Every year, chemical engineering students from across the country meet for a competition of accuracy and precision. The competition, which was hosted by the American Institute of Chemical Engineers (AIChE) from Oct. 14 to 16, is a challenge to design a chemically-powered car that will travel a specified distance. The car that stops closest to the finish line is the winner. This year, the cars had to travel 68 feet under their own power while carrying a 350-gram load. Out of 32 teams in the national competition, UC Davis placed second.
The UC Davis team has about 20 students who are broken into four sub-groups: the chassis team, the battery team, the stopping mechanism team and the programming team.
“The car was built completely from scratch,” said Nick Rossow, a junior chemical engineering major and member of the UC Davis team. “It is a little bigger than a shoebox.”
Building the car took about three months, and after it was completed in April, the team kept refining the design until the competition in October.
The team built its own battery from aluminium plates and copper plates, and built the chassis out of Plexiglas and roller skate wheels. The six-cell battery used bleach as an oxidizer and got up to 12 volts. The reaction inside the battery is highly corrosive and renders the battery unusable after a few hours. The copper and aluminium plates have to be cleaned with acid before they can be used again.
In addition to making a chemical reaction to make the car go, the teams also had to make a chemical reaction that would cause the car to stop after a specified time. This reaction is called the stopping mechanism. The difficulty behind the stopping mechanism is figuring out when it is supposed to start.
The teams each know how fast their cars move, so based on how far the cars have to travel, the team can calculate when to make the stopping mechanism kick in.
“This is an accuracy competition,” said Audrey Magnusen, a senior chemical engineering major and captain of the UC Davis team. “We didn’t know until an hour before the competition how far our car had to travel.”
The Davis team’s stopping mechanism is called an Iodine Clock Reaction. This is a mixture of potassium iodide, sodium thiosulfate, hydrogen peroxide and sulfuric acid all combined in a starch solution. When these ingredients mix, the mixture changes from clear to dark blue, signalling the car to stop. The team had to calculate the exact ratios of each chemical that would make the car stop at the right time.
Although the main competition was an accuracy contest for proximity to the finish line, there were also various sub-competitions such as best poster and and the safety award. The team from Texas Tech University won the safety award for designing the safest battery. Its battery was designed to safely contain and disperse all of the heat generated by the chemical reactions in the battery.
“The reaction we chose to power our car creates a large amount of hydrogen and heat. The car’s battery was triply contained inside glass containers and then a polyethylene [an acid-resistant plastic] container,” said Thomas Hoover, captain of the Texas Tech team.
“Without safety, nothing can be accomplished,” he said.
Every car at this competition was unique. Each team had a different chassis, different design and different chemical ratios. Even though many teams used the same chemical reactions to stop and start their cars, they were all implemented differently.
The competition provided a perfect medium to learn not just about chemical engineering, but about cooperation, teamwork and working under strict time constraints.
“We learned that there are a ton of ways to achieve the same goal,” Rossow said. “There is more than one right way to do something.”
The competition was sponsored by Chevron and ConocoPhillips.
HUDSON LOFCHIE can be reached at science@theaggie.org.
