Calorimetry Challenge

The goal of the Calorimetry challenge is to design, build, and test a calorimetry setup to measure the heat given off in a chemical reaction. Using an arduino, we need to code an immersion heater and stirring rod to control temperature. All of this needs to be done in a Styrofoam cup.

Final printed pieces

To start, we used Autodesk Inventor to 3D model the cover and stirring rod of the setup. The cover needed a place to hold the immersion heater and allow for a thermistor to pass through, while the stirring rod needed to mix the heat throughout the water. We based a lot of our designs on the example provided to us in class. The only inconvenience was trying to accurately measure all dimensions of the cup. It was time consuming, but we were able to do so using a caliper. The above mentioned thermistor needed to be wired into a voltage divider circuit and monitored by an analog pin on the arduino; the transistor-mechanical relay circuit needed to control the immersion heater through a digital pin on the arduino. The first time through, we accidentally forgot to change the units in Autodesk to inches. The piece printed in millimeters and was extremely small. Then we had to restart both pieces because we forgot to save the originals. On the right is are pictures of how the parts appeared on Inventor. Below is an image of the final printed pieces.

Next we completed the Thermistor Calibration. First we wired the thermistor on the breadboard and wrote a code to get corresponding values of Serial Monitor readings at various temperatures. Here is a copy of the code. We placed the thermometer inside the warm water and got the initial temperature (in degrees Celsius) and the Serial Monitor reading. As the water cooled, we gradually collected more data points. Once we had enough data, we graphed the points and found the equation y=0.352x-153.073. 

We finished wiring the general Arduino setup using this guide. The goal was to make a mock-up experiment where we'd light up a large bulb instead of the immersion heater. To do this, we wrote a program that puts heat in for 10 seconds, then stirs for 10 seconds, then puts out a temperature and total heat added in the Serial Monitor. Once the mock-up worked, we replaced the bulb wiring with the immersion heater one. The video of our experiment can be found here. The image below was our final successful setup.