Diesel-Like Engine Could Boost Fuel Economy By 50% 721
bonch writes "Autoparts manufacturer Delphi has developed a diesel-like ignition engine running on gasoline, providing a potential 50 percent efficiency improvement over existing gas-powered engines. Engineers have long sought to run diesel-like engines on gasoline for its higher efficiency and low emissions. Delphi's engine, using a technique called gasoline-direct-injection compression ignition, could rival the performance of hybrid automobiles at a cheaper cost."
Re:What's the advantage over diesel? (Score:5, Informative)
FTFA: Diesel is dirty and requires expensive exhaust systems.
Re:Any engine technicians around to translate? (Score:4, Informative)
The key distinction, as I'm aware, between diesel and gasoline is all about the ignition to begin with. In a gas engine, you create a spark to ignite a carefully mixed gas/air vapor. In a diesel, you don't need the spark, instead using sheer pressure from a much higher compression ratio. (this also leads to higher power per stroke, and therefore greater theoretical efficiency) Presumably they've found some way to reliably ignite gasoline without said spark, thus reaping the same compression ratio benefits or some such thing, I would guess.
Re:From a buffoon (Score:3, Informative)
There are diesel hybrids being sold right now in Europe. Also, Audi will probably win this years 24h of Le Mans with a diesel hybrid (Audi R18 TDI e-tron quattro, google it), which will be a first. That is bound to attract a lot of notoriety and drive more manufacturers to employ that technology onto its roadgoing cars.
Re:Any engine technicians around to translate? (Score:2, Informative)
Check out this link on HCCI, which this sounds like it's based on...
http://en.wikipedia.org/wiki/Homogeneous_charge_compression_ignition
Basically, emissions from Gasoline are more easily cleaned up than Diesel, but the need for spark ignition hurts its efficiency over traditional Diesel engines and the lower compression of traditional gassoline engines means that they extract less energy from the combustion of gasoline (as a percentage of total energy content) than diesel engines do from Diesel fuel. This has the potential to be more efficient than a gasoline direct injection atkinson cycle gasoline engine of similar power output specification and, if it retains the gasoline engine's preferred characteristics for usage in road going small hybrids, will non-trivially imporve the efficiency of Hybrid vehicles as well as regular gasoline only vehicles.
Re:From a buffoon (Score:5, Informative)
What keeps diesel engines from becoming a standard in the US? I know regulations nearly disappeared them from the market, but that was for environmental reasons, which are the very reasons why diesel cars are attractive. While in Europe it is not outside the norm, here it seems like you are committing a crime if you run a diesel engine.
Also - since diesel engines are so efficient and all - what stops them from making a hybrid car that benefits from the even greater efficiency of diesel? or this new type of diesel like gas engine for that matter?
Many reasons diesel hasn't been popular in the U.S. One reason is environmental concerns - at least in the north east U.S. and California, our emissions standards, particularly for particulates and sulfur compounds, are much stricter than Europe. A second reason is that people tend to buy cars based on horsepower, and diesels lag there. Third, lots of people have bad memories of noisy, smelly diesel engines from the 80's. Fourth, diesels cost more. All that said, they are making a comeback with the newer offerings from VW and BMW (and Mercedes?).
I believe the reason diesels haven't been seen in hybrids is a combination of several factors. One, they are heavier than gasoline engines which in a hybrid already facing weight issues due to batteries could be a problem. Second, they are more expensive than gasoline engines, and again hybrids already face a cost problem. Third, the efficiency gains using gasoline engines have been sufficient to set them significantly apart from most non-hybrid cars, so the additional mileage you might get from using a diesel instead isn't worth the additional cost and weight.
Re:Any engine technicians around to translate? (Score:4, Informative)
Efficiency of gasoline is better than oil in the same conditions. But diesel engines have much higher compression ratios (needed to burn the oil and give the self combustion). The problem with gasoline is/was that you could not get those compression ratios until now without explosion or engine melt. :)
Sorry for the simplification
Re:Well let me be the first to say... (Score:5, Informative)
It is niether a bad idea nor magic. By pulsing injections they make the combustion behave closer to the Carnot cycle ideal, which is more efficient than the Otto cycle.
That aside, I have my doubts about the 50% improvement. And diesels are already closer to the Carnot cycle so you could say they are effectively running a diesel on gasoline.
One important benefit it could have over diesels though, is that diesel burns fairly slowly compared to gasoline - which is the reason why diesels rarely rev above 5000 or so. If they manage to get diesel-type efficiency but with faster-burning gasoline, it could result in an engine that feels and behaves like a gasoline engine but has the mileage of a diesel. That would be nice.
Re:Redundant (Score:5, Informative)
It's probably inevitable-- it's just a question of when. Battery cost per kWh has been decreasing at around 10% per year, and gasoline is getting consistently more expensive. It seems incredibly unlikely that both of these would stop moving toward the crossover point.
Gasoline engines have been keeping up with that 10% though. In 1998 the Ford Mustang GT with a 4.6L V8 had about 215hp. In 2011 the Mustang GT 5.0L V8 packed in 412hp. That's about 7% a year increase in power and a slight increase in mileage. It stands to reason if that extra efficiency was put towards more mpg instead of more power, that crossover point could be farther out than you think.
The good news is it's getting better on both fronts and fast!
Re:Was only a matter of time (Score:4, Informative)
All questions answered (from TFA):
[T]he researchers found that if they injected the gasoline in three precisely timed bursts, they could avoid the too-rapid combustion that's made some previous experimental engines too noisy. At the same time, they could burn the fuel faster than in conventional gasoline engines, which is necessary for getting the most out of the fuel.
They used other strategies to help the engine perform well at extreme loads. For example, when the engine has just been started or is running at very low speeds, the temperatures in the combustion chamber can be too low to achieve combustion ignition. Under these conditions, the researchers directed exhaust gases into the combustion chamber to warm it up and facilitate combustion.
Mark Sellnau, engineering manager of advanced powertrain technology at Delphi Powertrain, says the engine could be paired with a battery pack and electric motor, as in hybrid cars, to improve efficiency still more, although he notes that it's not clear whether doing that would be worth the added cost.
Re:Well let me be the first to say... (Score:5, Informative)
I have my doubts about the 50% improvement.
Careful reading reveals that your doubt is well placed, but you misread their claim:
technology that could improve the fuel economy of gas-powered cars by 50 percent...Diesel engines are 40 to 45 percent efficient in using the energy in fuel to propel a vehicle, compared to roughly 30 percent efficiency for gasoline engines.
So all they really claim is that a diesel engine that runs on gasoline has roughly the same efficiency as a fuel-oil powered diesel.
Re:Redundant... What's "This."? (Score:5, Informative)
It means "I approve of the above message which neatly encapsulates most of my feelings on the matter".
Re:Any engine technicians around to translate? (Score:5, Informative)
Gasoline engines tend to be limited in their compression ratios, because if you compress the air-fuel mixture too much, it'll spontaneously ignite while the piston is on the upstroke, a phenomenon called pre-ignition [wikipedia.org] or engine knock (because of how it sounds, I suppose). Diesel fuel burns a bit differently than gasoline, and diesel engines take advantage of spontaneous ignition: they purposefully have high compression ratios to heat up air in the cylinder, then inject the fuel when the piston is at/near the top of its stroke, where it immediately ignites. But diesel, as a fuel, has some practical downsides which has limited its more widespread adoption, primarily how cleanly it burns.
If, on the other hand, you could produce an gasoline engine that uses diesel-like compression ratios, and inject the gasoline at maximum compression, as a diesel engine does, you could have the best of both world: greater efficiency due to high compression ratio, cleaner running due to burning gasoline. But such an engine, for various technical reasons, has historically been difficult to achieve. Maybe these guys are really on to something.
Re:Was only a matter of time (Score:5, Informative)
Well, as the article pointed out, they are using a much finer grained control of the injection precisely to control knock, injecting fuel in up to three shorter bursts.
This also allows them to space those bursts at precise times during the power stroke, such as when the piston is going down, and the expansion of the initial burst of fuel is losing effectiveness due to combustion chamber expansion reducing the instantaneous pressure. Adding a burst of fuel at that point gets you extra power at what would otherwise be the downward (backside) of the power curve.
Previous approaches to this were attempted with variable valve actuation [osu.edu], (essentially getting rid of the cam shaft and using other means of controlling valves more precisely). Costly, but effective.
This approach (precisely controlling fuel delivery) allows you to shape the combustion profile to the continuously varying cylinder volume and perhaps adjusting that for changes in engine loading as well.
Re:Well let me be the first to say... (Score:4, Informative)
WV's bluemotion polo will do 78MPG and 0-60 in 13.9.
Naturally, it's not sold on this side of the pod.
Re:From a buffoon (Score:2, Informative)
Oh, and I almost forgot.
The emissions in question are particulates and nitrogen oxides.
Diesels tend to emit physically large particulates that are visible, when inhaled don't go far into the lungs, and fall out of the air quickly.
Gasoline engines tend to emit small particulates, and a lot of them, that are not visible, when inhaled go far deeper into the lungs, are more likely to cause cancer, and stay in the air a lot longer. But, their particulate mass is low, so until recently, nobody's cared. (New emissions standards will restrict the particulate number, as well.)
Any engine that runs lean tends to emit high amounts of nitrogen oxides, and diesels have to run lean or they start smoking. Of course, lean burn also reduces fuel consumption, improving energy independence and all... Nitrogen oxides are a smog precursor in certain situations... but those situations are all in areas where volatile organic compounds are low. In a high VOC environment, which is essentially any area with a lot of plant or modern human life, nitrogen oxides actually destroy smog... and all of the areas that have smog problems are high VOC. Yeah, I'm gonna say that that one's completely misguided.
So, modern diesels tend to run high amounts of cooled EGR, and particulate traps and NOx neutralization technology (either traps, or spraying urea into the exhaust stream). The traps require that fuel be sent into them to burn things off, too. Yes, this is ridiculous, and seriously hurts fuel economy.
Re:What's the advantage over diesel? (Score:4, Informative)
You haven't really understood it. You take crude oil, and you refine it by essentially splitting it up into constituent parts. Diesel is one of the things you end up with, petrol is another. One is not the waste product while the other is the "true" product- they're both just products of refining crude oil.
You are right that you can't create one without the other- so if we all went diesel, you'd have a lot of petrol going unused. But realistically there's no danger of that ever happening; the demand for all oil products is huge and dynamic- whenever something gets cheaper due to a drop in demand, someone else quickly finds a use for it at the new price point.
Re:Well let me be the first to say... (Score:5, Informative)
I can see from your email address that your in the UK. In the US diesel is actually more expensive than gasoline. This is primarily due to taxes but the pricing is also influenced by refinery capacity. In any case, diesel is not substantially cheaper at the retail level.
Re:Well let me be the first to say... (Score:5, Informative)
Because there are countries like the U.S., where the infrastructure for gasoline is much better than for diesel. And diesel exhaust has more CO2 per Joule than gasoline, because longer carbohydride molecules have a higher carbon/hydrogenium ratio than the shorter ones.
Re:Redundant (Score:4, Informative)
No I don't see all electric in 20 years.
Unless we solve the problems of...
1. Range
2. Recharge Time
3. Getting the Grid to handle all the cars.
4. How do we generate all that electricity to do so.
1. Range is increasing with every generation, and is already sufficient for 90% of daily needs.
2. Recharge time is also improving steadily, and is more a matter of infrastructure for convenience than time required. Recharge overnight at home, recharge during the day at the office, recharge while shopping, etc.
3 & 4. No clue - but I assume there are engineers working on solutions. Let them.
Range and Recharge time. is the biggest issue for me. I travel 30 miles to work and 30 miles back. That is 60 miles.
Charge at home overnight, charge at the office, you should have a mostly full charge when beginning either leg of your commute.
Most electric cars are pushing 100 miles, but that is the ideal range... what is the range going up a mountain?
Range will be effected by terrain -it is no matter your fuel source.
What if the batteries after 8 years are not optimal...
Batteries need to be replaced when they get old, oil needs to be changed, tires need to be replaced... its a fact: maintenance needs to be done.
Next my parents live 800 miles away. Say I have an electric car that can do 500 miles per run. I drive mostly there, however I need to recharge. Can I recharge in 5-10 minutes or will I need to spend the night charging my car. I do not have the money for a car to drive to work and a car to drive longer ranges. So we will still need chemical powered cars, until these issues are fixed. I am happy to see that they are getting a lot more fuel efficient.
The answer to these concerns is to rent a car for longer trips. I see Hertz has rental cars as low as $14 /day for some sort of econobox. I think my last multi-state driving vacation was about $150 for a week in a mercedes c240 (thanks to a free upgrade coupon).
That is a good sign, because electric cars are not going to solve all the problems.
Electric cars or hybrids do not have to be perfect. They need to be good enough for daily use - we use diesel rigs (18 wheelers) for hauling big loads, and dont say that because a honda civic cant haul the same load every day it isnt a viable commuter car. Different solutions for different problems.
Re:Redundant (Score:3, Informative)
Re:Well let me be the first to say... (Score:3, Informative)
I'm guessing with proper tuning, you'll get exactly the kind of performance you want.
They are raising the efficiency at which the engine burns gasoline. This can be used to propel a commuter car to same speeds with same acceleration, but using less fuel.
Or, increasing the amount of power you get out of a certain engine size, since the power is constrained by the amount of air-fuel mixture you can burn, which then depends on RPM/engine volume and possible use of turbos/superchargers.
So if you suddenly improve the amount of energy you get out of the same amount of fuel, it's not a bad thing.
Re:What's the advantage over diesel? (Score:4, Informative)
Your data must be old. Diesel engines, horsepower for horsepower are not heavier than a gasoline engine.
At a cost of about $5000 :)
Diesel is not a by product of the refining product because it is an actual component product (intentionally manufactured).
If you don't "crack" the petroleum and just do fractional distillation, then you will end up with some proportion of diesel and some proportion of gasoline. Yes, they are intentionally making diesel - but it's not as if they could reconfigure the plant and make much of that into gasoline without other tradeoffs. This certainly isn't my field, but when I last looked into it, most of the refineries that can crack the fuel are in Texas - with Chavez striking a deal with China to build one their as well. It's a relatively expensive process, so you don't do it unless you have to - but once you have the capability you can make the diesel/gas ratio almost anything you want. Obviously, they make this ratio match the market - as you mention in your post. In Europe, the market is distorted - not only does the government tax diesel lower, but the refineries there simply make more diesel than the market would otherwise need. I'm not saying that the European refineries can't crack hydrocarbons - they've been doing that since the early 20th century - but they are geared for the high-quality stuff from the Middle East, while the US has to deal with oil sand sludge from Canada and the almost unusable stuff from South America (a barrel of Venezuelan crude only provides about 5 gallons of gasoline in a normal refining process). You wouldn't build that kind of a refinery in Europe because you have easier access to high-quality crude.
Here is an excellent primer that includes a discussion of cracking. [hubpages.com]
Re:From a buffoon (Score:5, Informative)
Really? 99%?
Could you cite that?
Thanks.
I don't know if it actually works out to 99%, but in general, road wear rises with the 4th power of axle weight, so trucks account for the lion's share of wear and tear on roads:
http://www.pavementinteractive.org/article/equivalent-single-axle-load/ [pavementinteractive.org]
On the other hand, 99% might not be that far off: