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.

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.

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.

Numerical Study on Stagnation Point Heat Transfer by Jet Impingement in a Confined Narrow Gap

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Y. Q. Zu ◽  
Y. Y. Yan ◽  
J. Maltson
Keyword(s):  
Heat Transfer ◽  
Numerical Study ◽  
Computational Cost ◽  
Jet Impingement ◽  
Diameter Ratio ◽  
Eddy Simulation ◽  
Plate Length ◽  
Flow And Heat Transfer ◽  
Air Jet ◽  
Target Spacing

In this paper, the heat transfer characteristics of a circular air jet vertically impinging on a flat plate near to the nozzle (H/d=1–6, where H is the nozzle-to-target spacing and d is the diameter of the jet) are numerically analyzed. The relative performance of seven turbulent models for predicting this type of flow and heat transfer is investigated by comparing the numerical results with available benchmark experimental data. It is found that the shear-stress transport (SST) k−ω model and the large Eddy simulation (LES) time-variant model can give better predictions for the performance of fluid flow and heat transfer; especially, the SST k−ω model should be the best compromise between computational cost and accuracy. In addition, using the SST k−ω model, the effects of jet Reynolds number (Re), jet plate length-to-jet diameter ratio (L/d), target spacing-to-jet diameter ratio (H/d), and jet plate width-to-jet diameter ratio (W/d) on the local Nusselt number (Nu) of the target plate are examined; a correlation for the stagnation Nu is presented.

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.

scholarly journals Local Heat Transfer Distributions in Confined Multiple Air Jet Impingement

2000 ◽  
Vol 123 (3) ◽  
pp. 165-172 ◽  
Author(s):  
Suresh V. Garimella ◽  
Vincent P. Schroeder
Keyword(s):  
Heat Transfer ◽  
Heat Source ◽  
Jet Impingement ◽  
Reynolds Numbers ◽  
Air Jets ◽  
Air Jet ◽  
Multiple Jets ◽  
Single Jet ◽  
Radial Outflow ◽  
Target Spacing

Heat transfer from a discrete heat source to multiple, normally impinging, confined air jets was experimentally investigated. The jets issued from short, square-edged orifices with still-developing velocity profiles on to a foil heat source which produced a constant heat flux. The orifice plate and the surface containing the heat source were mounted opposite each other in a parallel-plates arrangement to effect radial outflow of the spent fluid. The local surface temperature was measured in fine increments over the entire heat source. Experiments were conducted for different jet Reynolds numbers (5000<Re<20,000), orifice-to-target spacing 0.5<H/d<4, and multiple-orifice arrangements. The results are compared to those previously obtained for single air jets. A reduction in orifice-to-target spacing was found to increase the heat transfer coefficient in multiple jets, with this effect being stronger at the higher Reynolds numbers. With a nine-jet arrangement, the heat transfer to the central jet was higher than for a corresponding single jet. For a four-jet arrangement, however, each jet was found to have stagnation-region heat transfer coefficients that were comparable to the single-jet values. The effectiveness of single and multiple jets in removing heat from a given heat source is compared at a fixed total flow rate. Predictive correlations are proposed for single and multiple jet impingement heat transfer.

An Investigation of the Effect of interrupted fin arrangements on the Thermal Performance of a Heat Sink under a Free Convection Condition

2019 ◽  
Vol 7 (1) ◽  
pp. 43-53
Author(s):  
Abbas Jassem Jubear ◽  
Ali Hameed Abd
Keyword(s):  
Heat Transfer ◽  
Steady State ◽  
Natural Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Numerical Study ◽  
Ansys Fluent ◽  
Fluent Software ◽  
Steady State Heat ◽  
Steady State Heat Transfer

The heat sink with vertically rectangular interrupted fins was investigated numerically in a natural convection field, with steady-state heat transfer. A numerical study has been conducted using ANSYS Fluent software (R16.1) in order to develop a 3-D numerical model.  The dimensions of the fins are (305 mm length, 100 mm width, 17 mm height, and 9.5 mm space between fins. The number of fins used on the surface is eight. In this study, the heat input was used as follows: 20, 40, 60, 80, 100, and 120 watts. This study focused on interrupted rectangular fins with a different arrangement and angle of the fins. Results show that the addition of interruption in fins in various arrangements will improve the thermal performance of the heat sink, and through the results, a better interruption rate as an equation can be obtained.

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%.

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