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Solar Still Device help

  1. Mar 16, 2007 #1
    Hey guys I am trying to design a efficient solar water distilling device for a school project.


    That image provides a general idea of what it will look like without going into specific detail in case other competing groups know of these forums.

    I have already a way to concentrate the sunlight to specific areas of the tray which has a thin layer of water. I do not completely grasp the advantage of concentrating the energy to one point rather than an even distribution since there is no increase of energy.

    I was thinking about using some low priced solar panels hooked to resistors that run through copper tubes in the water to heat the system. When I went to a local electronics shop they told me the idea is not practical because the solar panels will not produce significant wattage to cause heat. Any counter arguments?

    If I had more time, I wanted to build a parabolic dish to concentrate energy to a pressure controlled system (control pressure to lower water boiling point) to increase efficiency but my group has decided against it due to the complication of calculating exactly where the parabola's focal point is and building a parabola mirror system is not practical for the time given.

    So as you guys can see I am not asking you to design my project for me because we do have ideas on the table, but maybe someone here can help with some suggestions.

    Thank you for your help.
  2. jcsd
  3. Mar 17, 2007 #2


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    Nice drawing.

    How about thinking about a lens, or even thinking about colours which reflect/absorb heat?
  4. Mar 17, 2007 #3
    done, we are experimenting with lens on the top and assuming black absorbs the most heat so the tray that holds the water will be that color.

    Need something to get us the edge for most efficient! I want to seal it and reduce the pressure but that is not practical
  5. Mar 17, 2007 #4
    about the lens, what is the point of focusing energy? Unless lens can produce more energy?

    Sorry I had misread what you had said,

    Do you think if we used a energy absorbing colored lens it would be a good idea? I believe it would cause the lens to heat up and slow down the water heating, and once the water heated it would be harder to condensate since the lens are not as cool as they could of been.

    On the reverse side, if we used reflective lenses then energy would be diverted while keeping the lens cooler... Which would do more harm since the water is missing out on energy.
    Last edited: Mar 17, 2007
  6. Mar 18, 2007 #5


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    While I can't speak for Brewnog, I'm pretty sure that he did not refer to a coloured lens. The lens is simply to concentrate the most available light on the target. The colour of the target determines how much of that energy gets absorbed as opposed to being reflected away. Darker is better from a thermal standpoint. If you were using photovoltaic cells rather than water (to produce electricity), then the chemicals used in the cells would determine the most efficient frequency to let through.
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