1. Thermally managing high power devices using heat pipe assemblies
Apec 2016
Thermally managing high power devices using heat pipe assemblies
March
Mersen Canada Toronto
Abdul Samad Jawed, EIT, Applications Engineer
Cliff Weasner, Lead Applications Engineer / Product Manager
Ahmed Zaghlol, Ph.D, P.Eng., VP Engineering and Business Development

2. Problem statement
Objective: Focus on cooling requirement for a single high power IGBT module that is used for a DC-DC Converter Application
IGBT Module
140mm x 190 mm
4000W losses
Ambient = 40°C
Maximum heat sink temperature: 85°C
Available flow rate: 7-11 m/s
DT = 45°C

3. Problem statement - Cont’d
Solution constrained to air cooling – Why?
Customer does not have infrastructure for liquid cooling
Liquid cooling system is more complex in terms of design, costs and maintenance
Air cooling only requires fan and ducting which is cheaper to purchase, setup and maintain

4. Aluminum Vacuum Brazed
air cooled technology
Thermal management road map
____ Higher Resistance Trend
____ Lower Resistance Trend
Aluminum Bonded Fin
Copper Bonded Fin
Heat Pipe Assembly
Tube Based Cold Plates
Aluminum Vacuum Brazed
Copper Vacuum Brazed

5. Available Technology – air cooled
High fin density air cooled heat sink is simulated using CFD
Cross sectional view
All Aluminum
All Copper
DT = 84°C
DT = 54.6°C
Module
High fin density

6. Next in air cooled technology
Thermal management road map
____ Higher Resistance Trend
____ Lower Resistance Trend
Aluminum Bonded Fin
Copper Bonded Fin
Heat Pipe Assembly
Tube Based Cold Plates
Aluminum Vacuum Brazed
Copper Vacuum Brazed

7. What is a heat pipe? Sealed vessel
Working fluid such as water, methanol, acetone, etc.
Liquid vaporizes at evaporative section
Vapor condenses at condenser section
Liquid flows from condenser section to evaporator section
Heat Pipe
( capillary forces )
Thermal Siphon
( gravity )
Heat Source
Heat Sink g
Evaporator
Adiabatic
Condenser
Wicking Structure

8. How are heat pipes used in application?
Spreading perpendicular to a plane
Spreading outside a plane
Spreading in a plane

9. Available Prototype Current available prototype Matching
Mounting pattern for IGBT module
Surface area
Number of heat pipes
Condenser
Adiabatic Section
Evaporator

10. CFD Design
Ducting
The diagram shows the thermal model for the cfd analysis based on the boundary conditions discussed
Heat pipe model based on previous experimental test correlations with thermal analytic models
4000 W Device
Air outlet
Air Inlet

11. CFD Results 11 m/s air flow speed
Conservative approach shows potential solution that will work
Temperature rise of C

12. Experimental setup Sample setup for testing Calibrated Wind Tunnel
Air duct (cardboard)
Heater block
Heatsink

13. Experimental results
The graph below shows the experimental results gathered by testing the prototype
10% difference in performance

14. Conclusion
The customers required a solution to cool 4000W from a single megadual igbt using air in which traditional air cooling could not solve
heat pipe assembly is able to meet the thermal requirements for cooling a 4000W IGBT module
Design process of CFD & quick thermal tests to validate the thermal model assumptions is key to provide quality solutions on time

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Thank You
Please visit us at Booth 1725