Solar Parabolic Trough Charcoal Oven

[Turtle]

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.:) :) :confused: :doh:

[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]

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.;)

[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!:doh: :evil:

 

[Racoon]

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!:doh: :evil:

 

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]

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!:doh: :evil:

 

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

 

"what the hell is that?!"

[Turtle]

*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.:eek: :eek2:

 

 

That looks AWESOME DUDE!

I burnt my Cornea just viewing the attachment! :eek:

Good job Turtle-san..

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

 

Thanks Rac. Here's some answers.:hihi:

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.:eek2: :)

[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.:shrug:

[Cedars]

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

[Turtle]

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. :hihi: :shrug:

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?:hihi: :doh:

[InfiniteNow]

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... :rant:

 

 

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_hs/episode/0,2763,FOOD_24696_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! :mad:

 

 

 

Cheers. ;)

[Turtle]

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_hs/episode/0,2763,FOOD_24696_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?:rant: :) :mad: 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:hyper: )

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.

[InfiniteNow]

Infinite, by all means report back if you get or make one..

http://www.sunoven.com/order.asp

 

At a hundred and ninety bucks, not too likely anytime soon. :thumbs_up

 

But at an avg temp btw 360 and 400, I don't see why a turkey'd be too difficult. :eek_big:

[cwes99_03]

Well a turkey in July anyway :esmoking: !

[Turtle]

It is clear & Sunny today & I have the oven cooking away on its charge of leaves & branches. By the end of the day about 15 hours total baking time. Ambient temperature unsure as my thermometer is in direct sunlight now (gotta move that thing!).

HOT!

/forums/images/smilies/devilsign.gif

[Racoon]

It is clear & Sunny today & I have the oven cooking away on its charge of leaves & branches. By the end of the day about 15 hours total baking time.

 

Then what?

Mix finished product in the soil? or Make enough for super-rich Potted Plants soil?

 

I need to build one of those guys for Pot Plants...errr Potted Plants :evil: :)

 

Your attachments make it easy to follow. Again, a pat on your sore back. :eek:

 

I love the this thread,

the 'coon