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B Your Opinion On This Solar Cooker

  1. Oct 14, 2016 #1
    First of all, even I did mentioned Solar Cooker, the main goal is to reach most temperature of 500ml of water in 30 minutes.

    Basic information that I have is some material with different thermal conductivity. I seek for simple english language and a bit complex physics language. The idea of this design is using box (or any same priced material) as the outer or the case.

    Next I'm attaching or making a contact of a metal with many fins (to increase surface area) with the box from the inside and finally the 'idk just an idea', making many folds of aluminium foil (or other same priced material) in the box with each end of box touched.

    The water will be placed on a box's base sized plate (I'm thinking of a metal plate with a short wall on the sides). Refer to my nice (very very very ugly) image drawn (barely) by paint. Ugly but you can understand the concept.

    Photo Labels : Black - Box , Aqua - Metal with fins (solid not empty) , Purple - Folded aluminium foil (touching metal on each side), Green - A Peaking area (can be open to place water and monitor temperature), and the Maroon - Metal plate to place water

    Attached Files:

    Last edited by a moderator: Oct 14, 2016
  2. jcsd
  3. Oct 15, 2016 #2
    I'm sorry, but the drawing is completely unintelligible. Is this viewed from the side? The Top? Where is the sunlight coming from, and what is it reflected onto? There are probably designs for solar cookers on line, I suggest you google them.
  4. Oct 15, 2016 #3


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    I can see what he means. The pipes are all illuminated by the sun. Spreading the water over a large area will pick up more power.
    A rule of thumb is that a maximum of about 1kW falls on a Square metre of surface and that should give a clue about the area that your 500ml of water needs to cover (given the time requirement). There'll be losses, of course, if you are using such a lot of piping - partly because the pipes need also to be warmed and also, the large area will radiate (lose) an appreciable amount of IR. Using a parabolic reflector system, the losses will be less as the heated volume can be kept in a smaller space. Most solar ovens use a reflector system and can reach extremely high temperatures.
    The Optics don't need to be too special as it's not actually necessary to focus the heat onto a single spot - just the 500ml container. A reflector can be made easily with papier mache´and covered with kitchen foil. You don't want wrinkles so you need to cut out thin strips which can be stuck down and still stay optically flat enough (shiny). I did this once, with an old satellite (0.5m dish) and could boil a small blackened tin of water in full sun very quickly. (No numbers, I'm afraid)
    Last edited: Oct 15, 2016
  5. Oct 17, 2016 #4
    Sorry for lack of information, its is from the top view.
  6. Oct 17, 2016 #5
    So to sum it up, it is better to use direct sunlight, as in parabolic reflector it will focus in giving direct sunlight towards an desired area. So my idea of 'keeping the heat' is basically bad due to loosing of heat, am I correct?
  7. Oct 17, 2016 #6


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    Yes. A compact shape will reduce the heat loss and you get the advantage of the gathering power of a massive reflector.
    You really must do some calculations or you don't know what size your reflector needs to be. Are you ok with that?
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