, and had huge fun with them. We calculated and cut a half-parabola in 10mm ply, and mounted it, along the axis, to pivot on a piece of metal pipe banged into the ground. Piling rocks and stones around it to just clear when the curve was turned round the axis, we covered the mound thus formed with cement and skimmed it off with the wooden form.
Next day the parabolic cement bump was sanded smooth and given a coat or two of gloss paint. This mould served many times. When dry, we smoothed aluminium cooking-foil all over, and burnished it down with the back of a spoon. We then built up, over several days, layers of newsprint papier-maché with a dose of PVA wood glue in, and eventually radial "ribs" made from old rope. The resulting dishes, about 45" in diameter, were flexible but surprisingly strong. The mould was 48" in diameter, but the dishes were afterwards trimmed neatly, and edged with split cable-insulation.
The kids used them;
- As umbrellas, when it rained...
- As Frisbees™, until they got too bent to fly...
- As shields, wash-basins, for collecting blackberries...
And of course for their original purpose: to concentrate sunlight. The focal length was about six feet, and when freshly-made the hot-spot about 2" - 3" wide. Three dishes together, in bright sunshine, would ignite a paraffin-soaked rag as it fell through the combined focus, and our coffee-pot, already as black as night from having been on the open fire, boiled in a very short time.
For an industrial process you could make them much bigger, though for water-heating a linear collector with a pipe along the focus could be more appropriate.

thats a good iedea but to exspensive to make for industreal use plus to mantan wear I live is in japan we have big tiefuns in the summer from jun to nov with in this time thare about 15to20 tifuns or small heracans .Iam now traying a new way buy suing soler and a boler than a 20leter plastic brum and and recicol the water twice thean pump into the mold .do you think it will work????

Have not de-fragged my brain lately,yet I know disney, I think in L.A. Cal. U.S.A. built a huge concert hall modeled after ship sails or something like that & exterior was largely stainless steel- some shiny, some not. After apartment dwellers across street complained bigtime about extreme a/c bills & unable to use balconies-plus 150 degree sidewalks-the shiny steel was sanded. Maybe stainless, polished of course could be your answer-just a thought.

I like this idea alot can you seand me a blue prent of one ?MR.handyman thank you

Kindof busy right now seeking funds to finish my 200 mpg prototype car-however, will search my un-organized files over next few days & see what I can find.Recomend searching Modern Marvels - extreme engineering , architecture,engineering mistakes & solutions , how stuff works.com,& myth busters @ discovery.com-will reply in 3 days or less if I find any data In my notes.Good luck.