What is area of capture of parabolic collector?

Sounds suitable for Domestic hot water supply.

Not sure enough insolation* area to provide KWH...

milo

"Chandu of APIX-SEP has made a Parabolic Solar Cooker that I think could run a small steam powered electric generator."

This will run a small toy steam engine. To generate power a much larger boiler to supply a continuous flow of steam to a 1/2 HP or larger to drive a generator to light a bulb or two. More lights, a TV or other appliances would require a much larger steam supply.

Venturer writes:

The maximum power available from su<>nshine, "Insolation", is 1 kW per square meter. Actually it's a little less. This is principally reduced by lack of atmospheric clarity and by the "cosine angle" loss of receiving sunshine at les<>s than perfectly perpendicular to the absorption surface.

Then you have losses arising from imperfections in the surface of your reflector and losses due to re-radiation at the absorber. The hotter the absorber is, the greater the rate of re-radiation losses.

To boil water and create steam, you have to raise the temperature of the absorber above 100°C. If you're lucky and keep tracking the sun as it moves, on a clear day you may have several hundred watts of thermal energy available. Then you'll be faced with the thermal inefficiencies of converting heat energy to electricity. High-efficiency power stations do not exceed 40% efficiency.

These are physical principles and absolute limitations of which you should be aware.

Why don't you try using a Sterling engine instead of a steam powered engine.

It would operate at lower temperatures and be safer, more efficient.

'Small' is the problem with steam turbines. As the size decreases the visceral losses increase and so the overall efficiency decreases. Sometimes simple piston engines are the best solution. However, focusing, and using the heat directly on a Stirling Cycle engine would possibly be much more efficient. I don't have the time to do the math here, but your friend could.

There is a company which makes a small Stirling engine which is coupled to a generator, so it is definitely possible for him to emulate that.

Good fortune,

Cheers,

S

Stueywright "There is a company which makes a small Stirling engine which is coupled to a generator, so it is definitely possible for him to emulate that."

There IS??? Who is it??? What does it cost??? Where can I buy one???

Stan,

Here it's called the Whispergen. You can access more info on their site: whispergen.com

Crap visuals but if you listen CAREFULLY you'll hear how it works. I've seen it several times and it really does 'whisper'. They use nitrogen as the working fluid.

I think that it may be an Aussie development.

Cool.

Keep going on the site into the explanatory videos. They're better.

Cheers,

S

ps Don't forget, I'm here already. I can chase stuff down.(aussie for"look for it")

"Here it's called the Whispergen. You can access more info on their site: whispergen.com"

The Whispergen IIRC is made in NZ for use on Yachts, Lighthouses, other locations requiring a source of electricity as well as home Combined Heating and Power. They are called CHP machines. The intent and purpose is to provide home heating, hot water and electric power for the home and to export excess electric power to the grid.

They are totally unsuitable for use with a solar heat source of any kind. The cost of the machines was on the order of $10,000 US or AU.

Currently there are no Stirling engine machines manufactured for mass market and general applications.

Stueywright Whispergen is NOT selling the Stirling engine separate and apart from the CHP machine. They are dedicated to production of the CHP machine.

Sunpower of Athens Ohio manufacture reciprocating Stirling engine generators as complete sealed units.

To the best of my knowledge you CAN NOT purchase a Stirling engine of any reasonable power output anywhere in the world at a reasonable price. Sunpower had/has one at a price of approximately $10,000.

It might be better to use a piston steam engine to drive the generator as turbines use a lot of steam. The Green Stream Engine site shows how their design produces rotary power. Also check out Tesla Turbines which use a little less steam at lower temperatures and are less finicky than bladed turbines. The main problem is the size of the collector, since there is a finite amount of solar energy per meter of area. A collector made like an elongated Venetian blind with each slat reflecting heat on the boiler tube and automatically following the sun could be made large enough to provide the power.

At night you could use an expensive battery pack or you could use a fuel burning boiler at night. The efficiency would rise if the waste heat from the steam was used to thermo-electrically make electricity [and also the exhaust of the fueled boiler], or to heat the home's water or to heat the home.

Try a sterling heat engine. There are many types on the market, shop around. They used to use one in a Winnebago to generate electricity a few years back. Check around and see what you can find. They are very efficient for using waste heat.

Guest:"Try a sterling heat engine. There are many types on the market, shop around. They used to use one in a Winnebago to generate electricity a few years back. Check around and see what you can find. They are very efficient for using waste heat."

Sorry Guest. You are grossly misinformed. I don't know the sterling heat engine you refer to BUT there are NO Stirling engines fitting your description on the market today.

The Stirling engines currently being manufactured are for CHP Combined Heat and Power or special applications and are too expensive for ordinary use.

I have a crude parabolic reflector that is tracking pretty well on equatorial mount with a dripper tracker. (The reflector moves but the focus stays in the same spot all day). I think any parabolic dish that doesn't have that feature is a waste of time. So you have to have an OFF CENTER section of the dish if you are serious about solar. Almost every solar parabolic for sale just is the centre of the dish. WRONG way to do it Check out the tracking page at solarcooking.org for more details of the simple trackers. Brian