Abstract
Wide band-gap (WBG) power devices have been investigated for their higher power densities, efficiencies, and operating temperatures. However, implementation of WBG devices may cause increased volumetric heat generation despite efficiency increases due to a significant decrease in volume. To fully take advantage of the benefits offered by these devices, the packaging, including cooling infrastructure, must also be addressed. Additive manufactured (AM) structures, based on unit cells seen in stochastic foams, have been investigated as an improvement in thermal management for electric vehicle power electronics. Metal foams have a high specific surface area, high thermal conductivity, and low relative density, which makes them excellent for heat transfer applications as demonstrated extensively in prior literature. Additionally, additive manufacturing offers the ability to print directly on a substrate which eliminates a thermal interface layer and make complex structures for little to no increase in cost. Designed foams were examined specifically for their ability to locally control relevant parameters to tailor the heat transfer performance. The design of the AM foam samples, as well as discussion of relevant parameters for proper characterization with respect to thermohydraulic performance, were discussed. Two geometries — one with local, spanwise densification with decreased pore size and another with uniform density and pore size throughout — were investigated for thermal management of several discrete heaters. Pore-scale models with decreased computational domains were used to obtain closure terms for volume-averaged (VA) modeling. The VA models were then used for full-scale modeling of five chip heaters cooled with the designed metal foams.
