L.E.D. Revolution?... My idea for thermal efficiency...

[Neekz]

Hello all! Doing my daily absorption of the Internet (Always hunting something down...), I find myself eyeing P.W.M's for my array on Schmamazon (Does Amazon seriously not take Paypal? Corporate bickering's lame ...). Well I scroll down, and what do I see in my "Customers Who Bought Items in Your Recent History Also Bought" section (Lol they have like 5 of them constantly distracting you...) but This. It's called a "Peltier Cooler", Thermoelectric Cooling. They allow for rapid heat dissipation, at the price of power (Mainly 12vdc...). For smaller setups probably not practical, but in the high-watt/density (Or expensive BIN...) arrays it could definetely help efficiency (possibly canopy temp, through cooler bulb/lenses). Would like to hear y'all thoughts...

 

[hempfield]

Don't event think to cool your leds by using a Peltier element. This will drastically reduce the efficiency of the entire setup.

To keep the LEDs cool, just use a proper heatsink with silent fan, like the ones designed for CPUs . Take a look here : https://www.icmag.com/ic/showthread.php?p=5669925#post5669925

 

[Neekz]

I don't know, guy's over on candlepower.com are using em for 50w chips in their flashlights (Even more ridiculously inefficient IMO, batt powered ...). Their not the most efficient at their job (5-8%), and yes they still need to be heat sunk themselves but I see no negatives besides energy losses... Cheapo no-name 100w diodes can put out something like 8000 lumens (Approaching the HID ballpark with a single bulb...). Now if it helps reduce the heat sink size down the 5-8% it helps, then why not (assuming you can deal with the added watt usage...). Usefull on something like this...

[YOUTUBEIF]http://www.youtube.com/watch?v=18th3T2sxNE[/YOUTUBEIF]

Now I can't see why you'd shy anyone away from experimenting, with that attitude (Don't wander, stick to the tried and true...), nobody would be using L.E.D.'s... I guess the problem with that would be such a focused, intense light pattern, but try arguing that with the H.I.D. dude's lol... I also thought of the possibility of the cooler bottle-necking the sink but check this out lol...

And if condensations a worry (Water cooled peeps got some tricky solutions...), the can be controlled to the exact degree (With a thermostat if necessary, their often used in Wine Coolers...). Positive thinking to all

 

[habeeb]

I think a fun project to "just do it"

but in the real world, were not even close to this, when fans / heat sinks still can improve before looking at the tech, which uses lots of energy ( the whole point of LED is to conserve energy )

there still improving fan design, also heatsink design. I talk about this when looking at Noctua..

also we are not even anywhere to know what the future of LED will look like. when we hit a efficiency point we want, then people will start improving on the other aspects, where they are at the beginning of LED tech with thermal properties and design. things I feel will change, you might not see them for say, but they will be there to improve the LED point blank. we might have multi chips , maybe even the same single chips, but LED has a ways to go before we need to look into squeezing every last drop with peltiers.

also what I understand, you need a fan to cool the peltier, its gets super cold on one side, super hot on the other. so were no where but complicating things by adding the peltier. obviously it can cool below what a fan can ( ambient temps, but still for that, the extra power needed, I don't think offsets the light output gained. ) I've thought about this before also, but the complication of this thing, I left it with an idea..

who knows, maybe you need to build one, and show us what it can do. were not all the same, and even everyone's DIY is completely different. maybe you need to go for it. don't let us stop you if you want to do it.. change only comes from difference....

my opinion.

 

[SupraSPL]

Unfortunately Hempfield is right, the system efficiency would plummet. Peltiers are notoriously energy inefficient. And as Habeeb pointed out efficiency is the point of LED.

I experimented with this a while back. I took apart two mini fridges. One used a peltier (68w) and the other a small compressor (~110w). Keep in kind that small compressors are very inefficient compared to large ones. Despite that, the small compressor annihilated the peltier in terms of energy consumption and getting the job done.

The peltier had to run nonstop and could not get the keep the temp down. The compressor would kick on for a short while and reach my target temp with no trouble.

 

[babelfish]

Unfortunately Hempfield is right, the system efficiency would plummet. Peltiers are notoriously energy inefficient. And as Habeeb pointed out efficiency is the point of LED.

I experimented with this a while back. I took apart two mini fridges. One used a peltier (68w) and the other a small compressor (~110w). Keep in kind that small compressors are very inefficient compared to large ones. Despite that, the small compressor annihilated the peltier in terms of energy consumption and getting the job done.

The peltier had to run nonstop and could not get the keep the temp down. The compressor would kick on for a short while and reach my target temp with no trouble.

:/ we need better peltiers! soon!!!! i'd like to put em on those 50-500w led's i dream about...

 

[alesh]

:/ we need better peltiers! soon!!!! i'd like to put em on those 50-500w led's i dream about...

Sorry but no peltiers can improve the LED's best advantage, its efficiency. For 500W unit, 1kg of well-shaped aluminium could do the work, though.

 

[devilgoob]

No. He's talking if you heat the hot side of the peltiers with the LED's, and have heatsinks on the other side, that the peltiers would generate electricity for fans.

 

[hempfield]

Keep in mind that the Peltier elements act as insulators when they are not powered up. This is why such elements are the weak point of the entire chain.

A much more efficient cooling for LED is liquid base cooling, but this also means a more complicated setup but has the advantage of quick cooling and you can move the heat away from the growing space easily.

 

[foomar]

This heat pipe tec has been used in industry for at least 50 years , not sure if its applicable to DIY without a workshop .

Without current a peltier is more of a duvet and cost me an overclocked processor , heat pipes increase tranfer to a heatsink by a significant amount , but at a cost that may not be viable.

Some pc chip coolers use them but the design is poor and more about marketing.

I can vouch for their ability to move heat fast , sales ploy at ind exhibitions was to get someone to hold one end of a metre long pipe then hold a lighter at the other end.
You drop the bar after about five seconds or lose skin in ten.

Notice the suppliers of industrial high wattage led lighting are mainly useing heavy oversize passive heatsinks without a fan.

 

[babelfish]

This heat pipe tec has been used in industry for at least 50 years , not sure if its applicable to DIY without a workshop .

Without current a peltier is more of a duvet and cost me an overclocked processor , heat pipes increase tranfer to a heatsink by a significant amount , but at a cost that may not be viable.

Some pc chip coolers use them but the design is poor and more about marketing.

I can vouch for their ability to move heat fast , sales ploy at ind exhibitions was to get someone to hold one end of a metre long pipe then hold a lighter at the other end.
You drop the bar after about five seconds or lose skin in ten.

View Image

Notice the suppliers of industrial high wattage led lighting are mainly useing heavy oversize passive heatsinks without a fan.

this would likely be far superior to any current led heatsync tech.

and probably have a pricetag to match. however, it just might be worth it.

 

[foomar]

15 years ago acetone filled 4 x 35 mm pipes of copper were around 10 pence each on a 10k order with a die setup one off charge , quite cheap as there is not very much makeing in them , just simple low tolerance tube and presswork on fast autos.

Suprised the complicated extruded/diecast sinks do not incoporate them , for a 20% boost or to use less metal in the sink.


If you used exotic materials and forced air through a hollow blade style sink , or used water cooling you could greatly increase the rate of heat transfer but the cost could outway any benefits.

Would a 10% increase in thermal tranfer allow the leds to be driven 10% harder or would that still shorten life ?.

 

[babelfish]

well its not like we're supercooling them to drive them harder...