dr. michael ohadi

professor

director of smart and small thermal systems lab

university of maryland

this lecture will discuss development of a self-contained two-phase flow system suitable for cooling electronics in a wide range of applications. the investigated technology involves use of an innovative, forced-fed evaporation and condensation technique that has shown promising potential in cooling of low volume, complex high flux electronics for both commercial and military applications. the technique has the potential to replace conduction cold plates in many other applications which require high heat dissipation rates and a high degree of reliability.
the technique utilizes high performance micro-structured surfaces consisting of alternating fins and channels, coupled with a force-fed mechanism in the evaporator and condenser. the force-fed mechanism provides a highly vigorous micro-channel convective heat transfer environment with the net effect of substantially higher heat transfer coefficients without the high pressure drop penalties that are normally associated with such flows. our recent results demonstrate dissipation heat flux levels well above 300 w/cm² with corresponding heat transfer coefficient of close to 90,000 100,000 w/m²-k, using hfe-7100 as the working fluid. for the condensation mode, the force-fed method produces heat fluxes up to 58 w/cm² with a heat transfer coefficient of 32,000 w/m²-k using hfe-7100.