[homeworld1031tx]

I've been thinking about this for a while, and after seeing the post in the Toyota FT-HS concept and jlitman talking about the new turbo/hybrid Subi, I figured I would ask about it in here.

What do you guys think about a system that used a turbine in the exhaust system to spin a generator instead of an induction turbine? Would that not be the ultimate way to harness free energy? What limitations do you guys see on this system?

 

[Nasty_impulse]

I believe most remote turbo setups are done this way and have proven to not working very well.

 

[homeworld1031tx]

Why is that? too hard to spin the generator?

 

[omabramo]

I believe most remote turbo setups are done this way and have proven to not working very well.

remote turbos?? you mean those electric ones?

hmm, interesting, but the energy isnt free. would the extra energy gained be more than the extra energy needed to overcome the added backpressure? only one way to find out...

 

[omabramo]

this could be a better alternative to the belt-drven alternator if it is more efficient, anyway, it's just another way to improve battery life

 

[marc]

how about a twin-charged (like the vw super/turbo) hybrid diesel

 

[SilverBullet GTS]

Using the emmissions to try and power all that equipment in the car and you are lookin at one seriously restricted exhaust.

 

[homeworld1031tx]

All the talk about the restricted flow is meaningless, because a normal turbo adds its own restriction just as this system would. You just forget about the added restrictions due to the extra gain in power it produces. The loss can be seen when comparing a centrifugal supercharger to a normal turbo system; the driveline loss in the supercharger is the extra build on what the turbo experiences. In this setup, it would create a restricted flow just as a normal turbo would, but instead of making up for it by adding FI to make more power, it would channel it into an electric motor to create more power, while saving emmisions.

 

[omabramo]

i dont think it will work the way you think. to add more power to the electrc motor by doing this will just fry it. you can also just add current/voltage amplifiers to the circuit for more power, and add another motor to the already existing ones

keep thnking though

 

[Shizuma]

^I'm with omabramo on this one, the only plausible way I could see of utilizing something like that would be to use some sort of capacitor to activate a secondary more powerful motor.....but then again I like the smell of race fuel and ozone burning :wiggle:

 

[homeworld1031tx]

The point isn't to add more power to a motor, and even if it was then it could be routed to the battery and stored for later use. The point of a system like this would be to have a generator running all the time (as long as the normal gas engine is running) to provide power for an electric motor as a supplement [so the engine size could be reduced] - it would run the same way any generator does, producing modifiable power to run an electric motor. The generator would be 90 percent effecient, and then the motor it drives would also be 90 percent efficient (so overall efficeincy would be at 80%), so it would be a great method to make extra [free] power instead of using it to boost power IMO. I'm sure there are some flaws with the system as someone else would have done it by now, I just can't find any so I'm hoping you all will lol

 

[omabramo]

dammit, just add another alternator, it'll do the same, and will be easier to do

 

[homeworld1031tx]

I still don't think you are getting the reasoning behind this. Alternators run off of the engines crank power, taking power away from it and it is also less effecient (looses 10% through heat). If it is on the exhaust system, it runs off of energy that would otherwise be wasted, just as a turbo does.

 

[SickCelica696]

The prius works off regenative braking since most the cars energy is wasted in changing motion. The brakes power the generators on each wheel. That is the only hybrid system I have seen work well. I don't think a "turbogenerator" or something would work out

 

[omabramo]

I still don't think you are getting the reasoning behind this. Alternators run off of the engines crank power, taking power away from it and it is also less effecient (looses 10% through heat). If it is on the exhaust system, it runs off of energy that would otherwise be wasted, just as a turbo does.

meh, i get what you're sayng, its just that you're assuming the extra power used to overcome the added backpressure is negligible or less than the power needed to drive the alternator... i do not know which one is more efficient, so to me, they are equal.

if you're that deadset on improvng thermal efficiency, just heatwrap all you can find

Work - Heat transfer = change in(KE+PE+U).... so reducing heat transfer = more power

 

[homeworld1031tx]

Alright, I get what you are saying now. So now I'll explain why it I think it would be more effecient:

Back pressure created by an induction turbine or generator connected to a turbine on the exhaust path = Same

Gas Engine = 40% effecient vs. Generator + Electric Motor = 80% effecient

All the heat and energy in the exhaust path is going to be wasted energy, that is why turbos are preferable to superchargers; they run off of energy that would otherwise be wasted to create extra power. So I'm figuring on top of the effeceincy gains, the backpressure increases would be negligable

 

[omabramo]

i'm sorry, but i still dont see much of a point to this...
(these kind of conversations are fun)

from what i understand: you are looking to raise the efficiency of the electricity used up in an automobile by adding a generator driven by exhauast gas...

me: not too interested in battery life. i see this as being something that would just take up some power from the go in order to buy more battery life, IMO, not really worth it(as to probably why they use brake energy instead of this)

and i dont really see how heat energy is used for this... turbine doesnt depend on temperature, but the mass air flow to turn. if exhaust gas was to be at a really low temperature at the same flow rate, you would see better performance in a turbocharger.

please, clear up my confusion on this, or anything that i might be mistaken on.

i dont mean to discourage you from developing this, by all means, have fun with it

 

[homeworld1031tx]

Lol I'm not doing this for battery life, I ment it as something to be used on hybrid systems, so it could run a generator. And you are right about the air flow in the exhaust doing all the work, the point I was trying to push is that the airflow in the exhaust tract is wasted power, it is something that can be harnessed/recycled and put to other uses (such as this one). This isn't for performance, it is for efficeincy.

 

[omabramo]

haha, ok, but exhaust flow isnt really wasted power. i see wasted power as being in the form of energy used to move engine internals/accesories, in heat transfer, and in unburned fuel

 

[homeworld1031tx]

true, but i figured since the 'advantage' of a turbocharger over a supercharger is that it can forcefully induct air without using direct engine power, using it to spin a generator to drive a motor would be more effective.