Pitch and aspect ratio effects on single-phase heat transfer through microscale pin fin heat sinks

Abstract Heat transfer and pressure drop of single-phase liquid flow is characterized in eight micro pin fin heat sinks with varied pitch and aspect ratios. The pins are diamond shaped with respect to the flow and have transverse pitch-to-diameter ( S T / D h ) and aspect ( H pin / D h ) ratio variations in the range of 1.7–3.0 and 0.7–3.2, respectively. The fluid used is PF-5060 over a Reynolds numbers (based on pin fin hydraulic diameter) range of 8–1189. Flow visualization is performed on all the heat sinks and flow transition into unsteady vortex shedding is observed only in those with specific pitch and aspect ratios. Flow visualization reveals upstream propagation of the onset of vortex shedding along the length of heat sink with an increase in Reynolds number. The existence of vortex shedding in micro pin fin heat sinks affects the prediction error of heat transfer correlations in literature. To address this gap, together with data from a prior study using liquid nitrogen [1], separate correlations are developed to predict Nu in the steady and unsteady regimes. The resulting correlation for the unsteady regime shows significantly decreased dependency of Nusselt on the Prandtl number compared to the non-vortex-shedding condition.

[1]  D. Tuckerman.  Heat-transfer microstructures for integrated circuits , 1984 .

[2]  T. Brunschwiler,et al.  Vortex shedding from confined micropin arrays , 2013 .

[3]  V. Narayanan,et al.  Single-Phase Cryogenic Flow and Heat Transfer Through Microscale Pin Fin Heat Sinks , 2016 .

[4]  Donald C. Price,et al.  Performance of pin fin cast aluminum coldwalls, Part 2: Colburn j-factor correlations , 2002 .

[5]  A. Koşar,et al.  Forced convective heat transfer across a pin fin micro heat sink , 2005 .

[6]  Issam Mudawar.  Assessment of high-heat-flux thermal management schemes , 2001 .

[7]  A. Koşar,et al.  Laminar Flow Across a Bank of Low Aspect Ratio Micro Pin Fins , 2005 .

[8]  H. Rothuizen,et al.  Interlayer cooling potential in vertically integrated packages , 2008 .

[9]  T. Brunschwiler,et al.  Microvortex-enhanced heat transfer in 3D-integrated liquid cooling of electronic chip stacks , 2013 .

[10]  Robert J. Moffat,et al.  Describing the Uncertainties in Experimental Results , 1988 .

[11]  R. Cardenas,et al.  A Generalized Critical Heat Flux Correlation for Submerged and Free Surface Jet Impingement Boiling , 2014 .

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

[13]  R. Pease,et al.  High-performance heat sinking for VLSI , 1981, IEEE Electron Device Letters.

[14]  A. Koşar,et al.  Convective flow of refrigerant (R-123) across a bank of micro pin fins , 2006 .

[15]  T. Brunschwiler,et al.  Experimental investigation into vortex structure and pressure drop across microcavities in 3D integrated electronics , 2011 .

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

[17]  W. Qu,et al.  Liquid Single-Phase Flow in an Array of Micro-Pin-Fins—Part I: Heat Transfer Characteristics , 2008 .

[18]  Donald C. Price,et al.  Performance of Pin Fin Cast Aluminum Coldwalls, Part 1: Friction Factor Correlations , 2002 .

[19]  R. Prasher,et al.  Nusselt Number and Friction Factor of Staggered Arrays of Low Aspect Ratio Micropin-Fins Under Cross Flow for Water as Fluid , 2007 .

[20]  A. Koşar,et al.  TCPT-2006-096.R2: Micro Scale pin fin Heat Sinks —Parametric Performance Evaluation Study , 2007, IEEE Transactions on Components and Packaging Technologies.