Mark A. Trautman

Heat Transfer Enhancement Using Synthetic Jets for Cooling in Low Form Factor Electronics in Presence of Mean Flow

This paper reports the results of our experimental studies on interaction of synthetic jets with a bulk flow over a heated surface in a low profile channel as well as its impact on overall heat transfer enhancement. Particle image velocimetry (PIV) studies were conducted to study the impact of jet frequency, mean flow velocity and synthetic jet orientation on the flow and heat transfer characteristics. The results showed an increase in jet velocity and hence heat transfer with an increase in frequency. Reduction in mean flow velocity facilitated entrainment of the synthetic jet and also led to its delayed dispersion. The thermal results were consistent with the flow patterns observed and heat transfer enhancements as high as 30% were observed. However, regions of attenuated heat transfer were also seen in cross-flow which needs careful consideration during thermal design.

Investigation of Microporous Coatings and Mesoscale Evaporator Enhancements for Two-Phase Cooling of Electronic Components

An empirical study of pool nucleate boiling enhanced with a microporous coating was conducted within the context of microprocessor cooling. A thermal test vehicle (TTV) emulated the heat load from a general purpose microprocessor and delivered a moderately nonuniform heat flux density distribution at the boiling surface that would be typical of mainstream microprocessors. The TTV was affixed to a copper test coupon that formed the bottom surface of a sealed boiling chamber containing FC-72 at atmospheric pressure. A design of experiments was conducted on multiple test coupons to identify how the microporous coating, the base thickness of the coupon, and the height of small pin fins affect the combined conduction and boiling heat transfer from the test coupon. The data revealed that the presence of the microporous coating was the most significant factor of the three tested and indicates that the presence of fins as short as 0.5 mm may play a role in reducing hysteresis in the boiling curve.

Investigation of Microporous Coatings and Meso-Scale Structures for Two-Phase Cooling of Electronic Components

An empirical study of pool nucleate boiling enhanced with a microporous coating was conducted within the context of microprocessor cooling. A thermal test vehicle (TTV) emulated the heat load from a general purpose microprocessor and was used to deliver a non uniform heat flux density distribution at the boiling surface. The TTV was affixed to a copper test coupon that formed the bottom surface of a sealed boiling chamber containing FC-72 at atmospheric pressure. A design of experiments was conducted on multiple test coupons to identify how the microporous coating, the base thickness of the coupon, and the height of small pin fins affect the combined conduction and boiling heat transfer from the test coupon. The data revealed that the presence of the microporous coating was the most significant factor of the three tested and that very short fins (0.5 mm) were sufficient to manage hysterisis in the boiling curve.Copyright