Solar Parabolic Trough Charcoal Oven

[Turtle]

Sun! Very sunny day. I put the oven out about 40 minutes ago & it is now at 180 deg F. Just air inside (and an oven thermometer) so far. Photo below. WARNING! Do NOT look directly into the reflector!

[Racoon]

Originally Posted by Turtle

Sun! Very sunny day. I put the oven out about 40 minutes ago & it is now at 180 deg F. Just air inside (and an oven thermometer) so far. Photo below. WARNING! Do NOT look directly into the reflector!

That looks AWESOME DUDE!

I burnt my Cornea just viewing the attachment!

Good job Turtle-san..

a pat on the back, and more questions too....

[Cedars]

Originally Posted by Turtle

Sun! Very sunny day. I put the oven out about 40 minutes ago & it is now at 180 deg F. Just air inside (and an oven thermometer) so far. Photo below. WARNING! Do NOT look directly into the reflector!

*wonders if the military is repositioning satellites to answer the question

"what the hell is that?!"

[Turtle]

Originally Posted by Cedars

*wonders if the military is repositioning satellites to answer the question "what the hell is that?!"

I have a squadron of F-15's just South of me at PDX.

Originally Posted by Racoon

That looks AWESOME DUDE!
I burnt my Cornea just viewing the attachment!
Good job Turtle-san..
a pat on the back, and more questions too....

Thanks Rac. Here's some answers.
The oven is hovering just below 200° F in full Sun & an ambient air temperature of 64° F. That is less than half of what we need. If I resilver the reflector with foil, I expect a small increase in temp. On a warmer day, I expect a small increase in temp. However, I do not think this reflector is big enough to reach our target 450° to 500° F.
A feature of the large solar troughs is the inclusion of Dewar tubes around the receivers to retard heat loss to the atmosphere. I am not getting a Dewar tube.
http://en.wikipedia.org/wiki/Dewar_tube
http://en.wikipedia.org/wiki/Dewar_flask
So, I think a trough in the 12 foot range (mine is 42") with the same uninsulated stove-pipe tube is sufficient to get to 500° F. While I consider that task, I have in mind to jam some yard debri in the tube & bake the hell out of it just to see how it changes.

[Turtle]

I have sat watching the oven a while, beer in one hand, pestle grinding charcoal in the other, & I noticed it is driiping water out now. I packed the receiver (black tube) firmly & nearly full with yard trimmings including Rhodedendron stems & leaves, flowering Plum stems & leaves, Maple dead stems, & some unidentified miscelaneous trimmings. I left room for the thermometer in the end I have capped with folded foil. This keeps blowing off in the wind and/or from the pressure inside the receiver. I just crimped it tighter & knifed in a small vent hole. The dripping end has a 'factory' cap that is tight fit but not air tight (or water tight obviously).
In just reading a new post in the terra preta thread I saw a first mention of 'brown' charcoal, which is apparently less heated & contains more plant resins. Perhaps this oven suffices after all.
I find I actually need the reflector inclined higher, but I have not added the safety chains to the receiver & struts so I have to rely on gravity to hold it in place.
This concludes this irregularly scheduled report.

[Cedars]

Has the temp changed at all from the last reading you posted?

[Turtle]

Originally Posted by Cedars

Has the temp changed at all from the last reading you posted?

It's a little after 6:00 PM here & the temp dropped below 120°F inside the receiver. The Sun is still bright, but at too low an angle to hit more than half the reflector at the angle I have it.(Once I have the retaining chains attached & holding the receiver this is adjustable through 90°) The ambient temperature reached 70°F & now is dropping. Last nights low reached 36°.
If this charcoalizing is to work well I think we need to have an oven sufficient to reduce 1 receiver tube charge per Sun cycle.
By the way, for you calculus whizzeesss; given the dimensions earlier, what is the surface area of the inside of my trough in square inches?

[InfiniteNow]

Originally Posted by Turtle

I ran across this idea in reading links on the 'terra preta' soils. That discussion aside, making charcoal out of yard debris rather than composting it appeals to me so I have started building an oven.
So far, I have a 2 foot length of black-painted galvanized steel stove pipe as the vessel which is suspended at the parabolic trough's focal point. (Photo attached below).
As I have a bit of work to do building the trough, I don't want to make it too small and so not achieve the 450F to 500F temperatures I need inside the tube. So, any ideas of how big I need to build the trough? The width I have fixed at 20"; this gives the pipe 4" of extension to accomodate further modules.

First off, Turtle my man, you are one righteous mathematical artist and inventor, and I am continually impressed by your interests and energy. Now, let me wipe off my nose (removing the brown) and get to my point...


I was watching FOOD Network last night, this show called "Ham on the Street." The episode was called "Free Food." Anyway, he used a solar oven, and I was like "Holy trucking Fhit! That's just like Turtle's whatcha mabob!"

Thought I'd share the link.

http://www.foodnetwork.com/food/show..._42428,00.html


At the bottom of the page is a link for "WHERE TO FIND: Solar Oven."

SUN OVENS International, Inc.
39W835 Midan Drive
Elburn, IL 60119
Tel: (630) 208-7273
Fax: (630) 208-7386
Tel: (800) 408 7919
Website: http://www.sunoven.com/usa.asp

After checking them out, I've totally decided that I WANT ONE!

Cheers.

[Turtle]

Originally Posted by InfiniteNow

I was watching FOOD Network last night, this show called "Ham on the Street." The episode was called "Free Food." Anyway, he used a solar oven, and I was like "Holy trucking Fhit! That's just like Turtle's whatcha mabob!"

Thought I'd share the link.

http://www.foodnetwork.com/food/show..._42428,00.html

After checking them out, I've totally decided that I WANT ONE!

Cheers.

Sweet! I wonder if that oven will cook a ham to a charcoal cinder? Although in shadow, it looks like the oven is sitting on the same wagon as mine!?
I cooked the wood debri yesterday for about 5 hours; water continued to slowly drip out but the temp stayed around 150°F. Today is rather overcast.
Infinitet, by all means report back if you get or make one. (I actually hoped to entice you with the spinning disk, not the oven )
I wonder if a 20 foot trough is enough to blaze a turkey?...Mmmmm....

[cwes99_03]

Hey turtle could you graph the temperatures over the period of a day for us? Preferably a sunny day, I wanted to know the length of time (and time of day) for cooking and such if you have a fixed axis.