P17280: Hot Wheelz Thermal Management System

Jordan's Work

Table of Contents

Senior Design I

Problem Definition (Weeks 1-3)

Work initially done in notebook. Expectations for deliverables not known at the time.

System Design (Weeks 4-7)

  1. Benchmarking
    • Purpose: Compare several different products to determine which is best.
    • Thermal Paste Benchmarking
    • Material Benchmarking
    • Summary: The thermal grease was not used in the end. We are still in the process of selecting the material.
    • Approximate time spent: 60 mins
  2. Feasibility - Mineral Oil Thermal Management
    • Purpose: Determine viability of mineral oil as a potential method for cooling the components.
    • Feasability analysis of Mineral Oil
    • Summary: Advantage: Takes less power to cool the components and there are no 'hot spots'. Disadvantage: Hard to change components, adds weight and complexity to the system. Verdict: Although a cool system, it does not fit the scope of the project.
    • Approximate time spent: 30 mins
  3. Feasibility - BMS heat generation
    • Purpose: Attempt preliminary calculations without data to model the temperature generated from the BMS controller. This was to help determine appropriate testing range for the temperature stickers.
    • BMS modeling
    • Summary: It was very difficult to do a quick calculation for how the system generated heat. I knew what the maximum power draw was, but didn't know for how long. I knew the weight from the website, but didn't know the material/materials used in it. This made it very difficult to get an accurate temperature. After watching the feasibility analysis module, this is a preliminary question. It ties in with the engineering requirements in terms of how much power the GV battery will need to supply. Something to look into further as time goes on.
    • Approximate time spent: 60 mins
  4. Feasibility - Motor Controller Model
    • Purpose: Develop heat transfer model for the motor controller.
    • Initial Model.
    • Summary: This was very helpful in devoloping more testing for the next phase and for narrowing down a selection for the Pugh Chart. Since the current system does not produce a lot of heat at baseline, some of the more intensive systems, such as liquid cooling, would be overkill. As the model gets refined it will be important to test and validate the model to see how much of it is useful. This will be good to tie into the engineering requirements.
    • Approximate time spent: 360 mins
  5. Feasibility - Interview Dr. Micheal Schrlau about liquid cooling.
    • Purpose: Determine viability of liquid cooling system.
    • Schrlau Interview notes
    • Summary: Liquid and air cooling is very dependent on the parameters of the system, such as the ambient temperature and how hot the system gets. More information was needed to make the best choice.
    • Approximate time spent: 60 mins
  6. Feasibility - Interview Jeffrey Botticello about EVT team’s current thermal management system
    • Purpose: Communicate with Electric Vehicle Team about what their current thermal management system is to avoid making the same mistakes.
    • Botticello Interview notes
    • Summary: EVT motorcycle does not currently have thermal management system to base our system off of.
    • Approximate time spent: 60 mins
  7. Feasibility - DAQ mounting
    • Purpose: Determine method for mounting the DAQ device to the car for testing.
    • Summary: Used a quick and dirty method of attaching the DAQ with zip ties. This was cost effective and worked well, and we were able to get all the data we needed.
    • Approximate time spent: 15 mins
  8. Concept Development - Brainstormed design concepts with the team
    • Purpose: Pick a design to pursue for further analysis.
    • The link to our morph/Pugh chart is here
    • Summary: This was a team effort, but contributed to the selection criteria and the overall structure of the morph chart.
    • Approximate time spent: 180 mins
  9. Pugh Chart - Concepts
    • Purpose: Define different concepts to use in the selection process. We had struggled with our first round of Pugh Chart because all of our designs concepts were basically the same. I came up with different designs that incorporated more concepts in the morph chart.
    • The link to our morph/Pugh chart is here
    • Summary: We worked as a group on the final 6 Concepts together to come up with the list we have now. We lost some efficiency since we had to redue the 6 concepts, but the process helped us better understand Pugh Selection.

Preliminary Detailed Design (8-11)

  1. Proof of Concept - Justification of Design Parameters
    • Purpose: Model current heat sink for the motor controller to determine whether fins are necessary.
    • Resistance Modelling for Heat Sink
    • Summary: Based off the current amperage assumption of 200 A, fins are not needed to keep the controller from reaching 85 degrees C (performance degradation begins at this temperature). Since heat sink is good enough, more time and energy can be focused on other aspects of design i.e. the battery management, thus increasing team efficiency.
  2. Proof of Concept - Controller Testing so Far
    • Purpose: Collect data to verify model predictions for the motor controller system.
    • Motor Controller Test Bench Testing Plan
    • Summary: Many problems were encountered trying to get the test setup to work, and due to time constraints we did not finish testing. I mostly worked on trying to fix the mechanical side of things and although some good problem solving was employed in this process, overall the testing was unsuccessful. Some learning experiences gained from this was to recognize that the problem was larger than our current experience could handle and to seek outside assistance earlier. We spent a lot of time trying to get the test bench to work and lost perspective on other aspects of the project that still needed to get done.
  3. Proof of Concept - Controller Testing to be Done/Theoretical Models
  4. Procurement - Assembly
    • Purpose: Define process for assembling the motor controller heat sink plate for the next phase.
    • Preliminary%20Detailed%20Design#Assembly
    • Summary: The new heat sink will be assembled the same way as the old one. Since fins are not needed, the process should be fairly painless since the team already has experience both purchasing and mounting this sub component.
  5. Procurement - BOM of controller
    • Purpose: Develop a Bill of Materials for the motor controller heat sink and identify any potential issues.
    • Bill of Materials for the Motor Controller
    • Summary: Again, since the team has experience procuring and assembling the motor controller without fins, there should be no anticipated problem with the BOM.
  6. Test Plans - Controller
    • Purpose: Develop test plans to validate the motor controller sub-system model and anticipate, avoid, abate and accommodate any potential problems.
    • Potential Test Plan for the Motor Controller Heat Sink
    • Summary: Making sure that an appropriate hot plate is purchased that meets the requirements needed to perform this test successfully will be important. There is a potential risk to purchase a hot plate that can not be easily controller and or the power being delivered is not known. This is true of purchasing a fan, where it will be important to controller the air speed effectively.
Section Time Spent Projected Time Efficiency
Controller Justification of Design Parameters 600 mins 60 mins 10%
Controller Testing so Far 1200 mins 120 mins 10%
Controller Testing to be Done/Theoretical Models 180 mins 30 mins 16%
Controller Assembly 30 mins 10 mins 33%
Controller BOM 60 mins 10 mins 16%
Controller Test Plan 150 mins 60 mins 40%
Overall 2220 mins 290 mins 13%

Detailed Design (12-16)

  1. Project Objective Statement
    • Purpose: Define objective of project concisely.
    • See Detailed Design page
    • Summary: Rewrote the statement. Tried to use as few words as possible and still convey the purpose of our project. This was not a significant part of the phase and took me 5 mins.
  2. Batteries - Finalized Concept Selection
    • Purpose: Design final sub-system concept for the battery box and internal battery structures.
    • See Detailed Design page.
    • Summary: Worked with Caitlin throughout entire phase to develop a solution for cooling the battery box. Helped develop the idea to have independent channels cool each structure individually rather than the entire system. Helped develop panel idea to channel flow to specific areas of the battery structures.
  3. Batteries - Testing So Far
    • Purpose: Test airflow and barrier concept on a test rig.
    • See Detailed Design page.
    • Summary: Worked with Caitlin to develop a test rig to see the airflow. Designed both revisions of the test box (the first revision that didn't work and the final revision seen in the videos). Procured many materials needed for building the box. Helped build both box revisions, and participated in both box testing as seen in the video. A significant amount of time was spent on this testing. Although testing was successful, doing actual testing with the selected fans and vents will be important to see if enough air moves through the front batteries of concern. The air did move for our test rig, but I'm not sure if it will be enough heat transfer to keep those batteries cool. So that is a risk to reduce in the next phase (and most likely over winter break).
  4. Batteries - Testing to be Done
    • Purpose: Define parameters for future testing procedures.
    • See Detailed Design page
    • Summary: Wrote this section to outline some of the concerns when testing. Testing will be critical to verify our assumptions.
  5. Batteries - Theoretical Models
    • Purpose: Define amount of static pressure that the fans most overcome through the system.
    • See Detailed Design page.
    • Summary: Worked with Caitlin on the initial heat transfer problem. We worked for several hours coming up with the solution. We made some very large assumptions (because the geometry of the box makes it difficult to model effectively) and although we aren't entirely confident the static pressure is accurate it was helpful in establishing parameters for fan benchmarking.
  6. Batteries - Benchmarking
    • Purpose: Benchmark different thermal insulation to use as a sealant and as the internal barrier in the batteries.
    • Insulation Benchmarking
    • Summary: One of the concerns with the selected material, the ultra flexible foam rubber, is that it wont fit or wont be easy to work with to act as a barrier within the battery box. Another concern, which was not made aware of during the benchmarking, was that UL fire rating is also important. A review of the material and subsequent testing will be required to ensure that this material is the right option. This was difficult to determine, however, without ordering the sample and trying them out.
  7. Batteries - Procurement
    • Purpose: Define manufacturing process for the supplementary components of the battery structure.
    • See Detailed Design page.
    • Summary: One of the largest issues with our construction is that it has never been done before, and as such there will be some efficiency issues that go along with any new manufacturing process. This is especially true for the battery structures, which I anticipate will take much longer to complete than the Hot Wheelz Team is allotting for, and that as a result our schedule will also be pushed back. It will be important to work with the team when building the sub-systems to ensure that both of our teams stay on track.
  8. Batteries - Test Plans
    • Purpose: Define plans to test the battery sub-system.

Battery Test Plan

Efficiency for Detailed Design
Section Time Spent (mins) Projected Time (mins) Efficiency
Finalized Concept Selection 2,800 720 25.7%
Testing So Far 1440 300 20.8%
Testing to be Done 90 30 33.3%
Theoretical Models 1080 120 11.1%
Benchmarking 240 60 25.0%
Procurement 240 60 25.0%
Test Plans 480 120 25.0%
Overall 6370 1410 22%

Gate Review/MSD I notes

  1. Work to be completed
    • New Panel Concept - Based on our final review, there was concerns with one panel in particular on the rear pack, and that the panel should be bent and screwed in rather than try and epoxy tabs to the battery structure. Additionally, based on a review of our design with the Hot Wheelz Team, concerns arose over the use of screws in the battery structure. The concern was that the structure was already weak (with tight tolerances between several of the batteries and the edge of the structure) and that screws would further weaken it. Industrial Velcro was suggested over screws. A re-design of the panels is needed, as well as a different construction method. I have concerns with the Velcro, specifically related to air sealing, but I understand the concerns of the team. Based on a conversation with my father, an alternative design for the battery structures could solve both the structural and mounting issues that have been brought up. GE iron grip is a possible silicon based adhesive that could be used. A 'C' shaped structure, where the ends of the poly carbon are bent so that the structure resembles a c shape, is another possible solution. Using a box pan finger break over a hot wire also might be a good solution to bend the panels and or structures.
    • Battery jig - Another area of concern is the jig that will be used to assemble the battery structures. One of my first ideas was to use a piece of plywood with holes in it that would align with the batteries to keep them straight for installation. Based on a conversation with my father, he suggested using the same CNC to mill out the holes so that it was accurate to the model that the team has of the box. Whether this will be completed by the Hot Wheelz team or our team is yet to be decided, but this will be an important component for construction in the next phase.
    • Light rig/table - Further design refinement for the light rig, as well as light construction, is needed. Based on a conversation with my father, using a terminal strip might be a good way to wire the lights in series. This way it will be easy to connect and disconnect the lights. Additionally, a way to mount and protect users from the heat of the lights is needed. The lights will likely get very hot, and making sure that people don't hurt themselves and get burnt it important. I hope the rig will be constructed by the next phase so that it is ready to be used on the sub-system. Additionally the table to hold up the rear packs needs to be designed and built. I'm not expecting this to be difficult, but it is another small project that would be good to get out of the way before the next phase.
  2. Learning from MSD I
    1. 4 A's - Learning how to apply the 4 A's (Anticipate, Avoid, Abate and Accommodate) has been extremely helpful for designing the car. At the beginning of the semester this was not something I thought about, but as I was helping to construct the test battery rig I was thinking about how sealing would probably be difficult when we were constructing it in addition to thinking about the final battery structure construction. As mentioned, what I'm most worried about for next phase has to do with anticipating problems with battery structure construction, and I've spent a lot of time trying to come up with alternatives to make this process easier and faster. I find myself approaching many other problems by applying the 4 A's, and I think this is has improved my overall efficiency.
    2. Team work - Learning how to be part of engineering team was another learning experience. I've been on teams before, but it has either been a sport's team (which has different set of objectives) or a small class project (where the goal was to get a good grade). In senior design, the goal was to make a product that works well, and this change in dynamic came with it a change in how I was a team member. One of the biggest aspects of this for me was listening. In a lot of the other teams I've been on, it often feels like individuals that work on the same thing but not together. But to get the best product you have to work together, and that requires listening. Sometimes you don't always have the best idea, and getting feedback on your idea and or listening to what someone else has to say, and maybe conceding your own idea to theirs, is important to working effectively and creating the best solutions. Learning to listen was very important to me to try and be a good teammate, and I think we came up with some good solutions as a result.
    3. Time management - Another aspect that played into my efficiency is how I'm spending my limited time. I've always struggled with this skill and I've been working on it since I first started attending college. MSD has helped me to prioritize what I should be working on, and for how long. This comes from understanding when something is 'good enough' so that specific tasks don't drag out for a long time. The best learning experience I had with this was with the dyno, when we spent 3 weeks trying to get it to work rather than moving on and trying something else. From that I learned that remembering to stay on task, and use my time efficiently, was as important as what I was actually working on.
  3. Improvements for MSD II
    • One of the largest struggles this semester was communication between the guide and the team. It was very difficult for us, especially in the beginning, to understand what your expectations were and how we could meet them. This is especially true of the metrics of quality. Often it was very difficult to understand what your were saying or what your were expecting from us for a particular phase. A way that we can improve this for next phase is for us to be more clear when we don't understand something and say directly 'we don't know what your expecting of us'. I think from your perspective when we don't understand something it is important to update that particular item, most notably the metrics of quality, so that for future teams there can be a better understanding of what is going on.

Senior Design II

Subsystem Level Prep (Weeks 1-2)

Subsystem Level Build & Test (Weeks 3-5)

Subsystem and Systems Level Build, Test & Integrate (Weeks 6-8)

Systems Level Build, Test & Integrate (Weeks 9-11)

Verification & Validation (Weeks 12-15)