Mechanical Engineering Department
BS in Mechanical Engineering
Lawrence Livermore National Laboratory has invested considerable effort to develop new standard for nuclear grade HEPA filters that can withstand high temperatures along with methods to optimally test not only the experimental filter media, but also new frame seals and media binders. Therefore, LLNL in collaboration with Cal Poly has designed and built a Mini High Temperature Testing Unit (MHTTU) to recreate conditions observed during a fire and to test different materials in an effective, inexpensive, regulated and reliable method. The existing prototype was unable to achieve the ideal testing conditions of 1000°F air at the low flow rates of 1.25-12 ACFM; therefore, this project looks to optimize previous efforts on building a portable and reliable MHTTU to collect more information and perform different tests in various materials utilized in the construction of ceramic HEPA filters. Based on previous teams’ inputs, our team performed a heat transfer analysis to determine critical heat loss points and to optimize the design of the MHTTU. After several idea generation sessions, it was decided to modified the geometry of the testing chamber and the insulation of the system. The MHTTU also lacks a robust control system and a user interface; therefore, a more reliable interface and more versatility during the tests were implemented in the system. With the current design, we were able to improve the maximum temperature of the system to 837°F; however, we were not able to fulfill heat up time of 15 minutes. After carefully recording the temperature of the surrounding material during testing, we believe that the immersion heater is not powerful enough to have an effective heat transfer to air. After testing was completed, it was confirmed that the heater coils cannot reach 1000°F in less than 15 minutes of heat up. Therefore, a more powerful heater is needed to achieve testing parameters.