3 led cooling

LED COOLING WITHPIEZOELECTRIC FANS

Alic Chen Hiva Esmaeili Alan HarbottleAlic Chen, Hiva Esmaeili, Alan HarbottleProf. Paul Wright

/12PROJECT OVERVIEW: ACTIVE HEAT SINK COOLING SYSTEM

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ACTIVE HEAT SINK COOLING SYSTEM

Thermal management using piezo-electric actuators for fan-less convection improvement of passive cooling bodiesconvection improvement of passive cooling bodies

Improved heat transfer from a given heat sink geometry: 50 x 60 mm, 30mm Height

Temperature reduction at the surface from 100-120°C >> 60-70°C Temperature reduction at the surface from 100-120 C >> 60-70 C (20W Heat)

Long term stability >20000 Hours Mechanical failure Robustness against dust, humidity

Acoustic emission < 45 dB(A)

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10 mm

Example of a heat sink with Piezo-fan Piezo Systems, Inc.3”+

115V @ 60Hz

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FAN CONFIGURATIONS3

‘Forward’ Orientation ‘Vertical’ Orientation

‘Horizontal’ OrientationHorizontal Orientation

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EXPERIMENTAL SETUP4

PiezoFan

Thermocouple position 4x10W Heaters Behind Block

Thermal Insulation

4x10W Heaters Behind Block

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PIEZOELECTRIC FAN TESTING5

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FINDINGS6

‘Vertical’ Orientation

‘Horizontal’ Orientation

Vertical config provides more of cooling than the horizontal config at all coverage levels.

In vertical configuration 12 5% and 25% coverage provide almost identical In vertical configuration, 12.5% and 25% coverage provide almost identical cooling.

In horizontal configuration, 12.5% coverage provides more cooling.

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FINDINGS7

‘Forward’ Orientation

‘Vertical’ Orientation

‘Horizontal’ Orientation

At all heights, the forward configuration provides more cooling. For all configurations 1mm fan distance provides greatest cooling For all configurations, 1mm fan distance provides greatest cooling.

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PARTICLE IMAGE VELOCIMETRY8

Photos of flow using PIV setup by over-seeding with atomized oil – collaboration with Pello

“Laser”

CameraPiezo Fan

Plexi-glass Chamber

Pi fPiezo fan

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VELOCITY MAGNITUDE9

500µs snapshot d ito determine

bulk flow rate and flow pattern.

Piezo fan

Horizontal orientation viewed from

αviewed from side.

α ≈ 45-50°α

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HOT WIRE ANEMOMETER10

Data taken at “grid gpoints” to measure bulk flow velocity

R lt h fl Results show flow splitting (α ≈ 45-50º) similar to PIV

Piezo fan

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COMSOL SIMULATION11

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HEAT SINK DESIGNS12

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LOOKING AHEAD…13

Continue design iterations to take advantage ofContinue design iterations to take advantage of flow profile

Perform flow visualization through heat sinksPerform flow visualization through heat sinksPIV & hot wire anemometer

E i t ith d i tili i lti l fExperiment with designs utilizing multiple fansExplore vortex effects near fan tip

QUESTIONSQUESTIONS