119: AIChE ChemE Car Competition

In 1999, The American Institute of Chemical Engineers (AIChE) introduced efforts towards producing alternative chemical energy sources by starting an annual student chemical engineering competition, the AIChE Chem-E-Car Competition. This competition revolves around building a small-scale (shoebox size) car that is powered by energy produced by a chemical reaction. A chemical reaction must also be used to stop the vehicle. Students compete with teams from other universities in guiding their car as close as possible to a certain target distance. The distance the car must travel, which is usually between 15-30 meters, is not revealed until the day of the competition. The operation of the car is controlled by varying the concentrations and quantities of the reactants. The designed car must be capable of driving the target distance in less than two minutes. 

To achieve this goal, we utilized 16 thermal electric generators (TEGs), which generate current and voltage when exposed to a temperature differential. This temperature differential is created by placing a hot reactor on one side of the TEGs, and a cold reactor on the opposite side. The hot reactor consists of an exothermic (heat generating) acid-base reaction of sodium hydroxide and hydrochloric acid contained in a copper chamber. This hot reaction reaches 50-55ºC. The cold reactor is filled with a mixture of ethylene glycol and water; when frozen, the cold reactors reach an approximate temperature of -30ºC. The TEGs are “sandwiched” between the hot and cold reactors and wired in two sets of series in parallel to produce enough current and voltage to power the car’s motor.

For the stopping mechanism, we used an “iodine clock” reaction. The reaction has two steps: the first step produces iodine molecules, and the second step consumes them. When the rate of production of iodine exceeds the rate of consumption of iodine, a color change occurs due to the excess iodine molecules in the solution. The time before the color change can be altered by varying the quantity of thiosulfate, a key reactant in the consumption of iodine. The color change was detected by a photosensor that relayed information to an onboard Arduino controller, which triggered the car to stop after the solution turned dark. We generated a model to correlate the required amount of thiosulfate to the time required to reach the specified distance based on the velocity of the car.

The 2024 FAMU-FSU College of Engineering Chem-E-Car team’s car was called the ‘TEG-C’ for ‘Totally Epic Go-Cart.’ We traveled to Auburn University in Auburn, Alabama to compete in the annual Southern AIChE Regional Annual Conference. We were proud to take home first place in the Chem-E-Car Poster Presentation session.