UA Researches Fuels to Improve Engines, Cut Emissions

TUSCALOOSA, Ala. – In an effort to improve combustion engines while reducing harmful emissions, engineering researchers at The University of Alabama will test how blended fuels can work with advanced engines.

Sponsored by the U.S. Department of Energy, the research team of Drs. Ajay K. Agrawal and Joshua A. Bittle of UA’s mechanical engineering department will experiment with different blends of fossil and biomass fuels in a test chamber that mimics an advanced compression ignition, or ACI, engine. They are looking for a range of optimal fuel blends that would allow automobiles to use less fossil fuel while producing fewer harmful emissions.

“Efficiency and emissions all depend on how we introduce and burn the fuel inside the engine, and that’s what we are trying to understand so we can do it better,” said Agrawal, the Barfield Endowed Chair professor in mechanical engineering. “If we can engineer this process, we can have a significant impact.”

UA was one of eight universities selected to participate in the Co-Optimization of Fuels and Engines, or Co-Optima, initiative. Two offices in the Energy Department — the Bioenergy Technologies Office and the Vehicle Technologies Office — are collaborating to maximize energy savings and on-road vehicle performance while reducing transportation-related petroleum consumption and harmful emissions.

ACI engines are the next generation of combustion engines that will deliver both high efficiencies and low emissions. Agrawal, Bittle and their students will examine the combustion properties and performance of biofuels and blends using advanced diagnostic techniques to create a model that will help optimize the use of these fuels in ACI engines.

Researchers have an opportunity to optimize fuels and engines to complement each other — unlike today’s approach, where fuels and engines are modified independently of each other, Bittle said. Currently, biofuel blends, such as the fuel with 10 percent ethanol available at most commercial gas stations, exist primarily because of economic and geopolitical reasons rather than robust scientific justifications, he said.

“If we can optimize the fuel and the engine at the same time, we can achieve cleaner, more efficient combustion,” said Bittle, an assistant professor. “It will allow for a complementary engineering basis for introducing biofuels that also improve the engine performance.”

A 1 or 2 percent bump in engine efficiency could save billions of gallons of petroleum gasoline and drastically reduce emissions, Agrawal said.

To help with the project, the two professors will use a machine they developed to experiment quickly with different fuel blends while monitoring the process with advanced optical techniques integrated with multiple high-speed camera systems. The Constant Pressure Flow Vessel, or flow rig, is a chamber where air is supplied at the same temperature and pressure as an engine would have just before fuel injection. Cameras record the event as the fuel is injected, ignites and combusts. The air flow cleans the flow rig which is ready again for the experiment at a rate of five fuel injections per minute.

“With this highly capable diagnostics, we can see what goes on inside the engine at realistic test conditions and understand how fuel and air mix and react, which affects various emissions produced in the engine,” Agrawal said. “We can use this information to develop better methods and tools to significantly improve fuel efficiency and reduce emissions.”