To develop a flow regime map for convective boiling in microchannels and to propose flow pattern-based models to predict the corresponding heat transfer coefficients, a thorough understanding of the existing flow patterns and their transitions is necessary. In the present study, high-speed photography is employed to observe the flow patterns in flow boiling of a dielectric liquid, FC-77, in parallel silicon microchannels of depth 400 μm and widths ranging from 100 to 5850 μm. In each test, liquid mass flux and inlet subcooling are fixed at 250 kg/m2s and 5°C, respectively, while the heat flux to the bottom of the heat sink is increased form zero to a value near the critical heat flux. Temperature and pressure are measured at several locations. A high-speed digital video camera is used to observe boiling patterns at frame rates ranging from 2000 to 24000 frames per second (fps). The images presented show a top view of the horizontal microchannels, at a location along the heat sink centerline and near the flow exit.
Date of this Version
T. Harirchian and S. V. Garimella, “Flow Patterns During Convective Boiling in Microchannels,” ASME Journal of Heat Transfer Vol. 130, 080909, 2008.