Measurements and modeling of two-phase flow in microchannels with nearly constant heat flux boundary conditions

Two-phase forced convective flow in microchannels is promising for the cooling of integrated circuits. There has been limited research on boiling flow in channels with dimensions below 100 mum, in which bubble formation and flow regimes can differ from those in larger channels. This work develops single and multichannel experimental structures using plasma-etched silicon with pyrex glass cover, which allow uniform heating and spatially-resolved thermometry and provide optical access for visualization of boiling regimes. Boiling was observed with less than 5 degreesC of superheating in rectangular channels with hydraulic diameters between 25 and 60 mum. The channel wall widths are below 350 mum, which minimizes solid conduction and reduces variations in the heat flux boundary condition. Pressure drop and wall temperature distribution data are consistent with predictions accounting for solid conduction and homogeneous two-phase convection.