Flow visualization of two phase flow of R245fa in a microgap with integrated staggered pin fins

We have visualized two phase flow cooling of R245fa refrigerant in a 1 cm × 1 cm × 200 µm microgap, equipped with circular pin-fins. The device has the microgap with sparse circular pin-fin arrangement of transverse pitch, longitudinal pitch, and pin-fin diameter of 225 µm, 225 µm, and 75 µm, respectively. On the back side of the chip, four integrated platinum heaters are fabricated and are arranged in series. The microgap is installed in a closed flow loop that is pressurized. The inlet flow is subcooled at the elevated pressure. Flow boiling is obtained in the microgap for a range of heat flux values between 7 W/cm2 to 34 W/cm2. Using a high speed camera, flow visualization results are presented for the range of heat flux values.