eBook 2016 Shining light on solar panels
This section is provided by Tim Gibbs.
1. Onboard Solar concentrators in spacecraft.
I am currently doing research on Solar Collectors - Concentrators. This is with reference to the Solar Vaporization/Dissociation System (SVDS) for improving rocket motor performance in space. The idea seems doable and I have recently found has been around since the 1950's. Issues to think on with regard to SVDS:
a) Collection area.
b) Level of concentration of light.
c) Alignment to the sun and other losses.
d) Thermal physical expansion of the SVDS unit.
e) Applied mathematical ideas: 'Stefan's law' and the 'input output power balance equation' (this includes losses).
Facts found so far
1) From my own 1st stage mathematical model and rough calculations, localized temperatures of 900 deg C+ could be achieved for SVDS.
Note: The fuel Aerozine 50 is a 50/50 mix by weight of hydrazine and unsymmetrical dimethylhydrazine (UDMH). It was used by the Apollo Lunar Module and the Service Propulsion System engine. It has a boiling point of 70 deg C. It could be possible (with the SVDS unit) to preheat this fuel to 1 times its boiling point. This increase could thrust a space craft, lowering fuel requirements.
2) Other work done in the field of solar collector concentrators gives temperature figures, for example for parabolic reflectors, of 200-700 deg C.
3) Also see Build it Solar: the Renewable Energy site for Do-It-Yourselfers - lots of home built systems.
Note: There are claims of 3 K Watts or 950 deg C for one unit, also 1200 deg F for another.
Note: 2) and 3) items are all Earth based units and as such only get on a sunny day approx 75% of the sun's radiation (this is due to absorption by the atmosphere). Outside the atmosphere you would get even more of the sun's radiation upping SVDS performance.
Note: There is also a history of concentrated solar power going back to the time of Archimedes (in legend) to repel an invading Roman fleet from Syracuse.
Note: The Antoine Lavoisier diamond experiment used a burning glass to set fire to a diamond to find out what it was made of.
2. The optimal arrangement of reflectors in solar panel tracker arrays.
We find the angle, 55.7 degrees relative to the panel, and the length, 0.65 of the length of the array, of reflectors surrounding the edge of an array also with corner mirrors, when sunlight is vertically above the panel, as it would if it were a tracker array. This gives 3 times the power output for this type of array compared with an array with no reflectors.
3. Shining light on solar panels.
This report shows how to raise power output by reflecting light on solar panel arrays on flat roofs. It contains an Executive Summary and a Technical Report.
4. Solar Cookers.
In Salta, Argentina, a very novel type has been developed. The concentrator is a Fresnel type reflector. In the focal region, solid aluminum bricks are heated up to 400 deg C. Then the hot bricks are put in an insulated oven in a school. The oven permits either the baking of bread or cooking for up to 20 to 30 kg of food. Another variant heats water in the focal region, producing steam, which can be used to directly boil food in the cooking pots.
5. Cracking hydrocarbons by solar power. This is currently done using hydrocarbons, but would be efficient in Saudi Arabia. Caspian Sea oil which is normally particularly polluting could be processed in this way by using solar concentrators to speed chemical reactions. At sea a floating solar chemical plant at the equator could convert waste to dissociated chemicals which are recyclable.
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