fresnel lens

Discussion in 'Off Topic' started by eastwoodo4, Jun 12, 2009.

  1. eastwoodo4

    eastwoodo4 Member


  2. Mountainman

    Mountainman Active Member

    well -- that's a cool -- fun THING to have -- toy for big guys !!
    does get one to thinking -- don't it ??

    watch that THING
     
  3. eastwoodo4

    eastwoodo4 Member

    i just boiled the **** out of some water in a glass bottle.it was spewing out the top.the idea mm is to boil water in a boiler and run a steam engine.so u can run a generator.from my first test i can tell u that this will work for a hot water heater,cooking in a frying pan,making a solar oven,distilling water and much more.
     
  4. bluegoatwoods

    bluegoatwoods Well-Known Member

    It's easy to believe that it's good for those things.

    But isn't it crazy that in a world that had better be thinking about fresh water conservation a still is illegal?
     
  5. SimpleSimon

    SimpleSimon Active Member

    Somebody better tell Sears, then. They sell home water distillers that sit on your countertop.

    The biggest problem with Fresnel (and other types) solar water heaters/boilers is that in order to maintain a constant "sweet spot" focus on your boiler, the frame the lens is mounted in must track the sun across the sky. Fortunately, there's a very simple and effective way to do just that which requires no motors or clockwork, and only three parts.

    Take a pair of small double acting hydraulic cylinders, and mount one of them on each side of the frame for the lens, with a shield between the cylinder and frame tall enough to shade the cylinder from the lens side. The two cylinders must be connected to each other at both pressure inlet couplings by high pressure hose, and the hydraulic fluid should be replaced by refrigerant fluid. Whichever cylinder gets more sun differentially heats up, and the refrigerant expands, pushing on the opposite cylinder until the pressures in both equalize, at which point the two cylinders should both be aligned with the sun, meaning that the lens between them is also. The entire frame and lens with cylinders assembly and collector/boiler should be set on a pivot axis so that can happen, and the actuator rods of the cylinders push against an L shaped arm to the fixed portion of the frame.

    Mother Earth News wrote that idea up in the late 1970's, and I built one. Took a bit of tweaking, and you want to use the lightest weight hydraulic cylinders you can get, but it works just fine. If you go a step further, and mount the entire assembly on a pair of posts that allow you to change the angle with the earth surface beneath it, you can optimize it with periodic adjustments to a true collection plane perpendicular to the received sunlight.

    What I built was a totally passive solar air heater that took in ambient air, and on a clear day would output air 80 degrees fahrenheit hotter, on average. I set it up to control air flow through an insulated flexible duct/thermostatically controlled damper into a friends dome home (which we built entirely of cardboard) by simple convective flow. The only electricity it used was controlling the damper. The dome was a 32 foot diameter vertically shortened ellipsoid, with a 14 foot high central peak. Kept it nice and warm in the Oregon high desert in winter (subzero days weren't unusual).
     
    Last edited: Jun 12, 2009
  6. eastwoodo4

    eastwoodo4 Member

    i was thinking if u put the fresnel lens up off the ground about 6 feet.then u could use a paribolic mirror close to the ground and hit the same boiler as th lens.
     
  7. SimpleSimon

    SimpleSimon Active Member

    You could do that, sure. Get an old style antenna dish, clean it thoroughly, xat it thinly with spray on adhesive and line it carefully with aluminized mylar film, put it under your boiler to catch the concentrated light from the fresnel lens that doesn't focus cleanly on the boiler tube.
     
  8. eastwoodo4

    eastwoodo4 Member

    the mirror would be off set slightly.it wouldnt use no light that came thru the lens.it would have its own light to make a whole nother beem.
     
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