Fun With The Sun - Solar Furnace

Fresnel Lens Magnifier

Those full page magnifiers are great for solar experiments. Why, because of the Fresnel lens design. I bought a 5 pack from Amazon As you can see below I made an adjustable frame and burning platform. Anything short of metal either burst into flame or began to aggressively smolder. So my first experiment was a penny. At first nothing happened and I became bored after a couple of minutes, then I realized the platform was acting as a heat sink. I used a small piece of bark as an insulator between the penny and the platform. Of course I used my needle nose pliers since it was really hot. I had to be quick as well since the bark instantly began to flame and burn.

This is where things became interesting. After about 90 seconds the penny had turned into a pool of zinc with a thin layer of actual copper on top. Zinc by itself has a melting point of 787.15 °F; the copper softened and became malleable and crumbly. The Zinc cooled to a hard chunk.

I have not identified the top temperature yet, but 800 °F is nothing to laugh at and it can be dangerous so proper caution should be applied. Don't look at the burn spot too long, it will mess up your eyes. Use thick sun glasses or welding mask.

I have some ideas to increase output and I want to see if I can make some sort of steam engine. Some tracking motors mounted to the lens so that it would track the sun around a central point, which would be steel water enclosure. Heat it up and use the steam power... Check back often for updates.

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