Two-phase flow and heat transfer in pin-fin enhanced micro-gaps

Thermal management of integrated circuits (IC) has emerged as one of the key challenges for continued performance enhancement of modern microprocessors. Cooling schemes utilizing two-phase, microfluidic technologies are some of the more promising modular thermal management solutions for next generation devices. In this study, the flow and heat transfer in pin-fin enhanced micro-gaps are experimentally investigated. It has been known that pin-fin structures inside micro-gaps can increase convective heat transfer coefficients in single phase flow conditions. However, two-phase microfluidic cooling is becoming an increasingly popular method in thermal control of electronics, and this cooling strategy has not been well characterized for pin-fin enhanced micro-gaps. Pin-fin, micro-gap structures studied had a pin diameter, height and pitch of 150μm, 200μm and 225μm, respectively, providing an aspect ratio of 1.33. Both the overall micro-gap width and length are 1cm. The working fluid used was R245fa. The structure contained a transparent cover which allowed for visualization of flow through the micro-gap. A high speed camera allowed for image capture and characterization of various two-phase flow regimes. The thermal performances of the heat sink were experimentally evaluated using pressure drop and temperature measurements.