An Experimental Study of the Enhancement of Air-Cooling Limits for Telecom/Datacom Heat Sink Applications Using an Impinging Air Jet

2005 ◽  
Vol 128 (2) ◽  
pp. 166-171 ◽  
Author(s):  
Eric Sansoucy ◽  
Patrick H. Oosthuizen ◽  
Gamal Refai-Ahmed
Keyword(s):  
Experimental Study ◽  
Flat Plate ◽  
Heat Sink ◽  
Target Surface ◽  
Junction Temperature ◽  
Air Cooling ◽  
Nusselt Numbers ◽  
Air Jet ◽  
Numerical Predictions ◽  
Nozzle Plate

An experimental study was conducted to investigate the heat transfer from a parallel flat plate heat sink under a turbulent impinging air jet. A horizontal nozzle plate confined the target surface. The jet was discharged from a sharp-edged nozzle in the nozzle plate. Average Nusselt numbers are reported for Pr=0.7, 5000⩽Re⩽30,000, L∕d=2.5, and 0.833 at H∕d=3 where L, H, and d define the length of the square heat source, nozzle-to-target spacing, and nozzle diameter, respectively. Tests were also conducted for an impinging flow over a flat plate, flush with the top surface of the target plate. The average Nusselt numbers from the heat sink were compared to those for a flat plate to determine the overall performance of the heat sink in a confined impingement arrangement. The experimental results were compared with the numerical predictions obtained in an earlier study. Although the average Nusselt numbers obtained from numerical simulations differed from the experimental measurements by 18%, the disagreement is much less significant when related to the junction temperature. Under typical conditions, it was shown that such discrepancy in the Nusselt number lead to an error of 6% in the prediction of the junction temperature of the device.

Enhancement of Air Cooling Limits for Telecom Heat Sink Applications Using Impinging Air Jets

2003 ◽  
Author(s):  
Eric Sansoucy ◽  
Patrick H. Oosthuizen ◽  
Gamal Refai-Ahmed
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Heat Sink ◽  
Numerical Study ◽  
Target Surface ◽  
Air Cooling ◽  
Air Jet ◽  
Model Average ◽  
Nozzle Plate ◽  
Target Spacing

A numerical study was carried out to investigate the heat transfer rate from a parallel flat plate heat sink under a turbulent impinging air jet. The target surface was confined by a horizontal nozzle plate. The jet was discharged from a sharpedged nozzle in the nozzle plate. The numerical model included the standard k-ε turbulence model. Average Nusselt numbers are reported for Pr = 0.7, 5000 ≤ Re ≤ 30000, L/d = 2.5 and 0.833 at H/d = 3 where L, H and d define the length of the square heat source, nozzle-to-target spacing and nozzle diameter, respectively. Enhancements of heat transfer rates, relative to the bare heat source, were found to vary from 1.9 to 3.5 and 4.1 to 12.0 in the presence of a base and a heat sink, respectively. The coefficient of enhancement was strongly dependent on the Re. The spacing H/d was also altered for L/d = 2.5 at Re = 30000. The enhancement in heat transfer due to the heat sink was shown to increase slightly with nozzle-to-target spacing. The Nusselt number was correlated in terms of Re, fluid properties and geometric parameters of the configuration.

Mixed Convection of Impinging Air Cooling Over Heat Sink in Telecom System Application

2004 ◽  
Vol 126 (4) ◽  
pp. 519-523 ◽  
Author(s):  
Siddharth Bhopte ◽  
Musa S. Alshuqairi ◽  
Dereje Agonafer ◽  
Gamal Refai-Ahmed
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Mixed Convection ◽  
Heat Sink ◽  
Three Dimensional ◽  
Source Surface ◽  
Air Cooling ◽  
Transfer Rates ◽  
Nusselt Numbers ◽  
Air Jet

The current numerical investigation will examine the effect of an impinging mixed convection air jet on the heat transfer rate of a parallel flat plate heat sink. A three-dimensional numerical model was developed to evaluate the effects of the nozzle diameter d, nozzle-to-target vertical placement H/d, Rayleigh number, and the jet Reynolds number on the heat transfer rates from a discrete heat source. Simulations were performed for a Prandtl number of 0.7 and for Reynolds numbers ranging from 100 to 5000. The governing equations were solved in the dimensionless form using a commercial finite-volume package. Average Nusselt numbers were obtained, at H/d=3 and two jet diameters, for the bare heat source, for the heat source with a base heat sink, and for the heat source with the finned heat sink. The heat transfer rates from the bare heat source surface have been compared with the ones obtained with the heat sink in order to determine the overall performance of the heat sink in an impingement configuration.

Mixed Convection of Impinging Air Cooling Over Heat Sink in Telecom System Application

2003 ◽  
Author(s):  
Musa S. Alshuqairi ◽  
Gamal Refai-Ahmed ◽  
Dereje Agonafer
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Mixed Convection ◽  
Heat Sink ◽  
Three Dimensional ◽  
Air Cooling ◽  
Transfer Rates ◽  
Nusselt Numbers ◽  
Air Jet ◽  
Discrete Heat Source

The current numerical investigation will examine the effect of an impinging mixed convection air jet on the heat transfer rate of a parallel flat plate heat sink. A three-dimensional numerical model was developed to evaluate the effects of the nozzle diameter (d), nozzle-to-target vertical placement (H/d), Rayleigh number and the jet Reynolds number on the heat transfer rates from a discrete heat source. Simulations were performed for a Prandtl number of 0.7 and for Reynolds numbers ranging from 100 to 5000. The governing equations were solved in the dimensionless form using a commercial finite-volume package. Average Nusselt numbers were obtained, at H/d = 3 and two jet diameters, for the bare heat source, for the heat source with a base heat sink and for the heat source with the finned heat sink. The heat transfer rates from the bare heat sources surface have been compared with the ones obtained with the heat sink in order to determine the overall performance of the heat sink in an impingement configuration.

Experimental and Numerical Study of Methanol-Water Mixture Single-Phase Heat Transfer in a Micro-Channel Heat Sink

2012 ◽  
Author(s):  
Chun K. Kwok ◽  
Matthew M. Asada ◽  
Jonathan R. Mita ◽  
Weilin Qu
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Heat Sink ◽  
Single Phase ◽  
Numerical Study ◽  
Pure Water ◽  
Molar Fraction ◽  
Water Mixture ◽  
Micro Channel ◽  
Numerical Predictions

This paper presents an experimental study of single-phase heat transfer characteristics of binary methanol-water mixtures in a micro-channel heat sink containing an array of 22 microchannels with 240μm × 630μm cross-section. Pure water, pure methanol, and five methanol-water mixtures with methanol molar fraction of 16%, 36%, 50%, 63% and 82% were tested. Key parametric trends were identified and discussed. The experimental study was complemented by a three-dimensional numerical simulation. Numerical predictions and experimental data are in good agreement with a mean absolute error (MAE) of 0.87%.

Thermal Performance Evaluation of Friction Stir Welded Flat Plate Heat Sink Using CFD Analysis

2015 ◽  
Vol 787 ◽  
pp. 505-509
Author(s):  
A.K. Lakshminarayanan ◽  
M. Suresh
Keyword(s):  
Flat Plate ◽  
Heat Sink ◽  
High Efficiency ◽  
Base Plate ◽  
Software Tool ◽  
Cover Plate ◽  
Air Cooling ◽  
Cooling Systems ◽  
Plate Heat ◽  
Friction Stir

In an era of compact cooling requirements, where air cooling systems seem to be ineffective and consistently, being replaced by liquid cooled systems, with greater watt density heat energy dissipation. Such cooling systems must work with good quality enabling high efficiency. Hence, an attempt is made to fabricate an aluminum alloy based flat plate heat sink with cover and base plate using friction stir welding. The base plate is machined to obtain channels for fluid flow and the cover plate is fitted in the base plate and welded. Two such configurations of these heat sinks were fabricated with varying channel lengths and number of channels. The flow characteristics of the model for these configurations were analyzed numerically using computational fluid dynamics (CFD) software tool, ANSYS fluent 14.

Experimental and Computational Characterization of a Heat Sink Tester

2007 ◽  
Author(s):  
Aalok Trivedi ◽  
Nikhil Lakhkar ◽  
Madhusudhan Iyengar ◽  
Michael Ellsworth ◽  
Roger Schmidt ◽  
...  
Keyword(s):  
Heat Sink ◽  
Accurate Determination ◽  
Thermal Characterization ◽  
High Heat ◽  
Heat Fluxes ◽  
Thermal Design ◽  
Heat Sinks ◽  
Junction Temperature ◽  
Air Cooling

With the continuing industry trends towards smaller, faster and higher power devices, thermal management continues to be extremely important in the development of electronics. In this era of high heat fluxes, air cooling still remains the primary cooling solution in desktops mainly due to its cost. The primary goal of a good thermal design is to ensure that the chip can function at its rated frequency or speed while maintaining the junction temperature within the specified limit. The first and foremost step in measurement of thermal resistance and hence thermal characterization is accurate determination of junction temperature. Use of heat sinks as a thermal solution is well documented in the literature. Previously, the liquid cooled cold plate tester was studied using a different approach and it was concluded that the uncertainty in heat transfer coefficient was within 8% with errors in appropriate parameters, this result was supported by detailed uncertainty analysis based on Monte-Carlo simulations. However, in that study the tester was tested computationally. In this paper, testing and characterization of a heat sink tester is presented. Heat sinks were tested according to JEDEC JESD 16.1 standard for forced convection. It was observed that the error between computational and experimental values of thermal resistances was 10% for the cases considered.

On numerical investigation of nonuniformity in cooling characteristic for different materials of target surfaces being exposed to impingement of air jet

2017 ◽  
Vol 08 (03) ◽  
pp. 1750024 ◽  
Author(s):  
Siddique Mohd Umair ◽  
Nitin Parashram Gulhane
Keyword(s):  
Heat Transfer ◽  
Thermal Diffusivity ◽  
Flow Regime ◽  
Heat Sink ◽  
Heat Storage ◽  
Material Selection ◽  
Radial Distance ◽  
Jet Impingement ◽  
Target Surface ◽  
Air Jet

Heat transfer using air jet impingement technique is one of the conspicuous tasks in the looming world of electronic packaging system. Here, the material selection of heat sink becomes one of the prior and important assignments to construct a heat sink with desired characteristic cooling rate. In order to study the material effect of heat sink over the cooling characteristic, the present work takes an initiative in plotting the Nusselt magnitude over the radial distance for different material of heat sink. This is done by computing the flow regime and heat transfer characteristic of a 2D axis symmetric geometry in commercial simulating software, ANSYS CFX. The computation of cooling characteristic in form of Nusselt profile is done using SST + Gamma–theta turbulence model. Since the prediction of heat interaction due to the intermediacy and transition in the flow regime is a unique issue of this problem. The results for Nusselt curve signifies a tangible elevation in local Nusselt value (nonuniformity) with decrease in thermal diffusivity of target surface. Also the nonuniformity is observed to vanish above a critical range (66.76[Formula: see text]mm2/s) of thermal diffusivity. This happens due to presences of abnormal turbulence of heat flow which occurs inside the target surface. Since the variation in thermal diffusivity causes some imbalance competition between the heat storage and dissipation capabilities. Above all the target surface carrying thermal diffusivity less than 66.76[Formula: see text]mm2/s possesses a dominating heat storage capability, on behalf of which some heat transfer occurring in near jet and far jet regions are being restricted. These are transferred towards stagnation region in radial direction.

Experimental Study of Laminar Heat Transfer to In-Tube Flow of Non-Newtonian Fluids

1980 ◽  
Vol 102 (3) ◽  
pp. 397-401 ◽  
Author(s):  
S. D. Joshi ◽  
A. E. Bergles
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Circular Tube ◽  
Tube Flow ◽  
Temperature Dependent ◽  
Nusselt Numbers ◽  
Numerical Predictions ◽  
Uniform Wall ◽  
Uniform Wall Heat Flux ◽  
Newtonian Behavior

An experimental study is reported of heat transfer to laminar flow of two water-methocel pseudoplastic (power law) solutions in a circular tube subjected to a uniform wall heat flux. The object of this study was to evaluate the effects of non-Newtonian behavior and temperature-dependent consistency on heat transfer. The experimental Nusselt numbers are compared with numerical predictions and experimental data. Two correlations are recommended according to the temperature-dependence of the rheological characteristics.

scholarly journals Cold Zone Exploration Using Position of Maximum Nusselt Number for Inclined Air Jet Cooling

2017 ◽  
Vol 64 (4) ◽  
pp. 533-549 ◽  
Author(s):  
Sunil B. Ingole ◽  
K. K. Sundaram
Keyword(s):  
Reynolds Number ◽  
Nusselt Number ◽  
Leading Edge ◽  
Jet Impingement ◽  
Target Surface ◽  
Air Cooling ◽  
Cold Zone ◽  
Jet Cooling ◽  
Air Jet ◽  
Cold Spots

Abstract Inclined jet air cooling can be effectively used for cooling of electronics or other such applications. The non-confined air jet is impinged and experimentally investigated on the hot target surface to be cooled, which is placed horizontally. Analysis and evaluations are made by introduction of a jet on the leading edge and investigated for downhill side cooling to identify cold spots. The jet Reynolds number in the range of 2000 ≤ Re ≤ 20 000 is examined with a circular jet for inclination (Θ) of 15 < Θ < 75 degree. Also, the consequence of a jet to target distance (H) is explored in the range 0:5 ≤ H/D ≤ 6.8. For 45 degree jet impingement, the maximum Nusselt number is widely spread. Location of maximum Nusselt number is studied, which indicates cold spots identification. At a higher angle ratio, the angle is the dominating parameter compared to the Reynolds Number. Whereas at a lower angle ratio, the inclined jet with a higher Reynolds number is giving the cooling point away from leading edge. It is observed that for a particular angle of incident location of maximum Nusselt Number, measured from leading edge of target, is ahead than that of stagnation point in stated conditions.

An Improved Optimization Approach for Thermoelectric Refrigeration Applied to Portable Electronic Equipment

2005 ◽  
Author(s):  
Robert A. Taylor ◽  
Gary L. Solbrekken
Keyword(s):  
Heat Sink ◽  
Waste Heat ◽  
Temperature Drop ◽  
Heat Sinks ◽  
Junction Temperature ◽  
Air Cooling ◽  
Optimization Approach ◽  
Operating Current ◽  
Te Modules ◽  
Module Geometry

The electronics industry has relied heavily on air cooling to dissipate waste heat. Each new generation of technology is smaller and more powerful, pushing the limits of air-cooled heat sinks. A competing constraint is that the thermal solutions need to be smaller and lighter, particularly for portable devices. A viable strategy to extend the limits of air-cooled heat sinks in a mass effective way is thermoelectric (TE) cooling. In general, the limiting COP of currently available TE materials requires that TE modules be operated at near optimum conditions. The conventional approach for optimizing TE modules ignores external irreversibilities, such as the heat sink temperature drop between the TE hot side and the ambient. The current study reviews two schemes for optimizing the operating current and compares their performance. The comparison between the COP maximizing current and the junction temperature minimizing current identifies where the two approaches yield the exact same performance. Performance regimes are then identified where the junction temperature minimizing approach provides an advantage over the COP maximizing approach. A significant extension of the current modeling activity over previous studies is allowing the TE module geometry to be optimized in addition to the operating current. When the TE module geometry is allowed to be optimized, it is found that using TE refrigeration operating at the junction temperature minimizing current will always have a performance benefit relative to a heat sink alone. The way this performance is achieved at higher heat loads is that the TE module elements must be made very thin.

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