Implementations of Deflectors to Improve the Performance of Heat Sinks

2012 ◽  
Author(s):  
J. P. Ramirez-Vazquez ◽  
A. Hernandez-Guerrero ◽  
J. L. Zuñiga-Cerroblanco ◽  
J. C. Rubio-Arana
Keyword(s):  
Heat Sink ◽  
Numerical Study ◽  
Electronic Devices ◽  
Constant Heat Flux ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Hydrodynamic Behavior ◽  
Constant Heat ◽  
Pin Fin ◽  
Global Performance

This work presents a numerical study of the thermal and hydrodynamic behavior of a pin-fin heat sink where deflectors are placed along the flow of the coolant air; the effect of the arrangement of the fins and deflectors in the global performance of the heat sink is investigated. The fin geometry analyzed is rectangular, and the arrangement of the fins is inline. The heat sink is placed in a channel in which air flows, and a constant heat flux is applied at the bottom wall of the heat sink with values equivalent to the heat fluxes generated by current electronic devices. Deflectors are placed in the top of the channel in order to drive the air flow into the front and end of the heat sink. The results for the Nusselt number and for the pressure drop along the heat sink are reported. The best dimension of deflectors and pitch for the arrangement based on the thermal and hydraulic performance is attained.

Hydoroil-Based Micro Pin Fin Heat Sink

2006 ◽  
Author(s):  
Ali Kosar ◽  
Chih-Jung Kuo ◽  
Yoav Peles
Keyword(s):  
Heat Sink ◽  
Hydraulic Performance ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Transfer Coefficients ◽  
Pin Fin ◽  
Nusselt Numbers ◽  
Friction Factors ◽  
Pin Fins ◽  
Micro Pin Fins

An experimental study on thermal-hydraulic performance of de-ionized water over a bank of shrouded NACA 66-021 hydrofoil micro pin fins with wetted perimeter of 1030-μm and chord thickness of 100 μm has been performed. Average heat transfer coefficients have been obtained over effective heat fluxes ranging from 4.0 to 308 W/cm2 and mass velocities from 134 to 6600 kg/m2s. The experimental data is reduced to the Nusselt numbers, Reynolds numbers, total thermal resistances, and friction factors in order to determine the thermal-hydraulic performance of the heat sink. It has been found that prodigious hydrodynamic improvement can be obtained with the hydrofoil-based micro pin fin heat sink compared to the circular pin fin device. Fluid flow over pin fin heat sinks comprised from hydrofoils yielded radically lower thermal resistances than circular pin fins for a similar pressure drop.

Pin-Fin Heat Sink With Horizontal Base and Blocked Edges

2008 ◽  
Author(s):  
D. Sahray ◽  
H. Shmueli ◽  
N. Segal ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Contact Resistance ◽  
Cross Section ◽  
Heat Input ◽  
Heat Sink ◽  
Numerical Study ◽  
Heat Sinks ◽  
Transfer Enhancement ◽  
Pin Fin

In the present work, horizontal-base pin fin heat sinks exposed to free convection in air are studied. They are made of aluminum, and there is no contact resistance between the base and the fins. For the same base dimensions the fin height and pitch vary. The fins have a constant square cross-section. The edges of the sink are blocked: the surrounding insulation is flush with the fin tips. The effect of fin height and pitch on the performance of the sink is studied experimentally and numerically. In the experiments, the heat sinks are heated using foil electrical heaters. The heat input is set, and temperatures of the base and fins are measured. In the corresponding numerical study, the sinks and their environment are modeled using the Fluent 6 software. The results show that heat transfer enhancement due to the fins is not monotonic. The differences between sparsely and densely populated sinks are analyzed for various fin heights. Also assessed are effects of the blocked edges as compared to the previously studied cases where the sink edges were exposed to the surroundings.

scholarly journals Cooling Performance of Heat Sinks Used in Electronic Devices

2018 ◽  
Vol 171 ◽  
pp. 02003
Author(s):  
Ibrahim Mjallal ◽  
Hussein Farhat ◽  
Mohammad Hammoud ◽  
Samer Ali ◽  
Ali AL Shaer ◽  
...  
Keyword(s):  
Heat Sink ◽  
Electronic Devices ◽  
Heat Fluxes ◽  
Electronic Cooling ◽  
Heat Sinks ◽  
Passive Cooling ◽  
Short Term ◽  
Cooling Systems ◽  
Thermal Output ◽  
Electrical Devices

Existing passive cooling solutions limit the short-term thermal output of systems, thereby either limiting instantaneous performance or requiring active cooling solutions. As the temperature of the electronic devices increases, their failure rate increases. That’s why electrical devices should be cooled. Conventional electronic cooling systems usually consist of a metal heat sink coupled to a fan. This paper compares the heat distribution on a heat sink relative to different heat fluxes produced by electronic chips. The benefit of adding a fan is also investigated when high levels of heat generation are expected.

Thermal Analysis of Miniature Low Profile Heat Sinks With and Without Fins

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
V. Egan ◽  
P. A. Walsh ◽  
E. Walsh ◽  
R. Grimes
Keyword(s):  
Heat Transfer ◽  
Heat Sink ◽  
Volume Flow Rate ◽  
Electronic Devices ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Superior Performance ◽  
Low Profile ◽  
In Series ◽  
Heat Sink Design

Reliable and efficient cooling solutions for portable electronic devices are now at the forefront of research due to consumer demand for manufacturers to downscale existing technologies. To achieve this, the power consumed has to be dissipated over smaller areas resulting in elevated heat fluxes. With regard to cooling such devices, the most popular choice is to integrate a fan driven heat sink, which for portable electronic devices must have a low profile. This paper presents an experimental investigation into such low profile cooling solutions, which incorporate one of the smallest commercially available fans in series with two different heat sink designs. The first of these is the conventionally used finned heat sink design, which was specifically optimized and custom manufactured in the current study to complement the driving fan. While the second design proposed is a novel “finless” type heat sink suitable for use in low profile applications. Together the driving fan and heat sinks combined were constrained to have a total footprint area of 465 mm2 and a profile height of only 5 mm, making them ideal for use in portable electronics. The objective was to evaluate the performance of the proposed finless heat sink design against a conventional finned heat sink, and this was achieved by means of thermal resistance and overall heat transfer coefficient measurements. It was found that the proposed finless design proved to be the superior cooling solution when operating at low fan speeds, while at the maximum fan speed tested of 8000 rpm both provided similar performance. Particle image velocimetry measurements were used to detail the flow structures within each heat sink and highlighted methods, which could further optimize their performance. Also, these measurements along with corresponding global volume flow rate measurements were used to elucidate the enhanced heat transfer characteristics observed for the finless design. Overall, it is shown that the proposed finless type heat sink can provide superior performance compared with conventional finned designs when used in low profile applications. In addition a number of secondary benefits associated with such a design are highlighted including lower cost, lower mass, lower acoustics, and reduced fouling issues.

Experimental and Numerical Study of Transient Electronic Chip Cooling by Liquid Flow in Microchannel Heat Sink

2010 ◽  
Author(s):  
Jingru Zhang ◽  
Tiantian Zhang ◽  
Yogesh Jaluria
Keyword(s):  
Liquid Flow ◽  
Heat Sink ◽  
Single Channel ◽  
Numerical Study ◽  
Numerical Models ◽  
Heat Removal ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Chip Cooling ◽  
Microchannel Heat Sinks

Cooling of electronic chips has become a critical aspect in the development of electronic devices. Overheating may cause the malfunction or damage of electronics and the time needed for heat removal is important. In this paper, an experimental setup and numerical model was developed to test the effects of different parameters and their influence on the transient electronic chip cooling by liquid flow in microchannel heat sinks. The temperature change with time of the system for different heat fluxes at different flow was determined, from which the response time can be obtained. Three different configurations of multi-microchannel heat sinks were tested during the experiment. Numerical models were then developed to simulate the transient cooling for two of the configurations. A good agreement between the experimental data and numerical results showed that single-channel models are capable of simulating the thermal behavior of the entire heat sink by applying appropriate assumptions and boundary conditions.

scholarly journals A parametric investigation of a PCM-based pin fin heat sink

2015 ◽  
Vol 6 (1) ◽  
pp. 65-73 ◽  
Author(s):  
R. Pakrouh ◽  
M. J. Hosseini ◽  
A. A. Ranjbar
Keyword(s):  
Heat Sink ◽  
Phase Change Materials ◽  
Electronic Devices ◽  
Operating Time ◽  
Heat Sinks ◽  
Geometrical Parameters ◽  
Base Temperature ◽  
Pin Fin ◽  
Heat Transfer Calculation ◽  
Acceptable Agreement

Abstract. This paper presents a numerical investigation in which thermal performance characteristics of pin fin heat sinks enhanced with phase-change materials (PCMs) designed for cooling of electronic devices are studied. The paraffin RT44 HC is poured into the aluminum pin fin heat sink container, which is chosen for its high thermal conductivity. The effects of different geometrical parameters, including number, thickness and height of fins, on performance are analyzed. Different aspects for heat transfer calculation, including the volume expansion in phase transition as well as natural convection in a fluid zone, are considered in the study. In order to validate the numerical model, previous experimental data and the present results are compared, and an acceptable agreement between these two is observed. Results show that increasing the number, thickness and height of fins leads to a significant decrease in the base temperature as well as operating time of the heat sink.

On the Characterisation of Finned and Finless Heat Sinks for Portable Electronics

2007 ◽  
Author(s):  
V. Egan ◽  
P. Walsh ◽  
E. Walsh ◽  
R. Grimes
Keyword(s):  
Thermal Resistance ◽  
Heat Sink ◽  
Electronic Devices ◽  
Heat Fluxes ◽  
Heat Sinks ◽  
Axial Fan ◽  
Maximum Heat ◽  
Maximum Heat Transfer ◽  
Low Profile ◽  
Profile Height

Reliable and efficient cooling solutions for portable electronic devices are now at the forefront of research due to consumer demand for manufacturers to downscale their existing technologies. The power required for these technologies now has to be dissipated over smaller areas resulting in elevated heat fluxes. The most popular choice among engineers in terms of cooling solutions is to integrate a fan with a heat sink and for portable electronic devices this involves the use of a low profile solution. In this paper an experimental investigation on the thermal performance of a finned and finless heat sink integrated with an axial fan, for the purpose of cooling a microchip, is presented. The objective is to characterise the performance of each heat sink in terms of thermal resistance and to develop an understanding of the flow structures in such systems. One of the smallest commercially available fans is used in conjunction with each heat sink giving a total footprint area of 465m2 and profile height of 5mm. Thermal resistances are measured over a range of fan speeds and detailed velocity measurements were taken of the flow within the heat sinks using Particle Image Velocimetry (PIV). The thermal analysis results indicate that the thermal resistance of the system is of order 30 deg C/W for both heat sinks. However, the finless heat sink resulted in slightly lower values over a range of intermediate fan speeds. Hence, indicating that the maximum heat transfer density, for a range of fan speeds, can be achieved with a finless heat sink. The results also define the limiting heat fluxes that can be dissipated in low profile miniature applications.

Geometrical Effects in Optimal Performance of Energy Dissipation of Pin Fin Heat Sinks

2009 ◽  
Author(s):  
J. L. Zu´n˜iga-Cerroblanco ◽  
A. Herna´ndez-Guerrero ◽  
G. J. Kowalski ◽  
J. C. Rubio-Arana
Keyword(s):  
Heat Sink ◽  
Optimization Model ◽  
Constant Heat Flux ◽  
Heat Sinks ◽  
Design Parameters ◽  
Transfer Coefficients ◽  
Technical Literature ◽  
Pin Fin ◽  
Friction Factors ◽  
Geometrical Effects

This work describes the hydraulic and thermal behavior of pin-fin heat sinks when subjected to a constant heat flux with values equivalent to those generated incurrent electronic devices. The fin geometries analyzed are rectangular, circular and elliptical. The experimental analysis is performed for pin-fin in-line arrangement. The heat sink arrangement is also analyzed numerically for pin-fin in-line and staggered arrangements; and the results are compared. The thermal resistance and pressure drop is reported for all arrangements for different air velocities. The experimental and numerical results are compared and validated with recent technical literature. The Entropy Generation Minimization (EGM) is used to obtain an optimization of the heat sink pin fin arrangement. Analytical and empirical correlations for heat transfer coefficients and friction factors are used in the optimization model. This optimization model considers all relevant design parameters for pin-fin heat sinks, including geometric parameters, material properties and flow.

Optimization of Pin-Fin Heat Sinks Using the Two Medium Anisotropic Porous Model

2002 ◽  
Author(s):  
Seo Young Kim ◽  
Andrey V. Kuznetsov
Keyword(s):  
Heat Sink ◽  
Numerical Solutions ◽  
Solid Phase ◽  
Numerical Study ◽  
Heat Sinks ◽  
Thermal Dissipation ◽  
Uniform Heat Flux ◽  
Pin Fin ◽  
Geometric Conditions ◽  
Optimum Porosity

A numerical study has been carried out to optimize the thermal performance of a pin-fin heat sink. A pin-fin heat sink placed horizontally in a channel is modeled as a hydraulically and thermally anisotropic porous medium. A uniform heat flux is prescribed at the bottom of the heat sink. Cold air is supplied from the top opening of the channel and exhausts to the channel outlet. Comprehensive numerical solutions are derived from the governing Navier-Stokes and energy equations, using the Brinkman-Forchheimer extended Darcy model and the local thermal non-equilibrium (LTNE) model for the region of heat sink. Results from this study indicate that the anisotropy in permeability and solid-phase effective thermal conductivity changes substantially with the variation of porosity. The pin-fin heat sinks considered in the present study show an optimum porosity of 0.75<εopt<0.95 for maximum thermal dissipation depending on the flow and geometric conditions. Generally, a thick pin-fin displays a lower optimum porosity.

Effect of Fin Pitch and Height on Pin-Fin Heat Sink Performance

2008 ◽  
Author(s):  
D. Sahray ◽  
H. Shmueli ◽  
N. Segal ◽  
G. Ziskind ◽  
R. Letan
Keyword(s):  
Heat Transfer ◽  
Free Convection ◽  
Contact Resistance ◽  
Cross Section ◽  
Heat Input ◽  
Heat Sink ◽  
Numerical Study ◽  
Heat Sinks ◽  
Transfer Enhancement ◽  
Pin Fin

In the present work, horizontal-base pin fin heat sinks exposed to free convection in air are studied. They are made of aluminum, and there is no contact resistance between the base and the fins. The sinks have the same base dimensions whereas the fin height and pitch vary. The fins have a constant square cross-section. The effect of fin height and pitch on the performance of the sink is studied experimentally and numerically. In the experiments, the heat sinks are heated using foil electrical heaters. The heat input is set, and temperatures of the base and fins are measured. In the corresponding numerical study, the sinks and their environment are modeled using the Fluent 6.3 software. The results show that heat transfer enhancement due to the fins is not monotonic. The differences between sparsely and densely populated sinks are analyzed for various fin heights.

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