SUBJECT: Ph.D. Dissertation Defense
   
BY: Justin Broughton
   
TIME: Friday, November 18, 2022, 4:00 p.m.
   
PLACE: https://gatech.zoom.us/j/94812940466, Virtual
   
TITLE: Single-Phase and Boiling Flows in Traditionally and Additive Manufactured Foams for Inverter Thermal Management
   
COMMITTEE: Dr. Yogendra Joshi, Chair (ME)
Dr. Satish Kumar (ME)
Dr. Vanessa Smet (ME)
Dr. Sreekant Narumanchi (NREL)
Dr. Muhannad Bakir (ECE)
 

SUMMARY

Wide-bandgap (WBG) devices are attractive replacements for silicon devices currently used in electric vehicle (EV) inverters due to favorable properties including increased breakdown voltages, faster switching, and higher operating temperatures. These properties allow for smaller packages from device to system levels, but taking full advantage of the benefits requires a system-level reexamination and redesign. The present work examines cooling solutions that could provide improved form factor and thermal management in EV inverters. Metal foams are appealing due to their high specific surface area, high thermal conductivity, and low relative density. Combining this with additive manufacturing (AM) leverages the aforementioned advantages along with those of AM, including eliminating thermal attachment materials and allowing for complex designs. Traditionally manufactured metal foams were compared to additive manufactured metal foam samples. Post experimental validation, additional numerical models investigated the flow behavior, effect of varying attachment thermal conductivities, and interfacial heat transfer. Representative geometries were used in conjunction with volume-averaged flow simulations to evaluate metal foams as a thermal management solution for inverters, and to demonstrate AM foams' ability for targeted cooling. Boiling simulations examined multiple geometric modifications to microchannels. Resulting heat transfer and pressure drop changes were quantified, with bubble dynamics providing insight into microscale flow boiling phenomena while laying the groundwork for future boiling simulations in AM foams. Experimental and numerical work investigated flow boiling in AMMFs with vapor pathways for efficient bubble removal. Experimentally validated simulations demonstrated the advantages of AM, particularly with regards to pressure drop. Changes in bubble dynamics resulting from pathway integration were investigated using the numerical models.