Solar Parabolic Trough Charcoal Oven

[Nitack]

Originally Posted by freeztar

Cool!
I was watching those over the past weekend, with the same search term.
One thing that comes to mind while watching the vids at utube is safety. We should consider creating a "safety protocol" for handling these potentially dangerous apparatuses. For instance, tinted safety goggles should be a requirement for any experimenting done with fresnel lenses. I also think it's wise to keep fire retardant nearby on every occasion. If we do manage to delve into electricity generation, then more fail-safes are needed. I'm not directing this at anybody in particular (I'm not trying to be Mr. Mom ).
But nonetheless, it needs to be said for those that may be unfamiliar with the capabilities of the technology involved.

I don't know about you, but once my big lens arrives I will be using welding gogles. No way no how I am going to blind myself with this project.

Of course, it seems to be just us three, so no impending liability concerns forseeable...

What are you talking about? We are the beginning of the movement! Viva la charcoalers! "Charcoal for the Climate" (CFC, maybe not such a great acronym)? "Charcoal Creation Initiative" (CCI, I could get behind that)? "Charcoal Changing the Climate Back" (CCCB, might be too long for an acronym)? Carbon Capture Through Charcoal (CCTC, eh)?

Until my lens comes I have nothing but time to come up with this stuff

[DougF]

Make that four as I'm following this thread too,
I was planning to make one along with you but just last week the landlord put the property up for sale I guess it will have to wait till I can find a new place.

Back to topic.
the design you've worked out seems sound to me and should work nicely.
for the mirror could you use a old satellite dish coated in foil? just thinking.

[Nitack]

Originally Posted by DougF

Make that four as I'm following this thread too,
I was planning to make one along with you but just last week the landlord put the property up for sale I guess it will have to wait till I can find a new place.

First of all Doug I am very happy you are here. More heads mean more solutions.

Back to topic.
the design you've worked out seems sound to me and should work nicely.
for the mirror could you use a old satellite dish coated in foil? just thinking.

I like the satellite dish idea because it might cut down on the amount of adjustments we would have to make to the lens angle during production. Its curve might help to naturally turn the light to the right direction as the sun moves. I think we will need something more reflective than aluminum though. Perhaps that stuff that some one suggested earlier in the thread.

[Nitack]

OK, American Science & Surplus: Incredible Stuff at Unbelievable Prices definitely does not get a good review from me. The lens I ordered from them took an ENTIRE WEEK to leave their warehouse. It shipped out last night, when I ordered it almost an exact week prior. It wasn't even a backorder thing, I actual called them and they said it was in their warehouse. I have a feeling that if I had not called it still would not have shipped out.

Their price was nice, haven't gotten the lens yet so can't attest to quality, but there service leaves much to be desired.

[Turtle]

Originally Posted by Nitack

... I like the satellite dish idea because it might cut down on the amount of adjustments we would have to make to the lens angle during production. Its curve might help to naturally turn the light to the right direction as the sun moves. ...

I don't think that is the case. The reflective parabolic dish is focusing the Sun's rays the same as the Fresnel. While the dish may require less frequent adjustment to maintain high temp at the focus, both setups require regular adjustment of their axis to the Sun for optimum output.

There is no advantage using a parabolic mirror vs. a flat mirror in the setup we described, with the Fresnel focsuing the rays and bouncing the beam off a horizontal mirror up to the receiver vessel bottom.

I have an idea for a tracking mechanism. Get the drive unit off of one of the Meade AutoStar (or similar) telescopes and attach your lens to it instead of the telescope. Potentially expensive, but you might find a used one. Just a thought.

[freeztar]

Originally Posted by Turtle

I don't think that is the case. The reflective parabolic dish is focusing the Sun's rays the same as the Fresnel. While the dish may require less frequent adjustment to maintain high temp at the focus, both setups require regular adjustment of their axis to the Sun for optimum output.

There is no advantage using a parabolic mirror vs. a flat mirror in the setup we described, with the Fresnel focsuing the rays and bouncing the beam off a horizontal mirror up to the receiver vessel bottom.

I concur.

I have an idea for a tracking mechanism. Get the drive unit off of one of the Meade AutoStar (or similar) telescopes and attach your lens to it instead of the telescope. Potentially expensive, but you might find a used one. Just a thought.

That would work probably, but sounds a bit expensive. I had an idea for a track system. Let me draw it up and I'll post it in a few.

[freeztar]

Here we go.
The major problem with this sytem is that the height of the fresnel stand and the coupling joining the fresnel to the stand must be adjustable to accomodate the sun's changing inclination. A crank could be rigged onto the track for moving the stand (something like curtains with rope and pulleys). There is probably a way to have the fresnel angle adjust as it is moved along the track, but I can't picture how right now. Thoughts?

[Nitack]

Sadly enough Freez, your artistic skills are better than mine. You have the right idea, but it would be difficult to impliment I think. First, the track is the hardest part for obvious reason. Also, we would need a tracker hooked up to the lens to change it's angle as well.

I have been thinking on this a lot over the past few weeks... wife says I have been talking about solar power and lenses in my sleep! The fresnel will be viable if it is attended, but for something more passive or less labor intensive Turtles parabolic design will end up as the way to go I think. I am still going to construct my Fresnel setup, but after that is demonstrated to be effective I think I am going to attempt to make the turtle setup work as well.

[freeztar]

In other news, I got my package of fresnel lenses the other day and hope to do some experimenting this weekend. This morning I took one out (8"x10") in the sun and burnt a hole through a green leaf in about 15 seconds. Not too bad, but I had hoped for more. I plan on using several at a time to turn up the heat. I bought an oven thermometer so I'll post some temperatures over the weekend.

[Nitack]

OH! picked up a dutch oven and oven thermometer today at lunch. Now I just need my lens (supposed to arrive tomorrow), and to build the frame and stand and I am ready to put theory to the test!