GAS-ASSISTED EVAPORATION HEAT AND MASS TRANSFER
Evaporation plays a critical role in nature and many industrial applications. Evaporation has been studied extensively to address extreme thermal challenges in electronics. This chapter presents an overview of evaporation-based cooling techniques, followed by a detailed description and performance characterization of two novel techniques that leverage gas-assisted thin film evaporation. These methodologies combined can potentially address both localized and averaged cooling requirements, which are critical bottlenecks in high-performance microelectronics. One of the techniques utilizes a novel hybrid thermal management device, which improves the performance of conventional air-cooled heat sinks using on-demand and spatially controlled droplet impingement evaporative cooling. The other cooling methodology makes use of microscopically thin liquid films to provide efficient heat and mass transfer. In this technique, the use of nanoporous membranes maintains thin liquid films, minimizing the possibility of dry-out by exploiting capillary confinement of the fluid. In combination with flow of dry air, this arrangement yields record high heat and mass fluxes. A detailed computational analysis is carried out to determine the relative effects of the performance-governing parameters, which is also supported by experiments, using a microscale device supporting gas-assisted thin film evaporation. While the understanding gained in these techniques enables dissipation of high heat fluxes for electronic cooling, it is also relevant in applications relying on efficient evaporation and phase separation such as membrane distillation and climate control systems.
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Illustration of composite TIMs with a percolation of spherical nanoparticles, and high aspect ratio nanowires. NANOSTRUCTURED THERMAL INTERFACES
Photograph of copper/diamond sintered wick structure. RECENT ADVANCES IN TWO-PHASE THERMAL GROUND PLANES
The microchannel with a single pillar used by Jung et al., and an SEM image of the pillar with a flow control slit at 180 deg (facing downstream). ADVANCED CHIP-LEVEL LIQUID HEAT EXCHANGERS
Schematics of thermal boundary conductance calculations. NONEQUILIRIUM MOLECULAR DYNAMICS METHODS FOR LATTICE HEAT CONDUCTION CALCULATIONS
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