Team Helios at Lafayette approached the design review with the goal for both the thermal comfort and thermal storage teams to share what they have been working on, the design requirements that have been considered through the development of the alpha prototype, and how what we’ve learned will inform the next stages of the project:
The thermal storage team shared information about the PureTemp PCM they ordered, calculations that were performed to determine the thermal energy required to freeze the PCM and the minimum amount of time it will take to freeze the PCM, and other design considerations that went into the development and evaluation of four possible heat exchanger designs.
The thermal comfort team summarized the calculations and other metrics they used for the selection of the duct shape, duct material, duct size, and transition piece required for the transition from a rectangular to circular duct.
Both teams used CAD models to more clearly represent the heat exchanger and duct designs, and CFD models to represent the velocity and corresponding pressure drop through these same heat exchanger and duct designs.
The design review sparked a great conversation with Professor Sabatino and Professor Malali regarding ideas that we have and haven’t yet considered in the development of the alpha prototype.
The thermal comfort team posed the question about concerns regarding the use of rivets instead of spot welding to make connections → Professor Sabatino responded that he’d be more concerned about air leakage and minor head losses associated with flow splitting and hitting the flat end when it enters the duct than with that caused by the rivet.
Professor Sabatino mentioned pressure coming from the fan and determining the optimal operating range from the fan curve, a graph which typically represents static pressure as a function of the volumetric flow rate.
Professor Sabatino seemed to agree with the thermal storage team’s plan to use thermal paint and fittings on the end of the tubes to combat PCM leakage, and mentioned taking PCM expansion/contraction through phase changes into account.
Professor Malali questioned the Reynolds number of the flow through the tubes, which should be turbulent due to the staggered tube formation.
Final Takeaways/Suggestions:
- The Pugh Matrix is concerning on its own as there’s a lot of information we weren’t able to fill in, but the use of CFD is good for justification.
- Take the valves out of the CFD models to give a better idea of how the ducts themselves perform.
- Look into pressure at the inlet to see the pressure drop and consider the effectiveness of thermal paint and other sealing techniques.