The hydrodynamic and heat transfer behavior downstream of a channel obstruction in the laminar flow regime

Abstract Micro-fluidic systems have been proposed as potential solutions for the cooling of next-generation Integrated Circuits (ICs) and Photonics Integrated Circuits (PICs). For PICs, integration of micro-fluidics may enable greater laser-bar array densities and, consequently, greater transmission bandwidth. To cool the μm scale hot-spots produced by the laser-bars, a passively actuated structure situated in a micro-channel could regulate temperature by disturbing flow in a target location as required. To this end, a proof-of-concept passive structure was developed from a Shape Memory Alloy (SMA), and demonstrated at the millimeter scale in previous work. The objective of this study is to measure the heat transfer augmentation at a target surface downstream of the obstruction. Two experiments were performed to measure the flow field and heat transfer downstream of the test pieces in a square miniature channel for a range of obstruction Reynolds numbers (Re ≈ 50–170) and opening area ratios (β ≈ 0.2–0.5): using Particle-Image Velocimetry (PIV) and infrared (IR) thermography of a Joule-heated foil respectively. A 50% improvement was observed in the foil area averaged heat transfer coefficient (relative to the unobstructed channel) for Re w = 176 and β = 0.19 . A correlation was developed to interpolate Nusselt number (Nu) from a given Re and β for the studied geometry, and analysis of the correlated exponents showed an improvement in heat transfer relative to a simple pillar obstruction. This was attributed to the wake that formed downstream of the test pieces. The findings of this work are relevant to the modeling and design of practical micro-fluidic systems for targeted hot-spot cooling in future integrated circuit packaging.

[1]  B. Massey,et al.  Mechanics of Fluids , 2018 .

[2]  P. Giannattasio,et al.  Low Reynolds number flow in rectangular cooling channels provided with low aspect ratio pin fins , 2010 .

[3]  A. Bar-Cohen,et al.  THERMAL SCIENCE AND ENGINEERING - FROM MACRO TO NANO IN 200 YEARS , 2014 .

[4]  S. Kandlikar.  History, Advances, and Challenges in Liquid Flow and Flow Boiling Heat Transfer in Microchannels: A Critical Review , 2012 .

[5]  Frank P. Incropera,et al.  Fundamentals of Heat and Mass Transfer , 1981 .

[6]  A. Koşar,et al.  Thermal-hydraulic performance of MEMS-based pin fin heat sink , 2006 .

[7]  Muhannad S. Bakir,et al.  3D heterogeneous integrated systems: Liquid cooling, power delivery, and implementation , 2008, 2008 IEEE Custom Integrated Circuits Conference.

[8]  Stuart W. Churchill,et al.  Correlations for Laminar Forced Convection with Uniform Heating in Flow over a Plate and in Developing and Fully Developed Flow in a Tube , 1973 .

[9]  S. J. Kline,et al.  Describing Uncertainties in Single-Sample Experiments , 1953 .

[10]  Junkyu Jung.  Physics of active flow control around a pillar at the micro scale , 2011 .

[11]  M. Yovanovich,et al.  Laminar Forced Convection Heat Transfer in the Combined Entry Region of Non-Circular Ducts , 2004 .

[12]  J. Stafford,et al.  The heat transfer performance in a square channel downstream of a representative shape memory alloy structure for microfluidics applications , 2015, 2015 31st Thermal Measurement, Modeling & Management Symposium (SEMI-THERM).

[13]  E. Walsh,et al.  Characterizing convective heat transfer using infrared thermography and the heated-thin-foil technique , 2009 .

[14]  A. Bar-Cohen.  Gen-3 Thermal Management Technology: Role of Microchannels and Nanostructures in an Embedded Cooling Paradigm , 2013 .

[15]  Alexandre Shen,et al.  A Vision for Thermally Integrated Photonics Systems , 2014, Bell Labs Technical Journal.

[16]  Jeff Punch,et al.  On the hydrodynamic characterization of a passive Shape Memory Alloy valve , 2015 .

[17]  E. N. Sieder,et al.  Heat Transfer and Pressure Drop of Liquids in Tubes , 1936 .

[18]  Stéphane Colin,et al.  Heat Transfer and Fluid Flow in Minichannels and Microchannels , 2005 .

[19]  S. Garimella,et al.  A COMPARATIVE ANALYSIS OF STUDIES ON HEAT TRANSFER AND FLUID FLOW IN MICROCHANNELS , 2001, Proceeding of Heat Transfer and Transport Phenomena in Microscale.

[20]  A. Zukauskas.  Heat Transfer from Tubes in Crossflow , 1972 .

[21]  Vanessa Egan,et al.  A statistical analysis for time-averaged turbulent and fluctuating flow fields using Particle Image Velocimetry , 2012 .

[22]  S. Garimella,et al.  TRANSPORT IN MICROCHANNELS - A CRITICAL REVIEW , 2003 .

[23]  Y. Leblebici,et al.  Heat-removal performance scaling of interlayer cooled chip stacks , 2010, 2010 12th IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems.

[24]  Yoav Peles,et al.  Convective heat transfer and mixing enhancement in a microchannel with a pillar , 2013 .

[25]  F. Varas,et al.  Heat transfer enhancement in micro-channels caused by vortex promoters , 2010 .