Speed of Sound Vortex Would Boost Engine Efficiency by 5-10%

Princeton Plasma Physics Laboratory (PPPL) have patented a novel design for rapidly spinning the gas in combustion engines to boost efficiency by 5-10%.

The ability to absorb energy while being heated of an ideal spinning gas is greater than that of a stationary one. A gas rotating at roughly the speed of sound, when used in a thermodynamic cycle, could allow engines to operate at lower temperature more efficiently than conventional internal combustion engines.

The invention uses an eight-cycle engine, rather than a four-cycle engine, in order to spin the gas at the right points in the cycle

51 thoughts on “Speed of Sound Vortex Would Boost Engine Efficiency by 5-10%”

  1. Cost of catalytic converters for NOx has been accepted for the last 20 years at least, and it is not an obstacle or a problem. 4 is the best of them by far. Clean hydrogen can be produced by electrolysis powered by any non-carbon generator, starting with nuclear. Apparently you do not know what you are talking about.

  2. 1,2 and 3 all create NOX, thus not desirable due to cost of effective exhaust after treatment. 4 is appalling…if we can figure out where to get hydrogen cleanly. So far, no one has shown that I any kind of cost-effect process.

  3. Something weird about this one. Some kind of opposed cylinder setup, where the ostensible cylinder head in a conventional setup would have a spinning plate.


    I wonder if similar could be achieved with a reverse vortex combustor setup within the cylinder, with vortex air injection along the cylinder wall via valve openings that are exposed at max cylinder volume…

  4. Now, I always thought engines needed to be in the rear fuselage of an airplane–where they can be worked upon in flight–a bank of radials or something. The smaller electric motors don’t need as big of a nacelle–and can just stick out of the wing leading edge.

  5. I wish I could but will be have an extended vacation in Leavenworth….By and large, though, it has to do with molecular alignment and purity in metal-hydrogen systems. You don’t need palladium or platinum.

    I’m pretty confident the HE problem is very solvable and at a very reasonable cost.

    btw, I like your comments here on this topic. On H2 production costs I heard from KOGAS they will be able to get to just about $1 with their new SMR plant. And this isn’t yet at the huge scale needed (ie to go from 70mt/yr to 700mt/yr globally by 2040). No battery tech comes close.

  6. reminds me of 1900 when gasoline was sold in the pharmacies because gasoline was less efficient than electric cars at the time and completely lacking in infrastructure.

    True, H2 production is nowhere near what is needed to power a hydrogen economy. Only 70m tons today, mostly all for fertilizers. To power the economies that Japan and Korea have both signed up for and are presently investing in, global H2 production will need to be about 600-700m tons by 2040. Of the roughly $280bn of investment earmarked by 2030 for a hydrogen economy, about 40% of this is for H2 production, and $70m tooling up vehicle and power production (H2 is intended to be used for nearly all of Koreas and Japan’s electricity), the rest is infrastructure. Over 10 years this is a very reasonable and low investment structure.

  7. converting all those ICE btu’s into EV equivalent means electricity capacity will need to more than double. AND it means figuring out how to charge all those vehicles that aren’t in the garage, e,g urban settings. Now you could solve the power issue with nuclear, but that is a huge expense, as is laying down new wiring and chargers everywhere.

    The Koreans and Japanese have figured this out. The H2, production is simple (SMR) and very cheap, and you can use the existing ICE gas station infrastructure (though of course separate pumps and compressed).

    Lastly, the “power demand at night” is very localized. In most major urban areas the demand is quite constant, especially where you have industry, server farms, aircon etc.

    From an environmental view, I much rather have hydrogen fueling than batteries made from bad stuff powered by even more bad stuff.

  8. Some of my business is in the no..4 and working with the folks you mention. The challenge isn’t the car, though I fully expect the stack power on the Nexo to hit >120kW soon. That is a matter of squeezing in more plates, some better geometries. It’s all the rest of the value chain, from H2 production to at the pump. Especially the former. There isn’t enough cheap global H2 production to handle mass adoption, not even close. So the Koreans, for example, are building huge SMR plants to make the feedstock. $5bn worth of capex for next year alone.

  9. I’m in the no. 4 eco system. It is very exciting. Once you get past hydrogen embrittlement the rest is easy. And this is being overcome, but not clear yet the cost impact.

  10. Desperation concentrates the mind most effectively. We are probably going to see an inversion here where EVs go from niche to mainstream and ICE goes from mainstream to niche.

  11. While I can’t find any reference to a Pirogue carburettor what you are describing sounds similar to a number of high mileage fuel systems developed over the years by everyone from Smokey Yunick to the Honda F1 team.

    The Honda F1 example in particular was based on electronic fuel injection for their turbo motors back in the late 1980s when the turbo cars had to meet very difficult fuel limits per race while the non-turbo cars did not. This was introduced as a way to stop the turbo cars from dominating the races compared to the more commercially useful (for F1 authorities) high revving V8s, 10s and 12s.

    So Honda spent a fortune leveraging the latest Japanese tech at the peak of the Japanese boom to develop a special efficiency mode for their turbo cars with fuel heating and dozens of other tricks to make the cars both faster AND more efficient.

    Once it was seen that this was not going to slow down the turbo motors the entire class of engines were banned, fuel restrictions on racing was dumped, and the technology was abandoned. Because racing rules are based on money, not what us engineers would like to see.

    These days we see this sort of thing in the big diesels (non-rigid trucks and larger) where, as usual, the fact that you have a half million dollar truck (or $100 million dollar ship) chewing vast amounts of fuel per day means that spending $20k on a heavy complex system to reduce fuel usage by 5% is a good investment.

  12. Err… not quite as simple as that, not if we push things further than we currently do.
    Yes, by the standards of 2020, catalytic converters can break them down. But not 100%. 99% or so.
    But look forward to the proposed, and in some cases already passed, legislation for what emission requirements are going to be required in 2030 and what counts as “clean” by 2020 standards no longer passes.
    Also, back in the 1980s to early 90s, there were experiments with extreme lean burn engines to get fantastic fuel economy, that was knocked on the head because it doesn’t work without pumping out lots of NOx.

    Of course, there are also a whole bunch of brilliant (and in my experience gorgeous, but this may be a biased sample) chemists working to improve catalytic converters way beyond our current tech. They may well solve the issues that way.

  13. Technological forecasters, and related commenters (including amateurs such as myself) have been saying for literally decades that
    Dozens of things, from A, B, C to X, Y, and Z are just waiting on better batteries.

    And to a reasonable extent we have been correct. And A, B and C have come to pass. D, E, and F are starting to appear, G, H, I are in development… As batteries get better and better in both W.h/kg and W.h/$ (and to a small degree W.h/L) more and more things on that long list have flipped over to commercial viability.

    But we just have to hope that we get most of the way through that list before battery tech runs into some sort of fundamental limit.

  14. The Pirogue carb seemed to have superior fuel efficiency claims, and drawings of it are readily available on the internet. If you study the images you’ll notice it simply has a couple A2A heat exchangers: One likely to heat the fuel mixture to a monoatomic state, and second one to cool and condense the fuel mixture before it enters the combustion chamber. The other mechanical features on it are air pumps which today could be easily substituted with mini 12v turbine fans. The carb’s design also seemed to use a tap off of the exhaust provide the heat and negative pressure from the engine cycle to provide the active airflow and a pump for cooling air. A similar system could easily be adapted for an EFI system.

  15. There is a FUD campaign going on against EV’s. Gas engines are supposed to be cleaner etc… These inventions are real but they are not realistic from a price stand point, so they will never be implemented. Expect other “breaktroughs” in ICE-car technology. Remember VW had to cheat emissions-tests because they couldn’t make diesels cleaner without making them considerably more expensive.

  16. I agree. The only thing we are really waiting for are more advanced batteries. And I don’t think we will have to wait beyond a decade for those. Too many young smart people have been paying attention, and know how important batteries are. They all have had smartphones for years and had to concern themselves about charging. They know about electric cars…

  17. As has been discussed previously, recharge facilities is probably much easier to do for aircraft
    — Far fewer new facilities needed (one or two locations per township) than for cars (dozens to hundreds of locations)
    — Range anxiety, while a new and big deal for cars, is standard operating procedure for aircraft and they have established methods for dealing with it.
    — For complex and dangerous recharge facilities (say with water cooling and megawatt plus level power transfer rates) airfields are already set up to require training and certification for anyone doing stuff on aircraft.

  18. 23 kw/h @ 100km/h, for a 2 person aircraft. More when climbing, but that is usually done just once per flight: https://www.youtube.com/watch?v=vgdj9HpdzvI
    These trainer aircraft have much lower cost of operation.

    They said the same sorts of things about electric cars not that long ago. No charging infrastructure…no range…

  19. Here’s a quote on the cycle. “The invention features an eight-cycle engine, rather than a four-cycle engine, in order to spin the gas at the right points in the cycle.” The goal is to make a cooler running engine which emits less NOx. The article says it runs at “1,300-1,800 degrees Celsius from around 2,500 degrees Celsius.”

    There have been 6-stroke and 8-stroke engines in the past. I saw a 6 which uses extra cycles to pull air in through the exhaust to cool the engine. I read about an 8 which has a set of strokes for injecting water into the cylinders so the water pulls the heat out, turns to steam, and adds a power stroke.

  20. Electric aircraft?
    Seriously in the near future?
    I’m tiring of reminding posters that :

    (D) Disadvantages with electric aircraft are … 

    № D1 — specific energy of batteries
    № D2 — non-declining energy-use mass
    № D3 — recharge / swap infrastructure requirement
    № D4 — no apparent ‘cost per kilometer’ advantage E over Petrol
    № D5 — substantial parasitic mass overhead E-over-petrol

    (A) But there ARE ADVANTAGES, too

    № A1 — nearly no-fail electrical motor reliability
    № A2 — motor specific power (mass) is excellent
    № A3 — fairly easy regenerative energy recovery
    № A4 — WAY lower engine maintenance overhead
    № A5 — No atmospheric emissions

    (P) And some “pushes” 

    № P1 — in-flight fire hazard
    № P2 — all-power failure survivability
    № P3 — cabin creature comforts
    № P4 — flight time per finite range

    (R) Resulting in (‘at this time’) realities 

    № R1 — range – passenger – takeoff mass tradeff
    № R2 — substantial increased wheel-trolley loading
    № R3 — An interesting “certification” challenge
    № R4 — Huge industry interest … fast dev cycles.

    with a bit of a LOL, “your mileage may vary

    -= GoatGuy ✓ =-

  21. ” second grid to serve electric car fleet”
    What second grid????
    There would be an expansion of the existing grid but to the extent that batteries are good enough for electric cars they can be charged when other power demand is low so nuclear plants be run continuously & be closer to 100% of the power supply, thus improving the economics of the power grid. This sounds way easier than setting up a hydrogen distribution system.

  22. I wonder if the extra cycles are non combustion cycles, where air is compressed, heated, and expanded. The increased coefficient of convective heat transfer could be the air taking heat from the cylinder walls, and piston head. The air cycles might cool the engine enough to make a dedicated cooling system unnecessary, particularly with advanced materials, or more air cycles.
    You’d fuel every four strokes starting, and warming up the engine, then add as many air cycles to keep the cylinders, and pistons under a set temperature. You might use engine braking to heat the engine without fuel, turning the heat into work later.

  23. You could save the cost of a catalytic afterburner for NOx. You’d also not be forced to use excess air to keep combustion temperatures lower.

  24. That is old data. Google “National Hydrogen Roadmap, Pathways to an economically sustainable hydrogen industry in Australia” (2018). The cost of hydrogen made in Australia drops to $4 in 2020, and stabilises at about $2.5 from 2025, assuming the federal plan is carried out. The driver is a new way to monetise coal, a new export industry – all levels of government are in on it. Japan will get that hydrogen first, and it is quite possible that others may still pay $14, as no one will say no to such profit margin, even if it is only temporary.

  25. Hydrogen is hydrogen, everything else is Greta talk. Japan made a deal with Australia to supply liquified hydrogen by sea, made from abundant brown coal in soth Australia. Both countries are all-in on that, and nothing will stop that now. It is happening now, it is not the future. And Greta cult may now sustainably cry themselves dry.

  26. This needs more details for understanding, in no particular order:
    1 Japan did not, does not and will not wait. It is a stated policy that Japan builds hydrogen economy for itself. Toyota (Mirai) and Honda (Clarity) both havea fuel cell car in production, with specs equal, comparable or better than gasoline cars. Toyota and others have a hydrogen filling station in production. Japan made a state level deal with Australia to supply liquid hydrogen by sea, the first ship is already built. It is happening – in Japan. South Korea wants that too, and they can.
    2 No one, nowhere, ever, will pay for a second grid to serve electric car fleet. They exist only while their load is a rounding error for existing grid. Transport is about half of all energy consumption, hence the need for a second grid, which is absolutely unfundable. Trillions of dollars worth of infrastructure in a fairly short time.
    Conclusion. This is no longer a team effort: any developed country can choose their own way, and go alone. Japan (and probably South Korea) chose hydrogen economy, as their oil is all imported anyway, and they may as well import or make (both from NPPs and perhaps solar) their own hydrogen. Importing it, oddly, ticks the green box on the country level, as the CO2 count is based on where it is made, not who paid for it. Perhaps some countries, like Norway, Sweden and some in South America, may go all electric, as they have abundant cheap hydro generation, and not much industry.

  27. I don’t think people are going to put up with diesel locomotives and semis for several decades either.
    Ship engines maybe. There is no reasonable way to run a ship powered by batteries that crosses oceans. That would require a lot more than 3x the current energy density. And the extra weight and space are not a problem except in retrofits. And 5-10% efficiency gains can be worth quite a bit in shipping. Ships already have the most efficient cylinder engines. I think these are the best today: https://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C

  28. With 8 cycles, it almost certainly will weigh more and be larger for the same horsepower. That makes it less attractive for aircraft. Also, it takes a lot more work to certify an aircraft engine. Most of the airplanes using traditional combustion engines are using an engine from the 1950’s with fairly poor efficiency. They use old engines because they know almost exactly when something is likely to fail. Then it is serviced before that and planes don’t fall out of the air. Electric aircraft are the only things likely to replace these old aircraft/engines. All it takes is breakthrough batteries, because electric motors are very reliable when engineered and built well…which does not cost a fortune to do. 3x energy density should do the trick. Aircraft are actually more efficient than cars when electric…it is just the dang battery weight. Aircraft don’t have to be designed to protect occupants in case of an accident, it is pretty hopeless if you smack another aircraft in the air anyway. That means less weight, and lighter thinner materials. They don’t have side mirrors. They don’t have to go up and down a lot. They just get up to the desired altitude and stay there until they are nearly there and land. Cars are going up and down hills all the time around corners, starting and stopping, accelerating and braking. And, of course, aircraft are more aerodynamic. And without all the cowlings and such to get air to cool and feed the engines efficiency soars.

  29. If you read the link, you discover that the inventors don’t think the extra complexity is worth the savings at the same temperature. They’re thinking instead that they can run the engine at the same efficiency at lower temperatures because of the increased gamma, which reduces NOx emissions. It really only makes sense if you suddenly need to reduce NOx a lot.

  30. And to add to that, hydrogen is a pricey way to fuel a vehicle. At the pump hydrogen ends up costing ~$14/kg; that means a mid-sized sedan like the Toyota Mirai costs more than 20 cents per mile to fuel. In comparison, according to fueleconomy.gov, a plain gasoline Camry costs 7.5 cents per mile; a Tesla Model 3 3.6 cents per mile. I just don’t see a path for hydrogen vehicles to get anywhere near competitive with plug-in electrics, aside from silly amounts of government subsidies.

  31. The actual researchers appear to be saying something subtly different.

    They are not saying: remake the whole engine for a 10% boost in fuel efficiency.

    They are saying: If you have to remake the whole engine anyway for nitrogen oxide pollution control reasons, then doing it this way allows you to regain most of your fuel efficiency, up to 10%.

    As mentioned in the previous article, the chances of anyone developing a whole new automotive ICE from scratch is pretty low these days, as it will probably be outdated by electric solutions long before it can pay for itself. And doing so with one that only maintains current fuel efficiency, rather than drastically improving it, is even more unlikely.

    If this was an add-on tech that could be in the showroom within a couple of years? Sure, that might work. But it sounds like a new engine design from scratch, so it won’t even be on sale until the 2030s at least, in which case just give up and go home.

    However, let us not forget heavy diesels and aircraft engines. Does the same idea apply? There is probably room for improvement in those markets which should (for energy density reasons) still be making solid sales for decades to come.

  32. Your summary is the path that Toyota and Hyundai (and the related ecosystems of other companies around these two behemoths) were betting on.

    And I’ll agree that say 10 years ago the physics fundamentals seemed to indicate that this was the most likely approach to work out.

    But we are not seeing any progress in cost effective Hydrogen compared to the clear market acceptance of battery electrics.

    Now they may be waiting for the perfect moment to release their category killer fuel cell vehicles… but they appear to be leaving their run a bit late.

    (Though it would be a stroke of evil genius to wait until every other competitor has invested the $50B before pulling the rug from under their feet…)

    Having said that, 80% of so of taxis in Australia in 2019 are currently LPG ICE plus electric motor hybrids, made by Toyota. Which are getting the price equivalent of something like 2 L/100 km (= 118 US MPG)

  33. Except that hydrogen isn’t a fuel. It’s either derived from natural gas as it mostly is now and is no more sustainable or zero net carbon, or it’s an energy storage medium that’s both inherently less efficient than batteries and completely lacking in existing infrastructure. None of these hybrid technologies has a serious future.

  34. I believe it’s fairly normal for a technology to reach its peak as it is being phased out in favour of a new tech.

    There are a few reasons for this:
    — This is just the latest version of the old tech. One should expect it to be the best. Most techs improve over time.
    — The new tech often needs the development of new, subsidiary techs. These can often be applied to the old tech as well, which didn’t need the new subsidiary tech, but is certainly improved by it.
    — Competition improves the breed. Especially if the new tech demonstrates that bug A is not something you just have to learn to live with.

    A relevant example is steam cars. Originally c.1900 steam cars were a valid competitor to petrol cars, but as petrol cars solved their various problems they pulled ahead. By c.1930 steam cars were a tiny, shrinking, minority. But those steam cars still being made were far, far better than the ones in 1900.
    — Petrol cars had shown that it was possible to make engines that can be up and running almost instantly. In 1900 steam cars took ages to build steam from cold, but people were comparing them to trains which took hours. By 1930 they’d redesigned boilers to be going in a couple of minutes.
    — Petrol cars NEEDED on board electrical systems to be practicable, so the systems of alternators, batteries etc. had to be developed. Steam cars could be done using mechanical valves and manual lighters. But once electrical systems were available off-the-shelf, then use electrics.

  35. The speed-of-sound parts occur within the cylinder itself. Where there is already an explosion going on. There are layers of solid metal, water coolant, more metal, engine covers, sheets of sound absorbing materials, and more metal before any remaining sound gets out into the environment.

  36. Completely aware of all of that. We are living in the golden age of cars, even though a lot of stuck in the 1960s muscle-car types don’t see it. As for your last sentence, it’s a necessity. We need to put a definitive end to pollution, from all sources, for all our sakes.

  37. Not necessarily – acoustic metamaterials have come a long way in reducing sound levels without impacting airflow drastically.

    I’m just waiting on a pair of sound isolating headphones that use them – active noise cancelling isn’t great for audio quality.

  38. Remember that ICE goes perfectly well with electric motors. It is batteries that are in.. shall we say, existential peril? 🙂
    Here is a series of possibilities:
    1 oil-derived fuel ICE + electric motors, both always in optimal modes;
    2 methane ICE + electric motors
    3 dense hydrogen fuel ICE + electric motors
    4 dense hydrogen fuel FC + electric motors
    Toyota and Honda are a sneeze away from item 4, really just a matter of executive action; item 1 was done with Prius long ago; item 2 is an electric motor away in buses and such, as they already run on methane, and on electric power, but not both (as far as I know); item 3 may be the sweet spot for land transport.

  39. Yeah, let’s remake the entire engine for a 10% boost. There are better efficiency pickups recently that don’t require a retooling of the engine. Someone tell the smart guys at Princeton how economics works.

  40. I’m not gonna write off electric cars just yet. ICEs are only getting better through absolute necessity, because they’re dying. And that’s a good thing.

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