2nd "law" violations > Heat to electric energy conversion
Mini solar tower
Steven Dufresne:
Hi All,
This is something I've been trying just to see how far it can go. I have a 2'x4' fresnel lens which here in Ottawa, Ontario, Canada means I'm intercepting around 640 watts of sunlight in July. I then have a mini solar tower, basically a tube with an absorber inside it. The absorber uses the concentrated sunlight to heat the air in the tube. The hot air rises and when it exits the top of the tube, turns a turbine. Even if I end up with only 1% efficiency that means I should get 6.4 watts out. That's the plan anyway.
So far I'm done version 4 and am starting to make version 5. I haven't gotten any noticable airflow yet. In version 3 the internal temperature of the tube was only 65C (150F) but by version 4 it was at least 165C (330F). But that melted the extruded polystyrene I was using as insulation. For version 5 I bought some Roxul insulation, a mineral insulation, which should be able to take the heat.
Details at:
http://rimstar.org/renewnrg/mini_solar_power_tower_fresnel_lens.htm
along with videos for the different versions, or you could just go straight to the videos on youtube...
Versions 1, 2 and 3: http://youtu.be/v1aQ73ZdZVA
Version 4: http://youtu.be/zuLlz-YlrL8
I am having doubt's that the hot air will actually rise but instead just leave the tube from both ends, but version 5 should start giving some indications of success or failure.
-Steve
http://rimstar.org http://youtube.com/rimstarorg
FatBird:
A better way is to shine the Hot SunLight on the Boiler of a Steam Engine, that drives a small generator.
There are hundreds of small steam engines for sale on Ebay.
FatBird:
Here is a nice little Generator advertised for small Steam Engines.
.
Steven Dufresne:
@FatBird,
Yup, I'm aware of that option and have a stirling engine I plan on trying later once I have a mirror arrangement set up with the fresnel lens. For now I'm trying this mini solar tower idea.
-Steve
http://rimstar.org http:///youtube.com/rimstarorg
Cherryman:
Hi, always nice to vids of people experimenting!
My two cents: I think your solar tower is to short. In order to get a better flow and pressure difference you could try more length, i do not think you will get any noticeable "torque" with such a short heating collector , which is as I understand open at both sides.
See it as a chimney, it needs a certain length to work best.
I understand it is a proof of concept set-up, but in gthe end you might want to go for steam (1600x volume) Or try a water cooled small solar-panel at the Fresnel focus ;)
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