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Best Method of Focusing Solar Power

  1. Nov 17, 2011 #1
    If I keep this up, I'm going to get a rep around here :).
    So, I recently acquired a fiberglass satellite dish which I plan to use for building a cheap, solar powered distillation machine. The idea is to have the dish, calculate the focal point, and run a double glass plated chamber at the focal point. THis allows light in, lets it get heated, then retains the heat long enough for it to boil. Keep in mind, as a high school freshman, this is partially for fun, but I might enter it in a science fair. I want this to be as resourceful and documented as possible.
    So, here's the real question. I'm thinking of either a) Taking an acrilyc plexiglass mirror and placing it on the fiberglass dish, then putting it in an oven and molding it into the parabolic shape, or
    b) Gluing on hundreds of small mirrors.

    I want to know, would the first idea work or would the mirror get too warped and make light go through diffiuse reflection, or would it still be specular? Which method would be best for my project of boiling water?
    With the amount of water I have, I need about 298000 J. The sun gives off about 1000 W/m^2, I believe (a bit more, but I'm averagin and including nightfall). That's just background info, but what do you guys think?
     
  2. jcsd
  3. Nov 17, 2011 #2
    Any ideas on this? I don't mean to go crazy asking but I'm honestly not sure if I can keep specular reflection when the acrilyc melts.
     
  4. Nov 17, 2011 #3
    It will be tough to mold it properly in my opinion. Glueing hundreds of tiny mirrors is something that I've seen be done before, but I can understand why that wouldn't be your favourite approach.
     
  5. Nov 17, 2011 #4
    A few shaving mirrors I would have thought would do the trick
     
  6. Nov 17, 2011 #5

    Drakkith

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    Staff: Mentor

    I'd say get about 10-20 small mirrors and place on the dish. They don't need to be curved, and it might be easier than making one big curved mirror or using hundreds of small ones. It really depends on how much time you want to spend on this.
     
  7. Nov 17, 2011 #6

    Bobbywhy

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    Gold Member

    If the parabolic dish is smooth enough you may use aluminized mylar. It's thin, light weight, cheap, and highly reflective.
     
  8. Nov 17, 2011 #7

    DaveC426913

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    Gold Member

    As I mentioned before, and Drakkith re-mentions: your focusing doesn't have to be excessively accurate or excessively granular. If your heating vessel is, say, 4 inches in diameter then your mirrored tiles do not need to need much smaller than 4 inches. As long as the "beam" from each mirror is smaller in diameter than the heating vessel, you're good to go.

    You'd only need a smooth surface if you wanted a point focus.
     
  9. Nov 17, 2011 #8

    Bobbywhy

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    Gold Member

    Last edited by a moderator: Apr 26, 2017
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