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Air-Electric Drive System

Discussion in 'Technical Discussion' started by TRY, Oct 23, 2006.

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  1. K1W1

    K1W1 Senior Member

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    Hi,

    Well written Marmot.

    TRY if you would be kind enough to give us a list of the days the facility will be unattended between now and the end of May I am sure it will enable those here who are willing and able to make the effort to visit the plant the ability to make their plans accordingly.

    It's kinda strange though I always thought the major close down holiday month in France was August.

    I await your reply with interest.
  2. TRY

    TRY Senior Member

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    Unattended or attended?

    You got me confused here, K1W1!
    I would expect you to visit when the plant is attended, no?
    Furthermore, I'm not in charge of visitors.
    You'll have to apply to the plant directly, via the website I suppose, explaining who you are, what the purpose of your visit will be, etc.

    As for France, yes May is interrupted with long and longer weekends and bridge days, due to public holidays, so now you know!
  3. K1W1

    K1W1 Senior Member

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    Hi,

    I see from published data that the official holidays in May are the 1st, 08 and 12th so that leaves a few other weekdays when the excuse of a public holiday can not be used.

    You never answered my question as to what is a Yacht Forums visitor and as for not being in charge of visitors you must have something to do with it judging by your "If you would like to see something more than the showroom, please give me notice, asap.
    Looking forward to meeting you all!"
    statement to another YF Member.

    I did look at the website for info as to the opening hours etc and have to admit that a bell did start ringing when I saw the contact was a free e mail addy.

    To me this is just further indication of the flyby night nature of the whole operation.
  4. The Reverend

    The Reverend New Member

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    Flyby Niight

    This not a flyby night operation! they have beeen pulling the 'this car will be available soon - give us your money' line since at least the year 2000.

    http://www.rexresearch.com/negre/negre.htm
    Last edited: Apr 18, 2008
  5. K1W1

    K1W1 Senior Member

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    Hi,

    The Reverend-Great Link, Is Mexico over run with these incredible cars yet?
  6. The Reverend

    The Reverend New Member

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    Good Point.
    One of the reports in the link I posted (dated Nov 99) mentions a that Mexico City has purchased 40,000 (yes 40.000!) of these machines.
    I must admit despite spending some considerable time there I have never seen a single one of these cars or seen an air refil station.
    I think the engineers and others on this forum have exposed this car for what it is.
    I find it sad that worlwide there are people struggling to develop and try new ideas all the time meanwhile there are oprations like this milking the uninformed investor and giving engineering development a bad name.
  7. K1W1

    K1W1 Senior Member

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    Hi,

    That also corresponds with my request from colleagues in South Africa and Australia for info about these wonder cars- no one has seen or heard about anything they can recall.
  8. Marmot

    Marmot Senior Member

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    It looks like they managed to blow some hot air on Tork over at Yacht Report.
  9. K1W1

    K1W1 Senior Member

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    Hi,

    Maybe he was standing too close to the exhaust:eek:
  10. brian eiland

    brian eiland Senior Member

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  11. K1W1

    K1W1 Senior Member

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  12. Marmot

    Marmot Senior Member

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    I was looking at the Tata site the other day and couldn't find any reference to the things either.

    I am saddened and shocked that this gift to mankind is finding so little acceptance in these difficult times.
  13. Dan Evans

    Dan Evans Senior Member

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  14. Marmot

    Marmot Senior Member

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    It just stimulates my gag reflex because it illustrates the incredibly low level of technical literacy in the majority of the population today.

    What is even more distrubing is that the lead-in on that video was by the host of one of those television "science" shows and many if not most of his audience will not see this for what it is.

    Just for the record, K1W1 and I visited the showroom in Nice last year and they really weren't too happy to see us. We didn't get any answers to our questions. It seems you have to be an investor to prove to them you are not a skeptic, only then they will explain how they have rewritten the laws of thermodynamics.
  15. Grecko

    Grecko New Member

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    Being new here, I read this entire thread with interest, being primarily involved in propulsion engineering professionally, perhaps I can add a bit to the discussion.

    This engine appears (I say appears because not much has been released as to what is really going on here) to be basically a Brayton cycle engine using external combustion to heat the working fluid (air). Being involved with gas turbines (which run on a Brayton cycle) for over 35 years, including performing preliminary design for a major engine manufacturer and managing advanced engine projects probably makes me as qualified as anyone to take a quick look at what is going on here.

    Our good friend Mr. Try has claimed an efficiency that he says is considerably better than other engines, and was at one point claiming an “efficiency” of 20%. What he did in that post however, was to substantially understate the efficiency of the competitors engines, and if we look at a typical diesel engine the efficiency can be as high as 40% for a good size propulsion engine, and into the low 30’s for smaller generators. The very low efficiency for gasoline engines is probably true for operation at low power and throttle settings, but if you had a very small gasoline engine running at a higher power factor, the efficiency would be better than 20% so there isn’t as much advantage here in their concept as one might think at first blush, other than perhaps the ability to burn a lot of different fuels and not make a lot of emissions that are associated with intermittent combustion.

    The efficiency of any Brayton cycle engine is going to be defined by the pressure ratio and maximum temperature, along with the efficiency of the compression and expansion components. Gas turbines can be very efficient, but as the sizes get small the efficiency of the compressors and turbines get poorer and the pressure ratio becomes limited, so we generally find that typical small Brayton cycle turbines aren't very efficient.

    Using pistons and cylinders to do the compression and expansion is quite efficient, but plumbing the air into and out of the system actually transfers the losses to the ducting between the components. Still, it is possible and some other folks have done it before and have made small Brayton cycle engines using pistons and cylinders instead of turbo machinery. The advantage of such a system is that it can operate with a reasonable efficiency at very small flow sizes, where turbomachinery isn’t feasible. Also, like a steam engine, when you are stopped, the engine can be stopped and there is no power drain, so if you are operating in a stop and go environment, the concept might have some advantages there.

    I did a quick cycle analysis model and it appears that a 20% thermal efficiency could be obtained with a cycle similar to what Mr. Try was claiming. Not entirely sure since he has been cryptic about the real cycle pressure ratio. The storage system of high pressure bottles is probably just that, a storage system for short term operation without the heat supply being used, so there really isn’t anything special here that I can see, but without full disclosure of how the system works we can’t know that for sure.

    A piston/cylinder arrangement restricts the total airflow and tends to limit the maximum power that can be developed, so what you are actually looking at here is a concept that is best suited to a small generator and not a propulsion engine for a craft of any size.

    Bottom line is what Marmot and K1W1 have long suspected, there is no free lunch and the basic laws of thermodynamics aren't going to be violated. This engine isn’t doesn't appear to be substantially lighter or a lot more efficient than what is out there already. Most of what we have here is really just clever advertising, saying that the car “runs on air” and in doing so be able to advertise the concept as being “green” and therefore be able to raise investment as opposed to really being able to revolutionize transportation.

    Hope this sheds some light on the concept and answers some of the questions that were out there..
  16. Marmot

    Marmot Senior Member

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    The thermal efficiency of large slow-speed marine diesels now exceeds 50 percent.

    It's just a compressed air motor, an overly complex one to impress the marks. None of the vehicles on display, or any of the poorly done exhibits in the showroom, indicated any type of external heating or regeneration. I think they show one being used as a generator just so they can show that it produces kW, they don't say how many kW it takes to generate the air to drive it. They absolutely refused to disclose the inlet air pressure and flow rate for a given output unless you are an "investor."

    Even with external heating of the stored compressed air, the efficiency of this air car can not approach the thermal efficiency of a modern automotive diesel engine.

    The air car proponents have used efficiency numbers (as well as websites) derived from "compressed air storage" power plants which use large underground caverns filled with compressed air from electric powered compressors which run at night when electrical power is cheap. During the day this air is fed to the burners of a gas turbine that drives a generator that feeds the grid. It's a clever idea similar to the pumped storage hydro plants used in mountain regions and if the energy used to pump the air storage is ignored, the efficiency figures can look pretty good to the gullible investor. In my opinion, that is what the air car folks are counting on.

    What amazes me most about this company is that it still exists and they still get unqestioning press coverage.
  17. Grecko

    Grecko New Member

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    Yes, of course, but I had in mind engines in the 200 - 2000 hp range, where SFC is in the .36 to .38 lb/hp-hr range, up to the maximum that one would consider for this concept.

    Mr. Try, in one of his earlier posts had mentioned that the air was heated prior to expansion, that's why I was assuming that there was still heating involved. If there isn't any heating going on in the latest versions, the efficiency of a compressed gas system is really going to be poor. The reason is that if you don't immediately use the compressed gas it cools and you lose a tremendous amount of energy. This is why compressed gas is really poor energy storage medium, even for relatively short periods of time. Underground storage would only work if you had geothermal heating available to heat the air it might make sense, but if you didn't forget it.

    Absolutey true, at best it is going to be half that of an automotive diesel...

    Agreed. It is unfortunate that the press doesn't do a bit of research and find out if the system has an merit before giving publicity to programs like this.
  18. Marmot

    Marmot Senior Member

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    It has been done for quite a while and has considerable potential for economy if the primary compression is powered by offpeak grid, solar, wind, or some other periodically low cost supply.

    The heat lost in the storage is a toss up, intercoolers are needed between stages anyway. The energy lost through cooling in storage is a loss but the mass flow is the same from atmosphere all the way to the burners and that is what matters. These systems use recuperators to recover heat from the exhaust so they have the best of both worlds, high density and high temperature in to the burners without having to use inlet chillers. Look up compressed air energy storage, it's an interesting concept but to claim the same numbers for this air car are a bit too much of a stretch.
  19. Grecko

    Grecko New Member

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    Yes, I can see that if you had very cheap (solar or wind) energy that you wanted to store, and retreived it via a burner with a recouperator upstream that you could indeed make a worthwhile system out of it. Depends I guess on how much air you can store and at what pressure. As you noted, this car has little or nothing to do with that...

    Interesting that we have not heard from Mr. Try lately. He was supposed to be an "investor" of sorts and now he is strangely quiet...
  20. K1W1

    K1W1 Senior Member

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    Hi,

    I understand that the YF Member TRY burst a hose and has withdrawn from the fray once he realised that there were many people out there who were not hood winked by his baseless ravings or blinded by Mr Negre's equally unfounded on fact smoke and mirrors action.

    As MARMOT said above they were really visibly uncomfortable having us in their "showroom" asking a few questions. It would seem that the invitation ot visit offered by TRY was only for those who blindly accepted the blurb they read and would have really been a variation of the Smoke and Mirrors that still used the smoke but the mirrors had been replaced by some pipes.:D