Forced Convection Air Cooling of Simulated Low Profile Electronic Components: Part 2—Heat Sink Effects

1991 ◽  
Vol 113 (1) ◽  
pp. 27-32 ◽  
Author(s):  
G. L. Lehmann ◽  
J. Pembroke
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow Rate ◽  
Heat Sink ◽  
Heat Sinks ◽  
Air Cooling ◽  
Channel Spacing ◽  
Heat Transfer Behavior ◽  
Low Profile ◽  
Transfer Behavior

Forced convection air cooling of an array of low profile, card-mounted components has been investigated. A simulated array is attached to one wall of a low aspect ratio duct. This is the second half of a two-part study. In this second part the presence of a longitudinally finned heat sink is considered. The heat sink is a thermally passive “flow disturbance”. Laboratory measurements of the heat transfer rates downstream of the heat sink are reported and compared with the measured values which occur when no heat sinks are present. Data are presented for three heat sink geometries subject to variations in channel spacing and flow rate. In the flow range considered laminar, transitional and turbulent heat transfer behavior has been observed. The presence of a heat sink appears to “trip” the start of transition at lower Reynolds numbers than when no heat sinks are present. A Reynolds number based on component length provides a good correlation of the heat transfer behavior due to variations in flow rate and channel spacing. Heat transfer is most strongly effected by flow rate and position relative to the heat sink. Depending on the flow regime (laminar or turbulent) both relative enhancement and reductions in the component Nusselt number have been observed. The impact of introducing a heat sink is greatest for flow rates corresponding to transitional behavior.

Forced Convection Air Cooling of Simulated Low Profile Electronic Components: Part 1—Base Case

1991 ◽  
Vol 113 (1) ◽  
pp. 21-26 ◽  
Author(s):  
G. L. Lehmann ◽  
J. Pembroke
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Flow Rate ◽  
Turbulent Heat Transfer ◽  
Base Case ◽  
Air Cooling ◽  
Turbulent Heat ◽  
Electronic Components ◽  
Channel Spacing ◽  
Low Profile

Forced convection cooling of a simulated array of card-mounted electronic components has been investigated. An important feature of the simulated components is their relatively low profile (height/length = 0.058). Laboratory measurements of heat transfer rates resulting from convective air flow through a low aspect ratio channel are reported. The effect of variations in array position, channel spacing and flow rate is discussed. In the flow range considered laminar, transitional and turbulent heat transfer behavior have been observed. The behavior due to variations in flow rate and channel spacing is well correlated using a Reynolds number based on component length.

A Study of Forced Convection Direct Air Cooling in the Downstream Vicinity of Heat Sinks

1990 ◽  
Vol 112 (3) ◽  
pp. 234-240 ◽  
Author(s):  
G. L. Lehmann ◽  
S. J. Kosteva
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Heat Sink ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Air Cooling ◽  
Transfer Coefficients ◽  
Packaging System ◽  
Transfer Rates ◽  
Heat Transfer Coefficients

An experimental study of forced convection heat transfer is reported. Direct air cooling of an electronics packaging system is modeled by a channel flow, with an array of uniformly sized and spaced elements attached to one channel wall. The presence of a single or complete row of longitudinally finned heat sinks creates a modified flow pattern. Convective heat transfer rates at downstream positions are measured and compared to that of a plain array (no heat sinks). Heat transfer rates are described in terms of adiabatic heat transfer coefficients and thermal wake functions. Empirical correlations are presented for both variations in Reynolds number (5000 < Re < 20,000) and heat sink geometry. It is found that the presence of a heat sink can both enhance and degrade the heat transfer coefficient at downstream locations, depending on the relative position.

Effect of Flow Bypass on the Performance of Longitudinal Fin Heat Sinks

1994 ◽  
Vol 116 (3) ◽  
pp. 206-211 ◽  
Author(s):  
R. A. Wirtz ◽  
Weiming Chen ◽  
Ronghua Zhou
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Design Guidelines ◽  
Heat Sinks ◽  
Air Cooling ◽  
Regular Array ◽  
Electronic Package ◽  
And Performance

Heat transfer experiments are reported on the thermal performance of longitudinal fin heat sinks attached to an electronic package which is part of a regular array of packages undergoing forced convection air cooling. The effect of coolant bypass on the performance of the heat sink is assessed and performance correlations for reduced heat transfer due to this effect are developed. These correlations are used to develop design guidelines for optimal performance.

An Experimental and Theoretical Study of Finned and Finless Heat Sinks for Low Profile Applications

2009 ◽  
Author(s):  
Jason Stafford ◽  
Ed Walsh ◽  
Vanessa Egan ◽  
Pat Walsh ◽  
Yuri S. Muzychka
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Heat Sink ◽  
Theoretical Study ◽  
Convection Heat Transfer ◽  
Heat Sinks ◽  
Duct Flow ◽  
Transfer Rates ◽  
Low Profile ◽  
Small Footprint

This paper discusses the importance of developing cooling solutions for low profile devices. This is addressed with an experimental and theoretical study on forced convection cooling solution designs that could be implemented into such devices. Conventional finned and corresponding finless designs of equal exterior dimensions are considered for three different heat sink profiles ranging from 1mm to 4mm profile in combination with a commercially available radial blower. The results show that forced convection heat transfer rates can be enhanced by up to 55% using finless designs at low profiles with relatively small footprint areas. The advantages of both finned and finless geometries are presented along with the limitations of the customary finned heat sink design at low profile scales. The results also show large increases in heat transfer rates over that predicted which can be attained at the low profile scale based on geometry selection. Dimensionless comparisons are made between experimental results and combined hydrodynamic and thermally developing duct flow theory which is representative of the flow regime within both the finned and finless geometries. Overall, this paper provides optimization and geometry selection criteria which are relevant to designers of low profile cooling solutions.

Active Upstream Components for Enhanced Heat Transfer of Longitudinally Finned Heat Sinks

2010 ◽  
Author(s):  
John Daly
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Heat Sink ◽  
Performance Enhancement ◽  
Heat Sinks ◽  
Air Cooling ◽  
Active Components ◽  
Enhanced Heat Transfer ◽  
Current Standard ◽  
Piezoelectric Fans

With the ever increasing heat flux from next-generation chips forced convection cooling is beginning to reach its limits within current standard heat sink capabilities. Methods of extending the air cooling capabilities prior to a transition to liquid or refrigerant-based cooling which is seen as costly and complex, have become more critical. This paper investigates the enhanced heat transfer by the addition of active components upstream of a longitudinally finned heat sink. This paper addresses piezoelectric fans for natural and forced convection environments. Experimental measurements are taken for a low powered DC fan operating at a frequency of 114Hz. For the forced convection experiments a fully ducted flow was used. The main thrust of the paper is to determine the effects of piezoelectrics in augmenting forced convection systems at hot component locations. The effects on pressure drop, thermal resistance and pumping power with the addition of the technology are presented. The paper concludes by reporting on the performance enhancement and limitations of the piezoelectric fans compared to the conventional longitudinally finned heat sink geometry.

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.

Improving the Thermal Performance of a Forced Convection Air Cooled Solution: Part 1 — Modification of Heat Sink Assembly

2013 ◽  
Author(s):  
Saeed Ghalambor ◽  
John Edward Fernandes ◽  
Dereje Agonafer ◽  
Veerendra Mulay
Keyword(s):  
Pressure Distribution ◽  
Forced Convection ◽  
Thermal Performance ◽  
Heat Sink ◽  
Heat Sinks ◽  
Thermal Interface Material ◽  
Air Cooling ◽  
Interfacial Pressure ◽  
Interfacial Contact ◽  
Torque Analysis

Forced convection air cooling using heat sinks is one of the most prevalent methods in thermal management of microelectronic devices. Improving the performance of such a solution may involve minimizing the external thermal resistance (Rext) of the package. For a given heat sink design, this can be achieved by reducing the thermal interface material (TIM) thickness through promotion of a uniform interfacial pressure distribution between the device and heat sink. In this study, a dual-CPU rackmount server is considered and modifications to the heat sink assembly such as backplate thickness and bolting configuration are investigated to achieve the aforementioned improvements. A full-scale, simplified model of the motherboard is deployed in ANSYS Mechanical, with emphasis on non-linear contact analysis and torque analysis of spring screws, to determine the optimal design of the heat sink assembly. It is observed that improved interfacial contact and pressure distribution is achieved by increasing the number of screws (loading points) and positioning them as close to the contact area as possible. The numerical model is validated by comparison with experimental measurements within reasonable accuracy. Based on the results of numerical analysis, the heat sink assembly is modified and improvement over the base configuration is experimentally quantified through interfacial pressure measurement. The effect of improved interfacial contact on thermal performance of the solution is discussed.

Development of Heat Sinks for Air Cooling and Water Cooling Using Lotus-Type Porous Metals

2011 ◽  
Author(s):  
H. Chiba ◽  
T. Ogushi ◽  
H. Nakajima
Keyword(s):  
Heat Transfer ◽  
Porous Materials ◽  
Heat Sink ◽  
High Heat ◽  
Heat Sinks ◽  
Air Cooling ◽  
Water Cooling ◽  
Cooling Performance ◽  
High Heat Transfer ◽  
Micro Channels

In recent years, since heat dissipation rates and high frequency electronic devices have been increasing, a heat sink with high heat transfer performance is required to cool these devices. Heat sink utilizing micro-channels with several ten microns are expected to provide an excellent cooling performance because of their high heat transfer capacities due to small channel. Therefore, various porous materials such as cellular metals have been investigated for heat sink applications. However, heat sink using conventional porous materials has a high pressure drop because the cooling fluid flow through the pores is complex. Among the described porous materials, a lotus-type porous metal with straight pores is preferable for heat sinks due to the small pressured drop. In present work, cooling performance of the lotus copper heat sink for air cooling and water cooling is introduced. The experimental data for air cooling show 13.2 times higher than that for the conventional groove fins. And, the data for the water cooling show 1.7 times higher than that for the micro-channels. It is concluded that lotus copper heat sink is the most prospective candidate for high power electronics devices.

Sign in / Sign up

Export Citation Format

Share Document