Enhanced Surfaces to Improve Power Electronics Cooling - NREL - MORENO.pdf · 2013-03-27 · Suraj Thiagarajan Kevin Bennion Travis Venson 3M Wolverine Tube, Inc. University of Colorado,

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Enhanced Surfaces to Improve Power

Electronics Cooling MEPTEC: The Heat is On

San Jose, CA

NREL

Gilbert Moreno, Presenter

Sreekant Narumanchi

Suraj Thiagarajan

Kevin Bennion

Travis Venson

3M

Wolverine Tube, Inc.

University of Colorado, Boulder

Oak Ridge National Lab (ORNL)

Date: March 21, 2011

This presentation does not contain any proprietary, confidential, or otherwise restricted information.

NATIONAL RENEWABLE ENERGY LABORATORY

NREL Laboratory Overview

Experimental Capabilities

• Two single-phase flow loops

• Three two-phase flow loops

• Air cooling test bench

• Thermal transient tester

• ABC-1000 power supply (1,000 amps)

• ASTM thermal interface material (TIM) stand

Reliability Capabilities

• Thermal shock chamber

• Two environmental chambers

• High-potential (HiPot) tester

• C-SAM Scanning Acoustic Microscopy

Modeling Capabilities

• Finite element analysis

• Computational fluid dynamics

2

Credit: Gilbert Moreno, NREL

Credit: Jason Lustbader, NREL

Credit: Gilbert Moreno, NREL Credit: Gilbert Moreno, NREL


Outline

3

I. Background: Project objectives and motivation

II. Enhanced Surface Description

III. Surface Enhancements: Single-phase jet impingement

a) Fundamental experiments

b) System/package-level experiments

IV. Surface Enhancements: Two-phase heat transfer



V. Recommendations


Objectives

4

Project Objective:

• Investigate the use of surface enhancement techniques to

increase single- and two-phase heat transfer for potential

automotive power electronics cooling applications

Overall Objective:

• Achieve DOE Advanced Power Electronics and Electrical

Machines (APEEM) program weight, volume and cost targets


Outline

5









V. Recommendations


Enhanced Surfaces

• 3M: Copper microporous coating

• Wolverine Tube, Inc.: MicroCool finned surface

• Univ. of Colorado at Boulder (CU): Copper nanowires (2–3 and 20 µm)

• NREL: Copper spray deposition coating

Fundamental and system-level experiments conducted

6

Copper Microporous (3M) Copper Nanowire (CU) Spray Pyrolysis (NREL)

MicroCool (Wolverine)

Credit: Bobby To, NREL Credit: Bobby To, NREL Credit: Mark Mihalic, NREL Credit: Bobby To, NREL


Outline

7









V. Recommendations


Single-Phase Jets: Fundamental Study

8

• Enhanced surfaces were tested in free

and submerged jet configurations

• 12.7 mm (½”) diameter heater surface

with uniform heat flux

• Results compared to simple surface-

roughening techniques and finned

surfaces

• Enhanced surfaces had minimal effect in

channel flow configuration

HEATER

Stagnation

Zone

Wall Jet Zone

d =1.24 mm

Ud ,Tl

L=12.7 mm (heater diameter)

S = 6 mm

(~4.8×d)

Twall

Free Jet

HEATER

Stagnation

ZoneWall Jet Zone

d =1.24 mm

Ud ,Tl

L=12.7 mm (heater diameter)

S = 6 mm

(~4.8×d)

Twall

Submerged Jet



Free Jets

• Microporous coating (3M)

produced highest h-value

enhancement (~130%)

• Greater enhancement than that

reported in literature

• Microporous/roughened surfaces

outperformed finned surfaces at

higher velocities

9

0

25,000

50,000

75,000

100,000

125,000

150,000

0 3 6 9 12 15

He

at

tra

ns

fer

co

eff

icie

nt

(W

/m2-K

)

Nozzle velocity (m/s)

Free Jets

Baseline (Ra=0.3um)

Sandblasted (Ra=4.16um)

Finned (140% area increase)

Microporous (3M)

Micro Cool (Wolverine)

Spray Pyrolysis (NREL)

Nanowire (CU)



10

Submerged Jets

• Microporous/roughened surfaces

had minimal effect on performance

• MicroCool (Wolverine) produced

highest h-value enhancement

(~100%)

• Finned structures outperformed

microporous/roughened surfaces

(increased area effect)

0

25,000

50,000

75,000

100,000

125,000

150,000

0 3 6 9 12 15

He

at

tra

ns

fer

co

eff

icie

nt

(W

/m2-K

)


Submerged Jets

Baseline (Ra=0.3um)

Sandblasted (Ra=4.16um)

Finned (140% area increase)

Microporous (3M)

Micro Cool (Wolverine)

Spray Pyrolysis (NREL)

Nanowire (CU)


Outline

11









V. Recommendations


Single-Phase Jets: System-Level Tests

12

• Effect of surface enhancements in conjunction with impinging submerged jets

• Performance of cold plate with MicroCool finned surface compared with non-

coated cold plate (plain)

• Semikron SKM module used, powered using thermal transient tester

• Powered IGBTs (gated 10 volts). Sense current (100 mA) used to measure

junction temperature

MicroCool Surface directly over IGBTs and jets Credit: Gilbert Moreno, NREL (all images)



• Power to module: ~35 W per

IGBT

• MicroCool cold plate reduced

total thermal resistance by 7% at

higher velocities as compared

with plain cold plate

• Limited enhancement are a

result of the package resistance

13

0.00

0.10

0.20

0.30

0.40

0.50

0 2 4 6 8 10

Th

erm

al re

sis

tan

ce

: R

th (

j-l)

(K

/W)


Plain

MicroCool


0.1

1.0

1 10 100 1,000 10,000

Th

erm

al re

sis

tan

ce

: R

th

, j-

a (K

/W)

R"th, h-a (mm2 -K/W)

Coldplate Cooled

Baseplate Cooled


• Package becomes dominant thermal resistance with increasing heat exchanger performance

• Greater thermal performance improvements if jets impinged directly on baseplate

• Estimated 12% reduction in thermal resistance

14

Coldplate cooled

Baseplate cooled

12%

Semikron SKM


Outline

15









V. Recommendations


Two-Phase: Fundamental Study

16

• Utilize high heat transfer coefficients of two-phase to improve power electronics cooling

• Investigate means of further enhancing two-phase heat transfer

• Surface enhancements as well as other techniques

• Several novel refrigerants/coolants will be tested

• DuPont HFO-1234yf: Potential next generation automotive A/C refrigerant

• 3M HFE-7100, HFE-7000, Novec 649: Dielectric coolants

Credit: Gilbert Moreno & Charlie King, NREL Credit: Gilbert Moreno, NREL



17

Pool / Immersion Boiling

3M Microporous Coating

• Enhances heat transfer up to

500%

• Decreases boiling incipience

superheat (DT≈3°C)

CU Nanowire Coating

• Enhances heat transfer up to

100%

3M HFE-7100 Dielectric Fluid: Saturated boiling curves 1 atm

3M Microporous

coating

Credit: Bobby To, NREL



18

Spray Cooling: Flow Rate

Effect

• Distinct pool and spray boiling

curves for plain surface

o significant forced convection

influence

• Minimal forced convection

effect for microporous-coated

surface

o boiling dominant

• May be possible to employ a

passive two-phase cooling

scheme with spray cooling-like

performance 3M HFE-7100 Dielectric Fluid: Saturated Fluid (1 atm)


Outline

19









V. Recommendations


Two-Phase: System-Level Tests

20

Cu spreader

plate baseline

Cu spreader plate

with microporous

(3M) coating 440× Magnification

• Demonstrate effectiveness of immersion boiling with microporous (3M) coating to

cool an automotive power electronics module

• Lexus modules supplied by ORNL and coated by 3M were used

• Plain (non-coated) and microporous coated modules tested

Credit: Gilbert Moreno, NREL (all images)



Test Conditions:

• Saturated 3M HFE-7100

(dielectric) at atmospheric

pressure 83 kPa (~12 psia)

• Modules powered using a

transient thermal tester

• Powered IGBTs (gated 10

volts). Sense current (100 mA)

used to measure junction

temperature


21



Immersion Boiling with 3M

Microporous Coating

• Reduced total thermal resistance

by over 50% as compared with

existing dual sided cooling

• Achieved better performance

with no pump required

22

0

0.1

0.2

0.3

0.4

0.5

0 50 100 150 200

Th

erm

al re

sis

tan

ce

: R

th,

j-l

(K

/W)

Heat dissipated (W)

Immersion Boiling with Microporous Coating

Lexus Cooling Configuration [Sakai et al. (2007)]



23


Plain Microporous

Power dissipated: 28W

IGBT heat flux: ~17 W/cm2

Rth (j-l): 0.39 K/W Rth (j-l): 0.1 K/W



24


Plain Microporous

Power dissipated: 165 W

IGBT heat flux: ~100 W/cm2

Rth (j-l): 0.19 K/W Rth (j-l): 0.09 K/W


Recommendations

25

• The use of enhanced surfaces is recommended when implementing a

single-phase, jet impingement cooling scheme

• Submerged Jets: Wolverine MicroCool finned surface provides 130% heat

transfer increase

• Free Jets: 3M microporous coating provides 100% heat transfer increase

• Immersion boiling (two-phase heat transfer) used in conjunction with the

3M microporous coating should be considered as an alternate to

conventional single-phase cooling schemes

• Demonstrated to reduce total thermal resistance by over 50% and may

increase system efficiency (no pump)

• Package stack design must be matched with appropriate cooling scheme

• Additional research is recommended to investigate reliability of:

• Enhanced surface performance over time

• Effects of contamination and system seals in two-phase heat exchangers

NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

Enhanced Surfaces to Improve Power

Electronics Cooling

Gilbert Moreno

303-275-4450

[email protected]

Acknowledgements:

Susan Rogers, U.S.

Department of Energy


Documents

Enhanced Surfaces to Improve Power Electronics Cooling - NREL - MORENO.pdf · 2013-03-27 · Suraj Thiagarajan Kevin Bennion Travis Venson 3M Wolverine Tube, Inc. University of Colorado,