[QUOTE=oil pan 4;413251][QUOTE=Christ;413214]Turbochargers are /pressure/ engines, not heat engines. If the water evaporates while crossing the face of the turbine, the steam expansion rate creates a higher pressure differential across its face, thus increasing the power by which it can be driven. The heat is completely circumstantial to this
Quote:
If this worked why isnt it in use on large turbodiesel power generators, ship engines or gas turbine power plants?
I know some engineers I can pitch this idea to. I already know their first reaction will be to laugh at me.
Not to mention the idea of having liquid water droplets in contact with the turbine is a bad idea. Causing drag, erosion things things you dont want.
|
Some notes:
Gas turbine power plants and ship turbine engines already get this effect without adding water. The use compound turbines to wring all the heat out of the turbine. This is an old trick that dates back to steam turbines.
Large turbodiesel engines *can* do this. I think Audi (or maybe BMW) does this in research cars. It was originally done in military bombers:
Turbo-compound engine - Wikipedia, the free encyclopedia
Wright R-3350 Duplex-Cyclone - Wikipedia, the free encyclopedia
After dealing with the complexity of these engines, the engineers switched to turboprops and (and jets) and never looked back. I don't think piston-turbine-compound engines have any advantages over normal turbines (I'll explain the reason it at least justifies the research for the Germans a bit later).
As far as adding water to a heat engine: a simple experiment will help here (EPA willing). Do an A-B-A experiment changing from E0 to E10/E15/E85. Since there is almost certainly a degree of water in the alcohol mix, you will be adding water to your car's engine. If you notice a gain over the actual engergy containted in the gas, it was likely the water (unless your car can detect the E85 and crank up the CR), like the reverse. I know from at least one other time this was suggested, at least one forumite had a strong agrument that adding water *reduced* the pressure. It certainly removes a lot of heat (good old phase change) and the pressure of the resulting water vapor + air was indeed lower (our trusty forumite had checked the expansion coeffecients).
The real reason you would add steam (especially for automotive turbo-compounding apps) is that gas turbines operate in the 10k-100k rpm region and steam engines operate in the 100-10k regions. I wouldn't be surprised if the Germans didn't need any gearing (but I think running the steam at half the engine speed might be ideal). Steam makes it possible to directly couple the two engines without the huge gearboxes needed for turbines, and likewise is missing the exotic material requirements for ultra-high rpms. I'm still not convinced you couldn't mount a turbine (really, half a turbocharger) to a hybrid/range extender and drive a generator with it.
[edit: just noticed a thread with this link in it. Apparently adding water *does* work, just that you will be adding gallons/mile]
http://ecomodder.com/forum/180860-post10.html
detailed explanation about heating steam (never mentions the effects of pressure due to steam expansion. You really need to include that).
http://ecomodder.com/forum/showthrea...y-21437-3.html