Dr Song Lin – 30. May 2012Copyright © 2012 FrigoDynamics®1 The Future of Lighting Fixture Design LED Thermal Management Cavendish Conference Centre, London

Dr Song Lin – 30. May 2012 Copyright © 2012 FrigoDynamics® 1

The Future of Lighting Fixture DesignLED Thermal Management

Cavendish Conference Centre, London29.5.2012–30.5.2012

Welcome to


The majority of problems in a LED lighting solution are caused by

poor thermal management.

The fact is that LED heat dissipation mustprimarily utilize conduction and convection

means rather than radiation.

Abstract

Dr Song Lin – 30. May 2012 Copyright © 2012 FrigoDynamics® 3Copyright © 2012 FrigoDynamics® 3

LED junction temperatures are limited and hence heat management cannot solely depend upon

radiant waste heat dissipation anymore.

In fact, radiation is negligible.

Heat Management requires a SYSTEM approach

This is a paradigm shift, lighting designers must recognize when moving to LEDs

Abstract

!

Dr Song Lin – 30. May 2012 Copyright © 2012 FrigoDynamics® 4Copyright © 2012 FrigoDynamics® 4

Different heat dissipation mechanism in LED system, from conventional light sources

High Power LED Light Engines dissipating more heat and requiring better cooling solutions

Thermal management ensuring customers staying at the forefront of the lighting revolution

Lighting fixtures undergoing the most radical redesign in a century

Thermal challenges

Abstract


Proper control of Tj critical and key

LED dieTj

CaseTc

Waste Heat Disposal

Inside LED ModuleMain means = Conduction.

→→→→

ExternalMain means = Convection.

LED Module Manufacturer OEM Lighting Designers

The Challenge

Junction Temp (Tj) is monitored via Case Temp (Tc) as Junction Temp cannot be measured


Means

• Cooling options for LEDs range from natural convection into air, passive or active to liquid cooling means

• Air cooling with conventional heat sinks, fans and/or advanced two-phase technology is widely accepted by the market place and will remain the primary choice.

• The market reluctantly go for liquid cooling, such as cold plates, due to various issues associated with water near electronics and pumps.

Cooling Options


Means

PassiveAL heatsinksCU heatsinksAdvanced passive cooling methods

ActiveFans assisted heat sink (forced convection)Membrane assisted heat sink (forced convection)

Cold PlatesWater pumped underneath heatsource(for special applications and not covered here)


Passive

AL or CU heatsinks (natural convection)Material Thermal Conductivity (W/mK)

Aluminum (99.5) ~ 240Aluminum (Alloys) ~120 - ~180Copper ~ 400

~ 45°~ 45°

There is little heat transfer in horizontal direction

Heat travels downward in a ~ 45° angle to the surface. Therefore increasing the surface area with a larger heat spreader will not

significantly improve the thermal design.

die die

!


¹ Conventional passive coolers are confined to handling low power LED applications due to the thermal limitations of the materials used

AL or CU heatsinks (natural convection)Passive


Fan or Membrane assisted sinks

Fan or membrane assisted heat sinks increase the air flow thus significantly improving the convection properties of the heat sink

Results in much smaller area required to achieve the same thermal resistance.

http://www.nuventix.com/products/led-cooling/par25-cooler-32w/SUNON LA004-003A99DN - Cooling module; LED 40 W

Active

http://www.nuventix.com/products/led-cooling/par25-cooler-32w/

http://www.tme.eu/dok/l/LA004-003A99DN.pdf






Active

Fan or Membrane assisted sinks

² Fans can provide a much higher airflow than membranesthus can reach lower thermal resistance requirements


Advance Passive

The Passive Revolution 2-Phase-systems employ evaporative cooling technology to transfer thermal energy from one point to another by evaporation and condensation of a working fluid embedded in a vacuum tight vessel.

Heat Input

Evaporator

Heat Output

Capillary wick

Vapour Flow

Container

QLiquid Flow

CondenserAdiabatic section


Advance Passive

The Passive Revolution Based on this physical principle FrigoDynamics® has developed a patented platform ofadvanced passive HPK-Fin™ 2-Phase heat exchanger solutions.

They are extremely effective, light weight, eco friendly, 100% recyclable and easy to applycooling solutions. They pose neither cost nor risk of operation, and thus are the mostcost effective Solid State LED cooling solutions available.They are particularly well suited to cooling high power LEDs with a small heat source footprint due to being able to efficiently spread heat across all areas of the 2-Phase heatexchanger regardless of heat source size and meeting challenging ΔT requirements.

Material Thermal Conductivity (W/mK)

Aluminum (99.5) ~ 240Aluminum (Alloys) ~120 - ~180Copper ~ 4002-Phase device ~50,000 - ~200,000


Advance Passive

The LED market is highly demanding on eco friendly solutions. Reliability, longevity and cost of ownership are key. Passive cooling means are primarily considered for LEDs and modules.

The Passive Revolution

Many commercial and industrial LED applications are demanding thermal needs that conventional passive cast or extruded heat sinks can no longer meet, due to the thermal limitations of the materials used.

Substantial size and weight of heat sinks, along with significant and substantial performance degradation, when changing orientation, signifies that things must change.

Active cooling means are not suitable for your applications

Advanced passive cooling solutions can help when …..

Dr Song Lin – 30. May 2012

Advance Passive

The Passive Revolution


Pros & Cons

Active Solutions

Noise and SoundEchos and VibrationsProactively attract debris/dustIncreasing sound levelsReduced performanceReduced lifetimeCO₂ Emissions, not ecological friendlyWiring, ControllersCost of operationSpecs typically allow for ~10% failure rateSevere longevity concernsEverything whichs moves will stop movingHigh risk of operationPotential replacement costUnpredictable cost of ownership.

More compact form factorLower weightLower Tr case to ambientResource considerate(less material usage)

Pros Cons

Sunon LED 40 W

Nuventix Par25 – 32W






Pros & Cons

Passive Heat Sink Solutions

Bigger form factor than activeHigher WeightPerformance limitationsRequires more material per W coolingOrientation sensitive

No risk of operationNo cost of operationHighly reliableNo performance degradationLot of variations possibleNo CO₂ Emissions0 dB operation

Pros Cons


Pros & Cons

Passive 2-Phase HX Solutions

No cost of operationNo risk of operation, no frictionHighly reliable, nothing movingNo performance degradationNo CO₂ EmissionsResource savingCompact form factorsVery light weight0 dB operationApplication specifc scaleableCools all lumen valuesLot of variations possibleMeets Low ΔT requirementsOrientation insensitive

Pros ConsNo functional or operational consRequires volume


Pros & Cons

Summary in Brief

³ Required Tr case to ambient at Pth levels of 60W + at ΔT 30K (Tr c-a < 0.5 K/W)


Process

Thermal Design Process1. Determine aesthetic goals2. Determine envelope (dimensional) contraints3. Determine operation orientation(s)4. Calculate thermal power loss of chosen LED5. Determine max T case at max T ambient6. Calculate thermal resistance from case to ambient as

required.Select cooling means based on the above

If an extruded or cast AL heat sink does not meet the thermalrequirements, or is too big and/or too heavy and you want to avoid

active means or active means are not permitted or desired, FrigoDynamics® is here to help.!


Thank You

Thank Youfor your attention

[email protected]

www.frigodynamics.com

mailto:[email protected]

http://www.frigodynamics.com/

Documents

Dr Song Lin – 30. May 2012Copyright © 2012 FrigoDynamics®1 The Future of Lighting Fixture Design LED Thermal Management Cavendish Conference Centre, London