Stabilization of flow boiling in microchannel heat sinks with a diverging cross-section design

Abstract

This paper explores experimentally stabilizing flow boiling water in ten parallel microchannel heat sinks with a diverging cross-section design. Each diverging microchannel has a mean hydraulic diameter of 120 µm and a diverging angle of 0.5° while the channel depth is uniform at 76 µm. Flow visualization shows that heat flux and mass flux significantly affect the stability of flow boiling in the parallel microchannels. The extent of pressure drop oscillations may be regarded as an index for the onset of flow boiling instability. The stability boundary is plotted on the plane of the subcooling number (Nsub) against the phase change number (Npch) and compared with microchannels with a uniform cross-section design in the literature. The present study confirms that, in terms of stability performance, the flow boiling in the parallel microchannel heat sinks with a diverging cross-section design is superior to a uniform cross-section design.