L.E.D. vs HALIDE/T5/VHO

[StirCrazy]

Originally Posted by OceanicCorals-Ian-

Here is a recent quick review of the LED Aqua Illumination module. Note the PAR comparison.



http://reeftools.com/news/aqua-illum...ar-led-system/

yup, nice output but there 24" is from the top of the aquarium, they forgot to include the 2" the modual is above the tank so there 12 and 24" measurments should actualy be labled as 14 and 26.

Steve

[Lampshade]

For Cooling check out this online calculator:
http://www.novelconceptsinc.com/calc...resistance.cgi


Cree has a page regarding thermal management:
http://www.cree.com/products/pdf/XLa...Management.pdf
And their page about XP-E's:
http://www.cree.com/products/pdf/XLampXP-E.pdf

Sooooo.... I'm planning on a build with 120 LED's. The Thermal Resistance in the LED's are 9°C/W(XP-E Blue/White) and a good junction to the heatsink is 1°C/W per LED i can calcualte the minimum heatsink resistance needed driving them at 750mA at an ambiant 30°C(my house has AC, should never get that high). Thermal resistance is how much hotter something gets to disapate 1W of heat, so lower is better for a heatsink.

Aluminum is about 237 W/m*K at 26 Celcius.(wikipedia)

Use the formula for Heat from cree:
Tj = Ta + Ptotal (Rth j-sp/ NumLED + Rth sp-h + Rth h-a)
P = 120*.750A*3.25V = 292.5W
Rth h-a = (145°C - 30°C –9°C/W x 292.5W/120 – 1°C/W x 292.5W/120)/292.5W = 0.31°C/WIn

I need a min 0.31°C/W heat sink.

Using the calculator on novel i can find the size i need to meet that. I used the slab calculator and the one linked above and came up that a 10"x42" heatsink with 1" fins and .25cms of air flow, asuming .25cms average flow over the entire thing, 1 computer fan is .25, it would probably take 2 to make this consistant. This would have a C/W of : 0.0653926108°C/W, far more than needed.

Couple other pages for info on Cooling LED's:
http://www.qats.com/cpanel/UploadedP...a_0909_web.pdf
http://sound.westhost.com/heatsinks.htm

[mseepman]

Originally Posted by Lampshade

For Cooling check out this online calculator:
http://www.novelconceptsinc.com/calc...resistance.cgi


Cree has a page regarding thermal management:
http://www.cree.com/products/pdf/XLa...Management.pdf
And their page about XP-E's:
http://www.cree.com/products/pdf/XLampXP-E.pdf

Sooooo.... I'm planning on a build with 120 LED's. The Thermal Resistance in the LED's are 9°C/W(XP-E Blue/White) and a good junction to the heatsink is 1°C/W per LED i can calcualte the minimum heatsink resistance needed driving them at 750mA at an ambiant 30°C(my house has AC, should never get that high). Thermal resistance is how much hotter something gets to disapate 1W of heat, so lower is better for a heatsink.

Aluminum is about 237 W/m*K at 26 Celcius.(wikipedia)

Use the formula for Heat from cree:
Tj = Ta + Ptotal (Rth j-sp/ NumLED + Rth sp-h + Rth h-a)
P = 120*.750A*3.25V = 292.5W
Rth h-a = (145°C - 30°C –9°C/W x 292.5W/120 – 1°C/W x 292.5W/120)/292.5W = 0.31°C/WIn

I need a min 0.31°C/W heat sink.

Using the calculator on novel i can find the size i need to meet that. I used the slab calculator and the one linked above and came up that a 10"x42" heatsink with 1" fins and .25cms of air flow, asuming .25cms average flow over the entire thing, 1 computer fan is .25, it would probably take 2 to make this consistant. This would have a C/W of : 0.0653926108°C/W, far more than needed.

Couple other pages for info on Cooling LED's:
http://www.qats.com/cpanel/UploadedP...a_0909_web.pdf
http://sound.westhost.com/heatsinks.htm

Great links on this. Have you started your LED build yet? How big is the tank you're building over?

[lastlight]

Lampshade you should put together an online calculator for all that. Be a huge hit with the DIY LED crowd. Nicely done!

[Lampshade]

No start on a LED build yet... I've been doing a "bit" of research on this so i can justify the nearly $2000 expense. looks good so far, I'll probably start with some suppliment lighting to my MH's and eventually replace them. The tank's a 150gal 6" long, so i was planning on a fixture that size(10x48) and 40° optics, possibly 60°. Should get decent spread, i just want to avoid the zebra color's like i've seen some people have with 40° optics.

As for an online calculator, probably a good idea, haha, maybe i could get vertex or even cree to give me product for advertisements :P.