Sponsors: DARPA (ICECool Fundamentals Program), IBM
Collaborators: Santiago Group, Raytheon Integrated Defense Systems, IBM
Students: Tom Dusseault, Matt Hoffman, Ken Lopez, Prof. Damena Agonafer, Prof. Yoonjin Won (UC Irvine), Dr. Michael Barako
The development of high performance heat exchangers has enjoyed a long tradition of research at Stanford University dating back to the early work by Kays and London (Compact Heat Exchangers, 1984) and the progress by Tuckerman and Pease on the first microchannel heat sink (Electron Device Letters, 1980).
Here we honor and extend that tradition by exploring the extreme heat flux limits for the most challenging thermal management problems of our time, including GaN-based HEMT radar electronics and MW semiconductor lasers with local power densities exceeding 30kW/cm2. The primary novelty of our approach is phase separation – an extension of our earlier work using teflon membranes (see pubs below) – by means of a nanostructured copper bilayer. We integrate this with a distributed fluid inlet/outlet manifold, developed by Cooligy (our Stanford spin-off startup) for heat sinks found in the Apple G5 workstations. By combining distributed manifolding with phase separation, we target the absolute lower bound liquid film thickness and minimize the pressure drops and instabilities that plague conventional convective boiling. To target the absolute limits of hotspot cooling, the last phase of the project is to manufacuture the relevant portion of the heat sink using synthetic diamond with thermal conductivity exceeding 1000 W/mK.
This research activity engages multiple students focussing on boiling fundamentals, surface chemistry and phase separation in the porous bilayer, transport in variable-permeability porous media, and micro/nanofabrication. There are strong simulation and experimental components, as well as an active cooperation with the Santiago group and with Raytheon.
Visitors to this web page who have an interest in convectve cooling and microfluidics might also be interested in our archived projects (bottom of project page) on nanofluid heat transfer, hotspot cooling, and electroosmotic microchanel heat sinks.