Modern Darwinism: better engines through natural selection

Caterpillar Inc., the world's largest manufacturer of construction and mining equipment, diesel and natural gas engines, and industrial gas turbines, has funded a computer model to create more efficient engines

July 5, 2000
Web posted at: 2:43 p.m. EDT (1843 GMT)

By Environmental News Network staff

A century and a half after Charles Darwin's bombshell, could his rules of evolution help engineers design high-performance engines of the future?

Computer models are doing just that, by using genetic algorithms to simultaneously increase fuel efficiency and reduce pollution.

Peter Senecal, a post-doctorate engineer at the University of Wisconsin at Madison, created the computer models to help sort through literally billions of combinations of factors that determine engine performance.

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Senecal says the most important advance is in improving pollution emissions without sacrificing fuel efficiency, and vice versa. Normally, engine designers who concentrate on solving one problem end up with major tradeoffs in the other.

The results to date have been dramatic. Using a silicon graphics supercomputer, Senecal created a diesel engine design that reduces nitric oxide emissions by three-fold and soot emissions by 50 percent over the best available technology. At the same time, the model reduced fuel consumption by 15 percent.

This chart shows a completed cycle of the genetics-based computer model. The "optimum" point represents the best possible combination of factors that will achieve reduced emissions of both soot and nitric oxide. Those two pollutants are targeted for major reductions by the U.S. Environmental Protection Agency. The "baseline" represents the best existing technology.

Six engine performance measures were studied, including fuel injection timing, injection pressure, and amount of exhaust recirculation. The simulation was then reproduced experimentally in a real diesel engine.

"We found that the agreement was excellent between what was measured in the lab engine and what the computer predicted," Senecal says.

Senecal's research is turning heads in the engine manufacturing industry, which faces major new federal pollution control mandates by the year 2002. Caterpillar Inc., a manufacturer of diesel engines for trucks and heavy equipment, is funding his post-doctorate work that will focus on improving the geometry of engines.

Senecal says genetic algorithms have been developed in recent years for other engineering challenges, such as designing bridges and airplane wings. "I kind of stumbled onto this in the literature, and wasn't sure if it would work for something as complex as engine design," he says.

Mechanical engineering professor Rolf Reitz says Senecal's computer model is extremely versatile and could be used for all types of engines. While current work focuses on questions like fuel injection and air intake, studies of engine hardware are just beginning.

Reitz says the typical engine piston, for example, has not been fundamentally improved upon for decades. Yet engineers have no idea whether a different geometry could produce much better engines.

The diesel engine industry faces a U.S. Environmental Protection Agency mandate to cut nitric oxide emissions in half by 2002. Wisconsin's small-engine industry, also facing pollution-control deadlines, also has initiated a research program at UW-Madison using the genetic model.

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Peter Senecal
   •Master's work at the Engine Research Center
Caterpillar Inc.
U.S. Environmental Protection Agency
The University of Wisconsin Engine Research Center

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