In this work an experimental investigation has been performed to assess the heat transfer characteristics during subcooled flow boiling in diverging and segmented finned microchannels relevant to applications in electronics cooling systems. Experiments have been also performed in uniform cross-section microchannels to compare their performances with other two types of channels configurations. Arrays of microchannel consisting of 12 numbers of channels with rectangular cross-section have been fabricated on individual copper block for these three different geometrical configurations. Deionized water has been used as the working fluid in the experiment. Experiments have been performed mostly in subcooled boiling regions relevant to cooling of electronic components where bulk fluid was below the saturation temperature and the surface temperature was around the saturation temperature of the coolant. The heat transfer characteristics of all three configurations have been compared in terms of heat transfer coefficient and thermal instability during highly subcooled and developed subcooled flow boiling. Although diverging channel performs significantly better in saturated and superheated regions of boiling with high heat flux as observed in literature, in present work its performance has been found slightly better in subcooled boiling regions compared to uniform cross-section channel. Segmented finned channels have shown the best performance both in sensible heating and subcooled region and thus demonstrate high potential for electronics cooling applications.

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