Solar cooker

Know of a stove that has some Character about it for one reason or another, post it here.
churro
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Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Fri May 01, 2015 9:56 pm

I am a little embarrassed to be posting so much on a lightweight backpacking site about something that won't work for backpacking (yet), but I promise that there is a portable version in the works. Got supplies today...

I take after my grandfather in the sense that I'd rather work with what I have than with what I might someday buy. My grandmother told me a story once: she was a new bride, and she and my grandfather had just travelled by train to their first home together in Missouri. My grandfather had a job as a cabinetmaker, and they had just moved into an apartment together, and had bought a new stove with a vent-fan. When one of the motors quit on a jobsite tool, my grandfather had very thoughtfully salvaged the brand-new motor from the vent-fan on his new bride's kitchen range. My grandmother did not think it was so thoughtful, though, when she arrived home to find her kitchen disassembled. He did bring home the motor after the day's work was finished, but that clearly hadn't put the matter to rest, as she was still talking about it 50 years later.

I remembered that story today, and decided to just go ahead and spend 6 bucks on several mylar blankets, instead of risking that my lovely wife will be telling my grandchildren how I hoarded granola bar wrappers for 2 years just to make a solar cooker (and avoid paying $1.99 for mylar to make 2 of them). I still stand firm in my conviction that it could be done with "trash" (not my word).

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zelph
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Re: Solar cooker

Postby zelph » Sun May 03, 2015 1:11 pm

When one of the motors quit on a jobsite tool, my grandfather had very thoughtfully salvaged the brand-new motor from the vent-fan on his new bride's kitchen range. My grandmother did not think it was so thoughtful, though, when she arrived home to find her kitchen disassembled.


:mrgreen: Your grandfather is lucky to have both hands after that little adventure :mrgreen:

I had an idea.....use a thin wall plastic tube with 2 cup capacity and a trough like solar reflector.

The tubes can be made with fluorescent tube covers https://www.google.com/search?q=fluores ... CAcQ_AUoAg

This company has 5ml mirror sheet:

http://www.mirrorsheeting.com/

Just tossing out some light weight material ideas. These materials can be found if given enough time in thrift stores. Keep our eyes open :D

A couple years ago I did test with different rice brands. I used 1 cup rice to 2 cups water. I placed 2 cups 70 degree water into a 3 cup capacity pot and then put the one cup rice into the cold water. I proceeded to bring it to boil and let boil for 3 min and then let sit covered with towel for 10 min. It was cooked well enough to consume. All three test were positive with differend brands of rice. I'll see if I can find the test thread with the figures.

Here is a thread on cooking rice:

viewtopic.php?f=20&t=1854

Something I came across today while searching threads:

Re: cooking rice

Postby rik_uk3 » Sun May 24, 2009 7:39 am

Basmati is about the best 'non stick' rice to get, small grained it tends not to clump together as much as a standard long grain variety.

One option for cooking rice (and other food) is to bring the rice to a boil and then put in a wide mouthed Thermos flask, the rice cooks in its own heat and saves you fuel. This method works well with stuff like stews and a curry.


An idea for light weight backpacking size solar cooker:

http://www.soltac.com/

http://www.soltac.com/html/nepal.html
"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sun May 03, 2015 3:12 pm

Thanks for all those ideas and links, Zelph. When I last ran across that inflatable cooker it was still in development. Now it looks like they are not accepting orders. I might have to make my own. Somewhere I have an old r/c magazine that shows how to make a mylar dirigible using a soldering iron... (wheels turning :idea: )

I hit the big city yesterday and got a black, anodized non-stick cookset that happens to fit some Pyrex lids I've been hoarding. I also picked up som clear lids and such from the thrift stores (I thought I'd never get out of there: the old ladies were circling my 6 month old so like sharks. My mom calls it "grannylust"), then my son and I got out all of the pots and pans in the house (wife's out of town :twisted: ) and played mix-and-match to work out some nice solar cooking combos. After all was said and done, I counted up about 11 vessels that could all be used simultaneously, if I had enough reflectors.

I also made up a cardboard prototype of what I want to make from closed cell camping pads. For my cardboard prototypes, I have been using office clips to attach guy lines for windy days, but the foam version might have to include grommets for guy lines. The version I just made might become my "picnic cooker". A 10 quart Rubbermaid cooler with hinged lid and swinging handle makes a perfect base for the reflector and a 12 quart heavy anodized aluminum pot with a clear lid fits perfectly on the built-in stand. I also picked up an oven thermometer, so I'll test it out as soon as I get some good sun.

The nice thing about the cooler is that you can adjust the angle from high to low by swinging the handle of the cooler up or down and flipping the reflector 180 degrees. Another nice thing is that the cooler can be used to transport the raw ingredients. Here's a pic (baby included for scale)
IMG_4828.JPG
Last edited by churro on Sun May 03, 2015 3:46 pm, edited 2 times in total.

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Sun May 03, 2015 3:40 pm

I should add that the next step is to downsize the whole thing so it fits a typical pot one of you good folks might carry while backpacking. The end result should be a 3/4 length closed cell foam pad laminated on one side with mylar which can easily be folded into a reflector adequate to heat a 3-4 cup dark-colored pot inside a chicken-sized roasting bag. And of course you can sleep on it!

If my calculations are correct, a hot sunny day should yield nicely browned cornbread, and a partly cloudy day should still yield fully cooked rice, each in under 2 hours (during peak cooking times, 11:00 am to 1:00 pm).

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Tue May 26, 2015 2:06 pm

I made a double-angled twelve sided reflector out of cardboard and mounted it on a base made from scrap wood. A pot stand extends through a slot in the reflector, so the angle of the reflector may be adjusted without moving the pot.
IMG_4845.JPG
IMG_4846.JPG

Today is the first sunny day I've had in a while, so I set it up with a dry, empty cast iron dutch oven (10") with a pyrex lid on top and an oven thermometer inside.
IMG_4847.JPG
IMG_4848.JPG

As you can see, it's not perfectly clear. The high cirrus clouds make it a less-than-ideal day.
To guestimate the elevation adjustment, I leaned a broom on the top edge of the reflector so that the broom part was on the top edge of the shadow cast by the reflector. Then I stepped back to see it the plane of the reflector's lip was perpendicular to the broom handle.
IMG_4849.JPG

To get the orientation east and west just right, I stood behind and made sure the shadow cast by the reflector was more or less even with the base, then tweaked it a little to the west, so I wouldn't have to adjust it as much. (look at the shadow in the second pic)

The cast iron dutch oven weighs 7-8 pounds, I'd guess (with pyrex lid). There was no external enclosure (such as an oven bag) around it, and it is about 60 degrees F, slightly breezy. I started at 10:30 AM. After 5 minutes of heating, it passed 150* F; 10 minutes 200* F; 15 minutes 240* F; 20 minutes 280* F. After 35 minutes it stalled out around 320* F, about right for roasting a chicken. Then the clouds really started piling up and I decided to abort.

I am not sure how fast it will heat with food in it, but I figure if I can pre-heat a cast iron dutch oven to 320* on a mediocre day, I can certainly cook something (especially if I add an oven bag to help insulate the pot). I also noticed that the dutch oven took almost half an hour to drop below 200* once I took it off the rig. A decent cozy around it might just let me finish the cooking indoors while I make a salad...

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zelph
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Re: Solar cooker

Postby zelph » Tue May 26, 2015 3:33 pm

Looks like something from a science magazine :D and looks "big"

Do you wear welders goggles to look at the pot/thermometer and position of the suns rays on the reflector/concentrator? Looks totally bright out there.

It might be time for you to narrow down the amount of pot lids you have to a few "choice" sets for easy pickins when it comes time to cook that chicken. :mrgreen:

Have you been getting any of the rain coming up from the gulf that has been causing problems out west?

I had 2 clear days Fri and Sat to work on my leaky roof. It's been blowing rain pretty steady here this morning and I've been watching closely to see if my roof work has eliminated the leak.....so far I think I fixed it, whoooo! happy camper here in Illinois :D
"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Tue May 26, 2015 10:02 pm

zelph wrote:Looks like something from a science magazine :D and looks "big"


Can't believe I forgot to mention the size. The pot is about waist height on me, (5'9" or so), the reflector is 87.5 cm across, for about .6m^2 collection area. On a nice day, that should be in the neighborhood of 600 watts, plenty for a crockpot. :geek:

zelph wrote:Do you wear welders goggles to look at the pot/thermometer and position of the suns rays on the reflector/concentrator? Looks totally bright out there.

Just sunglasses. I try not to stare into it, but, well, you know how it is with a new stove... :oops: You can actually put your hand in the focal point with impunity. It's hot, but not scorching, and bright but not searing. The diffuse focal point is about the size of the pot, so it's pretty efficient without any noticeable hot spots.

zelph wrote:It might be time for you to narrow down the amount of pot lids you have to a few "choice" sets for easy pickins when it comes time to cook that chicken. :mrgreen:

Good point. On it.

zelph wrote:Have you been getting any of the rain coming up from the gulf that has been causing problems out west?

lots of rain, no problems, though. Inadequate snowfall followed by excessive rain and inadequate sunshine has pushed back the growing season this year, but no flooding here. Not sure what the hay will do- probably grow four feet as soon as we get some sun :D

zelph wrote:I had 2 clear days Fri and Sat to work on my leaky roof. It's been blowing rain pretty steady here this morning and I've been watching closely to see if my roof work has eliminated the leak.....so far I think I fixed it, whoooo! happy camper here in Illinois :D
[/quote]
Good work! Nothing satisfies like successful roof work.

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Tue May 26, 2015 11:44 pm

I volunteered to make the hour-each-way trip for groceries next week so that I would be able to get what I need to make some sort of killer solar meal. It's a win-win situation: my wife thanked me for "taking on" one of her chores, I get to play solar Iron Chef, and we both get a few good meals out of it. I'm thinking game hens with new potatoes, carrots and rosemary, with a honey, butter and brandy braising liquid, and a side of solar-roasted sweet potatoes pureed with New Mexico red chile, cinnamon and brown sugar. Or maybe pinto beans with those lamb and venison shanks I've been saving. Or I could try that crockpot beef tongue recipe my Grandmother gave me...

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zelph
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Re: Solar cooker

Postby zelph » Wed May 27, 2015 9:42 am

Colorado Gourmet Chef cooks beef tongue with solar cooker. It's been at least 40 years since I had beef tongue. My aunt would make it in her restaurant....good stuff :dinner:

Oh My!!!! I stumbled upon this solar grille thingy:

https://www.google.com/search?q=david+w ... CAgQ_AUoAw

http://www.braytonenergy.net/recent-pro ... ar-cooker/


"Nothing Ventured Nothing Gained" stove store = http://www.woodgaz-stove.com/

churro
Posts: 208
Joined: Tue Feb 17, 2015 12:00 pm

Re: Solar cooker

Postby churro » Thu May 28, 2015 9:06 am

That's good to see! I had found some documents describing that device as part of a grant program to design a solar cooker that could cook at night. I guess they succeeded in bringing it to market. Now I want one :shock:


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