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Solar box cooker test in London... in November!

 
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coconino



Joined: 21 Nov 2006
Posts: 77
Location: Sunny Brixton

PostPosted: Thu Nov 23, 2006 3:17 pm    Post subject: Solar box cooker test in London... in November! Reply with quote

Just last week I made my first box-type cooker and tested it in my local park last Sunday. Given that this is in inner-city London in November I was impressed with the result. Not hot enough to cook by, but certainly hot enough to prove the concept.

Out of interest, the result over three hours was that a 500ml jar of water was raised from 15C to 44.4C. This was with little or no direct sunlight into the box, which was kept horizontal and the sun was low.

The test was conducted with two glass jars, each containing 500ml of water, one jar was painted matte black with spray enamel. The jars rested on a bun tray (I didn't have anything flat to hand) and each jar contained a thermocouple sensor connected to a digital thermometer (the blue wires can just about be seen in the picture below). Ambient temperature was measured in partial shade using a normal household thermometer. Readings were taken every ten minutes.




Last edited by coconino on Sat Sep 01, 2007 4:56 pm; edited 1 time in total
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David Whitfield



Joined: 08 Nov 2006
Posts: 9
Location: Bolivia

PostPosted: Wed Dec 20, 2006 4:19 pm    Post subject: nice cooker Reply with quote

Hi Philip,
Thanks for posting the results of your experiment.
May I suggest that the next step be using a cooker style optimized for your latitude. that way more radiation will enter the cooking area.

If you need help or have questions just ask

Nice pictures
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coconino



Joined: 21 Nov 2006
Posts: 77
Location: Sunny Brixton

PostPosted: Thu Dec 28, 2006 10:53 am    Post subject: Re: nice cooker Reply with quote

David Whitfield wrote:
May I suggest that the next step be using a cooker style optimized for your latitude. that way more radiation will enter the cooking area.


Hello David, thanks for your comments.

I wonder if you would be more specific about what cooker type you mean? I would guess that something more like Joe Radabaugh's design or a parabolic reflector type, but I'd welcome suggestions as to what direction to follow.

-= Philip
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Brit from Norway



Joined: 27 Dec 2006
Posts: 17
Location: Norway

PostPosted: Thu Dec 28, 2006 9:44 pm    Post subject: Reply with quote

Hello!
I am happy to discover another solar cooking entusiast in Northern Europe. I live in Norway, at about 57 degrees north. For some years now i have tried several types of homemade solar cookers. The twelve-sided Parvati cooker of 60 cm diameter is efficient enough to cook a casserole dinner for three people here, at least from the end of February to the end of September. I also made a Heavens Flame cooker which worked nicely. My last one is parabolic, I just glued aluminum kitchen foil to a discarded parabolic tv-antenna of 120 cm diameter, and my husband made a stand for it. This one boils one liter of water in 15 minutes, however from November to March it will take up to 30 minutes.
Hope you will continue your solar cooking efforts!
Good luck!
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Brit from Norway



Joined: 27 Dec 2006
Posts: 17
Location: Norway

PostPosted: Thu Dec 28, 2006 10:53 pm    Post subject: Reply with quote

Hello again!
I think all the cooker designs can work in England. You just need to find a solution for tilting them towards the sun to catch as much sunlight as possible, and at the same time supporting the pot so it does not tilt with the reflector or box and spill the food. Some sort of greenhouse around the pot is very useful and maybe even neccesary when you use a panel cooker design. I use salad bowls for greenhouse, they work well.
Regards
Brit
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coconino



Joined: 21 Nov 2006
Posts: 77
Location: Sunny Brixton

PostPosted: Fri Dec 29, 2006 11:17 am    Post subject: Reply with quote

Brit from Norway wrote:
[...] The twelve-sided Parvati cooker of 60 cm diameter is efficient enough to cook a casserole dinner for three people here, at least from the end of February to the end of September. I also made a Heavens Flame cooker which worked nicely. My last one is parabolic, I just glued aluminum kitchen foil to a discarded parabolic tv-antenna of 120 cm diameter, and my husband made a stand for it. This one boils one liter of water in 15 minutes, however from November to March it will take up to 30 minutes.


Hello Brit, I'm pleased and amazed to read that you find possible to use solar cookers at such latitudes. Do you cook with these regularly? In the new year I want to try building the Parvati design and the Heaven's Flame so that I can begin testing as soon as the days get a bit longer. 60 cm diameter is much smaller than I would have imagined would be needed for the Parvati at these latitudes - my guess would have been at least 60 cm radius.

I have some gold mirror-board left over from a job which could be perfect for a cooker of some sort. I also just found a roll of Airtec silver bubble insulation in the street and want to try using that for a cooker too.
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Brit from Norway



Joined: 27 Dec 2006
Posts: 17
Location: Norway

PostPosted: Sun Dec 31, 2006 2:22 pm    Post subject: Reply with quote

Hello again!
In the summer I use the Parvati fairly regularly to cook. I also baked bread in it in a black cooking pot. A small round loaf of bread took two hours. The slow baking made the taste of homemade bread even better then usual.
The Parvati is great for food to cook slowly, or simmer. Fast cooking is only possible with a parabolic reflector where I live. If you follow the link of the twelve-sided Parvati cooker you will find a link to a photo gallery. There are a couple of photoes of my cooker and a stand I made for it.
I will try to put somthing about solar cooking in Norway at the Wiki soon.
Regards
Brit
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coconino



Joined: 21 Nov 2006
Posts: 77
Location: Sunny Brixton

PostPosted: Sun Dec 31, 2006 3:46 pm    Post subject: Reply with quote

Brit from Norway wrote:
If you follow the link of the twelve-sided Parvati cooker you will find a link to a photo gallery. There are a couple of photoes of my cooker and a stand I made for it.

It's impressive to see a cooker surrounded with snow! Was it really usable that day? I have some work to do over the next few days but once that's done I'll be building a Parvati and hoping for some blue skies.

I mentioned elsewhere that I'm due to give a brief talk on solar cooking to my local climate action group, so it would be good to have more than just one box cooker to show them.

With your permission, I would like to show that picture at my talk. If this is agreeable to you, would you email me a larger version and give more details about when it was taken and what you were cooking?
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Brit from Norway



Joined: 27 Dec 2006
Posts: 17
Location: Norway

PostPosted: Mon Jan 01, 2007 10:33 pm    Post subject: Reply with quote

Hello!
The photoes were taken about Easter in 2005. That day I just put some water in the pot for making tea. The pictures were taken some time after the cooking. I will try to send you more photoes. Sometimes the attachements dont really get attatched. You must tell me wether they get through all right.
Regards
Brit
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Brit from Norway



Joined: 27 Dec 2006
Posts: 17
Location: Norway

PostPosted: Sat Jan 06, 2007 3:45 pm    Post subject: Reply with quote

Hello! coconino!
Yesterday I posted a private message to you at this site. I did not find a way to attach photoes though, I believe that I will need to send photoes to your private e-mail adress from my private e-mail adress. Did you recieve my private message? Please let me know. Then we can exchange e-mail adresses, and I can send you the photoes.
Regards
Brit
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webmaster
Site Admin


Joined: 25 Oct 2006
Posts: 66
Location: Seattle, Washington

PostPosted: Sun Jan 07, 2007 7:11 pm    Post subject: Attaching photos to your mail Reply with quote

You can send photos by uploading them in the Solar Cooking Wiki: http://solarcooking.wikia.com

Then use the "Img" button at the top of the message entry box to link to your photo. Please give your photo a meaningful name and use underscore characters to separate the words, like this for example:

Solar_oven_cooking_in_snow_in_Norway.jpg

Thanks,

Tom Sponheim
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Brit from Norway



Joined: 27 Dec 2006
Posts: 17
Location: Norway

PostPosted: Tue Jan 09, 2007 2:33 pm    Post subject: Reply with quote

Hello again1
Today I wrote a piece about solarcooking in Norway and put some photoes in it at the wiki. How will other people find it there? I named it Solarcooking in Norway.
regards
Brit from Norway
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PostPosted: Tue Jan 09, 2007 9:44 pm    Post subject: Brit's piece is now here in the Solar Cooking Wiki Reply with quote

http://solarcooking.wikia.com/wiki/Brit_Bakken_Oedegaard
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coconino



Joined: 21 Nov 2006
Posts: 77
Location: Sunny Brixton

PostPosted: Sat Mar 17, 2007 9:55 pm    Post subject: Test 2, 11 March 2007 Reply with quote

Now the sun is starting to get high enough, and with a few clear days and some spare time recently, I tried the box cooker again and the result was a little better than the November test, with a peak temperature of 53C:



I'm not certain what caused the odd results from the first hour but they could be due to the black jar having spent a short time in the sun before the test began and then when the thermocouple was inserted it may have been in contact with the wall of the jar rather than being free in the water. The dip between 12:20 and 12:30 coincided with a change of location to find shelter from an increasing wind, and it could be that the thermocouple was free of the jar after the move. The subsequent results are clearly consistent with those from the November test.


Last edited by coconino on Sat Sep 01, 2007 4:57 pm; edited 1 time in total
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coconino



Joined: 21 Nov 2006
Posts: 77
Location: Sunny Brixton

PostPosted: Tue Apr 10, 2007 7:02 am    Post subject: Another test, still rather disappointing Reply with quote

Alongside the Parvati test yesterday, I tried this same box cooker again, and although the results were better than before, it is still rather disappointing compared to the powerful Parvati.

The test material was a black-painted glass jar containing 500 ml water.



Bearing in mind that the Parvati had boiled at 11:30 and I was eating (a small) lunch from it shortly after 12:10 the SBC's curve is very shallow. It was, however, still rising until at 13:30 patchy cloud started to appear, and I got the impression that it would have continued to rise had the sky remained clear. The final reading was the highest at 72C but there was more cloud approaching and it was time to abandon the experiment. On the plus side, it did reach pasteurisation temperature, and the temperature drops off slowly so it can stand short periods with reduced sun.

The next steps for this cooker will be to improve the reflector and improve the insulation, particularly on the window.
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