Solar Parabolic Trough Charcoal Oven

[Turtle]

Originally Posted by GAHD

You can also use those AOL CDs you got in the mail for so many years. CDs are pritty reflective, so they offer a cheap alternative.

Hot idea, let me know how it turns out.

I bet if you made a parabolic mold you could heat the cds & reshape them. Then, build a hexagonal array of them brought to the same focus. VERY Hot!

Originally Posted by Colby

Be careful with that, those can get incredibly hot if properly designed.

Building material for 1 solar oven - $15.00
Time spent on project - 6 to 8 hours.
Having something really big & properly designed that gets incredibly hot & requires carefullness - priceless.

[Cedars]

There was a website (which I cannot find now) about using aol disks to create a beam of focused light. He had great pics of things he tried to start on fire. It wasnt that big either.

Pictures included melted baby dolls. Burnt marshmallows and an attempt to pop Jiffy popcorn. Might be worth some looking into.

[Turtle]

Originally Posted by Cedars

There was a website (which I cannot find now) about using aol disks to create a beam of focused light. He had great pics of things he tried to start on fire. It wasnt that big either.

Pictures included melted baby dolls. Burnt marshmallows and an attempt to pop Jiffy popcorn. Might be worth some looking into.

Interesting! I wonder if they reformed them into parabolic form? I didn't check the math yet, but with a long focal length - say 12" - not much curve is needed.
In the mean time, my oven - with a focal length of 10" - is ready to test. Unfortunately it's raining here today & corrugated paperboard & white glue do notta lika the raina!

[Cedars]

Originally Posted by Turtle

Interesting! I wonder if they reformed them into parabolic form? I didn't check the math yet, but with a long focal length - say 12" - not much curve is needed.
In the mean time, my oven - with a focal length of 10" - is ready to test & I have it illustrated below. Unfortunately it's raining here today & corrugated paperboard & white glue do notta lika the raina!

His pictures (from memory) had an array of like 10 disks wide by 15 high. He adjusted each one to focus the light to one point. From what I remember that was a hassle. I do not remember him saying whether he bent the disks or not.

[GAHD]

I'd just bend the disks with a nut, bolt and washer arragement; that lets you keep adjusting each disk independantly. If they're mounted in circular holes, the flex should be self-correcting and uniform. No heating requred.

The final product looks pritty cool man! Can't wait to hear how it works.

[Racoon]

Agree with GAHD!
Nice work Turtle-dude!
When you zero-in on a project, you don't mess around.

I'll reveal a little-bit about Turtle here:
He is one hell of a Craftsman!
But that is obvious.
excellent job!

I'll need your blueprints or sumfin'
I need to make some Terra Preta...

Love the thread...

[Cedars]

Originally Posted by GAHD

I'd just bend the disks with a nut, bolt and washer arragement; that lets you keep adjusting each disk independantly. If they're mounted in circular holes, the flex should be self-correcting and uniform. No heating requred.

The final product looks pritty cool man! Can't wait to hear how it works.

ooooh... Good idea! Simple and functional.

[Turtle]

Originally Posted by GAHD

I'd just bend the disks with a nut, bolt and washer arragement; that lets you keep adjusting each disk independantly. If they're mounted in circular holes, the flex should be self-correcting and uniform. No heating requred.

The final product looks pritty cool man! Can't wait to hear how it works.

While bending with a nut/bolt might curve the disk, it likely won't make it a parabola. On the other hand even an array of flat mirrors is capable of arrangements reflecting to a common focus.
I didn't know how low-to-go on the algebra of the parabola. The equation is basic analytic geometry. In terms of the optics, only the parabolic curve reflects every incoming ray to the same point, called the Focus. By all means ask for more clarification if necessary on this.
Cloudy & rainy today again so no test; just as well as the modem went kaflooy today.

[GAHD]

Have you thought of how to adjust the tube based on what angle the sun's coming from? From what I see, it looks like it's prime focus will only come into effect while the sun is directly overhead.

[Turtle]

Originally Posted by GAHD

Have you thought of how to adjust the tube based on what angle the sun's coming from? From what I see, it looks like it's prime focus will only come into effect while the sun is directly overhead.

In reading on the large electric generating plants using these troughs, some automatically track the Sun on 2 axes, some 1 axis, & some are fixed. I plan to tip my reflector up with the tube at right angles to the Sun & periodically move it for maximum efficiency. Photos of that to come, as well as the temp readings.
I also read a lengthy dissertaion on different reflective materials, including mylar, aluminium foil, sheet metal, & more exotic films. Seems the biggest problem is degradation over the long run from UV light & weather. Foil came out on top I gathered, once you have the correct adhesive & master the 'no-wrinkles' technique.
Not one source have I found that gives any ratings about temperature vs. size.