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emperor_dane won our contest asking "What would you do with a used Boeing 747" -- congrats (they won a Pocket Ref, not a plane - Maybe next time)...
a used Boeing 747 could be turned into 2 huge solar-thermal collectors. The cylindrical shape of the passenger area would be perfect for 2 half-cylinder concentrators. these concentrators, once covered with mylar or similar reflective material would concentrate solar light onto a central pipe, painted black. finally the systems could use the plane's internal coolant/ temperature control systems as a heat exchanger. finally the fluid that convects through the exchanger could run through the original jet's fuel pump to act as a generator, using convective forces to generate electricity from otherwise considered refuse. here is a diagram -emperor daneMAKE: Blog: What would you do with a used Boeing 747? - Link.
Make, you have made my day. I just took a thermal and fluids exam 30 minutes ago.
seriously, thank you
-Dane
www.dklabs.co.nr
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Skip the mylar and polish the aluminum.
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The thermal and fluid theory seems sound, but I question the optics. Shouldn't the troughs be parabolic, not semi-circular? Probably close enough to make some power, but not nearly as efficient as it could be if the aircraft skin was bent into a parabolic shape. And for some more juice, you'd need a solar tracker mechanism. Maybe you could use the plane's hydraulics to turn the collectors.
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(1) markayak is dead on, a circular reflector would reflect light emitted from the tube back toward it, but wouldn't concentrate anything.
(2) the air conditioning system from an airliner is an air-cycle machine driven off engine bleed air. it's unclear how exactly you would use this as a liquid heat exchanger. of course, the air conditioner packs, fuel pumps, hydraulics, and other expensive components would typically be stripped from an aircraft like this before it is scrapped anyway.
(3) solar thermal systems such as ones this is intended to look like use oil, not water. for them to be efficient the fluid has to be very hot, and water would have to be under considerable pressure to not boil. assuming you used a correct reflector and unpressurized water, the unpressurized water would boil randomly and the sections of pipe containing steam would overheat.
(4) heated water will get you basically zero energy by convection. the way you extract energy from a system like this is typically with an closed cycle ammonia turbine. furthermore, engine fuel pumps are designed for injecting fuel at fairly high pressures, so even if they are a type which work backwards, (i have no idea what the fuel pumps in a 747 look like...) they would be inefficient at low pressure differentials.
my proposal would be to enchant it with my magic wand so it could fly again then use it to take all my leprechaun friends on a trip to pluto. unfortunately i lack the ms paint skills to illustrate that.
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