STUDY OF HEAT TRANSFER PROCESS
FROM A CIRCUIT BOARD
USING HEAT PIPES
Authors: Joaquín Capablo, Nelson Garcia-Polanco, John...
INDEX
1. Project Introduction
2. Studied System with SINDA/FLUINT
3. Results
4. Parametrical Analysis
5. Conclusions

13th...
1. INTRODUCTION

GREEN KITCHEN PROJECT: Innovative households can help reduce national energy consumption, not
only by imp...
Heat Pipes applications
Efficient transport of concentrated heat

From the space to your kitchen…
13th UK Heat Transfer Co...
Heat Pipes comparison
Effective thermal conductivity of heat pipe with
that of solid copper and solid aluminum rods

13th ...
Heat Pipes
• Advantages:
-Very high thermal
conductivity
-Accurate temperature
control
-Accurate geometric control
Peterso...
Studied system
1

2

3

4

Heat Generating Elements

Coin
Heat Spreader
Heat Flow
Heat Pipes

Air Cooled Heat Sink

Air Fl...
2. STUDIED SYSTEM WITH SINDA/FLUINT

SINDA/FLUINT® (www.crtech.com)
• Software for analysis, design, simulation, and
optim...
Basic Overview of SINDA/FLUINT
• MAIN SIMULATORS:
– SINDA: Network-style (circuit analogy) thermal simulator
• Nodes : Tem...
Basic Overview of SINDA/FLUINT
• GRAPHICAL INTERFACE:THERMAL DESKTOP
– Geometric CAD-based style
• Surfaces and solid part...
Basic Overview of SINDA/FLUINT
• Thermo-Electric Analogy
V2

V1

Re Rt

T2

T2-T1= Rt*Q

T1
I

≈

V2-V1= Re*I

Q

• Energy...
Basic Overview of SINDA/FLUINT
• Mass Balance to each Lump
MRL2

MRL1

dM/dt= ∑MRL

• Energy Balance to each Lump
QS-L
QL2...
Basic Overview of SINDA/FLUINT
• Basic Flow Data
-Network Description

-Operation Sequence

-Output Procedures

Nodes, Con...
Modeling Heat Pipes with SINDA/FLUINT
A Network-based Method to model a Heat Pipe

• Constant Conductance Heat Pipes (CCHP...
Modeling Heat Pipes with SINDA/FLUINT
Common Misconceptions when modeling a Heat Pipe

• Full two-phase thermo-hydraulic m...
Modeling Heat Pipes with SINDA/FLUINT
Typical System-Level Approach

• Network-style conductor fan approach:
– All walls n...
STUDIED SYSTEM
Heat transfer from a circuit board using heat pipes
Q1=10 W
Q2=20 W
Q3=250 W

Q4=50 W

Heat Sources Max. Po...
Effect of geometric discretization
• Heat Pipes Grid Refinement: 10 – 320 nodes
Temperature of Element 3
vs.

Heat pipes n...
STUDIED SYSTEM
Heat transfer from a circuit board using heat pipes

13th UK Heat Transfer Conference, September 2-3, 2013,...
Results: Evolution of the temperature
• Transient analysis:
200
180
160

T( C)

140
120
100

80
60

Circuit Board hottest ...
Parametric study
• Analyzed Parameters (in steady state):
– Heat pipes exchange coefficients:
• Vaporization coefficient
•...
Parametric study (I-II)
• Heat Pipes exchange coefficients
Vaporization Coefficient: 8.640 W/m2K

Condensation Coefficient...
Parametric study (III)
• Heat Load
Variation of the Heat Generated by the Heat Sources
200

T( C)

190
180

170
160
150
25...
Parametric study (IV)
• Heat Pipes Configuration
ΔL/L=7.5%
200,0
199,5

T( C)

199,0

198,5
198,0
197,5
197,0
0,00

0,20
0...
Conclusions
• Temperature distribution and energy transfer
from a circuit board using heat pipes
• Transient Analysis of t...
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Study of Heat Transfer Process using Heat Pipes

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In the present study the temperature distribution and the energy transfer from the electronics of a home appliance to an air-cooled heat sink via heat pipes is studied. The main objective of the research work is to ensure that the operation of electronic instruments is maintained under suitable working conditions. SINDA/FLUINT®, comprehensive software based on lumped parameter methods, specially focused in heat transfer and fluid flow modelling in complex systems, is used to create a model representing the cooling of an electronic board by transferring the dissipated energy to a heat sink via heat pipes.

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  • Comparison of the effective thermal conductivity of heat pipes with that of solid copper and solid aluminum rods. The effective thermal conductivity of the heat pipe is about 40 times larger than copper and 66 times larger than aluminum for the same heat input.
  • Study of Heat Transfer Process using Heat Pipes

    1. 1. STUDY OF HEAT TRANSFER PROCESS FROM A CIRCUIT BOARD USING HEAT PIPES Authors: Joaquín Capablo, Nelson Garcia-Polanco, John Doyle nelsongarciapolanco@gmail.con / joaquincapablo@gmail.com 2nd September 2013, Imperial College, London, UK
    2. 2. INDEX 1. Project Introduction 2. Studied System with SINDA/FLUINT 3. Results 4. Parametrical Analysis 5. Conclusions 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 2
    3. 3. 1. INTRODUCTION GREEN KITCHEN PROJECT: Innovative households can help reduce national energy consumption, not only by improving their energy efficiency, but also by reducing and reusing the waste produced in terms of heat and water. Marie Curie Action(Industry-Academia Partnerships and Pathways) 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 3
    4. 4. Heat Pipes applications Efficient transport of concentrated heat From the space to your kitchen… 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 4
    5. 5. Heat Pipes comparison Effective thermal conductivity of heat pipe with that of solid copper and solid aluminum rods 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 5
    6. 6. Heat Pipes • Advantages: -Very high thermal conductivity -Accurate temperature control -Accurate geometric control Peterson (1994) 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 6
    7. 7. Studied system 1 2 3 4 Heat Generating Elements Coin Heat Spreader Heat Flow Heat Pipes Air Cooled Heat Sink Air Flow 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 7
    8. 8. 2. STUDIED SYSTEM WITH SINDA/FLUINT SINDA/FLUINT® (www.crtech.com) • Software for analysis, design, simulation, and optimization of systems involving heat transfer and fluid flow: – – – – – – – Aerospace Energy Electronics Automotive Aircraft HVAC Petrochemical industries • NASA-standard analyzer for thermal control systems: 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 8
    9. 9. Basic Overview of SINDA/FLUINT • MAIN SIMULATORS: – SINDA: Network-style (circuit analogy) thermal simulator • Nodes : Temperature points • Conductors : Heat Flow Routes – FLUINT: Fluid network capabilities • Lumps : Thermodynamic points • Paths : Fluid Flow Passages • Ties : Heat Flow between Solid and Fluid Q R FR,A UA T,C 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK P,T,V 9
    10. 10. Basic Overview of SINDA/FLUINT • GRAPHICAL INTERFACE:THERMAL DESKTOP – Geometric CAD-based style • Surfaces and solid parts are geometrically modeled. • Data exchange with CAD and structural software. • Good performance for analysis requiring radiation calculations, contact conductances, heat pipes, TEC devices… – Specific module: FloCAD • Fluid Flow Analyzer • Generation of Flow Networks • Calculation of Heat Transfer Factors 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 10
    11. 11. Basic Overview of SINDA/FLUINT • Thermo-Electric Analogy V2 V1 Re Rt T2 T2-T1= Rt*Q T1 I ≈ V2-V1= Re*I Q • Energy Balance to each Node: QConvection QRadiation CS*(dT/dt)=∑QS+QSL+Qext QConduction Qext QS-L 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 11
    12. 12. Basic Overview of SINDA/FLUINT • Mass Balance to each Lump MRL2 MRL1 dM/dt= ∑MRL • Energy Balance to each Lump QS-L QL2 QL1 (dEi/dt)=∑QL+QSL 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 12
    13. 13. Basic Overview of SINDA/FLUINT • Basic Flow Data -Network Description -Operation Sequence -Output Procedures Nodes, Conductors, Lumps… Steady-State, Transient, Parametric Sweep What? When? -Control Parameters -Concurrent Logic -User Data Error Tolerance, Units,… Initialization, Customizing Arrays, Spreadsheet Pre-processing Fortran Logic DATA Spreadsheet Relationships Compiling OUTPUTS Post-processing PLOTS 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 13
    14. 14. Modeling Heat Pipes with SINDA/FLUINT A Network-based Method to model a Heat Pipe • Constant Conductance Heat Pipes (CCHPs): – Used in the aerospace industry for about three decades for supporting system-level design analysis. • Extensions possible for modeling: – CCHPs with Non-Condensible Gas (NCG). – Variable Conductance Heat Pipes (VCHPs) with NCG reservoirs. – Planar or Counter-Flow Thermo-Syphons. • Other methods for modeling: – Loop Thermo-Syphons (LTSs). – Loop Heat Pipes (LHPs). 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 14
    15. 15. Modeling Heat Pipes with SINDA/FLUINT Common Misconceptions when modeling a Heat Pipe • Full two-phase thermo-hydraulic modeling is required: – It represents a computational overkill in almost all cases • Heat pipes can be represented by solid bars of high thermal conductivity: – It does not simulate a heat pipes’s length-independent resistance – It cannot account for difference in film coefficients between vaporization and condensation – It does not provide information on power-length product QLeff 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 15
    16. 16. Modeling Heat Pipes with SINDA/FLUINT Typical System-Level Approach • Network-style conductor fan approach: – All walls nodes are attached directly via linear conductances/resistances to a single vapor node. – The wall nodes represent the liquid/vapor interface along each axial segment of length. 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 16
    17. 17. STUDIED SYSTEM Heat transfer from a circuit board using heat pipes Q1=10 W Q2=20 W Q3=250 W Q4=50 W Heat Sources Max. Power: 330 W Coin: -3 mm thickness -Copper Heat Spreader: - 20 mm thickness -Aluminum Heat pipes: -2 Heat Pipes -Diameter: 10 mm -Constant conductance (CCHP) -Negligible non-condensable gas (NCG) -Vaporization Coef.: 8.640 W/m2K -Condensation Coef.: 132.640 W/m2K Heat Sink: -4 Channels -Aluminum -Air flow: 0.05 m3/s 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 17
    18. 18. Effect of geometric discretization • Heat Pipes Grid Refinement: 10 – 320 nodes Temperature of Element 3 vs. Heat pipes nodes number 199,0 198,9 198,8 3 T( C) 198,7 198,6 198,5 198,4 198,3 198,2 198,1 198,0 0 50 100 150 200 250 Nodes number 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 300 350 18
    19. 19. STUDIED SYSTEM Heat transfer from a circuit board using heat pipes 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 19
    20. 20. Results: Evolution of the temperature • Transient analysis: 200 180 160 T( C) 140 120 100 80 60 Circuit Board hottest point: -Element 3 40 20 0 10.000 20.000 30.000 40.000 50.000 t(s) 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 20
    21. 21. Parametric study • Analyzed Parameters (in steady state): – Heat pipes exchange coefficients: • Vaporization coefficient • Condensation coefficient – Heat load: • Variation of the heat generated by the heat sources. – Heat pipes configuration • Variation of the length of the heat pipes 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 21
    22. 22. Parametric study (I-II) • Heat Pipes exchange coefficients Vaporization Coefficient: 8.640 W/m2K Condensation Coefficient : 132.640 W/m2K 198 196 196 T( C) 200 198 T( C) 200 194 194 192 192 190 5.000 6.000 7.000 8.000 VapCoeff (W/m2K) 9.000 10.000 190 100.000 110.000 120.000 130.000 140.000 150.000 CondCoeff (W/m2K) 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 22
    23. 23. Parametric study (III) • Heat Load Variation of the Heat Generated by the Heat Sources 200 T( C) 190 180 170 160 150 250 270 290 Heat Load (W) 310 330 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 23
    24. 24. Parametric study (IV) • Heat Pipes Configuration ΔL/L=7.5% 200,0 199,5 T( C) 199,0 198,5 198,0 197,5 197,0 0,00 0,20 0,40 0,60 0,80 Heat Pipes Length Variation 1,00 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 24
    25. 25. Conclusions • Temperature distribution and energy transfer from a circuit board using heat pipes • Transient Analysis of the studied system • Parametric Study: – Vaporization Coefficient – Condensation Coefficient – Heat Generated by the Heat Sources – Heat Pipes Configuration 13th UK Heat Transfer Conference, September 2-3, 2013, London – UK 25

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