Labs to investigate new approach to engines

February 16, 2016 by Greg Cunningham
Argonne is working with Achates Power and Delphi Automotive to develop an advanced engine that could yield efficiency gains of up to 50 percent. This illustration shows how such an engine operates, with opposed pistons moving toward each other, compressing gasoline until it auto-ignites. Credit: Achates Power

The U.S. Department of Energy's (DOE's) Argonne National Laboratory is working with Achates Power, Inc., and Delphi Automotive to develop an innovative new engine that could yield efficiency gains of up to 50 percent over a comparable conventional engine.

The research is being conducted under a three-year project funded by a $9 million award from DOE's Advanced Research Projects Agency-Energy (ARPA-E) and an additional $4 million of cost share from the team members.

The new combines two promising technologies—gasoline compression ignition and opposed pistons—to create a "super engine" that could fundamentally change the way internal combustion engines work in the light-duty transportation market.

"Conventional spark-ignited engines have improved so dramatically over the past few decades that there is little room to make big ," said Steve Ciatti, who will be the experimental lead for Argonne. "You need a game-changer to get into large double-digit efficiency gains, and we believe this engine is capable of doing that."

The new engine will meld the best characteristics of gasoline and compression ignition engines with an innovative piston architecture refined by Achates Power that sets two pistons moving in opposition in one cylinder. As the crowns of the pistons slide toward each other, they compress a mixture of air and gasoline to such extreme pressures that the mixture auto-ignites without the need for spark plugs in a process known as compression ignition.

As the pistons reverse course and slide to opposite ends of the cylinder, ports machined into the cylinder allow exhaust gases to escape while fresh air is taken in, then the pistons move together again to compress and ignite in a two-stroke cycle. The design eliminates cylinder heads—which are a major cause of heat loss and inefficiency in conventional engines—and allows the engine to run with diesel-like efficiency and power, while maintaining gasoline's emissions benefits.

An analysis by Achates Power indicates the new engine will yield fuel efficiency gains of more than 50 percent compared with a downsized, turbo-charged, direct-injection gasoline engine, while reducing the overall cost of the powertrain system.

Creating such a novel engine will require the expertise of all the team members, who bring together decades of experience in various aspects of engine design and production.

"The dynamics of this team are really perfect to make this project work," said Doug Longman, who will be the project manager for Argonne. "Combining Argonne's scientific and engineering experience with Achates Power's engine architecture and Delphi's expertise in fuel injection and gasoline direct-injection compression ignition will give us the tools to develop an engine we think is going to show very large efficiency gains."

Another key to the success of the project will be the modeling and simulation of the complex fluid dynamics and combustion inside the engine, which will be conducted through Argonne's Virtual Engine Research Institute and Fuels Initiative (VERIFI). By using high-performance computing to model and predict the movement of fuel and air in the cylinders, the VERIFI team will be able to optimize the design of the engine and fuel injectors using computing rather than prototyping, which will enable accelerated development.

"Modeling and simulation have become ever more important to engine designers in recent years," said Sibendu Som, Argonne's computational lead for the project. "Using VERIFI to optimize combustion technologies for industry has significantly shortened development times and helped lead to more efficient engines."

Shorter development time through computational modeling and efficiency gains developed through experimental research will be critical to the creation of an engine that can be widely adopted commercially. Many engines have been proposed over the years that show benefits over conventional spark-ignited gasoline engines, but the efficiency gains have not been dramatic enough to convince auto manufacturers to retool production lines and car designs to incorporate the new approaches. This novel research team is poised to break that barrier and create an engine that could transform the automotive market.

Explore further: Argonne pushing boundaries of computing in engine simulations

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6 comments

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Eikka
not rated yet Feb 16, 2016
while maintaining gasoline's emissions benefits.


Considering that diesel emissions are due to the high compression and temperature required for self-ignition, how is that possible?

A high compression lean burning gasoline engine makes NOx the same
winthrom
5 / 5 (2) Feb 16, 2016
would be nice in my airplane
KelDude
5 / 5 (2) Feb 16, 2016
This is the OPOC engine designed by Volkswagen scientist's about 3 years ago. I always wondered what happened to it. If you want to see the video with a demo of the unit operating, search for "Opposed-Piston-Opposed-Cylinder".
I hope it comes out soon, it's really an incredible engine.
greenonions
5 / 5 (1) Feb 16, 2016
Eikka
Considering that diesel emissions are due to the high compression and temperature required for self-ignition, how is that possible?


Probably because a major part of the emissions with diesels is the fact that they run lean - meaning there is excess oxygen in the exhaust. - https://www.quora...-engines
Eikka
5 / 5 (1) Feb 17, 2016

Probably because a major part of the emissions with diesels is the fact that they run lean - meaning there is excess oxygen in the exhaust.


Exactly.

The diesel-style ignition doesn't work well in fuel-rich or even stoichiometric conditions because the fuel isn't thoroughly mixed with the charge prior to being compressed. It cannot be pre-mixed to the compression or it would detonate and destroy the engine. Since the fuel and air are mixed in the cylinder and ignited simultaneously, there has to be an excess of oxygen or all the fuel won't react and the engine produces soot.

That's the reason why diesel engines make black smoke when you put your foot down. More fuel injected - more soot. It can be helped with complex injection schemes, but not completely eliminated.

This same issue applies to the compression ignition gasoline engine: if you inject more fuel you get soot, and if you inject less fuel you get NOx. Striking a balance is incredibly difficult.
Eikka
not rated yet Feb 17, 2016
There are ways to reduce the production of NOx in a diesel engine by recycling the exhaust gas to displace oxygen at low loads. Diesel engines with EGR can recycle as much ast 50% of the exhaust gasses back under certain loads, and that lowers the combustion temperature and pressure, leading to less NOx production at the expense of lower fuel efficiency and increased engine wear.

Then there's of course injecting ad-blue or similiar additive to react the NOx to less harmful compounds, but that's also a very fiddly business because too much at any time will produce ammonia out of the tailpipe and that's worse. The amount needed varies with the load of the engine, air pressure, EGR ratio, turbo pressure etc. which makes it almost impossible to use the right amount and manufacturers err on the side of caution by injecting too little - like Volkswagen.

The VW cheat was about increasing the amount of ad-blue injection when the car was under steady load in the test bench.

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