Fuel efficiency can save 7 billion dollars anually, according to Navistar test
Published on 1 April 2010
Aerodynamic drag is caused from pressure differences around the vehicle. At highway speeds, a semi-truck uses more than 50 percent of the energy produced by the vehicle engine to overcome aerodynamic drag, while rolling resistance consumes roughly 30 percent of the usable energy.
The full-scale tests began last month at the National Full-Scale Aerodynamics Complex, which operates under the direction of the Arnold Engineering Development Center, located at NASA Ames in Moffett Field, California. The goal was to identify drag reduction devices, both commercially available and under development, that show the potential for improving fuel efficiency. The wind tunnel's size (80 feet by 120 feet) makes it ideal for testing a full-scale semi-truck with a 53-foot trailer. An International® ProStar® sleeper truck, as well as a day cab, participated in the test.
Prior to testing, LLNL computer simulations identified critical drag producing regions around semi-trucks, such as the trailer base, underbody and the gap between the tractor and trailer. The laboratory's scientists estimate that with aerodynamic devices placed in these regions, the trucking industry could see as much as a 12 percent increase in fuel efficiency, which annually saves 3 billion gallons of diesel fuel, equaling approximately $7 billion in diesel fuel savings per year.
"This is a technology that could easily be installed on the tractor trailer trucks that are out on the highway today," said Kambiz Salari, LLNL's lead scientist on the project. "And its time to market is incredibly quick. In just three years, we could see these devices on the road and realize the real fuel savings."
Semi-trucks make up about 12 percent of the United States petroleum consumption (21 million barrels/day). The average fuel mileage of a semi-truck is six miles per gallon. But just a 1 percent increase in fuel economy in tractor-trailers translates into 285 million gallons of diesel fuel saved and $855 million saved annually. Just those figures alone are impressive to the trucking industry.
Prototype devices currently under development were provided by both LLNL and Navistar, who are collaborating to get proven drag reduction devices on the road. "Making our trucks more fuel efficient means we can not only travel further using less fuel, but it means we can get our goods to the general public in a more timely, and ultimately, less expensive way," says Ron Schoon, chief engineer of aerodynamics at Navistar.
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