After a lot of trial and error and redesign I managed to make
this fairly portable and storable fresnel lens and mirror arrangement.
The starting point was my
normal fresnel lens solar
cooker. And it works, as you can see by the fried egg below. It
took around 5 minutes for the cast iron pan to warm up enough to
sizzle droplets of water and then around 2 minutes to cook the egg
and 20 seconds to eat the egg sandwich (yum!).
Be sure to click
here to see full details on how I designed this fresnel lens
and mirror solar cooker.
The complete fresnel lens and mirror setup.
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First thing cooked on it.
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The mirror is an ordinary mirror that someone thew out years ago
and that I cut to the length I figured I'd need. On the right below
I flipped the mirror on its back so you can see that the mirror is
not at the focal point. It's only part way and that's why the mirror
doesn't get hot enough to crack from temperature gradients.
The very cool thing about this is that you can look down into the mirror
and see the sunlight on the bottom of the pan. In the photo on the left
below you can see that the pan is also not at the focal point. Instead
it's placed such that the light coming from the mirror is spread out
over the whole pan bottom for even heating. In the other two photos
I swivel the pan off center so you can see the edge of the light coming
from the mirror.
The pan centered...
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... swivelled to the left...
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... and to the right.
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The heat from the sunlight coming from the bottom of the pan isn't
as fast at cooking as the sunlight coming directly from the lens.
The nice thing, as the following photos show, is that if you want
some of that faster cooking heat you can just push the pan forward more
over the mirror and intercept some of the sunlight going from the
lens to the mirror.
Pan getting sunlight only from the mirror below.
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Pan pushed forward to get some sunlight from the fresnel lens above.
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And here's a video showing it's assembly and use. Enjoy!
Click
here to see full details on how I designed this fresnel lens
and mirror solar cooker.
