Flow Boiling on Micropin Fins Entrenched Inside a Microchannel—Flow Patterns and Bubble Departure Diameter and Bubble Frequency

Flow boiling of HFE 7000 in five parallel microchannels of 222 μm hydraulic diameter, each containing a single row of 24 in-line 100 μm pin fins, was investigated. High speed photography revealed the dominant flow patterns, namely, the bubbly flow, the multiple flow, and the wavy-annular flow. The interaction of the bubble with the pin fins during nucleate boiling from G=350 kg/m2 s to G=827 kg/m2 s and wall heat fluxes from 10 W/cm2 to 110 W/cm2 is detailed.