College teams build a car powered (and stopped) by chemical reaction
CHALLENGE: The Chem-E Car must run between 50-100 feet and carry a 50-100 mL payload of water. The tricky part? The car must be a new design each year, assembled onsite (when distance and payload specifics are revealted) and adhere to a 30-page safety document.
SPONSOR ORGANIZATION: American Institute of Chemical Engineers (AIChE)
THE BIG EVENT: This year the University of Arkansas hosted AIChE’s Midwest regional conference April 8-9, with 29 UNL attendees (Huskers appeared to be the largest group there). Chem-E-Car was one of several competitions there; UNL won another event, CHME Jeopardy, at the gathering and will compete in October at the University of Minnesota with the national AIChE conference.
TEAM: Though students from other majors are welcome, the team was comprised of UNL CHME students: sophomores Alison Drain (her brother, Schuyler, was team captain of the 2010 team), Mike Taylor, Aldo Martinez (2012 team captain), and Arthy Muthukumarappan; juniors Austin Mytty and Devor O’Connor. They note special thanks to CHME Lab Manager Leonard Akert, who dedicated many hours helping the team with safety issues.
COMPONENTS – The UNL Chem-E Car includes:
- Power Supply: the lead battery from a motorcycle, reduced from three cells
- Motor: borrowed from a rock crawler, to turn the Gears
- Stopping Mechanism: UNL experimented with a chemical timer, a reactive enthalpy of mixing. The stopping circuit monitors the resistance of aluminum foil in reaction vessel; when a solution of HCL and water dissolves foil, a sensor senses when circuit broken,
Recycled materials include lathe-spun plastic wheels with o-rings glued to the wheel rims for traction. The development process involved lots of testing and modeling to meet the prescribed amount of distance in the set time. A number of factors can affect performance: this year, the competition surface was a tarp-covered gym floor; conditions such as humidity can also have an impact.
DRAMA? The 2011 team tried to move past last year’s memories, when UNL was provided with the wrong strength of a chemical at the competition. This year, the stopping circuit “fried” and had to be rebuilt onsite.
WHAT YOU LEARN: Nothing goes right the first time!
WHAT THE EXPERIENCE DOES FOR YOU: Working on UNL’s CHME car creates a bond outside class. Team members talk about “stuff from class, and stuff you don’t learn in class.” It’s better than a lab course, team members say, because “In labs for class when things go wrong, you say ‘Oh, well!’ and account for that, then walk away,” said O’Connor, team captain. “With the Chem-E Car, it’s more like working in industry: when something goes wrong, you have to fix it.” This project also shows you can work with other engineers and apply your classroom learning in hands-on situations.
HOW DO YOU PREPARE? Starting in fall, the team met weekly, then three times a week, then daily when competition date was near.
WHAT’S COMPETITION LIKE? “At the event, other teams are really helpful (one let us borrow a soldering iron)—until you’re on the floor,” said O’Connor. “Then, it’s nerve-wracking – this year, our stopping mechanism failed and the car kept going past the prescribed distance.”
LEARN MORE: Watch a two-minute video “tour” of the car at http://engineering.unl.edu/movies/