Flow boiling of R245fa in a microgap with integrated staggered pin fins

Abstract

We present an experimental study of two phase flow of refrigerant R245fa in a pin fin enhanced microgap for a range of heat fluxes between 151 W/cm2 to 326 W/cm2. The gap has a base surface area of 1cm × 1cm and height of 200 μm. An array of hydrofoil shaped pin fins covers from bottom to top of the microgap. The pin fins have chord length, longitudinal pitch, and transversal pitch of 75μm, 450μm and 225μm, respectively. On the back side of the chip, four platinum heaters are fabricated and electrically powered in series to enable two phase flow in the microgap, which was part of a pumped flow loop. Heater and surface temperature data were obtained versus heat flux dissipated. Flow visualization was performed using a high speed camera in the heat flux range from 151 W/cm2 to 326 W/cm2. The amount of heat loss across the test section is also provided.