Gas turbine hybrid Jag

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Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 3:13 pm

http://www.telegraph.co.uk/motoring/mot ... ngine.html

About time too, I've been saying for a few years now that someone should do this. It seems like an obvious solution to the limited range of batteries and the slow throttle response that affected earlier turbine cars.

Other thoughts I've had on hybrids are:
1) Throw in some super capacitors to capture more of the regenerative braking energy (not rate limited on charging like batteries are).
2) Electric motor per wheel (either hub or if too heavy inboard on a driveshaft) for crazy 4 wheel drive capability with computerised equivalent to differentials.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 3:32 pm

I've thought the same thing for a long time as well. GM is on the right track with their Volt that is purely electric when it comes to powering the wheels but they still have a heavy, inefficient piston engine recharging the battery. Turbines never made sense in cars because they are only efficient at peak RPM but if the turbine's only job is range extending you can always burn fuel for the most gain. The only problem is turbines are expensive compared to piston engines and hybrids are already expensive. They require fewer repairs over their lifespan so it should come out roughly in the wash but it makes for a steeper cost of entry.

Per-wheel motors make a lot of sense as well. Think of the amount of power wasted and weight added trying to turn 4 wheels at the correct rate. Not to mention with a mostly empty engine bay batteries could be spread through the lower half of the vehicle and you can get some of that storage space back.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 3:37 pm

Yes, I've had similar thoughts but because this isn't my area of expertise I always assumed there were engineering details that made it far less obvious than it seemed on the surface. I figured they'd show up in vehicles like buses and (especially) tractor trailer trucks, where things don't have to be as small, the economics make the most sense, and maintenance is centralized (since servicing turbines isn't something your average mechanic is prepared to do). But train locomotives already take advantage of the low-end torque of electrics yet haven't attempted to harness the steady-state efficiency of turbines for cruise -- is the switch in fuel away from diesel been the obstacle, or is that just a very conservative industry?
notfred wrote:1) Throw in some super capacitors to capture more of the regenerative braking energy (not rate limited on charging like batteries are).
But aren't super-capacitors in the required capacity even more expensive than lithium batteries?
2) Electric motor per wheel (either hub or if too heavy inboard on a driveshaft) for crazy 4 wheel drive capability with computerised equivalent to differentials.
You want to keep unsprung weight to a minimum, which is why the common fantasy of a motor in every hub is wrong. But a motor at the wheel is a good idea. I've been somewhat surprised that no-one (AFAIK) has done a hybrid AWD implementation with the gas engine running the front wheels and electrics in the rear (which has the nice side-effect of eliminating the driveshaft hump in the cabin). Though of course it would be better to have the electrics running the front wheels all the time, and the gas engine driving the rear wheels only as necessary -- but then you need to put the gas engine in the rear.... hello, Porsche. Too bad batteries are so heavy.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 3:43 pm

UberGerbil wrote:I've been somewhat surprised that no-one (AFAIK) has done a hybrid AWD implementation with the gas engine running the front wheels and electrics in the rear (which has the nice side-effect of eliminating the driveshaft hump in the cabin). Though of course it would be better to have the electrics running the front wheels all the time, and the gas engine driving the rear wheels only as necessary -- but then you need to put the gas engine in the rear.... hello, Porsche. Too bad batteries are so heavy.


I think Nissan actually did that with the cube in Japan. If you ordered 4 wheel drive you had the gas engine powering the front wheels like normal and a small electric motor in the rear. I don't know if it was that popular.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 4:02 pm

I still think gerbils in dynamo wheels would be more efficient and green at charging the batteries and extending range. Gerbil Powah...! :lol:
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 4:28 pm

UberGerbil wrote:
notfred wrote:1) Throw in some super capacitors to capture more of the regenerative braking energy (not rate limited on charging like batteries are).
But aren't super-capacitors in the required capacity even more expensive than lithium batteries?
Not a pure super capacitor setup, more a mix of caps and batteries. The current hybrids don't actually recover that much energy from braking as I understand because the batteries have a limited charge rate. If you add a small capacitor bank in addition to the batteries then the braking energy can get dumped in to the bank pretty quickly and then charge the main battery bank more slowly.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 5:28 pm

notfred wrote:Not a pure super capacitor setup, more a mix of caps and batteries. The current hybrids don't actually recover that much energy from braking as I understand because the batteries have a limited charge rate. If you add a small capacitor bank in addition to the batteries then the braking energy can get dumped in to the bank pretty quickly and then charge the main battery bank more slowly.
Yeah, I understood what you meant: use the supercaps upstream from the batteries to buffer the instantaneous spike during breaking and then dribble it out to the batteries at the rate they can absorb efficiently. But you're still talking about a substantial amount of energy: a 1200kg Prius travelling at highway speeds carries almost exactly half a million joules in kinetic energy. I haven't gone shopping for super/ultracapactiors but I would imagine that something that can absorb 500 KJ at the voltages used in hybrid cars doesn't come cheap. At least, not yet.

Actually, after a bit of googling, I turned up the AFS Trinity "ultra hybrid" which, despite a raft of publicity a couple of years ago, hasn't seemed to progress past the prototype stage. That NYTimes story notes that current hybrids can only pass on about 50% of the braking energy to the batteries, and describes the ultracapacitors in the Trinity prototype:
NYTimes wrote:The ultracapacitors take up about as much space as the lithium ion batteries, although they store a total of less than one kilowatt hour. Mr. Bender described the entire package as looking like an 18-pack of Red Bull cans, shrink-wrapped.
Interestingly, the prototype leaves the factory FWD system intact and adds their own system in the rear, for intermittent AWD (though that would seem to be an artifact of the prototype and not an intended feature.)
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 5:41 pm

Does anyone else think that small-town mechanics and finely-balanced turbines spinning at tens of thousands RPM is a recipe for catastrophe?

Any car company offering a turbine hybrid (which from a thermodynamic viewpoint makes perfect sense) had best throw in free dealer maintenance of the turbine. Last thing I want is to pass a turbine-powered Pious (my pet name for the Prius, and I've yet to see one pass me) when the turbine disk lets go.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 6:34 pm

Captain Ned wrote:Last thing I want is to pass a turbine-powered Pious (my pet name for the Prius, and I've yet to see one pass me) when the turbine disk lets go.

Just because a Prius driver doesn't pass you and your misplaced testosterone doesn't mean they can't. :lol:
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 9:42 pm

With the small size of the turbines required, and the chassis/hood offering protection, I'm not sure a blade would be that deadly while you are in your car. That and I'm sure SAE would have guidelines for preventing that from being a cause of death in, say, an accident.

I wonder how loud such a contraption would be. Large turbochargers and blowers are loud enough. You would need a muffler for the intake too. It could be built in with the air cleaning system though, which would also be substantial.

There is room for a substantial efficiency gain, but these engines are not going to be nearly as efficient as aircraft engines. They won't be using the lightest, highest temperature materials for the turbine inlet like they do in aircraft. It's just too expensive, requires too much inspection, and the payback just isn't there for road use.

Also: I am all for serial hybrid designs. I won't be touching a parallel hybrid with a 10 foot pole. With serial hybrid/pure electric drive you can get a sharper throttle response than even formula 1 cars.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 9:51 pm

ekul wrote:
UberGerbil wrote:I've been somewhat surprised that no-one (AFAIK) has done a hybrid AWD implementation with the gas engine running the front wheels and electrics in the rear (which has the nice side-effect of eliminating the driveshaft hump in the cabin). Though of course it would be better to have the electrics running the front wheels all the time, and the gas engine driving the rear wheels only as necessary -- but then you need to put the gas engine in the rear.... hello, Porsche. Too bad batteries are so heavy.


I think Nissan actually did that with the cube in Japan. If you ordered 4 wheel drive you had the gas engine powering the front wheels like normal and a small electric motor in the rear. I don't know if it was that popular.


The Honda Dual-Note concept car also did something similar.

With all this craze for hybrids, I'd like to see a different metric for rating a car's environmental impact than simply measuring CO2 per km. What we need is a measure of the total invested energy cost of manufacturing a car, and its estimated impact over its life. It's good to see that GM is 'committed' (or at least paying lip service) to recycling Volt batteries, but battery disposal and waste management is still a big unknown for most, if not all, existing hybrids.

Sweet looking car, though.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 9:54 pm

I would think that it would be much cheaper to recycle these batteries than to mine, refine, and make new ones.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 10:03 pm

SpotTheCat wrote:Also: I am all for serial hybrid designs. I won't be touching a parallel hybrid with a 10 foot pole. With serial hybrid/pure electric drive you can get a sharper throttle response than even formula 1 cars.


The downside of serial hybrids is you need a *lot* more batteries than a parallel hybrid. LOTS more. A prius has an electric driving range of a couple of miles, and even the PHEV version with oodles of batteries stashed in the trunk only has an electric range of 12 miles.

The batteries add weight, you need larger and more powerful motors, and the cost and environmental impact of making and installing more batteries is amplified.

They (serial hybrids) are good in other respects - the drivetrain is simplified and more elegant from an engineering perspective (although the prius transmission system is hella cool), and driving electric-only offsets CO2 production to the local coal, nuclear or hydroelectric plant. Just pointing out that everything has advantages and drawbacks, which is why different players are moving in different directions rather than all doing serial hybrids. For instance, the Prius synergy drive transmission is very complicated, and Toyota didn't simply put the money and effort to design and manufacture it for no reason. They did it because the parallel drive system was more economically feasible - even with the added cost of the transmission - at the time.

As an engineer, my personal passion is for Stirling hybrid engines, but I also know that there are many technical and economic reasons why we don't see them on the market yet (if ever), despite NASA and GRC producing 70mpg stirling powered cars (using petrol-only) for research in the 70s.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 10:26 pm

Voldenuit wrote:
SpotTheCat wrote:Also: I am all for serial hybrid designs. I won't be touching a parallel hybrid with a 10 foot pole. With serial hybrid/pure electric drive you can get a sharper throttle response than even formula 1 cars.


The downside of serial hybrids is you need a *lot* more batteries than a parallel hybrid. LOTS more. A prius has an electric driving range of a couple of miles, and even the PHEV version with oodles of batteries stashed in the trunk only has an electric range of 12 miles.

The batteries add weight, you need larger and more powerful motors, and the cost and environmental impact of making and installing more batteries is amplified.

They (serial hybrids) are good in other respects - the drivetrain is simplified and more elegant from an engineering perspective (although the prius transmission system is hella cool), and driving electric-only offsets CO2 production to the local coal, nuclear or hydroelectric plant. Just pointing out that everything has advantages and drawbacks, which is why different players are moving in different directions rather than all doing serial hybrids. For instance, the Prius synergy drive transmission is very complicated, and Toyota didn't simply put the money and effort to design and manufacture it for no reason. They did it because the parallel drive system was more economically feasible - even with the added cost of the transmission - at the time.

As an engineer, my personal passion is for Stirling hybrid engines, but I also know that there are many technical and economic reasons why we don't see them on the market yet (if ever), despite NASA and GRC producing 70mpg stirling powered cars (using petrol-only) for research in the 70s.

The batteries don't need to be any more huge than in a prius. Total energy capacity is the bottleneck, not the power output of the cell. With a turboshaft (or regular automotive) engine giving, at minimum, the max charge rate specified for the battery pack, and at maximum whatever it can give, you wouldn't need such a huge battery pack.

Now, you're right about motor size. Though without a big, heavy, complex transmission there is a bit of the weight, cost, and complexity budgets left.

As far as Stirling engines in cars, I don't see them as practical as they are even less able to cope with power output fluctuates than gas turbines.
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Re: Gas turbine hybrid Jag

Postposted on Thu Sep 30, 2010 10:44 pm

SpotTheCat wrote:As far as Stirling engines in cars, I don't see them as practical as they are even less able to cope with power output fluctuates than gas turbines.


The research vehicle that NASA tested was able to cope fine (according to the paper) despite
a. Not having an electric motor buffer (as a hybrid would)
and
b. Not having a CVT (it used the stock gearbox of a Ford Escort or something)

I bet that with today's technology, it could be a lot better (they didn't have ECUs in those days). On top of that, Stirling engines (unlike gas turbines) can be manufactured in existing automotive plants - Stirling Research Company builds a lot of its engines in Detroit at ex-auto plants. And they're a whole lot more resilient and maintenance-free than gas turbines.

Stirlings, Gas turbines and even ICEs all have a peak efficiency operating range, that's just a fact of life. Even electric motors do (although they tend to be more resilient at typical operating conditions).
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Re: Gas turbine hybrid Jag

Postposted on Fri Oct 01, 2010 12:47 pm

notfred wrote:Not a pure super capacitor setup, more a mix of caps and batteries. The current hybrids don't actually recover that much energy from braking as I understand because the batteries have a limited charge rate. If you add a small capacitor bank in addition to the batteries then the braking energy can get dumped in to the bank pretty quickly and then charge the main battery bank more slowly.

The problem here is that batteries can take additional current at nominal voltage and increase charge density, while capacitors store charge as a proportional function of applied voltage. To get the regenerative benefit, the capacitors would have to start at some fairly low voltage, be charged to a much higher voltage by the regenerative capture, and then drained into the battery pack by a power converter. The extra circuitry to perform this task is not free, either in physical costs or efficiency.

Captain Ned wrote:Last thing I want is to pass a turbine-powered Pious (my pet name for the Prius, and I've yet to see one pass me)

I call 'em Prissies.
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Re: Gas turbine hybrid Jag

Postposted on Fri Oct 01, 2010 3:49 pm

This reminds me a lot of the system used by the Chrysler Patriot:

http://www.allpar.com/model/patriot.html

Talk about a car ahead of its time.
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Re: Gas turbine hybrid Jag

Postposted on Fri Oct 01, 2010 4:28 pm

SNM wrote:Just because a Prius driver doesn't pass you and your misplaced testosterone doesn't mean they can't. :lol:

Oh, they can't and I've yet to buy the Cobb AccessPort which gives me STi 1/4 mile times. 8)
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Re: Gas turbine hybrid Jag

Postposted on Fri Oct 01, 2010 4:31 pm

delsydsoftware wrote:talk about a car ahead of its time.

And in that you are 100% correct. The Patriot was so far ahead of its time that no one knew what to do with it.
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Re: Gas turbine hybrid Jag

Postposted on Sat Oct 02, 2010 3:43 pm

delsydsoftware wrote:This reminds me a lot of the system used by the Chrysler Patriot:

http://www.allpar.com/model/patriot.html

Talk about a car ahead of its time.

That was a very interesting read, thanks!
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Re: Gas turbine hybrid Jag

Postposted on Sat Aug 11, 2012 3:31 am

The obvious reasons for not putting a turbine into a car for my mind are:
-they have to be incredibly well balanced... i.e. a car's motion is very different to a stationary turbine, jet engine or what have you.
-if they aren't balanced... they fail CATASTROPHICALLY
-because they can fail catastrophically the thickness of material around them to protect everyone means the housing is too heavy to make an efficient car or a car that a regular joe could affort. (either due to density of the material required or the exotic material alternative).
-because of #1,2,3 = maintenance is very specialised and therefore expensive and you would be legally obligated to get it serviced, whereas with a motor you can skip getting it service and kill the car safely i.e. bad human behaviour doesn't put the rest of the public at risk because you were trying to stretch out your pennies between services.

Oh and I just realised I replied to a bot causing a stupidly old thread to come to the top... :/
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Re: Gas turbine hybrid Jag

Postposted on Sat Aug 11, 2012 7:19 am

This is where a wave disk engine (https://en.wikipedia.org/wiki/Wave_disk_engine) is supposed to step in.
Too bad it's still just lab prototypes to the best of public knowledge.
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Re: Gas turbine hybrid Jag

Postposted on Sat Aug 11, 2012 7:51 am

That was a necro post, guys.
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Re: Gas turbine hybrid Jag

Postposted on Sat Aug 11, 2012 12:10 pm

There were problems with turbine engines. First of all, turbine engines push a LOT of heat out of the exhaust, which would be very uncomfortable with a significant number of turbine engines in heavy traffic. Also, there were already tests with turbine engines in big rigs(tractor trailers for you city slaves). They had a LOT of torque, and didn't even need to shift down to climb steep hills. But they had to be geared down with enourmous transmissions, and they couldn't make the metal strong enough to stand the torque of the engine. They ended up going through transmissions on a daily basis, and had to scrap the project. Also, this green energy fad(which I hope goes away), would impact the economy and bring it to a halt. Tractor-trailers will never be efficient enough to pull an 18 ton load on battery power. And there isn't a battery big enough in the world to get a passenger jet off the ground. Laws of physics are the limit, and we are reaching that limit when it comes to pushing the weight of a vehicle.
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