The miniaturization of power electronics is a key obstacle in the advancement and proliferation of electric aircraft and vehicles. Electrification of transportation helps safeguard the environment and mitigates climate change. The power density and consequently the miniaturization of power electronics is ultimately limited by the ability to remove heat. More effective and reliable cooling mechanisms for heat sources with small surface area are needed. For example, power semiconductor switches that have the highest power density are directly connected without packaging offering the lowest cost, failure rate, and thermal resistance. These advantages are often undone by inadequate thermal transfer from the surface of the chip. Immersion cooling is known to provide the most reliable and highest performance thermal interface for chip-scale devices; however, conventionally, immersion cooling relies on gravity-dependent (physical-orientation dependent) convection or physical pumping, which limits its application and miniaturization in aviation and mobile applications. Ultimately, the goal of this project is to create a high reliability sealed cooling system with no moving parts. This project will help to support of undergraduate research for women and underrepresented minorities and to uncover new concepts for the classroom in the thermal management of power electronics. The goal of this proposal is to investigate combined methods and materials to greatly enhance the performance of immersion cooling without boiling. This will involve: (1) investigating the combined cooling mechanisms that involve different physics that have not been previously examined and modeled; (2) using new combinations of measurement methods to quantitatively determine the conditions under which the effective heat transfer coefficient is improved; and (3) quantitatively determining the stability of new immersion cooling materials under thermal and physical stress. New materials that undergo phase change without boiling will be studied. Measurement methods will include Schlieren imaging using markers for flow and temperature and direct measurement of the channel temperature of gallium nitride semiconductor devices.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.