By Tuan Nguyen
Posting in Design
Government researchers have developed an engine prototype that's cleaner than a diesel engine and almost twice as efficient as a typical gasoline-powered engine.
Recently, it seems like car engine innovation has become about moving away from the internal combustion engine and toward more environmentally-friendly alternatives like electric motors. But the truth is gasoline engines, which have been with us for well over a century, aren't headed for the junk yard any time soon.
With that in mind, engineers at the U.S. Department of Energy's Argonne National Laboratory have been hard at work on a project to improve the fuel efficiency of gas-powered engines. Their approach has been to figure out a way to take advantage of the highly fuel efficient technologies found in diesel engine while also keeping harmful emissions to a minimum.
So far, the result is a gas-powered prototype that's cleaner than a diesel engine and almost twice as efficient as a typical gasoline-powered engine.
The major difference between gas and diesel engines is the technology used to ignite the fuel. Gasoline engines are designed to mix air with the fuel prior to compressing and igniting the mixture. But in a diesel engine, the air is compressed first and then the fuel is injected. This makes it so the air is hot enough to ignite the fuel without spark plugs or the use of an air-restricting throttle, which allows the fuel to mix more evenly with air so that more of can be burned.
The drawback is that the process produces unacceptably high levels of nitrous oxides and soot. This is because diesel fuel is so easy to auto-ignite that it begins to react the moment it's introduced—long before all of the fuel is in the chamber.
Nitrous oxides are created when the flame jet created by the diesel injection burns so hot that nearby nitrogen and oxygen molecules in the air start to break apart and react. Meanwhile, soot is created inside the hot jet because the fuel doesn't have enough oxygen to fully burn, creating soot instead.
"What we want to do is combine the efficiency of diesel with the cleanliness of gas," said Steve Ciatti, an engineer working on the project. "So we lose the throttle and spark plugs, because those create inefficiencies. We start with a diesel engine and inject gasoline instead."
And since gasoline doesn't ignite immediately, the fuel can be injected several times to ensure that most or all of the fuel is mixed with the air before it is ignited, a process that significantly decreases NOX and soot emissions, he explains.
The trade-off, however, is that a combination engine has less power density than either. That is, at peak power—when you push the accelerator pedal to the floor—the engine provides about 75 percent the horsepower of standard cars you see on the road.
"But if you don't drive pedal to the metal, however," Ciatti said, "this won't affect the car's performance. It's excellent in the power range where most people actually drive."
So what's the next step for Ciatti's team? Improvements that would make the system predictable and reliable enough to be successful in a commercial vehicle.
(via Argonne National Lab)
Image: Argonne National Lab
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May 22, 2011
Developing a low revving but very high torque fuel efficient gas or diesel engine that feeds a generator that produces electrical power to batteries (or directly to) an electric motor-driven vehicle? The low revving engine would be computer controlled to maintain a minimum safe battery charge (but always running), thus the revving is computer monitored to smooth out and slow the acceleration and deceleration curves for maximum fuel consumption. The batteries allow for the instantaneous electrical power draw for short periods of large power drain (hard electrical motor acceleration). The high torque would allow for high ratios between the fueled engine and the generator output. The engine would not need fast acceleration as todays engines require due to the batteries covering for the brief electrical power demand and thus the engines can increase (or decrease) the revving at a very slow efficient pace.
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Does anyone remember when the gentle man from Barrie or Orillia made the carb that would get 40 MPG on any engine. Esso bought the design and scrapped it. All of these tales are miss leading and are or could be false. There is no Oil company that will allow anything or anyone to come out whit somethimg that will cut into their profits. Come on people get real. The final line is money! Canda has more oil than the Arabs, did the price drop? No. The US owns most of the Canadian oil production.
Clean Diesel is already the reality. My Grand Cherokee with the Mercedes 3.0 litre diesel has no discernable diesel emissions. I have checked the tail pipe by the finger wipe test and there is no carbon film. Unlike my newer gas powered car! I hope the Fiat version, when introduced by Chrysler, performs as well.
It's no wonder the US is failing in innovative technology when the US Department of Energy is leading the way researching "New" gasoline technology with our tax dollars instead of what we thought they were going to do...... innovate new energy technologies. Wow, and I thought it was just Hollywood that couln't come up with anything new. We're so screwed. Let me be the first to welcome our new Chinese masters!
The cleanest engines on the road today are diesel fuel powered, not gasoline engines, e.g. the Volkswagen TDI and the Mack MP ClearTech SCR near-zero emissions engines. Drive a bunch of these in Los Angeles and clean up the air... the air coming out of the tail pipe is cleaner than the air entering the engine.
How about we build an engin that has 1.5 times the power, even at 75% max power density you get 1.1 times the output and have fule usage of 75% of the original engin. As well you have more power and torque in the normal range. Best idea is still to combine this engin with an electric drivetrain, new batteries, and also lets put some reseach into improving energy production as well as energy storeage. Imagin a plug in electrice, with a high efficency gas/diesel engin powering a next gen alternator.
"We start with a diesel engine and inject gasoline instead.??? you mean it took the DOE to come up with the idea to try this.. AND it might double thermal efficiency?
Is this "new" engine normally aspirated or is it turbo-charged? It would seem to me that by adding a turbo-charger they could increase the density of the air in the cylinders and improve the fuel burn rate thereby increasing fuel efficiency and making more power available when needed.
WOW-what a wonder. Are the gas companies getting their "best gas mileage" pattens out, which they bought up to prevent us from getting the best mileage and keep their price of gas out of this world??????? I guess the electric automobiles are finally starting to worry these "money hogs" and they're loosening up some details. You know what I'm driving at with these comments.
I wonder if the new engine would work best in a hybrid situation - generating electricity at the engine's optimum efficieny range to run electric motor(s) to power the car, with a battery to store power for peak usage. Imagine a hybrid that gets 70-80 mpg!
This might have been an idea that was abandoned in the past due to the lower power density mentioned in the 3rd para from the bottom. Different priorities for different times
Yes, I know what you're driving at. ...but you're still wrong. http://www.snopes.com/autos/business/carburetor.asp
That was the thinking behind the Accord hybrid from several years ago. It didn't sell so Honda stopped making it. The market for hybrids was smaller then than it is now, so you might have a winner there.