Gas turbine/electric hybrid?

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Lack of fuel economy and pick-up was the principle operational deficiency of pure turbine power. Might not this be solved by using a gas turbine intermittently to charge a battery which then drives an electric propulsion
motor?
Electric motors develop maximum torque at zero rpm, making for snappy pickup and eliminating the need for a complex transmission. A battery stores energy for the motor, with the energy being replaced by a gas turbine. The turbine need not run much around town for short trips until the battery runs low on chemical energy and needs recharging. On the open road, the car is powered principally by the turbine, but since it runs at its efficient speed, it need not have a large fuel burn in terms of pounds of fuel per horsepower hour, which the bottom line should yield efficiencies no worse than a piston engine.
An automotive gas turbine, with waste heat regeneration, used at a constant speed would be quite efficient. Sizewise, the rotor probably need not be larger than a kitchen toaster for 80 hp out. Gas turbines also will run on a wide variety of gaseous and liquid fuels, helping to aleviate the high cost oil supply situtation. You could run a gas turbine on hydrogen electrolized from water using wind turbines for a fossil fuel-free transportation system. Alternatively, you could run a gas turbine on natural gas, LPG, kerosine, even liquid coal or any other clean burning fuel.
As for the high cost of gas turbine engine development and construction, there are solutions. The development should be by a consortium of cooperating companies, who will do the research and development and the government which will finance the project. It will take many billions of dollars. The government can invest these many billions and later reap licensing returns during production. Patent protection and enforcement will allow only those government-licensed companies to produce the patented power plants. Standardization will keep down the costs. Only one engine design, in three sizes need be developed: small, medium and large (80, 160 and 320 hp) for various sized passenger vehicles and small trucks.
Manufacturers can distinguish their products by differentiation of their chassis and body. For instance, Ford can go for round taillamps, GM can mount tail fins, and Chrysler can put racing stripes down the sides. The engines will all be the same, Thankfully for the mechanics who now struggle to service the myriad of makes and models which are all different, but all do the same simple end function: to power two tons of automobile down the road.
Costs can also be reduced by recycling the rotors, the most expensive part. When a car is junked, the rotor can go into a new car. This can be made legal by statute law. A used rotor will be as good as new one after inspection and refurbishing. The secret is in the HEPA air cleaner which will prevents all erosion of the rotor blades due to particular matter impaction. With a rotor lasting 25 to 50 years, the previously high cost of gas turbines will be just a footnote in the history of technology.
A diesel hybrid might work just as well and certainly should be considered, but it doesn't have the desired high-tech sound of a 50,000 rpm whine.
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Nomen Nescio wrote:
"Electric motors develop maximum torque at zero rpm......."
Is that so? Unfortunately Nomen, you are a poser, just cutting and pasting things you read. That leaves you making error after error in how things are or could be.
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Al Bundy wrote:

Depends on the type of motor used.
Actually turbine-electric makes some sense: turbines are efficient at constant speed and offer both high efficiency and light weight, offsetting the heavy batteries. Regeneration is unnecessary in a constant--power setup: the turbine expanders can be optimized for that regime.
Emissions would be a deal killer because it would take intense and long development to get them to recip standards. The best thing that could be done for turbine car buffs would be to enact a emissions _certificatiion_ waiver for turbine cars for a set time, so as to make it worthwhile for some company to build a fair run of them. The waiver should be carefully written to force the outright sale, not lease or test loan, of the cars so they cannot destroy them like the Chrysler TC program or the GM and Ford factory electrics.
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If you want to look at economical hybrids, look to a diesel-electric combination like locomotives use. In a vehicle hybrid of this sort the electric motors would always be the prime movers and the diesel would use an auto-throttle and auto-switch to either send the electricty directly to the motors or into storage batteries. You accelerator pedal would regulate the juice going to the electric motors only and not the RPM of the charging diesel. Since diesels are more efficient at idle than a gasoline motor of the same size/output, you can use the power in the batteries to do all the accelerating and stop-and-go driving (keeping the diesel at idle RPM for a much longer time than using a directly coupled motor) and only have the diesel increase RPM when you need either the batteries charged or a direct flow to the electric motors for power. In addition, a hybrid of this type would not need any significant leaps of technology or waivers for emissions.
Just my two cents worth - Jonathan

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Jonathan wrote:

It would make _more_ economic sense, but it still wouldn't make economic sense, not at US fuel prices. A few people would pay a lot of money for the novelty of a turbine car, diesels are not novel. Straight diesel cars, which do make economic sense, are unobtanium in the US, because of consumer apathy and emissions laws combined with a refusal to require Euro-spec fuel for the current generatioon of CRD engines.
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Al Bundy wrote:

Well Mr. Bundy, I am afraid that Nomen is correct, at least for permanent magnet electric motors. Have a look at:
http://claymore.engineer.gvsu.edu/~jackh/books/model/html/model-71.html#54931
John
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John Horner wrote:

Well John, you are wrong because you took a blanket statement and qualified it to suit your answer. Again, nice pasting job though.
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Al Bundy wrote:

There are a LOT of varibles in electric motor design that can effect at what RPM peak effort is achieved. Generally though with traction type motors used to power electric cars and such, they achive maximum torque at zero or very low RPMs to get the load moving.
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I think I may see where Mr. Bundy is saying. Without having read any of the links provided, it makes sense to me that at zero RPM the motor is putting out zero torque. Once any torque great enough to make the motor turn is applied, then the RPM is no longer zero.
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Olaf wrote:

What batshit!
If electric motors put out *zero* torque at zero RPM, they'd never begin to rotate at all. Internal combustion engines DO have zero torque at zero RPM, which is exactly why you need an electric motor to start them!
How much torque an electric motor does put out vs. RPM depends a lot on the design of the motor.
DC and AC/DC commutator motors put out their maximum torque at 0 RPM (but will burn out if held at 0 RPM because only one winding on the armature is carrying the full load). An example of a DC commutator motor is the starter motor in a car, or the traction motors in older locomotives. An AC/DC commutator motor is the type used in vacuum cleaners, hand power tools, and blenders.
AC induction motors put out their peak torque at a few percent less than their free running maximum RPM. As you lug them down, torque goes up at first, but lug them too far and torque begins to decline again, but it never drops to zero even at zero RPM. An example of an AC induction motor is a fan motor, AC blower motor, AC compressor motor, or shop air compressor motor. The most commonly used AC motors in the world.
AC Synchronous motors put out their maximum torque at the synchronous RPM. They're used in heavy industry because they can be set to run at leading power factor to compensate for induction motors that run at a lagging power factor- save's the industry money overall.
Variable-frequency drive motors are induction or synchronous motors driven by a variable frequency AC source, so that you can make them put out peak torque at any RPM you want. Modern AC locomotive traction motors are variable-frequency drive motors.
But regardless of the type, ANY self-starting electric motor puts out SOME torque at 0 RPM. An example of a non-self-starting type would be a synchrounous motor without any start/damper windings... but that's a laboratory curiousity as all real-world electric motors have a provision to give them self-starting torque.
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I agree. (Good thing you didn't refer to bull shit, then I'd have been offended.) After having thought about it after posting I realized a motor can put out torque without turning. I thought of a drill with keyless chuck. When the chuck tightens on the bit the motor is still putting out torque

Makes sense to me. :)
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Gas turbine engines are very expensive to build. I doubt that we will ever see significant application to automobiles. It has been tried, many times, and came up short.
John
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John Horner wrote:

And the V12 in the Lambo is a low build cost powerplant?? No, gas turbines are not necessarily incredibly expensive to build. My guess is the Allison 250 costs less to build than a Lyc or Continental recip of half the power: the P&W PT-6 is probably twenty or thirty thousand dollars of actual labor, materials, and other hard build cost.
There are probably five hundred people who would buy a turbine exotic car in the $200-300K price class in the US any given year, enough to make it doable. The "Bugatti" Veyron is well into seven figures, at which point buying a off the shelf ST6 at market price from P&WC becomes a legit option economically speaking. However, it would make for a miserable road car, but the Veyron probably is that to begin with, to say nothing of the modified Stingray the Granatellis foisted off on some dumb yuppie idiot for a six-figure price with a junk runout training PT6 they mooched off P&W a decade earlier many years ago.
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Bret Ludwig wrote:

Well now you are talking about a whole different animal, a high-priced vehicle for those with more money than sense. All in all not an interesting topic of speculation. I would agree that the only way a turbine has a fighting chance in automotive use would be as a fuel burner to power a generator for a true hybrid powertrain where there is no mechanical connection between the fuel burning engine and the drive wheels. Trains have been built with such a powertrain for decades, and AFAIK, none use a turbine engine. GE locomotives has made a bunch of these trains and GE is also a top builder of turbine/jet engines, so I bet they have looked at it in depth.
John
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Actually there have been a few turbine powered locomotive engines have been tried. The problem was and still is fuel consumption. Turbines of ANY size use LOT's of fuel rapidly. There have also been a few turbine powered autos built. They were dropped for two reasons, cost of production and fuel use. There are also turbine powered motorcycles. Jay Leno owns one and was telling on a show the other night that it is a very difficult bike to get used to ride since the turbine has a very high lag on both ends.
As for a turbine powered hybrid. Doubt you will ever see one. Heat production and fuel use are both VERY high as is noise.
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Steve W. wrote:
<<snip>>

What Jay Leno and a couple of other people have is a crude homemade motorcycle built around a surplus Allison turboshaft engine. Such things are very different than purpose-built automotive gas turbines which are relatively inexpensive to produce and designed to recover much of the wate heat via regeneration.
Several companies built prototype automotive gas turbines but none were ever sold.
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John Horner wrote: <<snip>>

I don't agree. High end vehicles such as Lambo, Ferrari, etc. do serve a purpose and are interesting to watch.
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I think I remember reading about lots of other issues, too.
There's a massive amount of airflow which all needs to be very well filtered -- I think the Chrysler turbine cars were needing the filters cleaned daily? Of course that's old technology but you'd still have the same basic problem to deal with and probably would still have very frequent filter replacement or maintenance. To say nothing of the replacement cost of Nomen's "HEPA" filters. That'd be one helluva HEPA filter for a turbine engine's airflow.
I think there was a problem with extremely high exhaust temperatures as well? There are ways to reduce that, of course, but it would probably still be a problem.
I think there'd be enormous investment of research dollars with very dubious returns on practical usefulness, and not very likely to see a great advantage even over conventional automotive hybrids.
I often wonder about using smaller engines with higher-pressure turbochargers as a low-cost way to raise fuel economy. Perhaps a modern 1-liter or 1.5-liter with a high-pressure turbo instead of a big V6? (Just a thought, not trying to hijack the thread...)

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Marcus wrote:

You have done your homework very poorly and need to go to the back of the class.
Chrysler Turbine Cars needed very little day to day maintenance including in the dustiest environments. Usually they would not see a mechanic in the three months the host family drove them.
The EGT at idle was so mild you could, as I actually have, put my feet under the tailpipes and felt pleasant warmth at idle. Under power it is hotter but never high enough to damage anything unless you tied the rear axle to a light stand and tried to pull away at full power on tarmac and even then all it would do is mush the tarmac a little. You would probably run out of fuel or tear up the transmission first.
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Yeah.... like all that technology developed under NASA/ Space funding.. total waste of money, considering we never saw any of it!
Good Catch!
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