Enhanced flow boiling heat transfer of FC-72 on micro-pin-finned surfaces

For the purpose of cooling electronic components with high heat flux efficiently, some experiments were conducted to study the flow boiling heat transfer performance of FC-72 on silicon chips. Micro-pin-fins were fabricated on the chip surface using a dry etching technique to enhance boiling heat transfer. Three different fluid velocities (0.5.1 and 2 m/s) and three different liquid subcoolings (15, 25 and 35 K) were performed, respectively. A smooth chip (chip S) and four micro-pin-finned chips with the same fin thickness of 30 mu m and different fin heights of 60 mu m (chip PF30-60) and 120 mu m (chip PF30-120), respectively, were tested. All the micro-pin-finned surfaces show a considerable heat transfer enhancement compared to the smooth one, and the critical heat flux increases in the order of chip S, PF30-60 and PF30-120. For a lower ratio of fin height to fin pitch and/or higher fluid velocity, the fluid velocity has a positive effect on the nucleate boiling curves for the micro-pin-finned surfaces. At the velocities lower than 1 m/s, the micro-pin-finned surfaces show a sharp increase in heat flux with increasing wall superheat, and the wall temperature at the critical heat flux (CHF) is less than the upper limit, 85 degrees C, for the reliable operation of LSI chips. The CHF values for all surfaces increase with fluid velocity and subcooling. The maximum CHF can reach nearly 150 W/cm(2) for chip PF30-120 at the fluid velocity of 2 m/s and the liquid subcooling of 35 K. (C) 2009 Elsevier Ltd. All rights reserved.