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Introducing Mechanical Engineer Thomas Wallner – Researching the Future of Transportation

bridges, vol. 32, December 2011 / News from the Network: Austrian Researchers Abroad

By Manuel Froschauer

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Thomas Wallner, a mechanical engineer by training and a principal investigator at Argonne's Center for Transportation Research, has been "in hydrogen for the last 12 years," as he puts it. Wallner is doing research in the area of alternative fuels, with a special focus on hydrogen internal combustion engines (H2ICE), a technology that should eventually pave the way for fuel cell cars.

 

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Thomas Wallner working on the “Omnivorous engine”
 

"Hydrogen is an exotic research area, with only a handful of laboratories worldwide working on it. This gives you the opportunity to do a lot of things that are very novel," Wallner says. From initially working exclusively on hydrogen, which is the simplest element and the most plentiful gas in the universe, Wallner has also spread to additional research areas.These include improving engines and adapting them to use different fuels, such as the "Omnivorous Engine," which automatically calibrates itself to any mix of gasoline and alcoholic fuels.
 

Apart from his work, Wallner is organizing sessions at the SAE International world congress, and he is publishing frequently in SAE's engineering magazines. SAE International is a global association of more than 128,000 engineers and related technical experts in the aerospace, automotive, and commercial-vehicle industries. Just recently Wallner was one of six who received the SAE Award as a distinguished presenter, an award received when three of your presentations are rated "outstanding" by the audience. Wallner is also a committed head of the Chicago chapter of ASciNA (Austrian Scientists in North America), a role in which he tries to support other Austrian scientists in the area and organizes a monthly cracker-barrel gathering at the Austrian Bakery . As an adjunct assistant professor at Michigan Technological University, in Houghton, Michigan, he mentors students for their master's thesis or their Ph.D. at Argonne. In addition, he has maintained good ties with his alma mater in Graz, Austria, and hosted a student from there who conducted research in his lab.


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From the Racetrack to the Research Lab
 

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The Argonne National Laboratory, one of the oldest and largest of the 16 National Laboratories, is owned by the Department of Energy and operated by the University of Chicago. The research centers around energy, biological and environmental systems and national security. It has roughly 3200 employees and the budget is around $800 million. Argonne was founded in 1946 as an extension of the Manhattan Project.

As a teen, Wallner disassembled and reassembled his moped for fun. He spent a lot of time on racetracks riding fast bikes but he was also an excellent student and made rapid progress at the Technical University Graz . Unsure whether he wanted to pursue a Ph.D. after finishing his master's degree, he spent the summer with a friend traveling from one racetrack to the next. Wallner was the truck driver, mechanic, and cook and his friend was a race driver in the German and Austrian Championship. When a new professor coming from BMW offered him a Ph.D. position at the same institute where he had written his master's thesis, Wallner accepted. While he was a senior Ph.D. candidate, a visiting group of US scientists came to that institute and Wallner was the one who showed them around. Over lunch they invited him to call them once he had finished his Ph.D. As Wallner explains, things happened quickly afterwards: "I finished my Ph.D. in 2004 and in late 2004 I called these guys up. Then I came in November 2004 for an interview and, five months later, I started working at Argonne National Laboratory in March 2005."

After his first year at Argonne as a postdoctoral researcher, Wallner became a permanent staff employee. "The main reason why I was hired was because then-President Bush had announced in 2003 a big hydrogen initiative with funding of a billion dollars," says Wallner. Being part of the Freedom CAR initiative , the goal of the hydrogen initiative was to reduce America's dependence on oil by developing the technology for commercially viable hydrogen-powered fuel cells and the hydrogen infrastructure needed to power cars, trucks, homes, and businesses by 2020 - even if major breakthroughs in hydrogen production methods, materials for the fuel tank, and engine technologies still had to be developed.

From today's perspective, the 2020 goal seems to be decades away, as the costs for hydrogen-fueled vehicles are still too high to compete with fossil fuel vehicles and a hydrogen infrastructure is lacking. Hydrogen has only been used in the space program to propel shuttles or rockets into orbit, because it is the fuel with the best energy-to-weight ratio. For other transportation needs, hydrogen never made the breakthrough. Nevertheless, research on hydrogen is important since it carries the potential to contribute to a carbon-free future in which hydrogen could be produced from renewable resources such as wind and solar electrolysis, or via the conversion of biomass to hydrogen.

Meet H2ICE, the Hydrogen Internal Combustion Engine
 

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In an internal combustion engine, a mixture of fuel and air is burned in the combustion chamber. The expansion of the mixture produces a force that moves the piston in the engine. This movement can, for example, be used to run a car or a pump.

As early as 1808, the Swiss inventor Francois Isaac de Rivaz designed the first prototype of an internal combustion engine powered automobile. Since gasoline had not been developed yet, he used a hydrogen and oxygen mixture that was ignited by electrical ignition to drive the engine.
Today, the fuel of choice is gasoline or diesel, but it would also be possible to use hydrogen as a fuel. Since internal combustion engine engineering has been continuously improved over the last two centuries, with large production capacities available, the H2ICE could be produced at a competitive cost. It is important to distinguish a H2ICE car from a hydrogen fuel cell car: Instead of producing electricity as a fuel cell would, the H2ICE will produce movement directly via combustion.

In the past few decades, Ford and BMW are the automobile manufacturers that have put the most effort into developing such a hydrogen car. BMW claims to have built "the world's first production-ready hydrogen vehicle" with the BMW Hydrogen 7. Wallner, who ran tests on the BMW Hydrogen 7, describes it as an "incredible car." He mentioned being amazed that "the level of sophistication and of detail is a whole new world."
 

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The BMW Hydrogen 7 is prepared for emission testing at Argonne National Laboratory. The liquid hydrogen fuel is stored in a 30-gallon super-cooled (−423.4 degrees Fahrenheit) tank, and is enough for the car to travel 125 miles. With the additional gasoline tank, the car can travel another 300 miles.

The advantages of such H2ICE cars are that hydrogen is easy to burn and almost pollution free. Even if a nationwide infrastructure for hydrogen is still missing, such a car wouldn't face any range problem, according to Wallner, since the "nice thing about the H2ICE is that it can potentially run on gasoline as well."

Wallner started his research by establishing a baseline on a single cylinder engine with port fuel injection. It took him and his team the first three years to do "some basic testing, figuring out the correlation between injection timing, pressure, and efficiencies." As a result of their findings, they changed the engine geometry so that the engine "runs now on a much longer stroke." The goals given by the Department of Energy (DoE) "included peak efficiency of 45 percent, which is a pretty challenging number considering that a diesel engine probably does 42 percent and gasoline engines are doing probably 37 percent." Nevertheless, the DoE goal was finally overtopped by 0.5 percentage points!  In terms of emission, the "target was to meet the US tier 2 bin 5 regulation." This regulation roughly defines the emissions of an average car. Since hydrogen combustion has mainly water as a by-product but virtually no greenhouse gases, the aim was to reduce the oxides of nitrogen [NOx ], which are produced by very high temperature combustion. NOx is harmful to human health in its own right and it also forms unwanted tropospheric ozone. "Typically the higher your temperatures are, the higher is your efficiency, so it is a trade-off between efficiency and low NOx emissions," explained Wallner. Without using any after-treatment but just by optimizing the hydrogen injection into the engine and the mixture stratification, they were able to demonstrate significantly lower emissions than the regulation would have allowed.
 

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Wallner (right) reviews data from emissions tests conducted on the BMW Hydrogen 7. The hydrogen-powered engine met the most stringent emissions performance standard to date: the Californian super-ultra low-emission vehicle (SULEV) standards.

The hydrogen project for which Wallner came to Argonne in 2005 has been funded at a level of $0.5 million per year and ended in September 2011. From the vehicle side, this technology has been demonstrated with the BMW Hydrogen 7. The remaining challenges are the missing infrastructure and, since hydrogen is an energy carrier, it has to be produced. Wallner considers this to be "the biggest challenge and that's why likely there won't be a large-scale introduction anytime soon."

Feeding the Omnivorous Engine

In terms of near-future application, the result of Wallner's omnivorous engine proof-of-concept project is more likely to be applied. According to the US Energy Information Agency (EIA), in 2010 there were already about 8 million flexible fuel cars on the road. The engine of a flexible fuel car works with gasoline or different blends of gasoline and up to 85 percent ethanol (E85) that can be produced from agricultural products. However, currently, only a few of the existing flex fuel cars are actually fueled with E85.

The idea of an omnivorous engine moves the original flex fuel idea even further along, so to speak, to a "fueling locally" level:  In the Midwest US, a lot of corn is produced, so cars could run on a very high level of ethanol; further East, one would use more butanol made from woodchips. Wallner explains: "You could fuel up all these fuels, and your engine would still perform at its best for whatever fuel you are running on. Our goal is to develop instrumentation so that the engine can optimize itself to a certain extent, regardless of what alcohol [fuel] it runs on."

The best information for calibrating the engine would be the pressure, but these sensors are very expensive, according to Wallner. Therefore he and his team were looking for another signal that could be correlated with the pressure in order to derive the relevant information for calibrating the engine. Eventually they chose to measure ions in the combustion chamber using the spark plug as a sensor. Wallner demonstrated that if alcohol was added to the fuel characteristics of the ion signal changed. Having found that correlation, he was able to determine knock behavior, combustion phasing and estimate alcohol content from the ion signal.

The Crystal Ball of Transportation

Taking a look into the crystal ball of transportation, Wallner predicts that, in the future, the US will move away "from a single fuel approach for passenger car application. We will probably see different blend levels of gasoline and ethanol. For example blender pumps where you can dial in what level of ethanol your vehicle can operate on." Also, Wallner believes that compressed natural gas (CNG) is soon going to be a hot topic in the transportation research arena. "Alternative fuels come and go in waves." he says. Under the Bush administration hydrogen moved into the spotlight, now it is the electric vehicle (again), and the next big research focus will probably lie in natural gas. He thinks that at Argonne, the know-how the researchers have built up with gaseous fuels, such as hydrogen, will prove valuable when transitioning to research on natural gas as a fuel. "A project will hopefully start in January, where we use CNG in a similar concept like a plug-in hybrid vehicle. It would have a smaller size CNG tank but you could also run it on gasoline." And so the quest continues for the fuel(s) of the future ...
 

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This article is based on an interview conducted by the author, Manuel Froschauer, with Thomas Wallner, mechanical engineer at Argonne's Center for Transportation Research.

 

References:

Argonne National Laboratory: <www.anl.gov> (accessed December 9, 2011).

Thomas Wallner's profile,  <www.anl.gov/wallner> (accessed December 9, 2011).

US Energy Information Administration. "Alternatives to Traditional Transportation Fuels" <www.eia.gov> (accessed December 9, 2011).

The White House, Council on Environmental Quality, "Hydrogen Initiative" <georgewbush-whitehouse.archives.gov/hydrogen> (accessed December 9, 2011).

DOE Energy Efficiency and Renewable Energy. "Hydrogen Use in Internal Combustion Engine" 2001 <http://www1.eere.energy.gov/hydrogen.pdf> (accessed December 9, 2011).

BMW, "BMW Hydrogen 7" <www.bmw.com/hydrogen_7.html> (accessed December 9, 2011).

Wikipedia, "United States Emission Standards" <en.wikipedia.org/USes> (accessed December 9, 2011).

Flickr, Pictures <www.flickr.com/argonne/> (accessed December 9, 2011).

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