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AntarcticPilot

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No fear of that here in Wales!
Probably dangerous in sunny climes: there's bound to be an angle at which the curved surface concentrates the rays onto a well-oiled teak item...

Another trick from that Archimedes chap :)
Actually, even a nearly flat piece of polished stainless will cause scorch marks. The cover for our balanced flue on a previous home left a scorched path on the adjacent lawn during sunny weather. I'd actually think that strongly curved surfaces wouldn't be too bad - the focus would be too close to the mirror surface for there to be much chance of there being anything flammable in range. The focal length is half the radius of curvature of the surface, and as the Sun can be regarded as being infinitely far away, its energy is concentrated at the focal point. And yes, I know that a spherical mirror doesn't concentrate all the energy at the focal point, but on a caustic curve. But for practical purposes, the danger point is at the focal point.
 

Dellquay13

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Actually, even a nearly flat piece of polished stainless will cause scorch marks. The cover for our balanced flue on a previous home left a scorched path on the adjacent lawn during sunny weather. I'd actually think that strongly curved surfaces wouldn't be too bad - the focus would be too close to the mirror surface for there to be much chance of there being anything flammable in range. The focal length is half the radius of curvature of the surface, and as the Sun can be regarded as being infinitely far away, its energy is concentrated at the focal point. And yes, I know that a spherical mirror doesn't concentrate all the energy at the focal point, but on a caustic curve. But for practical purposes, the danger point is at the focal point.
Thread drift, but I was impressed by rural truckstops hanging black kettles in front of large shiny parabolic dishes to heat water for tea in Tibet
 

AntarcticPilot

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www.cooperandyau.co.uk
Thread drift, but I was impressed by rural truckstops hanging black kettles in front of large shiny parabolic dishes to heat water for tea in Tibet
Solar cookers are a thing in lots of places without reliable electricity but with reliable sun.

There's a wonderful solar power station somewhere in France that uses mirrors to melt salt that is used to transfer heat to boilers and hence to turbines.
 

AntarcticPilot

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