Thermal Storage
The thermal storage prototype consisted of calculations related to thermal storage capacity, sketches, CAD models created in Autodesk Fusion 360, and a Pugh Matrix created for heat exchanger design selection. The team’s goal for the alpha prototype was to figure out the best way to implement the PureTemp PCM into the overall system, which required us to consider different heat exchanger configurations. The four designs initially considered, through sketches and discussion, were:
A: PCM tubes in middle, surrounded by an air duct, with more PCM surrounding the duct
B: Air flows through tubes, PCM surrounds tubes
C: PCM in tubes, air surrounds tubes
D: PCM in tubes, air moves in crossflow with tubes
With the help of a Pugh Matrix, the team narrowed these down to designs B and D. Two variations of design B (less + larger tubes vs. more + smaller tubes) and two variations of design D (coiled + staggered vs. straight + staggered tubes) were modeled in CAD. These thermal storage models were also brought into CFD to compare pressure drop and velocity magnitude of the air exiting the system. Each model was produced with the same constraints, with gauge pressure on one side and a volumetric flow rate of 3 m3/s applied to the other side. This provided an effective comparison between the four designs, organizing which systems were least to most efficient.
Thermal Comfort
The thermal comfort prototype was developed in Autodesk Fusion and CFD. The team decided to manufacture a custom duct piece to transition from the rectangular output of the thermal storage system to circular ducting. This piece was visually modeled using the sheet metal tool in Fusion 360 and features a schematic for how the material can be folded to achieve the desired end shape. Regarding the modeling of the rest of the ducting and dampers, CAD models for the the 10-inch to 8-inch transition wye duct splitter and 8-inch to 8-inch wye duct splitters were found online. An assembly of these components was produced in CAD to ensure their compatibility with the rest of the system.
For the transition piece between the rectangular and circular duct we needed to see if our CAD model could be reasonably manufactured by the machine shop. To test this we took pieces of poster board and outlined our design. We then cut it out and folded it into the shape of our completed transition piece design.
The entire assembly was then tested using Autodesk CFD. All CAD files found online were reproduced to ensure an air-tight fit in between components. The assembly was then imported into CFD. To model air flow through the system, a void was formed to create an air volume between all inputs and outputs to the system.To model pressure drop and velocity magnitude change through the ducting, the output of the dampers were modeled with gauge pressure, and a volumetric flow rate of 3m3/s was applied to the input of the thermal storage system.