Thermal Energy Control System
Senior Design Capstone Project
As the capstone of Notre Dame's mechanical engineering curriculum, seniors are grouped into teams and assigned a project to complete that utilizes aspects of their education from their entire academic careers. "The objective", this year, "was to control the thermal energy in a built part during and after the AM build process, in order to limit residual thermal stresses and thermal distortion which cause delamination and distortions that put the part out of design specification". Working within an extensive list of cost, size, power and more constraints, our team set out to build a thermal energy control system in one semester that could heat and cool a specified work-piece according to a given temperature profile.
We began with research and concept design to start the brainstorming process. One of my teammates spent multiple semesters doing research in an Additive Manufacturing lab on campus, so she was instrumental in this phase. After gathering initial data and concepts, we each presented multiple ideas to the group to benchmark and choose form moving forward. In order to make informed decisions, we also all performed different trade studies to find key statistics and metrics associated with certain design decisions. Considering we had started going down an exterior-interior two-shelled structure, I started exploring the most effective ways to cool the piece in our system. I focused mainly on Peltier plates, ceramic and metallic plates that take advantage of the current running through them to create a substantial temperature difference between the two sides of the plate. I calculated heat transfer models relating to using these Peltier devices in a convective sense (i.e. creating a cool air reservoir) and in a conductive sense (i.e. placing our work-piece directly on the cool side of the plate). The mathematical modeling eventually pointed to using the plates in a conductive fashion to rapidly cool the part when necessary and use fan convection otherwise.
Once all of the trade studies were completed, we moved forward with the build of our concept. While part of our team focused on the exterior and interior shelled structures, the rest of us focused on the coded control system (via Matlab and Arduino) and the associated electronics and sensors. Based on the premise of user-given inputs, we developed a control system designed to mimic any temperature profile given to a laptop connected to the structure.
We finally tested our artifact using times and temperatures given to us by our professors; after some code tweaking and day-of adjustments due to location and atmospheric environment changes, our artifact performed within 1 degree of the requested temperature for over 70% of all runs.
Throughout the project, our team designated roles within our group, made all of our own purchasing decisions, wrote individual and team concept memos, made seven different presentations as to the state of our progress and a final design presentation review (the slideshow below), conducted trade studies and presented findings, and prototyped multiple mechanical and electronic designs.
Team: Nicole Mejias, Patrick Penny, Drue Tranquill, Conor Triplett