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Originally Posted by serialk11r
Currently, nothing is being done to capture waste heat.
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Traditional turbos do capture waste heat (as has been said previously).
Turbo-diesels are a perfect example of this - where downsized engines give the same power for better FE.
If I dare bring Ideal gas law into this thread (it seems to add to arguments in the BSFC thread for some reason!), can I just confirm that we remember that decreasing the pressure of a gas, say by extracting
work across a turbine, will proportionately lower it's temperature - by the IG law.
Quote:
Originally Posted by serialk11r
My argument isn't that there isn't enough energy, just not enough waste energy... But I agree that this could be useful, it's something that should be implemented on all cars.
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Isn't this a bit of a contradiction? (I'm not saying that to be rude. I'm just interested.)
I think the key is that, as you also say, all the big wins in IC efficiency are in the bag.
Regarding back-pressure on the engine, we know that none is bad and too much is bad. So I can't see why a well chosen turbine (non-supercharging) wouldn't remain within that sweet-spot of back pressure all the time. A handy effect of using a generator is that the ECU can determine the load (equal to back-pressure) second by second by wave-chopping the output.
Quote:
Originally Posted by serialk11r
BMW's steam generation system produced double digit improvements in efficiency under [peak] conditions
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Unfortunately thermoelectric generators aren't very effective and steam based systems have high weight penalty...but there's so much potential.
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Cost to the manufacturer comes into this as well though.
The turbosteamer idea is probably around three times as complex as exhaust-generator-componding. And it would conservatively cost twice as much to integrate. So it would need to give a minimum of twice the mpg gain as the turbo-assist.
... which it might, but no one really knows yet.