NSTI Nanotech 2009

On the use of Segmented Flow to Enhance Heat Transfer in Microchannel Heat Sinks

A.R. Betz, D. Attinger
Columbia University, US

Keywords: heat transfer, microfluidics, bubbles, segmented flow

Abstract:

Liquid-cooling in microchannel heat sinks is used in high-power electronics. Single phase flow can remove from 1 to 1000 W/cm2, while evaporative flux can remove up to 10 times more. Boiling, however, increases the pressure drop and creates inconvenient instabilities. In this work, we propose to enhance single-phase cooling by injecting non-condensable air bubbles in a water stream. Circulating wakes behind bubbles have been shown to enhance mass transfer, and should correspondingly enhance convective heat transfer. Indeed our experiments with a polymer heat sink show that the heat transfer coefficient increased up to 140% over single-phase flow. Segmented flow in microchannel heat sinks offers an intermediate step between single-phase and evaporative flow.
 
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