Revving up the race for better fuel efficiency

Bringing fuel droplets down to size
Researchers at Temple University have taken several big steps toward the mass production goal with six months of road tests suggesting that another device, an inexpensive electrically charged tube that attaches to the fuel line, can likewise increase fuel efficiency.

The technology is based on reducing the fuel’s viscosity, allowing smaller droplets to be injected into the engine. Because of evaporation, combustion in an internal combustion engine must be completed quickly. Small fuel droplets offer an advantage because they burn more completely.

Automotive engineers have been actively exploring how to use very high pressure to reduce the droplet size, but the method would require an expensive engine redesign.

An electrical tube developed by physics professor Rongjia Tao and his collaborators, however, could be easily and inexpensively attached to the fuel line of an older car’s existing engine, near the fuel injector.

Within diesel and many other fuels, bigger molecules are held in suspension and possess a higher viscosity than the base liquid. Viscosity means more friction, the sworn enemy of energy. But when polarized in an electric field, those molecules clump together and get even bigger. Friction increases with the cumulative surface area of the suspended particles.

So, if engineers can reduce that surface area by getting many of the particles to aggregate, they can reduce the viscosity and increase the combustion efficiency.

The researchers first tested the device in Milan, Italy, in a diesel engine built by Italian manufacturer Cornaglia Iveco. As documented in the new study, published in the Nov. 19 issue of Energy & Fuels, the add-on yielded a 5 percent improvement in mileage.

Everyone was “very delighted,” Tao said — everyone except him. He was convinced he could do better when he realized that diesel fuel stays in the system less than one second.

After changing the design to allow fuel to linger longer, the team installed the device in a Mercedes-Benz and measured the equivalent of a 20 percent improvement in power output.

Building a fuel-efficient car from scratch
Political battles over increasing fuel efficiency standards are nothing new. And neither are attempts to build an ultra fuel-efficient car.

All of Detroit’s Big Three automakers created a concept car capable of at least 72 miles per gallon in the 1990s before the U.S. government-led Partnership for a New Generation of Vehicles was scrapped in 2001 over cost concerns. The partnership spent $1.5 billion to help U.S. manufacturers develop and produce an affordable family sedan rated at up to 80 miles per gallon,

But the urgency of coming up with less-polluting cars has ramped up interest not only in new technology aimed at reducing emissions, but also in competitions aimed at integrating that technology into a seamless and affordable whole.

Entrants in the $10 million Progressive Automotive X Prize, for example, are hoping to tap a range of innovations to create showroom-worthy cars capable of maintaining 100 miles per gallon over a variety of courses simulating real-life driving patterns.

Courtesy of Cornell 100+ MPG Ideas for the future have to start somewhere, like with this 1991 Geo Metro, a “mule” car that is allowing the Cornell 100+ MPG team to try out some of its fuel efficiency ideas, including a drive train featuring an electric motor.

“Basically it’s a race — the fastest car wins,” said Trey Riddle, a graduate student in Cornell University’s Department of Mechanical and Aerospace Engineering and leader of the university’s X Prize team. To become an official contender, however, each car must average an equivalent of 100 miles per gallon over the course.

Another entrant, Germany’s Loremo, already boasts an eye-popping fuel efficiency of 130 to 150 miles per gallon using concepts like minimal drag (thanks in part to a unique wing door-entry system) and a highly efficient 2-cylinder turbodiesel engine. The Loremo, short for “low-resistance mobile,” is slated for a 2009 release in Europe (with a base price of about $22,000), with a North American rollout possible by 2010.

None of Detroit’s Big Three automakers have joined the competition. Nevertheless, some industry observers believe the Chevrolet Volt, a plug-in hybrid featuring a 375-pound lithium ion battery, could reach 100 miles per gallon when it arrives in late 2010.

The Cornell 100+ MPG team, one of only two university entrants among more than 60 contenders in the X Prize competition’s mainstream auto class, is designing a plug-in hybrid electric car from scratch.

So far, a modified 1991 Geo Metro has allowed them to get their “hands dirty” and try out several new features, Riddle said.

The first qualifying race, slated for September 2009, will include an alternative class where nearly anything goes, and the mainstream class, which requires a car that seats four people, contains 10 cubic feet of storage and can accelerate to 60 miles per hour in 12 seconds. “They’re marketed more as a normal car that someone might want to buy,” Riddle said.

Which, after all, is the whole point.

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