50% Efficiency Boost From New Fuel Injection System 379
chudnall notes a Technology Review story on a new gas engine injection system that promises increased efficiency of up to 50%. "The key is heating and pressurizing gasoline before injecting it into the combustion chamber, says Mike Rocke, Transonic's vice president of business development. This puts it into a supercritical state that allows for very fast and clean combustion, which in turn decreases the amount of fuel needed to propel a vehicle. The company also treats the gasoline with a catalyst that 'activates' it, partially oxidizing it to enhance combustion."
Re:If you post before this (Score:1, Informative)
Nice try, but we call it 3.7 liters / 100km ;)
Re:Not just "similar" to a diesel (Score:4, Informative)
Eh, yes.
The fuel is named after the engine, not vice versa (i.e. it's a fuel to work in diesel engines). Diesel engines can use many different fuels.
Not a Diesel (Score:4, Informative)
People keep saying this is a diesel engine, but it is not. In a diesel engine, the air in the chamber is heated by compresssion up to something hot enough to ignite the fuel. In this design they are heating the fuel and pressurizing it before they inject it into the chamber, so that it turns to vapor as soon as it is injected into the chamber. Someone seemed to be making fun of the term 'supercritical' but that is the word for vapor that has completely transformed from a liquid and has excess internal energy. This is very different from spraying the gas with an atomizer.
Re:Doesn't solve the oil problem (Score:3, Informative)
In all fairness though, the renewable plans for transportation do include combustion engines.
The world seems to be aiming at two or three concepts:
1. Biofuels. Same old engine, sustainable fuel.
2. Electric engines. Sustainable electricity, new fuel tank, and (for cars at least) new engine.
3. Fuel cells. New fuel, new tank, and (for cars at least) new engine. Still in research stage it seems.
It seems that option 1 is the easiest to implement, because most of the existing infrastructure will be needed.
In the end, it'll be a transition, and it looks like we're developing all 2-3 in parallel.
Re:50% efficient car engines? Now that's news! (Score:2, Informative)
"50% Efficiency Boost"
"promises increased efficiency of up to 50%. "
Please, /., learn the difference between "50% efficiency" and "a 50% increase in efficiency". I come here to get away from the slapdash treatment of science in the mainstream press.
What the fuck are you talking about? The "X times more than is not the same as X times as many" fallacy does not apply here.
Re:I'm sceptical (Score:4, Informative)
Y'know, I don't really have a hard time believing that it could get 100mpg at 50mph... 50mph isn't *that* fast, for one, and for two, there's cars on the market today which are able to get 70mpg at those speeds. Even my 3-year old Chev aveo is able to pull about 50mpg at those speeds if I do it right. (arrow-straight, flat road, a/c off, windows closed, manual transmission) And I'm not talking about EPA posted results, I'm talking about real-world testing that I've done in my own car with me driving.
There's even an amatuer sport of sorts that comes from this, called hypermiling [wikipedia.org]. Some of the better hypermilers are able to get over 100mpg out of a car like mine, and the world record is over 200mpg out of a Honda Insight. So no, 100mpg out of a production car isn't that astonishing or out to lunch to me.
Re:I'm sceptical (Score:5, Informative)
They claimed 50% increase of efficiency.
The efficiency of combustion engines are ~20% so you could say that more than half is lost (80% actually). An increase with 50% would but it in the 30% range which seems reasonable to me.
Re:Not a Diesel (Score:3, Informative)
Actually, I have the definition of supercritical wrong. I had confounded it with superheated. Supercritical is a substance that is above its critical point, where the liquid and gas phases combine.
Re:Not just "similar" to a diesel (Score:3, Informative)
It would be better to have asked if the article describes a homogeneous charge compression ignition (HCCI) or diffusion burn process. There's a huge difference between them in terms of emissions and thermal efficiency. In the traditional diesel cycle, fuel combusts along a locally "rich" flame front that propagates outwards from the kernel. Since it's locally rich, you get particulate and NOx formulation. In HCCI, you have a uniform (lean) distribution of fuel and air that combusts simultaneously with lower emissions and higher efficiency as a byproduct. Both are compression ignition processes, but one is far more efficient than the other. The trick with HCCI has always been air/fuel ratio and combustion timing control and the large number of variables that can affect both. Playing with inlet conditions including the equivalence ratio, EGR rate, intake temperature and pressure, and adding "exotic" diluents are all potential control options. This system may be using one or more of them to achieve HCCI.
Re:I'm sceptical (Score:4, Informative)
It is right to be skeptical, but the theoretical efficiency of a typical Diesel is in the 50% range.
http://hyperphysics.phy-astr.gsu.edu/Hbase/thermo/diesel.html [gsu.edu]
This thing is not a Diesel engine, but it looks like it might be similar to one.
Re:If you post before this (Score:3, Informative)
Actually, that's why one should be skeptical (Score:3, Informative)
Actually, that's exactly why one should be skeptical: at heart it's just a Diesel engine. Using a Diesel engine with gasoline isn't even a new idea, such engines already exist. So exactly what is the magic bullet there?
And improving oxidation doesn't do much, unless your engine ejects a large quantity of fuel unburned. What limits the efficiency of either the Otto or Diesel cycles (either theoretical or in actual cars) isn't their failing to burn most of the gasoline. So pre-oxidizing and catalysts to improve oxidation can't even begin to account for the claimed efficiency improvement.
Re:1974 called - they want their hoax back. (Score:3, Informative)
Umm, you're right about ethanol blending (which is going to become increasingly hard to avoid). Ethanol has a significantly lower energy density of gasoline. Notice that I didn't say regular or premium. Despite your claims of 5% increase in gas mileage, there is no energy density difference between 87 and 92/93 octane fuels. The only thing that octane (and the difference between regular and premium gasoline) is in the knock resistance. If your engine doesn't knock with regular fuel, you gain exactly 0 performance benefit from using premium fuel. If higher octane equated to higher energy density (which you stated in your post), then ethanol would have more energy than gasoline. However, despite ethanol having an octane rating of 116, it has less energy per gallon. If you look at wikipedia, you'll notice that regular and premium gasoline are separated on the "octane rating" page, but in the same gasoline category on the "heat of combustion" page.
Re:NOx and emissions? (Score:2, Informative)
Re:Same old snake oil (Score:2, Informative)
Re:I'm sceptical (Score:2, Informative)
Miles per Gallon is the silly figure. It's so silly it's practically useless.
Hypothetical time!
Let's say that my neighbour and I work at the same building, 25 miles from home.
I drive my car at 50 mpg on the way to work and therefore burn 0.5 gallons of fuel. If on the way home I'm more frugal and drive at 55 mpg, I burn 0.455 gallons of fuel. A saving of 0.045 gallons over this morning's run.
Now let's say my neighbour's car's a bit more economical and he can drive to work at 70mpg, using 0.357 gallons on the way. If he follows my frugal lead and is careful on the way home he too saves 5 mpg and so at 75mpg only uses 0.333 gallons of fuel.
His "light foot" exercise nets him a saving of 0.024 gallons. From this we can see that an extra 5 mpg going from 50 - 55 mpg is more worthwhile than going from 70 - 75 mpg. Almost twice as effective.
That's why mpg is a silly value as every time someone posts a new "high score" they are actually posting less and less of an improvement.
l/100km give you an accurate, unbiased view of fuel consumption.
Re:If you post before this (Score:3, Informative)
I mean, really, if they can get this kind of car (0-60mph in 3.2 seconds) then there is no excuse for ALL cards to get such great ratings. The whole "hybrids are slow" is ridiculous.
Efficient or Green? You choose. (Score:4, Informative)
As any (mechanical) engineer knows, to get an efficient internal combustion engine you want compression pressures as high as possible and combustion temperatures as high as possible (an oversimplification, to be sure) because an internal combustion engine is a heat engine, and the greater the temperature and pressure difference between the combustion event in the cylinder, and ambient conditions at the end of the exhaust system, the more efficient it is.
UNFORTUNATELY, some three quarters of the gas that the internal combustion engine draws in from the atmosphere is Nitrogen, and when you expose Nitrogen to the high pressures and temperatures of a combustion chamber, what happens next is simple, and unavoidable, chemistry, you get oxides of nitrogen out the exhaust pipe.
So on the one hand an efficient engine will be running petrol / gasoline at 13:1 compression ratios, or diesel at 25:1 compression ratios, and polluting the crap out of everything.
On the other hand, a "green" engine will be running petrol / gasoline at 9:1 compression ratios, or diesel at 17:1, and wasting energy efficiency like an ice rink in Dubai.
You can't have it both ways.
Re:1974 called - they want their hoax back. (Score:2, Informative)
Heptane = C7H16 + 11 * O2 = 7 * CO2 + 8 * H2O
Octane = C8H18 + 02 = 8 * CO2 + 9 * H2O
When cracked at the refinery, the oil companies try to get as much heptane as possible while still being able to keep the RON (Research Octane Number) within the target range by adding additives. So no, the wiki article is too simplistic, and flies in the face of the fact that refineries can't produce as many gallons of premium as they can of regular for the same amount of crude - a higher ratio of C8H19 to C7H16 than regular, which requires an extra CH2.
the "octane rating" has nothing to do with octane content - ethanol being a good example of that. It helps reduce detonation in engines because it's a crap fuel source in comparison to both heptane and octane. Putting it into the gasoline mix raises the effective octane rating but lowers the energy density. Same as injecting water raises the effective octane rating but lowers the energy density. And yes, you CAN inject water into car engines to help control detonation - it's been done in racing since the 70s, and it's also a great way to clean out the carbon build-up on cylinder heads - take the air cleaner off, hold the throttle at full bore, and slowly pour water directly into the engine while it's running. (You can also do this with automatic transmission fluid if you want to unstick a ticking valve, but be ready for LOTS of dense white smoke).
Re:I'm sceptical (Score:3, Informative)
Re:Incorrect (Score:3, Informative)
Heptane = C7H16 + 11 * O2 = 7 * CO2 + 8 * H2O
Octane = C8H18 + 02 = 8 * CO2 + 9 * H2O
When cracked at the refinery, the oil companies try to get as much heptane as possible while still being able to keep the RON (Research Octane Number) within the target range by adding additives. So no, the wiki article is too simplistic, and flies in the face of the fact that refineries can't produce as many gallons of premium as they can of regular for the same amount of crude - a higher ratio of C8H19 to C7H16 than regular, which requires an extra CH2.
the "octane rating" has nothing to do with the actual octane content - it's a measure of detonation resistance compared to burning pure C8H18 - octane - instead of a mix of heptane and octane.
Re:I'm sceptical (Score:3, Informative)
If the fuel is just under the ignition point the ignition will consume all of the fuel more rapidly.
Re:Oops, correction: (Score:3, Informative)
Kerosine, not fuel oil. Diesel engines run on kerosine, and kerosine for motor fuel is called "diesel" because that's what kind engine it burns in. The fuel is named for the engine, not the other way around.
No, you were right the first time. Most diesel engines run on processed fuel oil [wikipedia.org], i.e. very heavy petroleum distillates. Kerosene is a very light distillate, used by jet engines in planes or rockets.
Re:Same old snake oil (Score:1, Informative)
There are dozens of web sites with people selling all kinds of in line treatements for gasoline - even with dyno reports to back up their claim. They all need just a little bit more tweaking... but they will be happy to sell you a version for $1xx dollars (or more).
That being said, Smokey Yunick had a car that he claimed 50+mpg and 0-60 in 5 seconds. Used a supercharger to pre-heat the air (positive displacement supercharger running at 1.1:1 - very low boost).
Let me put it another way. In drag racing, the engine only has to last for a little bit. In the outlaw classes (highly modified cars, the rules are loose enough that fuel injection is allowed), someone with the ability to increase performance 50% would clean up - heck 5% would do it. Engine life is not an issue. Emissions, not an issue. Raw horsepower for 5-7 seconds (the faster classes typically use nitro-methane so not a fair comparison) is the only issue.
Re:Like totally bogus, man (Score:3, Informative)
NO2 injection is not without its own costs and risks. It will add to the performance of the vehicle, but adds to the risk of predetonation, or worse. Plus you need a steady, cheap source of the gas, which is not really viable as an mass marketable additive.
That and NO2 is a contributor to climate change, reacting with ozone to the atmosphere when it burns.
So much for that.
Re:Same old snake oil (Score:3, Informative)
I think we all know how a Diesel engine works.
Re:Running Very Lean Re:Same old snake oil (Score:3, Informative)
Just watched The Core a few nights ago, so one of the eight people who got that reference.
Unobtainium [wikipedia.org] isn't specific to The Core.
Re:1974 called - they want their hoax back. (Score:3, Informative)
The difference between regular and premium on my car is 5%
be careful using premium fuel, because if the engine is tuned for a lower octaine, running a higher octaine will damage the exhaust valves. Higher octaine burns more slowly (which prevents detonation at higher compression ratios), and too high of an octaine and it's still burning when the exhust valves open. By the same token, too low an octaine and it will knock, damaging the heads, pistons, or (most likely) piston rings.
A cheaper way to stop spark knock than premium fuel is to adjust the spark timing. If it doesn't knock on regular, you're better off running regular.
Re:I'm sceptical (Score:4, Informative)
I'm skeptical because I've heard so many reports like this.
However it's not physically improbable to achieve 30% efficiency with an internal combustion engine. Even an ordinary ICE theoretically can achieve 37%. If the combustion temperature is raised, it is conceivable that higher efficiencies could be achieved.
As far as mileage is concerned, that's not related in a straightforward way to engine efficiency under ideal conditions. Toyota's Prius is rated at 51 MPG highway; that's not the electrical system doing that, it's an engine that's tuned to be very efficient at highway speeds and which doesn't have to deliver torque at low speeds.
It's not out of the question to almost obtain twice that in a ultralight prototype vehicle with an engine that marginally outperforms the Prius engine under those conditions, if the rest of the power train was a little simpler and more efficient. The key to the Prius engine is that it can be tuned for higher peak power because it doesn't have to generate much torque at low speeds.
I did RTFA, and it's more complex, really (Score:3, Informative)
I've read TFA, actually, and it still smells like bullshit to me. Sorry.
For a start, efficiency is not the same as unburnt fuel. I hope you don't think that your car actually dumps 80% of the gasoline unburnt out the back.
Not wasting energy by heating up the chamber walls, well, it's a noble goal but too bad it's impossible. Regardless of how you time the ignition and how it burns, you still have an expanding chamber full of hot gas. That's mostly why it's higher pressure than before the ignition. That's why it pushes at that piston. That's why that engine works. And if you really believe that hot gas in contact with metal won't transfer heat to that metal, just because of some magical way of heating up that gas... I have some logging rights in Sahara to sell ;)
Even if you managed to work that engine by supersonic detonation instead of deflagration, heck, even if you did it in zero time, the fact is that the same amount of heat per gallon has been released in that chamber, heating up the gas. How do you think that prevents that gas from transferring energy to the metal?
Really, any given piece of that cylinder is in touch with the same hot gas for the exact same percentage of the total time. How do you propose to make the same metal surface absorb less heat in the same amount of time from the same gas? Short of making the gas cooler, that is. But just burning the fuel in a fancy different way isn't going to cut it.
So, yes, maybe I should have picked that claim instead. It's a better BS flag than anything else.