Radial turbine at the end of the shaft

[elephant]

Well, we all agree: the energy efficiency of current combustion engines hardly exceeds 30% and we cannot recover pure heat. (except maybe by fixing 300 l of water in the trunk and by plugging in the central heating in the evening when returning ) Most of this energy goes into the exhaust as hot gas at high speed.

The turbocharging engine is already the start of a response because it recovers part of the energy from the gases produced by the exhaust to increase the power of the engine.

and if we mounted a radial turbine at the end of the motor shaft (so that looks like an oil burner turbine) powered by exhaust gas ?

would this be a good return?
Have we already thought about it? (maybe I break open door)
would it be more efficient than a turbocharged turbo?

this formula could have the following advantages:

smaller piston engine to save space for this new element
engine brake on a turbine engine (its absence has always slowed its development)
reduction in the volume of the exhaust pipe because a first expansion of the gases would occur in the turbine

I agree with you that this is completely outside the scope of our little garage background tinkering!

[Other]

Hello
This principle has been used by the SNCF
RNUR turbo diesel locomotive
it is a free piston generator two stroke diesel engine
two pistons (crazy) face to face with a synchronization system,
the exhaust gases activate a trurbine which provides all the driving force.
This was built at a time when the materials for the trubines did not support a high temperature, so the compressor and combustion is done with two opposite pistons and at the end of short expansion the exhaust gases have an acceptable temperature for the teeth of the turbines,
With years of experience in turbo engines (although the compressor eats a good part of the energy), they diluted the hot gases after combustion to have an acceptable temperature for the turbine at the outlet.

Andre

[elephant]

Thank you for getting up at 4 am specially to answer me
Apparently the idea is close although a little different (I suspected that I had not had a flash of genius, like that, suddenly in full insomnia)
That said, what do you think?

[Christophe]

It already exists on industrial engines: it's called the Turbo Compound.

When we type on google we see that it was useful on star aviation engines ... so not really new as a system ...

A "particular" version is under study, we talked about it recently: https://www.econologie.com/forums/turbine-el ... t1186.html Besides, you found the subject ...

[Capt_Maloche]

Yes Eleph, we haven't reinvented hot water

The best system is the one currently found in DCi Hdi and others: HP turbo and HP electronic injection

Because mounting a turbine at the end of the shaft does not make it possible to recover energy from the exhaust (dito the compressors on the mecedes for example) but only to compress the air to artificially increase the displacement.

That said, a turbo generates a lot of pressure drop in the exhaust and I don't know which of these two systems has the best performance.

[Other]

Hello Elephant

Thank you for getting up at 4 am specially to answer me

I live in another world 6 hours behind you
I am in Quebec, so I write in the morning and late at night, the day I tinker on the montages or travel to do tests

Andre

[jlvx]

have read that somewhere (but where ???? purchases-industrials.com?) a system developed by the British, does it seem to me called GATS or GART (acronym of ... ), which made it possible to recover electrical energy, by replacing (almost) completely the alternator, and consequently saving a few% of fuel.

[Capt_Maloche]

Turbo or Compressor?

The answer here: http://www.automobile-sportive.com/tech ... tation.php

There are also the so-called "hybrid" cars: http://www.cnetfrance.fr/cartech/produi ... ybride.htm

et http://www.hybridsynergydrive.com/fr/re ... aking.html

[elephant]

OK, thank you all for your answers, I will continue my information so as not to die an idiot.

Christophe: be careful, this small alternator is not the same thing, what I was talking about is a large turbine mounted at the end of the shaft

[Philippe Schutt]

on a gasoline engine, replace the air butterfly with a turbine? + alternator. The regulation would be done by a bi-pass.

- at full load, the alternator is bypassed by the bypass, and since there is no longer belt driven alternator, there is a gain in useful power.
-a partial load, a gain due to the absence of alternator driven by belt, and potentially a large electrical power
at very low load, it would probably still need a butterfly, finally, to see depending on the turbine or other ...

I do agree that an engine with a turbo has a better performance "full throttle", but at low load, isn't it the opposite? in fact, there is an exhaust brake, and the pressure restored to the intake is blocked by the throttle.