Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Turbulent Forced Convection Air Cooling of Electronics with Heat Sinks Under Flow Bypass Conditions
KTH, Superseded Departments, Energy Technology.ORCID iD: 0000-0001-6139-4400
2001 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

Air cooling is still the dominant method for dissipating theheat produced by electronic components. In a typical electronicdevice, the components are situated on a Printed Circuit Board(PCB). For most applications natural convection is sufficientto cool the components. However in some cases forced convectionair cooling, which provides more effective cooling, has to beused. In cases with high heat fluxes the switch from natural toforced convection is not enough and in these cases the surfacearea of the components must also be increased by means of aheat sink, i.e. a finned surface. The size of the components isoften considerably smaller than the PCB, and in cases whereheat sinks are used, the heat sink seldom covers the air flowduct formed by two parallel PCBs. Since the air flow is seekingthe path of least resistance, some of it will bypass the heatsink. This air flow bypass has a major impact on theperformance of the heat sink, why knowledge of the amount ofbypass flow is of vital importance.

The aim of this work has been to investigate the influenceof flow bypass on the performance of heat sinks used forelectronics cooling. The focus has been set on determining theparameters that influence the bypass, and to quantify theirrelative importance using experimental and numericaltechniques.

Experimentaland numerical parametric studies have beenperformed. The influence of duct dimensions, air velocity, fintype, array arrangement, fin height, and fin-to-fin distance onthe thermal and hydraulic performance of plate fin, strip fin,and pin fin heat sinks have been investigated. The flow wasturbulent, and the Reynolds number was varied between 1 700 and16 000. Measurements have been performed in a wind tunnel. Intotal 42 different heat sinks were tested in seven differentduct configurations. For the plate fin heat sinks and thecircular pin fin heat sinks, numerical predictions have beenperformed by using the finite element code FIDAP and the finitevolume code PHOENICS, respectively. For turbulence modeling therevised RNG k-ε model and the Chen-Kim k-ε model wereused.

The agreement between the results from the experimental andnumerical investigations was very good, suggesting that acombination of the two methods can be a powerful tool forpredicting the thermal and hydraulic performance of heat sinks.The experimental data can be used to validate the numericalmodel, which in turn can be used for parametric studies.

The results of the investigations showed that the thermalperformance was most influenced by the duct height, and the airvelocity while the hydraulic performance was dependent on allthe investigated parameters.

From the experimental and numerical results severalcorrelations have been developed to describe the relativeimportance of the investigated parameters. The agreementbetween the source data and the correlations is very good, aswell as the agreement between the correlations developed withdata from the experimental and the numerical investigationsrespectively.

Keywords: forced convection, heat transfer, pressuredrop, turbulent, air cooling, bypass, plate, strip, pin, fin,heat sink, electronics, experimental,numerical, CFD

Place, publisher, year, edition, pages
Stockholm: KTH , 2001. , x, 80 p.
Series
Trita-REFR, ISSN 1102-0245 ; 01/28
Keyword [en]
forced convection, heat transfer, pressure drop, turbulent, air cooling, bypass, plate, strip, pin, fin, heat sink, electronics, experimental, numerical, CFD
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-3127OAI: oai:DiVA.org:kth-3127DiVA: diva2:8890
Public defence
2001-04-26, 00:00
Note
QC 20100622Available from: 2001-04-20 Created: 2001-04-20 Last updated: 2010-06-22Bibliographically approved
List of papers
1. Thermal and hydraulic behavior of plate fin and strip fin heat sinks under varying bypass conditions
Open this publication in new window or tab >>Thermal and hydraulic behavior of plate fin and strip fin heat sinks under varying bypass conditions
2000 (English)In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 23, no 1, 47-54 p.Article in journal (Refereed) Published
Abstract [en]

Tests have been conducted in a wind tunnel with nine heat sinks of three different types including plate fin heat sinks and strip fin heat sinks arranged in both inline and staggered arrays. For each type, tests were run with fin heights (H) of 10, 15, and 20 mm while the heat sink width (B) was kept constant and equal to 52.8 mm. The width of the wind tunnel duct (CB) was varied in such a way that results were obtained for B/CB = 0.84, 0.53, and 0.33. The wind tunnel height (CH) was varied similarly, and data were recorded for H/CH = 1, 0.67, and 0.33 while the duct Reynolds number was varied between 2000 through 14000. An empirical bypass correlation has been fitted to the experimental data. Generally, the agreement between experimental data and correlation is within +/-10% for the thermal resistance, and within +/-20% for the pressure drop. From the experimental data, the fraction of the total airflow passing through the heat sink have been estimated and are compared to a simple physical bypass model.

Keyword
bypass, experimental, heat sink, physical model, plate fin, pressure drop, strip fin, thermal resistance
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-13623 (URN)10.1109/6144.833041 (DOI)000086499000007 ()
Note
QC 20100622Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2017-12-12Bibliographically approved
2. Modeling and characterisation of plate fin heat sinks under bypass flow conditions using computational fluid dynamics methods
Open this publication in new window or tab >>Modeling and characterisation of plate fin heat sinks under bypass flow conditions using computational fluid dynamics methods
2001 (English)In: Journal of Electronic Packaging, ISSN 1043-7398, E-ISSN 1528-9044Article in journal (Other academic) Accepted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-13626 (URN)
Note
QC 20100622Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2017-12-12Bibliographically approved
3. Influence of fin spacing, fin thickness and inlet velocity on the performance of plate fin heat sinks under varying bypass conditions using CFD
Open this publication in new window or tab >>Influence of fin spacing, fin thickness and inlet velocity on the performance of plate fin heat sinks under varying bypass conditions using CFD
2000 (English)In: International journal of heat exchangers, ISSN 1524-5608Article in journal (Other academic) Submitted
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-13625 (URN)
Note
QC 20100622Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2010-06-22Bibliographically approved
4. CFD modeling of the cooling performance of pin fin heat sinks under bypass flow conditions
Open this publication in new window or tab >>CFD modeling of the cooling performance of pin fin heat sinks under bypass flow conditions
2001 (English)Conference paper, Published paper (Other academic)
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-13627 (URN)
Conference
InterPACK 2001
Note
QC 20100622Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2010-06-22Bibliographically approved
5. Modeling of the thermal and hydraulic performance of plate fin, strip fin, and pin fin heat sinks: Influence of flow bypass
Open this publication in new window or tab >>Modeling of the thermal and hydraulic performance of plate fin, strip fin, and pin fin heat sinks: Influence of flow bypass
2001 (English)In: IEEE transactions on components and packaging technologies (Print), ISSN 1521-3331, E-ISSN 1557-9972, Vol. 24, no 2, 142-149 p.Article in journal (Refereed) Published
Abstract [en]

Tests have been conducted in a wind tunnel with seven types of heat sinks including plate fin, strip fin, and pin fin heat sinks. In the case of strip fin, and pin fin heat sinks, both in-line and staggered arrays have been studied. The pin fin heat sinks had circular and square cross-sections, For each type, tests were run with fin heights (H) of 10, 15, and 20 mm while the heat sink width (B) was kept constant and equal to 52.8 mm. In total, 42 different heat sinks were tested, The width of the wind tunnel duct (CB) was varied in such a way that results were obtained for B/CB = 0.84, 0.53, and 0.33. The wind tunnel height (CH) was varied similarly, and data were recorded for H/CH = 1, 0.67, and 0.33 while the duct Reynolds number was varied between 2 000 through 16 500. An empirical bypass correlation has been developed for the different fin designs. The correlation predicts the Nusselt number and the dimensionless pressure drop and takes into account the influence of duct height, duct width, fin height, fin thickness, and fin-to-fin distance. The correlation parameters are individual for each fin design. Further, a physical bypass model for plate fin heat sinks has been developed to describe the bypass effect.

Keyword
bypass, circular, experimental, heat sink, physical model, pin fin, plate fin, pressure drop, square, strip fin, thermal resistance, ARRAY
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-13624 (URN)10.1109/6144.926376 (DOI)000169256400003 ()
Note
QC 20100622Available from: 2010-06-22 Created: 2010-06-22 Last updated: 2017-12-12Bibliographically approved

Open Access in DiVA

No full text

Authority records BETA

Jonsson, Hans

Search in DiVA

By author/editor
Jonsson, Hans
By organisation
Energy Technology
Engineering and Technology

Search outside of DiVA

GoogleGoogle Scholar

urn-nbn

Altmetric score

urn-nbn
Total: 1378 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf