SUN POWERED TURBOGENERATOR IDEA

by Peter L. Peres 2005 <plp@actcom.co.il>

KEY H Hot heat exchanger 800-1000K, 2-3 bar 20-25kW C Compressor, part of turbocompressor I Intercooler, air inside, water outside MG Starting motor and generator R Radiator (cold heat exch.), water inside, air outside S Sump, cold water T Turbine, part of turbocompressor W Water pump, <50l/min

A sun powered turbogenerator idea of about 20-25kW thermal input, using as many ready made automotive parts (possibly from the junkyard) as possible. Hoping to obtain 1-2kWe output and 30-40C warm water.

Paraboloidal offset mirror (P):

30-50 m^2 mirror made from 3mm plate glass mirrors, each plate deformed from the back (by pulling an epoxied plate) to form a concave mirror surface. The required focal distance is 10-20 meters. The array will be 5-6 meters tall (ca. 2 house levels) and 5-8 wide.

It could be built as a lean-to to an existing structure. The offset mirror has a small inclination vs. vertical up to latitude 45 deg. N or S. This and the counterweight make the top bearing light. The top bearing is adjusted manually or by servo only in the North/South directon to follow the changing height of the sun.

Cold heat exchanger (R):

Domestic air conditioner chiller box, air outside, water inside, pressure 1 atmosphere, air flow cca. 0.1 m^3/sec. Vented to atmosphere through a pressure compensation hole.

Motor Generator (MG):

High speed custom made motor generator. Must work at 100k rpm, starter power ~200W, generator 1kW or more (hoped).

Heater (H):

Solar target and heat exchanger welded and bolted from engine exhaust manifold parts. Mates with turbine inlet using original hardware.

Power Converter Unit (PCU):

Is mounted on a wheeled carriage that runs on a semicircular track in front of the mirror, following its focal point. It contains the water sump, the turbine, the solar target and the controller and battery. It is connected with an electrical cable to the base of the mirror system. The unit can be wheeled into a garage, onto a truck etc. for service. If linked with a bar to the mirror axle base, can replace the azimuth servo.

Turbine + Compressor

Automotive turbo compressor Garrett etc. mass flow ca.  12 lb/sec @100k rpm and 1:2 pressure ratio. Mechanically modified for power pickoff using a thin long shaft coupled to the compressor inlet side rotor hub.

See also:

• http://ec.europa.eu/research/energy/pdf/solgate_en.pdf Detailed research paper on construction of a test system by the EU solgate group in Seville
• http://www.gizmag.com/waterless-solar-thermal-tower-power-plant/16738/ "...the solar Brayton Cycle system uses the concentrated solar energy to heat compressed air, which expands through a 200kW turbine to generate electricity."
• http://www.redrok.com/engine.htm Heat Engine Projects
• http://matteranenergy.com/Technology.htm Replacing the feed pump with a termal cycle injector

Archive:

• List post "Solar Steam Engines..."

Internal injection flash steam heat engine.

Solar Power, Heating and Cooling

Heat Engines

Comments:

• ww7164@yahoo.com " Is this system posible for a home application." James Newton replies: Sure, why not?

• hyena5@hotmail.com

  http://www.apctt.org/publication/pdf/nce_dec_solar.pdf Thanks for sharing,
  This concept will work. I've built radial jet engines using junk turbochargers in the past. The biggest hurdle to overcome with turbochargers is providing ample oil pressure to the hydraulic bearings. I also see little to gain from using a closed system unless you plan to use some kind of noxious mixture (like a sterling engine). Simply using ambient air in an open system will work with less components. I'm working on a similar system but I'm using axial components with a large angular rotation in order to utilize standard ball bearings (slower rotation speeds). Scientist in Israel have already developed a solar turbojet which reports to have very high effiecency output.
  
  You are definately on the right track!!!
  
  James Scott

Questions:

• szilagyi@alum.mit.edu asks:

  Peter, this is a beautiful idea. Have you had any practical problems with the generator shaft linkage? I have been contemplating using a turbo similarly, but I have no experience attaching shafts to anything that spins as fast as a turbo, so one of my main concerns is that practical issue. --Peter Szilagyi