| Specifications | Interpack2003-35104.fm kang |
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| Specifications | Interpack2003-35104.fm kang |
| Business section |
| Specifications | Interpack2003-35104.fm kang |
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| Content | 1 ABSTRACT This paper presents a physics based analytical model to predict the thermal behavior of pin fin heat sinks in transverse forced flow. The key feature of the model is the recognition that unlike plate fins, streamwise conduction does not occur in pin fin heat sinks. Thus, the heat transfer from each fin depends on its local air temperature or adia- batic temperature and the local adiabatic heat transfer coefficient. Both experimental data and simplified CFD simulations are used to develop the two building blocks of the model, the thermal wake function and the adiabatic heat transfer coefficient. These building blocks are then used to include the effect of the thermal wake from upstream fins on the adiabatic temperature of downstream fins in determining the fin-by-fin heat transfer within the pin fin array. This approach captures the essen- tial physics of the flow and heat transport within the fin array and yields an accurate model for predicting the thermal resistance of pin fin heat sinks. Model predictions are compared with existing experimental data and CFD simulations. The model is expected to provide a sound basis for a consistent performance comparison with plate fin heat sinks. NOMENCLATURE Aarea Aminminimum free flow area between pins (or pin fins) cpspecific heat Ddiameter of pins fper-pin friction factor hheat transfer coefficient i,j,kindex variables Llength of pin Mnumber of rows in the pin fin array Nnumber of pins in a row NuNusselt number Onumber of segments on each fin ppressure Pperimeter PrPrandtl number qheat transfer rate Qheat input at boundary ReReynolds number SLlongitudinal pitch of pin array STtransverse pitch of pin array Ttemperature Tbtemperature at boundary Uamean air velocity in the duct upstream of the pins Uo mean air velocity through minimum free flow area between pins XLnormalized longitudinal pitch of pin array (SL/D) XTtransverse pitch of pin array (ST/D) Xpitch ratio used for non-square arrays Greek Symbols λthermal conductivity µviscosity ρdensity ηfin efficiency θwake function or normalized adiabatic temperature rise χfriction factor ratio for non-square arrays Subscripts aair or approach adadiabatic ffin inair inlet conditions mmetal thermophysical property INTRODUCTION Air cooled heat sinks are the workhorse device for all sorts of com- ponents in the electronics industry. The widespread availability of user- friendly computational fluid dynamics (CFD) software now enables heat sink designers and to obtain a reasonably accurate prediction of heat sink performance. Although desktop computers have become powerful enough to run CFD models, a full parametric design study using CFD alone remains impractical because solutions times are still measured in hours and post processing analysis of large CFD data sets remains time consuming. Simple accurate numerical models for heat sinks remain highly desirable to expedite design trade-offs and optimi- zation analyses, e.g. [1-3]. ∆pN⁄ 1 2-ρUo 2- ©¹¨¸¨¸§· ρDUo µ-©¹§· XT1–() XL1–()-= SLST≠() THE THERMAL RESISTANCE OF PIN FIN HEAT SINKS IN TRANSVERSE FLOW Proceedings of IPACK03 International Electronic Packaging Technical Conference and Exhibition July 6–11, 2003, Maui, Hawaii, USA InterPack2003-35104 Sukhvinder Kang Aavid Thermalloy Concord NH kang@aavid.com Maurice Holahan IBM Corporation Rochester MN mholahan@us.ibm.com |
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| Following Datasheets | Thermal-Solutions-Brochure (8 pages) thermal-system_mg (1 pages) thermal (9 pages) thermalapplet-1 (9 pages) thermalbond4949a (4 pages) thermalbond4949b (5 pages) thermalbond4950a (4 pages) thermalbond4950b (5 pages) thermalbond4951a (4 pages) thermalbond4951aFrench (4 pages) |
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