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Few Questions about building a Solar Oven.

  1. May 18, 2009 #1
    I hope I am posting this on the right section.....

    In my Environmental Science Class, we are to design and build a solar oven(without using solar panels!). We will be baking a cookie.

    Me, being a "mathematician", remembered something about a parabola, that if light ray hits anywhere on the interior surface, it will reflect through its focus. I assumed for realistic three dimensions, this will work for a circular paraboloid(confirm that please). i.e. zr^2=x^2+y^2

    If I put a cookie at its focus, it should cook well(or ignite).

    The surface of the circular paraboloid will be reflectable

    I have a few questions-

    1. How exactly DO I create the frame of a circular paraboloid? I can't just stare at my calculator and yell "materialize!"

    2. What material should I use that has a high albedo, but is cheap-ish? I will spend no more than $30 on this.

    3. How will the size of the paraboloid effect the heat of the cookie?



    THE HOTTER THE BETTER. I want a high powered oven, if the cookie turns to ash, I'd be ecstatic.
     
  2. jcsd
  3. May 19, 2009 #2

    minger

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    You are right about the parabola first of all. Remember many many years ago when we first started learning about complex shapes. Remember the concept of a locus (loci?? sp?). Anyways, the locus of a parabola is a group of points that lie equidistant from a point and a straight line. See the wikipedia page for a proof showing the favorable reflective properties.

    Anyways, having seen a man win $100k for a solar oven, I briefly looked at some designs. Unless you want to spin a large amount of liquid metal into a parabola, you're going to have discretize it (for lack of a better word). A common design that I've seen it referred to as a Parvati Parabolic Cooker.

    Check out this site which has pretty good instructions for how to make a type of oven.

    http://www.angelfire.com/80s/shobhapardeshi/ParvatiCooker.html

    It seems that a common way to do this is to include a black box which will absorb the heat. Good luck,
     
  4. May 19, 2009 #3
    Okay thanks, now I other questions.

    Should I place glass at the top of the paraboloid to insulate the oven, or will light be dimmed too much?

    Should I put a rod from the bottom point to the focus and putting a small level platform on it because I will be baking ONE cookie?
     
  5. May 20, 2009 #4

    minger

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    Science Advisor

    Glass on top contributing to a "greenhouse" effect may be good. There's only one way to find out!
     
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