Skip to comments.The efficient choice among combustion engines
Posted on 09/12/2013 8:20:16 AM PDT by Red Badger
ETH researchers redesigned the conventional diesel engine of a VW Golf to run on 90% natural gas. Credit: Tobias Ott / ETH Zurich
Video at link.
Researchers at ETH Zurich have developed an internal combustion engine that emits less than half the CO2 compared to a regular engine without compromising performance. This corresponds to fuel consumption of less than 2.4 l per 100 km. This natural gas-diesel hybrid engine is based on a system of sophisticated control engineering.
The global energy markets are changing. New extraction methods are tapping into oilfields and natural gas deposits that have been inaccessible until now. The US, for example, is able to cover up to 83% of its total energy needs today; the government is even planning to increase exports of natural gas in the future. And there are new developments on the horizon: natural gas may also become an important fuel for vehicles on America's roads, thanks to the work of Swiss researchers at the Institute for Dynamic Systems and Control at ETH Zurich. They have developed a natural gas-diesel hybrid powertrain that emits just half the CO2 without compromising performance.
Diesel fuel injection instead of an ignition plug
ETH researchers redesigned the conventional diesel engine of a VW Golf to run on 90% natural gas. Instead of a spark plug as is standard with natural gas engines, the engine is ignited with a small amount of diesel injected directly into the cylinder. In doing so, the researchers were able to achieve a highly efficient combustion with a maximum efficiency of 39.6%.
Natural gas-diesel engines already exist, and are used industrially where power is generated and used in one place for example to operate large machinery. "In a vehicle, the engine speed and load change constantly, which means the engine system is far more complicated," explains Tobias Ott, a doctoral student in Professor Lino Guzzella's research group.
Innovative electronic combustion control
Ott developed the innovative electronic combustion control together with senior scientist Christopher Onder as part of his dissertation. A sensor that measures pressure in the cylinders plays a key part: using complex control algorithms, the researchers were able to adapt the amount and timing of diesel continually, allowing an engine system with highest efficiency. The researchers also linked the innovative natural gas-diesel engine to a small electric motor to further reduce consumption. However, it could also be installed in a vehicle without electric hybridisation, which would be crucial for industrial production in larger quantities.
Mass production a possibility in five years' time
The researchers demonstrated the reduction in emissions with experiments on a specially designed test rig and recently published the results in the specialist journal Energies. This proof of concept also involves solving final technical problems. "At the moment, we are concentrating particularly on the temperature in the catalytic converter," says Ott. For the converter to get up and running, it has to reach at least 300 degrees. "Our combustion engine converts heat energy into mechanical energy with such efficiency that the exhaust gas is not warm enough to create sufficient heat, particularly after start-up," adds Ott. The researchers want to solve the problem by modified control of the engine during the warm-up.
Christopher Onder is convinced that the natural gas-diesel engine can be produced in series production in five years. "The prerequisite is that we find an industrial partner who can take charge of developing a prototype," he explains. The researchers believe that the success of their engine depends critically on its production costs. They stress that their solution may not be cheap, but it is comparatively cost-effective. And because their concept is based on technology that already exists, it can be implemented quickly and is the perfect bridging technology for the next 10 to 20 years. The researchers are already engaged in negotiations with a car manufacturer.
Rest In Peace, old friend, your work is finished.....
If you want ON or OFF the DIESEL KnOcK LIST jut FReepmail me..... This is a fairly HIGH VOLUME ping list on some days.....
This doesn’t sound practical to me.
(1) Carbon build up will eventually cause pre-det issues with the natural gas being sucked in through the intake stroke, as the engine ages.
(2) Have to put two fuels in your car, granted it won’t be a lot of diesel all told, still annoying.
More practical would be if they had figured out a reliable injector pump design that could inject CNG into the cylinders at the required pressures for diesel ignition of natural gas. That is probably a very tough problem though... mechanically speaking. Also, increasing engine robustness while reducing weight, to handle the higher compression ratios required (ethanol takes 23:1, I’d expect natural gas to be somewhere between ethanol and diesel... have not looked this up).
A sensor that measures pressure in the cylinders plays a key part...
...aaaand there's one of the major technical hurdles, at least as I'm aware of. I haven't looked into it in a while. That pressure sensor is going to see on the order of 100 million pressure cycles over the life of the engine. That's a lot.
2.41 what per 100 km?
2.4 LITERS, That’s an ‘L’ not a ‘1”.........
And in the years prior to invention of petroleum fueled engines....machinery (pumps and lifts for coal mines) were fueled by pulverized coal.
It doesn’t look to me like they’ve solved an important issue in natural gas-diesel engines. Surprisingly, it’s soot. Liquid fuel disperses quite evenly in a diesel combustion chamber. Gas doesn’t disperse evenly. This leaves pockets of gas rich zones which have insufficient oxygen, and create soot. You know, the black stuff you see coming from diesel trucks when they accelerate. It seems like some in the “Green” community don’t like this.
We have "dual fuel" trucks in the US, that run on natural gas or diesel. While there's natural gas, it runs with gas plus a little diesel. When the natural gas tank is empty, it runs on pure diesel. This is a more practical arrangement until the natural gas infrastructure is built up better.
To calculate the CO2 emission from a fuel the carbon content of the fuel must be multiplied with the ratio of molecular weight CO2 (44) to the molecular weight Carbon 12 -> 44 / 12 = 3.7
Carbon Dioxide emission can be calculated as
qCO2 = cf / hf CCO2/Cm (1)
qCO2 = specific CO2 emission (CO2/kWh)
cf = specific carbon content in the fuel (kgC/kgfuel)
hf = specific energy content (kWh/kgfuel)
Cm = specific mass Carbon (kg/mol Carbon)
CCO2 = specific mass Carbon Dioxide (kg/mol CO2)
Angel Labs has a very old engine concept. Probably doomed to wankel status.
Not sure about the other design from EcoMotors. Looks very interesting. Submarine and some locomotive motors used that opposed piston tech, just not the opposed cylinder part.
The motors that were so reliable in subs, were never really popular in locomotives, they tended not to hold up in over the road use.
Best is to download the excel demo and watch it.
“...aaaand there’s one of the major technical hurdles, at least as I’m aware of. I haven’t looked into it in a while. That pressure sensor is going to see on the order of 100 million pressure cycles over the life of the engine. That’s a lot.”
Piezo might be able to do it.
No disrespect: but lookup Otto Lutz and the swing piston engine. Old news, terrible design, all the Wankel sealing issues. The Wankel is dead for a reason, and the swing piston engine has not seen a commercial application yet.
And in a world where CO2 emissions don't matter because AGW is no longer an issue, we need to concentrate on the highest possible efficiency, regardless of the CO2 levels.
Lowering CO and NOX I can understand...
That’s what we use - Kistler. They’re pricey and finicky. Not sure how well they last in continuous use. Not saying 100e6 + cycles isn’t possible. I just think it’s dicey for a low cost automotive part.
Not even close, the swing-piton engine is a reciprocating engine, the Angellabs engine is not. Download the excel file and watch it.