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Lithium-ion Battery Testing Chamber
Blog Post #4
Work Period November 11-November 25:
For the work period of November 11th - November 25th, Team 20 has focused on completing the remaining thermal analysis and the design of the locking system and the subsequential stress analysis. Once complete, these analysis tasks will provide the team with enough information to accurately select a material for the chamber construction, choose the correct insulation, and accurately design the ventilation system to account for the pressure and gases inside the chamber. Once all technical analysis results have been obtained, Team 20 will be able to begin completing the validation plan. For the locking mechanism we designed an electromagnetic system that activates at thermal runaway and can withstand 400N. We also assigned features to the inside of the chamber including sensor locations and exhaust port. The team is currently working towards completing CFD of gas flow from main chamber to holding chamber as well as working on budget given prices for chamber material and sensors with the changes in funding from Dr. Song.
Final Design and Key Features:
The final design of the lithium ion battery test chamber is a 10x10x10 cube that will comfortably allow testing a maximum of 4 batteries at a time. The material of the chamber, which is arguably the most important aspect to its success, will be stainless steel. Type 316L stainless steel specifically is the material that will be used. Its thermal properties will allow testing at high temperatures that could reach up to 700 C without failure or deformation. Coupled with Ceramic fiber insulation lined up on the inside of the chamber, the outside of the chamber will stay under 30C, which will allow the user to safely touch and use the chamber. Moreover, Type 316L stainless steel has high tensile strength, meaning the chamber could withstand the pressure increase due to gases released by thermal runaway of the batteries. The chamber will also include an electromagnetic lock. It consists of two parts, one will be installed on the top of the chamber frame and the other will be on the chamber door. The purpose of the lock is to keep the door locked in case the user tries to open the chamber while testing is underway. The magnetic lock has a holding force of 527 N and will need to tolerate the pulling force exerted by a human, which is 400 N. In addition, the design includes 4 thermocouples placed on the surface of the batteries and will be connected to the microcontroller. The main function of the thermocouples is to initiate safety measures such as triggering the magnetic lock when the thermal runaway temperature at 150 C is detected.
Analytical Results:
The first key analytical results the team has are the thermal analysis simulation results. Thermal analysis simulations were run using two materials, 316L stainless steel and copper, and ceramic fiber as insulation. The simulation using stainless steel showed that the chamber will successfully withstand the extreme temperatures that could reach up to 700 C. The inside of the chamber will stay at an average temperature of 400 C. In addition, the outside of the chamber will stay below 30 C, validating that it will be safe to touch and use during or after testing.
Tasks Completed Prior to Spring:
To prepare for Capstone II, Team 20 plans to order the electronic components and begin creating the electronic control system before the spring semester begins. This will allow the team to work out compatibility issues between the electronics ahead of time. Furthermore, the programming portion of the project can be dealt with ahead of time to avoid any problems later on in the spring semester during validation testing. The control system will consist of the measuring instruments, electromagnetic lock, and the ventilation fan.
Figures of Progress:
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