Competition Overview
The objective for this competition illustrates chemical engineering concepts and allows students to showcase their problem solving skills on a very technical level. The overall idea of this event challenges the design of a car to begin its movement by a chemical reaction, safely carry an unspecified weight for a precise distance, then utilizing another reaction to stop the car.
Energy Source
Our team elected to use an aluminum-air battery as the power source for this design, as it provided the necessary output but furthermore would be cost effective during the testing stages of this competition. This galvanic cell utilizes oxidation of the aluminum (anode) and the reduction of oxygen (cathode) to produce a voltage that will be sent to a small motor thus moving the car. The actual construction of the battery shows innovation from our team, as we were able to stack 5 cells inside a pill bottle, using a quarter as a conductor. From this idea, we can scale the power output and assure that the necessary output is being satisfied. Lastly, the pill bottles were placed in a series configuration that allows current to be conserved in the batteries.
Propulsion Design
In order to actually move the car, we decided to employ a small motor and gear that would turn the back axle thus propelling it to the specified distance. The power output from the batteries have been wired to a switch that can be manually turned on and off at the start at the competition. These wires are then connected to the motor that spins the gear connection located on the axle that turns the wheels. After all of the wires were properly connected, a protective sheet of metal was mounted to insure one would not get injured while the gears were moving.
Stopping Mechanism
Stopping the car at a very specific distance is vital in this competition, so our team wanted to include a stopping mechanism that could be calibrated on the day of the competition for the allocated length. For this scenario, our team decided to use an iodate version of an iodine clock which would provide a timed reaction that could be calibrated. Once the color change initialized from the reaction, a color sensor would send a signal to a computer chip and shut off power to the car. Because of the safety requirements, this clock must have two containment units. The primary containment involved using a pill bottle with a syringe and the secondary containment unit consisted of a constructed acrylic box.