TRANSPORTATION RESEARCH TAKES MULTI-PRONGED APPROACH TO CLEAN FUELS, ENGINES
09 March 2007 - DOE/Argonne National Laboratory

ES researchers are exploring alternatives to the well-understood, gasoline-powered engines in the Transportation Technology R&D Center. Although some of these new technologies, electric and hybrid electric vehicles, are already on the market, there is still much to learn. And fuel cells and other alternatives present even greater challenges. Argonne's engine and vehicle research is funded by the FreedomCAR and Vehicle Technologies Program in the DOE's Office of Energy Efficiency and Renewable Energy.

Argonne's Advanced Powertrain Research Facility allows engineers to study the performance of the components that power a vehicle. The APRF has the best available emissions instrumentation for testing a wide range of fuels, including gasoline, hydrogen, natural gas and diesel. The APRF instruments include:

A state-of-the-art four-wheel-drive dynamometer system for two- and four-wheel-drive vehicles up to 14,000 pounds. The system monitors engine performance under a variety of driving conditions and profiles, including tractive effort and coast down.
A custom-made data acquisition system, designed for testing fuel-cell, hybrid-electric and electric vehicles.

Engineers use the APRF to reveal the detailed interactions of hybrid powertrain components. Even before the hybrid electric Prius was available for sale in this country, Argonne mechanical engineers were testing the vehicle to understand its Japanese-built technology. The information provided valuable data to government laboratories and U.S. manufacturers developing viable hybrid technology. Research continues to understand technology trends and forecast future hybrid directions.

Mechanical engineer Michael Duoba said “Argonne’s APRF provides more comprehensive data than the manufacturers’ labs, so we collaborate regularly. By understanding the capabilities of state-of-the-art hybrid electric vehicle technologies, we can provide more informed directions for on-going research in hybrid engine, motor and battery technology.”

In addition to testing street cars, ES researchers use the APRF to study virtual vehicles. For example, engineers are testing a virtual fuel-cell vehicle to determine its energy storage needs. Clean-operating fuel cells, which are expected to run cars in the future, are like batteries that run on hydrogen gas.

Using Argonne-created software, a virtual fuel cell “powers” a real car on the dynamometer. The dynamometer simulates a road course and measures the vehicle's energy use. “We combine real and virtual components to explore the technical requirements of an entire powertrain system,” explained Vehicle Systems Section Manager Don Hillebrand.

Software tool for powertrain design
Today's vehicle designers are challenged by heightened competition and increased powertrain options as they create the next generation of vehicles. Accurate, flexible simulation tools are key as designers choose from a variety of fuel and technologies to power advanced vehicles. ES engineers developed the Powertrain Systems Analysis Toolkit to allow advanced vehicle designers to quickly narrow their focus to the most fuel-efficient configurations and components before building any prototype.

“With conventional vehicles,” explained PSAT lead designer Aymeric Rousseau, “there are only a few options: manual or automatic transmission, two- or four-wheel drive. With hybrids, for example, there are hundreds of options since the energy can come from one or more sources.”

PSAT provides accurate simulations of performance and fuel economy for hundreds of advanced vehicle configurations, thereby cutting development time and allowing automotive and truck manufacturers to bring cleaner, more efficient vehicles to market sooner.

Clean diesels – a contradiction in terms?
You may not be able to teach an old dog new tricks, but Argonne engineers are finding new “tricks” to clean an old technology. Diesel engines are the most efficient heat engines ever built. While American consumers prefer gasoline-powered vehicles, heavy-duty trucks and locomotives use diesel engines, because they are durable and 15 percent more fuel efficient than gasoline engines. Although diesels are more efficient, they produce soot, which is dangerous when inhaled, and nitrogen oxides, a precursor to ozone that contributes to smog.

Scientists are using novel techniques to understand diesel combustion in engines and exhaust systems. Engineers use the Engine Research Facility and Heavy-Duty Truck Engine Test Cell to study in-cylinder combustion phenomena under realistic operating conditions. The goal is to improve diesel engine performance and reliability, increase fuel efficiency and reduce exhaust emissions by discovering and evaluating new technologies.

Diesel-emission details
ES engineers created the first ever three-dimensional images of diesel emissions using thermophoretic sampling. Using a dynamometer to operate the engines from idling to full load, researchers ran tests using pump-grade fuel. They collected soot emissions at intervals along the tailpipe, and analyzed the samples under 250,000-times magnification on a transmission electron microscope. The microscope revealed that the mostly carbon particles are not spherical, as previously believed, but vary in shape depending on engine speed and load. Engine and Emissions Research Group Leader Raj Sekar said “We hope that these results will guide the design of an advanced particulate trap or other mitigation devices. We are also creating a database that will be used to study the health effects of emissions.”

Other basic research uses X-rays from the Advanced Photon Source at Argonne, this hemisphere's most brilliant source of research X-rays, to see diesel fuel pass through fuel injectors. Engineers simulated a high-pressure injection similar to that found in a passenger-vehicle engine. Previous optical methods only revealed an opaque image of the spray, but the APS study provided the spray's mass and uncovered a supersonic shock wave that may impact future fuel-injector design.

“We use this fundamental knowledge,” explained Sekar, “and work with industry to develop practical technology.”

Engineers are using simulation models to understand the effects of angle, timing, pressure, fuel mixture and air composition on particulate emissions. Argonne researchers are conducting controlled engine experiments to link the fuel spray research to engine combustion efficiency and emissions reduction in ES's Heavy-Duty Truck Engine Test Cell. The test cell is equipped with a single-cylinder version of a modern, electronically controlled truck engine along with state-of-the-art gaseous and particulate emissions measurement instruments.

Current in-cylinder engine research, for example, reducing particulate exhaust emissions by using late-cycle or oxygen-enriched air injection, is based on earlier Argonne-patented technology, and now includes collaboration with Caterpillar and Mack Truck.

Engineers are also applying this technology to locomotive engines with the Electromotive Division of GM using two 10-foot-tall single cylinder engines.

Hydrogen engines studied
Engineers continue to seek clean, economical alternatives to the finite supply of fossil fuel. DOE is funding Argonne and Sandia national laboratories to study hydrogen-fueled internal combustion engines. Using a renovated dynamometer test cell, ES engineers are evaluating the efficiency of direct-injected hydrogen internal combustion engines and are developing components and systems. Researchers are studying combustion phenomena at high speeds and loads, using precise measurements of fuel consumption, hydrogen-engine emissions and safety-equipment performance.

University vehicle competitions
In addition to sharing research with government and industry, ES operates university competitions for DOE. Auto companies and major auto industry suppliers donate cars and parts and provide support.

The university teams compete to redesign, build and test advanced energy-efficient clean vehicles. The three-year-long FutureTruck competition, challenged students from more than a dozen colleges to re-engineer a 2002 Ford Explorer for the highest fuel economy and lowest emissions.

http://www.anl.gov

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