 lighting fixtures, without the need for a fan. When heat isn't removed from LEDs, longevity and performance suffer.)
TO COOL: Nuventix's SynJet technology is an example of a system that can be used to cool light-emitting diode (LEDs) lighting fixtures, without the need for a fan. When heat isn't removed from LEDs, longevity and performance suffer.
Image: © NUVENTIX, INC.
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Light-emitting diodes (LEDs) really shine as an energy-efficient, long-lasting source of illumination in sensors, flashlights and video screens. For larger and more powerful LEDs to succeed in replacing incandescent and fluorescent bulbs in home and industrial lighting, however, they must be designed to better keep their cool.
Heat is the great enemy of LEDs. Because LEDs do not emit heat as infrared radiation like incandescent or fluorescent bulbs do, it must be removed from the device by conduction or convection. If an LED system does not have an effective way of getting rid of excess heat, rising temperatures will damage LED components, dimming the light and curtailing its lifetime, according to the U.S. Department of Energy.
The incandescent and fluorescent bulbs commonly sold today use a lot more electricity than do LEDs, but they are also better at shedding heat, says Christian Wetzel, an associate physics professor at Rensselaer Polytechnic Institute in Troy, N.Y. "LEDs may generate less heat," he adds, "but it still needs to be removed."
The norm for cooling an LED (which is actually a semiconductor that converts electricity into light) has been to place a copper or aluminum tube near the light to act as a heat sink and draw away excess heat. Another option has been to build a fan into the lighting system that can dissipate warmed air. A third idea that is gaining traction promises to remove heat more aggressively than metal tubes and more efficiently and quietly than fans: a pump uses an oscillating diaphragm to quickly push jets of air over the source of the heat.
"The way we attack the problem is not like the way a fan does by blowing as much air as you can through a system," says Mick Wilcox, director of marketing for Nuventix, Inc., the Austin, Tex., maker of SynJet, a synthetic jet technology that features a diaphragm that moves up and down when voltage is applied. "We use an electromagnetic approach very much like a speaker. SynJet's nozzles can be placed within a millimeter or two from the heat sink."
When SynJet's diaphragm moves, each pulse creates a "bullet" of air, Wilcox says. Because SynJet's airflow is more thermally efficient, less air is needed to provide cooling and the system as a whole makes less noise than a fan does, he says.
Philips Lighting has begun designing Nuventix's technology into its high-power LED lighting systems as an active cooling source. "Prior to SynJet, cooling was done passively, meaning with a bulky piece of aluminum, typically two to three times the size of the SynJet," says Geert van der Meer, Philips Lighting's global product marketing director for solid-state lighting (which includes LEDs). Philips's line of Fortimo powerful LED lights relies on active cooling because these lights are typically installed in a ceiling, which means there is very little available air space to provide ambient cooling, he adds. "Forced cooling is therefore a very attractive solution, especially for designs where quite some power needs to be cooled away."
Nuventix's technology comes at a price, of course. SynJet adds about 10 percent to the cost of the lighting unit, van der Meer says. "Philips has investigated multiple alternatives, like fans," he adds. "From a cost perspective, some alternatives look cheaper, but their reliability is not as good as SynJet, as most other technolog[ies] attract dirt over time, then become noisy and ultimately fail."
A technology such as SynJet could prove to be an attractive cooling option for LEDs, because it seems to work with any standard heat sink, Wetzel says. It remains to be seen, however, he adds, whether the diaphragm's movement can provide coughs of air that are powerful enough to reach all the areas that need to be cooled.
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9 Comments
Add CommentThis new cooling technology is meaningful. Although it adds about 10% to the cost, it's able to protect LED's components better and thus save money actually.
Reply | Report Abuse | Link to thisWhat words about the fools there at you is which do not study?
Reply | Report Abuse | Link to thisNear to the luminous diode it is possible to place, in the same case, isothermal converter heatvoltaic.
The composition will radiate light, to cool an environment to have the light diode and to give back in an external circuit surplus direct an electrical current.
Temperature of the diode will be lower than temperature of an environment and diode will not spoil.
The fools do not want to hear about this opportunity!
They like ways, complex and expensive at cost!
vetto@nm.ru
This is quite interesting...this particular article follows on the heels of a similar one published in the same Technology section of Scientific American. That previous article discussed a method to cool down computer processors that generate exponentially more heat as computational power increases.
Reply | Report Abuse | Link to thisIts based on the principle of electro-hydrodynamic cooling, which in the words of the author Larry Greenemeir, "uses an electrode to create a high-intensity electrical field that ionizes (electrically charges) the air molecules around it in tandem with a second set of electrodes to attract those charged particles. As the ionized air molecules move from one electrode to the others, they carry with them a steady flow of air".
The main advantage of this technology is its efficiency and complete lack of moving parts. I think this same method could be applied to LED cooling . Perhaps this technology was already evaluated and deemed technically unfeasible, but if I were Ventiva (the company trying to commercialize electro-hydrodynamic cooling) I would get a hold of Phillips and make a pitch.
Gosha is correct. If the recovered power is fed back into the LED, there is no need for external power after a brief period of temperature increase. That means that Edison company makes no profit.
Reply | Report Abuse | Link to thisI predict such energy recovery will be outlawed. The energy companies have great power here in California. For more information, google "mike duvall" to understand their political power.
I hope they don't hunt us down and " " us for what we now know! Maybe it is good to be a little paranoid, but who knows who out to get who?
Reply | Report Abuse | Link to thisWhat if instead of using DC current they used AC to lite the LED's. Then the devices could cool between cycles?
Reply | Report Abuse | Link to thiswhy people don't creat more means to reduce the heat incandescent and fluorescent bulbs emit?
Reply | Report Abuse | Link to thisWell, considering that incandescent lights by their very nature emit heat....
Reply | Report Abuse | Link to this"Incandescent: adj. 1a. white, glowing, or luminous with intense heat."
http://www.merriam-webster.com/dictionary/incandescent
Forced airflow definitely is a big plus. Another question is a way to provide such airflow. Why a diaphragm pump? Air forcing is provided in the millions of electronic devices by air fans - reliable, cheap and without pulsations.
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