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Thread: Fresnel Lens videos and steam generation

  1. #1 Fresnel Lens videos and steam generation 
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    Oct 2013
    Hello, this is my first post on this forum! I hope it is well received and that I don't violate anyone's sensibilities :P

    I have seen a number of "fresnel lens" videos on youtube. The idea, is that people are removing large fresnel lenses from old style big screen projection televisions. They then typically build some kind of wooden frame around them for portability/control, and commence pointing them at things, frying them with energy from the sun.

    First, I must say, I was disappointed in myself for not being ballsy/motivated enough to ask someone if I could take apart a TV at the local community electronics recycling roundup. However, I see these projection sets being given away on craiglist all the time (in the Denver area).

    I've thought to myself, what would I do if I had my own fresnel lens with which to burn things? I could literally have days of fun with this thing just being destructive. One of the videos online for instance indicates the user was able to melt pennies, zinc, copper and all. A little googling suggests the melting point of copper is at about 2000 degrees F. Surely there must be a way to harness this thing in a constructive fashion!

    After a bit of mind wandering I thought of the "solar thermal" power plants which use mirrors to focus light on a tower that heats water to steam, or in some cases salt to liquid. This thermal energy is then used to drive a steam turbine.

    What if there was a way to replicate this process on a very small scale? What if the fresnel could be pointed at some boiling container turning water in to steam, which drives a hodge podge fan turning an electric motor?

    I know a little bit about electricity but very little about how water interacts with heat. What material could I use that would hold the water and allow it to absorb the heat energy without melting? 2000 degrees is hot! How big would the container be? Surely pointing the device at a drinking glass would have far different effects than pointing it at a swimming pool. There must be some way to determine the best size vessel (experimentation is probably necessary).

    Where do I go from here?

    Maybe I need to look at those home water heaters that replace the huge water tanks? I wonder how they work.

    Anyone have some direction for me besides...

    Get a fresnel lens.
    Point it at some water.
    Brace for science!

    Maybe this is a silly idea because of "x" and you happen to know what "x" is?

    P.S. I'd link some youtube vids, but I do not know yet if that is okay to do on this forum. If you search for fresnel lens on youtube though, you'll find lots.

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