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[Simon F]

so the turbines just recharge the battery ?

If you mean, are the turbines only connected to generators/alternators, then yes. It would be unbelievably unpleasant to have gearing to drive the wheels.

If you meant do they just recharge the battery, I would say the power management would be far more complex with it being used to both charge and drive the electric motors and, in turn, using the motors to do regenerative braking.

 

[Simon F]

Do you have any source for that? In general, turbine engines are less efficient than piston engines. The reason they're used in aircraft is their mechanical simplicity and thus reliability.

I seem to recall that turbo fans were about 80% efficient, which is significantly greater than an ICE**. Judging from the size, I suspect they also considerably lighter than the equivalent piston engine.


**Which I always tend to read as In Circuit Emulator 8P

 

[aaronspink]

Do you have any source for that? In general, turbine engines are less efficient than piston engines. The reason they're used in aircraft is their mechanical simplicity and thus reliability.

It would take me quite a while, it was mentioned in several articles/press releases during the paris auto show where the car of unveiled. They are very high on these new generation microturbines both because they are more efficient and more flexible wrt fuel. One of the things that greatly increases the efficiency and has been true with turbines for a long time is that not needing variable power output means that the turbines can be designed for a better operating point.

But in general, turbines have been more efficient at generating power than piston engines. At fixes outputs/rpms they deliver high efficiency. Their efficiency only suffers when they have to operate in a wide band.

And no, turbines are used in aircraft because they provide better efficiency than piston engines. The piston engine is terrible inefficient.

 

[aaronspink]

Perhaps so, but turbines tend to be ear-shatteringly noisy sons of bitches, and spew lots of NOx compounds (which are quite unhealthy, as we all know.)

How have they solved those two issues?

Yes. These things are incredibly small. and they emissions are suppose to be better than any piston engine of the same output.

 

[Sxotty]

Do you have any source for that? In general, turbine engines are less efficient than piston engines. The reason they're used in aircraft is their mechanical simplicity and thus reliability.

This belongs in the energy thread we used to have, but mint is actually right from what I know. Specifically when considering smaller turbines the efficiency has generally sucked. ICEs were actually better. The emissions for turbines should not be too bad at steady state, which they should run at depending how the car is put together.

 

[Grall]

These things are incredibly small.

Yeah? Define "incredibly small", please... If they're to provide any meaningful amounts of power (specifically enough to run a sports car in this case; IE quite a few kWs' worth) there's of course a minimum size limit on them. I have seen (and heard!) truly incredibly small turbines, the kind used to power radio controlled model aircraft, and those too put out well over 100dbs of noise. They're quite literally hell-screaming loud despite being small enough to easily be held in your hand.

 

[Mintmaster]

I seem to recall that turbo fans were about 80% efficient, which is significantly greater than an ICE**.

80%?!? You are grossly misinformed, unless you're talking about combined heat and power generation (and it's very easy to direct >90% of heat where you want it).

Wikipedia quotes microturbines being 25-35% efficient, while the best automobile ICEs can peak over 40% (and a series hybrid will always be running at optimal RPM/load). Research engines have achieved over 50%.

Okay, I sold short the usefulness of turbines in aircraft, as their power density and noise tone are superior to piston engines. Still, I stand by may statement, and I think we should listen to the resident energy expert Sxotty.

 

[aaronspink]

Yeah? Define "incredibly small", please... If they're to provide any meaningful amounts of power (specifically enough to run a sports car in this case; IE quite a few kWs' worth) there's of course a minimum size limit on them. I have seen (and heard!) truly incredibly small turbines, the kind used to power radio controlled model aircraft, and those too put out well over 100dbs of noise. They're quite literally hell-screaming loud despite being small enough to easily be held in your hand.

Just under 2 ft in length and 70 KW per delivered electrical power (aka post generator power). As far as noise, a non-muffled piston engine produces one hell of a racket. Blandon Jets which makes the turbine is claiming 1/20th the weight and size for equiv power. Apparently Jaguar is going to rely on a combination of non-linear pathing and active cancellation to deal with the noise issues.

 

[Jawed]

 

[Grall]

Just under 2 ft in length and 70 KW per delivered electrical power (aka post generator power).

Yeah, gas turbine-powered generators can deliver huge amounts of electricity. Volvo showed a prototype hybrid car 17 years ago that charged its batteries using a gas turbine. Funny I didn't remember it until just now, heh. Anyway, one of this car's claimed uses was it could actually function as an external power source apparantly - you could hook it up to your single-famly house's power grid and it could run everything. It would seem its output was in "only" the 56kW range...which should realistically be enough take care of every god damn appliance you could think of really.

As far as noise, a non-muffled piston engine produces one hell of a racket.

Well, duh. Issue with turbines though is they produce racket both at intake and exhaust, and muffling either is a wee bit more complicated than ye bog standard piston clunker.

Apparently Jaguar is going to rely on a combination of non-linear pathing and active cancellation to deal with the noise issues.

I bet they'll have their work cut out for them... Interesting if they do manage to get it to work though, in a purely theoretical sense of course, since only about half a percent of the world's population will be able to afford one of these things. Maybe less actually.

 

[Simon F]

80%?!? You are grossly misinformed, unless you're talking about combined heat and power generation (and it's very easy to direct >90% of heat where you want it).

I see now that there are numerous "efficiency" measures and I could have a) misheard the figure b) assumed a different meaning of efficiency or c) the source may have been wrong. It was a long time ago. I did say "seem to recall" after all. .

Wikipedia quotes microturbines being 25-35% efficient, while the best automobile ICEs can peak over 40% (and a series hybrid will always be running at optimal RPM/load). Research engines have achieved over 50%.

Out of curiosity, does anyone know what the relative weights of the various engine types are?

 

[Lightman]

I see now that there are numerous "efficiency" measures and I could have a) misheard the figure b) assumed a different meaning of efficiency or c) the source may have been wrong. It was a long time ago. I did say "seem to recall" after all. .


Out of curiosity, does anyone know what the relative weights of the various engine types are?

From an extreme end of high performance engines, current F1 V8 2.4L engine weights 95KG!!

• All F1 engines are naturally aspirated V8's of 2400cc
• Engines are limited to 18,000rpm
• The weight is exactly 95kg (each manufacturer easily reaches this regulated minimum weight)
• Engine blocks are constructed of forged aluminium alloy, because of the weight advantages it gives in comparison to steel. Other materials would maybe give some extra advantages, but to limit costs, the FIA has forbidden all non-ferro materials.
• Crankshaft and piston rods are Iron based for strength.
• At its maximum pace the current V8 engines consume around 60 litres of petrol for 100km of racing.
• It's not exactly known how much oil such a top engine contains, but this oil is for 70% in the engine, while the other 30% is in a dry-sump lubrication system that changes oil within the engine three to four times a minute.
• Before its first track time and after each race, each engine is tested on an engine dyno to validate its performance and identify problems. A videoclip of Renault's RS24 on the dyno can be found here.

Source: http://www.f1technical.net/articles/4

 

[KimB]

May I ask why aluminum is considered a "ferro material" considering it isn't iron?

 

[Grall]

I heard once that under certain circumstances (probably when alloyed with other metals) alu can become magnetic... Perhaps that's why.

 

[Mintmaster]

We should really move the past ~30 posts to an "Automotive Technology" thread.

I see now that there are numerous "efficiency" measures and I could have a) misheard the figure b) assumed a different meaning of efficiency or c) the source may have been wrong. It was a long time ago. I did say "seem to recall" after all.

No worries. It's just a pet peeve of mine when misinformation propagates, whether claims have a qualifier or not. You're one of the smarter guys on B3D, so I think most of us generally hold your opinion in high regard.

aaronspink, here's a chart I found from a recent article:

So yeah, it's pretty damn hard to generate power efficiently in small quantities using a turbine. Add a constraint of small volume/mass/cost, and it's even harder. Remember that virtually the entire market for small turbines exists because electricity is expensive to deliver from centralized generation facilities, so they're very sensitive to fuel cost and there's stiff competition to deliver high efficiency.

In other words, I doubt a compact turbine suitable for automobiles has much chance at catching reciprocating engines in efficiency.

It would seem its output was in "only" the 56kW range...which should realistically be enough take care of every god damn appliance you could think of really.

Heh, that's actually enough to satisfy the combined peak of 10 households. Living doesn't need nearly as much power as even a tiny car

 

[Sxotty]

And here is a post with a link about the efficiency of some auto designs. The discussion can go there.
http://forum.beyond3d.com/showpost.php?p=1491398&postcount=123

 

[Jawed]

It seems there's plenty of parkour vids with grim stuff happening in them - this isn't one of those. Not even at the end.

 

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[Jawed]

Watch in HD