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Solar Oven

  1. Dec 1, 2011 #1
    Hello

    I am designing a solar oven that will be used to form denture moulds.
    My thoughts are designing an insulated box with a doubloe pane glass double creating a green house effect.

    But i would like to incorporate solar panels and a wired heated filament.

    My question is what is the best wire filament to heat a box to 150 degrees celcius
    and how many solar panels will it take to power a filament for an hour.

    thank you
     
  2. jcsd
  3. Dec 1, 2011 #2

    Mech_Engineer

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    Don't bother with the heating element and solar panels. The efficiency of the solar panels (~15-20%) will make the heating element overall much less efficient than piping sunlight straight into the box. Remember that sunlight is about 1000 W/m^2, so if you want more heat flux in the oven your best bet will be to increase the amount of light going into the box with a reflector. We made a solar oven in college using a parabolic reflector that could melt copper, so I think you can make one that gets hot enough for dental molds.
     
  4. Dec 1, 2011 #3
    mr. MECH

    Is it possible to use the solar panels to store energy into batteries for coil usage.
    ex. if i leave the solar oven out for three days is it possible to use coils than?

    also what materials did you use to insulate your chamber, your outer case and inner casing

    sorry if im stressing with these panels and coils my professor wants them

    ty
     
  5. Dec 1, 2011 #4

    Mech_Engineer

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    Sure it's possible, but I'm not sure there's a real advantage unless you want to use the over on a cloudy day.

    Haha we used carbdoard, but for a long-term solution I would use some sort of ceramic.

    Why? Use on a non-sunny day.
     
  6. Dec 1, 2011 #5
    yes exactly for non-sunny days
    i am so confused with solar panels. Whats the difference in series and parallel? If im heating a resistant coil do i need more amps or voltage?
    my main concern is if solar panels can generate enough energy to heat up a coil filament. and if so how many solar panels do i need to achieve this goal.
    i am a newbie and in need of help
    it would also be much appreciative if anyone has helpful data sheets on solar panels

    thank you
     
  7. Dec 5, 2011 #6
    A small DC air compressor would do a much better job of heating a space than a filament.
    Use sunlight to preheat the air feeding the compressor, and pass the compressed air through a heat exchanger before leaving the insulated space.
    This should let you double dip, and get a heat pump effect.
    A passive solar oven might get hot enough, with a few changes.
     
  8. Dec 5, 2011 #7
    so use solar panels to power the air compressor? how much energy do i need to operate one?

    also what do you mean by dump dip creating a heat pump effect?
     
  9. Dec 6, 2011 #8

    Mech_Engineer

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    I think john is suggesting you use a compressor and pressure tank to store energy rather than solar panels and a battery. Problem is, the compressor would need to run on solar panels anyway and would also need to be used as a turbine, so my gut feel is that direct to battery and a heating coil would be more efficient overall.
     
  10. Dec 7, 2011 #9
    Correct, a small 12 V compressor run off of the solar panels, with the compressor and heat exchanger in the heated space. All of the work done to turn the compressor stays in the box in the form of heat(Just like a coil). You also get adiabatic heating of the preheated air via compression. A heating coil can only have a efficiency of 1, A heat pump could go higher. This is an example of the type of compressor I am talking about, http://www.google.com/products/cata...=X&ei=NbTfTuXYGuGgsQLk-oirBw&ved=0CJcBEPMCMAI
    You would also need a way of slowing down the hot compressed air to allow it's heat to stay in the heated space.
     
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