Wave Disk Engine Could Be New Hybrid Powerplant

Lighter and smaller, new engine could cut the cost of making a car

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Imagine if an American research team developed a new internal combustion engine three to four times better at burning the fuel that's needed for a power generation system in a hybrid car, and was considerably smaller than the heavy, 1,000-pound powertrain assembly in today's cars?

What if such a novel engine could be connected, for example, to Nissan's efficient, relatively low-cost 24 kilowatt battery that runs the hybrid LEAF—a battery that surprised experts when its manufacturing cost was much lower than anyone had predicted?

What if such an engine allowed Detroit carmakers—or Japanese carmakers—to save quite a bit of money because such a small engine would reduce the total weight of the car by up to 20 percent? What if those savings were then passed on to consumers? What if this engine allowed a hybrid electric-gas vehicle to go much further on a single tank of gas?

Later this year, an engineering research team led by Dr. Norbert Mueller, an associate professor at Michigan State University's college of engineering, plans to have just an engine generating power through a 25-kilowatt battery, which will be capable of driving a full-size hybrid electric-gas vehicle.

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It's called a wave disk engine, which uses a novel internal system to generate shock waves, igniting a compressed air and fuel mixture that turns rotors. There are no pistons, crankshafts or valves. The shock wave rotor engine, connected to a battery, would turn the wheels of the car.

Mueller's research at Michigan State—in the shadow of Detroit's car companies—is funded by ARPA-E, the Advanced Research Projects Agency-Energy. The research project won a $2.5 million ARPA-E grant in 2009 and will be featured for a second time at the federal agency's annual innovation summit at the end of February.

"You have to be aggressive with your research in today's world if you want to get anywhere," Mueller says. "The wave disk engine is smaller, lighter and easier to manufacture."

In a traditional internal combustion engine, air and fuel are ignited, which in turn creates high-temperature and high-pressure gases that expand rapidly. As the gas expands, it forces the engine's pistons to pump and, in turn, powers the car.

According to ARPA-E's basic fact sheet, the wave disk engine "uses the combustion of air and fuel to build up pressure within the engine, generating a shock wave that blasts hot gas exhaust into the blades of the engine's rotors, causing them to turn, which generates electricity."

Mueller says they have four working bench prototypes.

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"We have engines—real, working, good-sized models—running right now," he says.

In 2012, the MSU research team will turn one of them into a 25 kilowatt wave disk engine and generator package.

"We'll be able to drive a full-sized hybrid, or even a hybrid SUV," he predicts.

When the wave disk engine was first unveiled at ARPA-E's innovation summit in 2011, it generated a small flurry of interest. A few critics said publicly that it seemed too good to be true—that, perhaps, its system of rotors with radial channels that work on timing as the shock waves are generated and move through the system might not be as efficient as predicted.

Mueller is happy to answer questions about the engine. While he says the design and system is novel and complicated, it works—and it can be scaled to full-scale hybrid cars, distributed power generating systems or even base power plants some day.

"The engine was obviously hard to design," he says. "But it's easy to manufacture. There are many parties—national and international—now interested in it, both in the automotive and base power sectors. Interest in the engine, that's not a problem."

Mueller genuinely believes he and the MSU research team have created something that is potentially revolutionary.

"I wouldn't be doing this if I didn't believe in the game-changing potential of this engine."

The potential is certainly there. The traditional internal combustion engine only uses 15 percent of its fuel for propulsion. The remaining 85 percent is essentially wasted. Hybrid gas and electric configurations are making inroads every year. But the wave disk engine promises a big step forward—it could use 60 percent of the fuel to create power, making it up to four times as efficient.

And because it's small—Mueller can hold the bench prototype engine in just one hand—it would, in fact, be relatively easy to manufacture and reduce the overall weight of a car by as much as 1,000 pounds, enabling hybrid vehicles to be 20 percent lighter and 30 percent less expensive.

What's more, if it's successfully scaled for use in a full-sized hybrid, it would reduce carbon emissions in such a car by 90 percent.

A wave disk engine hybrid that uses far less gas is easier and cheaper to manufacture and reduces carbon emissions? That would certainly be interesting. The American economy was built on innovation—and on research like what's going on at Mueller's engineering design shop at Michigan State University.

It may only be a matter of time before Mueller turns all the "What if..." questions into realities.

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