WEST LAFAYETTE, Ind. – Students from Purdue University will race a new solar car this week in an international competition to create the most fuel-efficient vehicles.
The car, Navitas, was designed and built entirely by students and will compete in the Shell Eco-marathon Americas 2013 from Friday (April 5) to Sunday (April 7) in Houston. The team won last year's Solar Urban Concept category with a different car, Celeritas, achieving an efficiency equivalent to 2,325 miles per gallon.
Navitas is about 250 pounds lighter than Celeritas, weighing in at a scant 200 pounds, said Zack Lapetina, president of Purdue Solar Racing.
The car's body and chassis are made primarily of lightweight carbon-fiber sheets sandwiched around a honeycomb center to add strength. Much of the weight reduction was achieved using a lighter composite, along with carbon fiber wheels and a titanium roll cage instead of steel. The student team also streamlined "communication protocols" to reduce wiring complexity and the weight of the electrical systems, he said.
Navitas - the Latin word for energy - represents an ongoing legacy: Purdue Solar Racing began 22 years ago, producing nine vehicles since then. About 35 undergraduate students are involved in the project in teams focusing on the car's electronic and mechanical systems, business, marketing and fundraising functions.
The vehicle is equipped with a system to concentrate sunlight for some of the solar cells, an innovation borne out of necessity. Whereas in previous years the cars could be covered with photovoltaic cells, they are now limited to .65 square meters of coverage.
The students attacked this challenge by using high-efficiency satellite-grade cells for a portion of the car and Fresnel lenses, which magnify sunlight, for the remaining lower-quality cells.
"We designed a passive mirror array that, in combination with the Fresnel lenses, gives us a wide angle of acceptance of incoming light," said Lapetina, a senior in aeronautical engineering. "This helps us to maximize the solar energy reaching the solar cells regardless of the direction our car is facing or the angle of the sun. This is a huge innovation because they magnify the sun's energy three times."
The photovoltaic cells convert sunlight into electricity to charge a bank of lithium polymer batteries, which then power a motor that drives one of the rear wheels.
Another innovation is the car's touch-screen dashboard, which provides GPS coordinates, battery level, solar array performance and other vital information, as well as a music player.
Participating students gain an employment edge, said Lapetina, who will work for General Electric Co. after graduating.
"The innovations in Navitas were achieved solely through the hard work and dedication of student members," said Galen King, adviser and professor of mechanical engineering. The work is entirely voluntary, with students receiving no course credits.
The vehicle has cost about $70,000 to design and build. Major project sponsors are Lockheed Martin Corp.; TE Connectivity; Advanced Pattern Works; Schlumberger; Airtech; Purdue's schools of Mechanical Engineering, Aeronautics and Astronautics, and Electrical and Computer Engineering; the College of Technology; and the Office of the Provost. A list of corporate sponsors is available at http://www.purduesolar.org/sponsors/
The Shell Eco-marathon Americas 2013 roster includes more than 150 teams from colleges and high schools in the United States, Brazil, Canada, Mexico and Guatemala.
Also leading the Purdue solar-car project are James Gilbertson, vice president of engineering and a mechanical engineering senior; Sally Ann Keyes, vice president of operations and a sophomore in mechanical engineering; Cody Thorson, vice president of business and freshman in cell and molecular biology; Emily Petersen, treasurer and sophomore in nuclear engineering; Zhe Kevin Wang, senior in mechanical engineering; Alex Van Almelo, a senior in computer engineering; Brian Kelley, a senior in computer engineering; Zack Smith, a senior in electrical engineering; Adam Loesch, graduate student in aeronautics and astronautics; and Mark Schmidt, a freshman in the First-Year Engineering Program.