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Flotherm Usage

Module → Box → Rack → Enclosure!

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IntroductionFlotherm Uses & Experience

Board/Module Level:P-Q Curves Detailed Thermal/Temperature Analysis

Box LevelSlot Flow Evaluation

Rack LevelVenting Selection and Justification

Shelter LevelECU And Venting Schemes

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Module LevelUsing Mezzanine Card Assemblies:Power Dissipation & Airflow EvaluationPrepared By:Michael R. Palis and Robert C. SullivanHybricon Corporation

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Modeling LevelAnalysis Technique Used:

Detailed ModelWind Tunnel Analysis

Flow Path DeterminationFlow Path PerformanceRelative Velocities

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Side View

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Intake View

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Flow Path Performance

Using Regions the following was determined:

Flow Minimized between cards as the component volume is filled!Found most of the air was flowing over the backsides of the cards!

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Chassis/Box Level EvaluationsBaseline Evaluations & Design!

Mass Flow-Rate Heat TransferFan Family Selection

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First Order Principles

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P-Q Characteristic Determination

Measure Finished CardsUse Published Correlations

Kavah AzarGordon Ellison

Use Flotherm’s Wind-Tunnel Analysis Technique

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Circuit Card Flow VariationsFlow Pressure Characteristics as Volume Utilization Increases

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0 5 10 15 20 25 30 35 40 45

CFM

Pres

sure

Dro

p (in

ches

of W

ater

)

Misc Processor cv=.34 Misc Data cv= .25 Medium Processor Cv=.17 TELCO Processor Card Cv=.54

Even Array CV= .11 Even Array CV= .15 Even Array CV= .17 Even Array CV= .22

Even Array CV= .33 Bare Card

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System Resistance CurveSystem Resistance Curve

0.000

0.500

1.000

1.500

2.000

0 100 200 300 400 500 600 700 800 900

Flow rate (CFM)

Pres

sure

(WG

)

Conservative System Resitance Bare Card Low Board System Resistassnce

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Air Mover CharacteristicsPerformance: Other Results:

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Air Mover CharacteristicsDisclose the Following Impacts:

Airborne Noise Increase with Higher Heat DissipationPower Requirements for Operation Air Movers Increases with Higher Heat DissipationDifferent Air Mover Technologies may increase the final SWaP (Size, Weight and Power) of the System Solution!

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Operating Point DeterminationSystem Operating Point Chart

0

0.5

1

1.5

2

0 100 200 300 400 500 600 700 800 900

Flow rate (CFM)

Pres

sure

( W

G)

Two Series Trays of 5118 N Conservat ive System Resitance Two Series Trays of A34362Two Series Trays of B34744 TWO Series Trays of 5218NH Bare CardLow Board System Resistassnce

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Translation to Flotherm Modeling

Flotherm Support/Web PartsAdvanced Resistance Generator Routine from The Support WebsiteSmart Parts:

http://www.smartparts3d.com/index.jsp

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CFDFlotherm

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Rack Level Modeling Example

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Rack Level Modeling Example

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Rack Level Modeling Example

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Rack Level Modeling Example

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Shelter/Enclosure Level Evaluations

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Standard Position

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Side Exhaust

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Center Console Variation

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ConclusionsDetailed Board and Module Levels is very quick and informative from detailed PCB Layout Information or from block volume allocations!Box Level Can Be done the the detailed Layouts, but using the generic volume resistance is faster at the chassis level!Rack and shelter level evaluations can be done for detailed results or assisting in making design allocations.