ledsogutma

8/18/2019 ledsogutma

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BAŞLANGIÇ

In more extreme cases of lighting, some type of active cooling may be required. This may be due to high heat

fluxes from closely located LEDs, a small volume or surface area that precludes natural convection, or an

extremely high ambient temperature condition. Any of these conditions may change the thermal budget in some

area and require an active cooling system.

arious !standard methods" for active electronics cooling have been proposed or used for LEDs as #ell, though

some special conditions apply for active LED cooling. To date, systems have used or proposed using simple D$

rotary fans, thermoelectric coolers %TE$s&, pie'oelectric fans %()*s&, synthetic +ets %-s& and liquid cooling %such

as microchannels&. Each of these has particular advantages, but also carries some disadvantages for cooling a

lighting system.

Active cooling for lighting has a fe# special requirements that are not necessarily required for every

semiconductor application. *or example, most lighting systems must not produce ob+ectionable noise levels. This

implies any active cooling system must be quiet, and moving active systems can generate ob+ectionable noise

unless precautions are used.

ther considerations for active light cooling systems are/

• Lifetime 0 Typically 12,222 hours for the LED product

• Lo# po#er consumption 0 An issue for TE$s as efforts are ongoing to improve energy and further

enhance Energy TA3 456 ratings for LED lights

• Lo# susceptibility to dust7foreign contamination 0 An issue for systems #ith moving parts and air

streams

• Ability to tolerate cyclic loading 0 An issue since lights are frequently turned on and off

• ystem cost addition 0 An issue today for liquid loop systems, such as microchannels

LUMEN OUTPUT

Lumen output is a 8ey factor in the adoption of LED lighting. Although LED

technology continues to advance, high9lumen9output LED applications cannot be

achieved #ith passive cooling alone. LED lights cooled by a passive heat sin8, rather

than #ith an active cooling solution li8e a synthetic +et, are inherently larger, #hich

ma8es retrofitting difficult. A smaller heat sin8 may result in a lamp or luminaire that is


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less reliable due to heat damage to the LEDs, or a source that produces insufficient

light for mar8et success.

Thermal dissipation is another 8ey factor that limits the lumen output of an LED light.

LED bulbs are available that are as much as :2 percent more energy efficient than

traditional incandescent lighting, but the LED components and the driver electronics

still create a considerable amount of heat. If this heat is not dissipated properly, theLED;s quality of light and life expectancy decrease dramatically.

SOGUTMA

HEAT SINKS

9equivalent LED retrofits

for A9lamps, and many also have solutions in place for ?2>9equivalent lamps. It is

#hen you get into the high lumen counts that thermal management becomes a

challenge. A heat sin8 alone #ill not cool a @1>9 or 22>9equivalent lamp.

The demand for these high brightness bulbs is evident 0 @1> and 22> lamps ma8e

up a significant piece of the lighting mar8et. Businesses are eager to ta8e advantage

of the energy and maintenance savings inherent #ith LED lighting. The Energy

Independence ecurity Act of C22@ #ill be requiring higher efficiency bulbs starting in

C2C. These ne# requirements have consumers loo8ing for an incandescent

replacement that has a good quality of light and a long life in addition to a high lumen

output.

In order to reach the desired lumen values in a fixed form factor, active cooling may

be required to dissipate the heat produced by the LED components. ome active

cooling solutions, such as fans, don;t have the same life expectancy as the LED

itself. In order to create a viable active cooling solution for high9brightness LEDs, themethod of thermal management must be inherently lo# in energy consumption,


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flexible enough to fit into a small form factor and have an expected life equal to or

greater than that of the light sources.

HEAT SINK ORNEKLERI (FOTO)

LED Heat sink L1!"#

Applications/ all >ash

ax. Thermal (erformance Fs9a/ .1C G$7>

ax. Thermal (erformance #7 yn-et Fs9a/ .C G$7>

i'e/ 22mm L x C@2mm > x @2mm <

ounting i'e/ 22mm x C@2mm

yn-et ption/ H*lo#=C

>all >ash LED

Available in both Round and Rectangular Mounting

Applications/ >all >ash, 3ecessed Do#nlights, Lo# Bay,

*loodlight, 3ectangular *orm *actors

ax. Thermal (erformance Fs9a/ . G$7>

ax. Thermal (erformance Fs9a #7 yn-et/ 2.= G$7>

i'e %3ect.&/ ==mm x Cmm x =@mm %L x > x x


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potlight LED

Applications/ Trac8lights, 3ecessed Do#nlights, (endant, Lo# Bay

ax. Thermal (erformance Fs9a/ . G$7>

ax. Thermal (erformance Fs9a #7 yn-et/ 2.=? G$7>

i'e/ 5=mm diameter, =Cmm heightounting urface i'e/ 1:mm

yn-et ption/ )*lo#2

potlight LED

Applications/ Trac8lights, 3ecessed Ad+ustable Do#nlights

ax. Thermal (erformance Fs9a/ C.C G$7>

ax. Thermal (erformance Fs9a #7 yn-et/ 2.:= G$7>

i'e/ :@mm diameter, 5:mm height

ounting urface i'e/ C:mmyn-et ption/ )*lo#:@

AA$ID THERMALLO% &i'asnn *'etii +a, -eatsink

*'*n.e'i/


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AKT0F SOUTMA

*or high9lumen output applications, passive cooling is not enough. In order to reach the desired lumen values in a small

form factor, active cooling is the perfect solution to effectively disperse the heat produced by LED components.

Active cooling solutions are a ne# contender in LED thermal management systems. Dissipating heat directly from the

core of the modules allo#s for less thermal resistance, ma8ing the entire assembly more efficient. Active cooling

technology offers thermal capabilities that are superior to passive heat sin8s and can raise performance #hile

significantly reducing the si'e of the lighting fixture.

Ebpm9papst firmasJnJn LED soKutmasJ iin MrettiKi ba'J fan eNitleri.


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SENTET0K 2ET SOUTMA

ynthetic9+et technology provides an active cooling solution for LED lighting, and has

been adopted by many ma+or global lighting companies. The compact cooling

modules address all of the constraints currently hindering the development of LED

lighting/ effective heat dissipation, small form factor and reliability.

ynthetic +ets are an alternative to the traditional fan and are much better suited to

the increasingly challenging demands of LED thermal management. The +ets are

formed by periodic suction and e+ection of air out of an opening that is caused by the

motion of a diaphragm, as displayed in *ig. . The first three panels in *ig. sho#the e+ection phase, during #hich a vortex accompanied by a +et is created and

convected do#nstream from the +et exit. nce the vortex flo# has traveled #ell

do#nstream, ambient air from the vicinity of the opening is entrained, as displayed in

the last t#o panels of *ig. .


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AAID T


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Figure 1


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Fi34'e "5 T-is s-67s a "/89: "/;9: 1/;9 &ine!t'4?e? -eat sink@ 7it- a 7att B'i?3e.4> LED a''a/ Cit- n6 ai' &.67@ t-is -as a t-e'a. 'esistan=e 6& ; C@eanin3 it =an -an?.e 6n. a+64t 1 7atts/ C-en a .67!s


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Fans Are Noisy

Yessiree... that fan in your microwave oven makes a racket, as does the fan in your PC or even

that window fan. But take a standard, low-speed under !"""-#P$% &C 'all-'earin(,

'rushless fan made 'y one of the top fan makers, such as &elta, N$B, )B$-Papst or others,

and operate it at the low end of its volta(e ran(e... and (uess what* +ts sound level can 'e lessthan - dB - completely inaudi'le in a dead-/uiet room when in a fi0ture seven feet or

more a'ove the floor. +n fact you will 'e hard pressed to hear it from one meter away in a

/uiet room. dB is way 'elow the !1-dB AN2+ standard for /uietest fluorescent li(htin(

'allasts.

Scratch Myth No.1.

Fans Are 3nrelia'le

&C 'rushless 'all-'earin( fans have one of the most visi'le and envia'le field histories of any

electromechanical component in the electronic industry. $illions of mission-critical

computers powerin( the +nternet and wireless communications systems have 'een operatin(!145 for well over a decade with fan-cooled power supplies usin( such fans.6hat does that

say a'out their proven relia'ility and user confidence*

2uch fans are 'acked up 'y what are called 78" reports.7 2uch reports provide life

e0pectancy when used at hi(h temperature and hi(hest speeds. At the very low speeds

employed in active-cooled 8)& luminaires, the life e0pectancies easily e0ceed "",""" hours,

much (reater than the life e0pectancy of the 8)&s themselves.

Scratch Myth No. 2.

Fans 6aste Power

A fan such as described above, cooling a 5229#att system, and operating at lo# speed,#ill use #ell under C #atts Q less than 2.@1O of system po#er... a 229#att system, less

than a #att.

Scratch Myth No. 3.

Fans 9ather &ust

It turns out that there is substantial real9#orld evidence that if you operate a fan at high

speed in a dirty environment or close to dusty carpeted floors, fan blades can indeed

accumulate dust, although that dust does not actually stop things from #or8ing. AP at a substantial height, and b& AL>AP operating at a verylo# speed. At very9lo#9air speed, the system differs little from a very9lo#9turbulence,

passively cooled %i.e., 'ero air speed& heat sin8 system. The result, evidenced in

numerous existing LED installations using active cooling, and supported by dust

chamber testing, is that after multi9year usage, any dust accumulation is so little as to be

irrelevant to the cooling process.

DİĞER ÇEŞİTLİ SOĞUTMA YÖNTEMLERİ


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HAVA İLE SOĞUTMA

)eta LED has developed an air9cooled LED light bulb. The Lifebulb consumes

2 #atts of po#er and puts out as much light as a standard ?2 #att incandescent, pretty much li8e existing LED

bulbs. The difference comesin the absence of an aluminum heat sin8.

)eta 8eeps its bulb cool by channeling air through the vents in the structure itself/ the vents are the strips and

holes separating the yello# LED arrays. The bulb does not come #ith a covering glass dome as air #ouldn;t

circulate if the electronics #ere completely covered. )eta might cover the LED arrays #ith a piece of glass, but

the vents #ill remain exposed.

Eliminating the heat sin8s and relying on ambient airflo# allo#s )eta to get the bill of materials for its bulb do#n to

close to R@ dollars, or nearly half the normal bill of materials. That means )eta;s bulbs that can retail, in mass

production, for R2.

SIVI İLE SOĞUTMA

Details on Liquid-Cooling Methodology

• Liquid-Cool Solution.

The liquid is a food-grade mineral oil which is harmless to the environment and people. By

immersing the hot LED and metal conductors in liquid the L!T"S liquid transfers heat away fromthe LED module to the surface of the glass. Similar to water-cooled nuclear plants L!T"S uses

liquid convection to efficiently remove heat from hotspots.


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• Thermal Conduction # $ % & % '△T(△D)

Thermal $*sorption # $ % Cp % '△T(△t)

o "etal + thermal conductivity & is large and has low heat capacity 'Cp), as a result metal

generally do not retain thermal energy.

o Liquid + !t has a high heat capacity 'Cp), as a result liquids generally have high heat

a*sorption capacity

• Localied otspots.

"uch of the LED heat generated is localied in small hotspots. Surrounding these small

hotspots *y liquid serves as an efficient medium for dissipating the heat.

• Dissipate eat from /lass Surface.

The liquid cools *y its contact with the glass cooled *y the air on all side. !n comparison

other conventional LED *ul* designs a heat sin0 near the *ase of the *ul* and attempts to

dissipate the heat only from the *ase.

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