Move over, hybrids. Two University of Missouri-Rolla researchers are working on a way to transform current automobiles into leaner, greener vehicles.
Rather than changing the design of a spark-ignition engine, the researchers are developing a control strategy that would learn “on the fly” how to operate the engine cleaner and more efficiently.
“The neural network controller would learn the dynamics of the engine and then come up with a control command that puts the system in a better mode of operation,” says Dr. Jagannathan Sarangapani, associate professor of electrical engineering at UMR. “One of the good features of a neural network controller is that it will learn online. That would allow us to put it on any car you want and it should be able to learn to some extent.”
Artificial neural networks are adaptive systems, which are based on biological systems. “When working on a problem, the neural networks ‘learn’ based on the successful connections they make between neurons or nodes,” Sarangapani explains. “The networks learn by modifying the weights interconnecting the neurons. Changing the weights changes the knowledge stored in the neural network.”
Spark-ignition engines need both fuel and air to operate, says Dr. Jim Drallmeier, professor of mechanical and aerospace engineering at UMR. “We need both of them together,” Drallmeier says. “If, however, I can operate the engine in a situation where I can give it less fuel for the same amount of air, the engine will behave differently. And that’s what we’re doing here. Current engine designs are not able to handle that well. What we’re trying to do is get it to the point where it does handle it well.”
Building on research done previously in the Internal Combustion Engine Laboratory on campus, the researchers are working to operate spark-ignition engines with much cooler combustion than previously possible, providing significant reductions in nitrogen oxide emissions.
“Our objective is to show a drastic reduction – more than 50 percent – in harmful products such as nitrogen oxides, carbon dioxides, and hydrocarbons coming out of an engine and to improve the fuel efficiency by about 5 percent,” says Sarangapani. “These are significant reductions in the long term. If you think about a 20-gallon car, that’s about a half a gallon to a gallon per tank of gas.”
The gain in fuel efficiency also provides an immediate reduction in carbon dioxide emissions. “If I’m using less fuel, I’m producing less carbon dioxide, which helps from the viewpoint of greenhouse gases,” adds Drallmeier.
Hydrocarbons, produced from evaporated and unburned fuel, and nitrogen oxides are federally regulated because they are precursors to acid rain, global climate change and ground-level ozone. A key component of smog, ground-level ozone is formed by reactions involving hydrocarbons and nitrogen oxides in the presence of sunlight. “If you’ve ever seen southern California in the summer, the nice green layer of haze they have there is due in part to nitrogen oxide emissions,” Drallmeier says.
Automobiles aren’t the only machines that may benefit from the research, Drallmeier says. “It’s not so much of whether it will work on a Chevy or a Ford, but whether it will work on spark-ignition engines across the board, from lawnmowers to four-wheelers,” Drallmeier explains. “Everything that has an engine comes under the U.S. Environmental Protection Agency regulations. They’re different but all are getting more difficult to meet. So everyone is looking at new ways, new strategies to try to do that.”
Receiving more than $500,000 in funding over three years from the National Science Foundation and the EPA, the researchers are collaborating with Caterpillar Inc., and Oak Ridge National Laboratories.
“This is not something that I would anticipate you’re going to see on a model year 2008 vehicle,” Drallmeier says. “This is something that’s going to take some time to implement. But given the fact that the emission requirements are getting stiffer and the fuel economy — both from the viewpoint of saving energy and from the viewpoint of carbon dioxide — is getting stricter, this is forcing us to look at different ways of operating engines.”