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Breakthrough laser cooling system could save space and energy


February 13, 2013

Professor Xiong Qihua and his team used a laser to cool the compound Cadmium Sulfide (Phot...

Professor Xiong Qihua and his team used a laser to cool the compound Cadmium Sulfide (Photo: Nanyang Technological University)

A research team at Singapore’s Nanyang Technological University (NTU) has successfully used a laser to cool down a semiconductor material known as Cadmium Sulfide. The results of the recently published study could lead to the development of self-cooling computer chips and smaller, more energy efficient air conditioners and refrigerators that don't produce greenhouse gases.

Cadmium Sulfide, an inorganic compound, is a type of group II-IV semiconductor commonly used in pigments to form the color yellow. It is also used as a thin-film layer in solar cells, sensors and electronics. Led by Assistant Professor Xiong Qihua from the School of Physical and Mathematical Sciences and the School of Electrical and Electronic Engineering, the research team optically-refrigerated the compound from 20° C (68° F) down to -20° C (-4° F).

The potential for using semiconductors as the basis for cooling structures powered by light could have some very usable permutations in the real world. Currently, high-powered devices such as Magnetic Resonance Imagers (MRIs), night-vision goggles, satellite cameras, and even air-conditioning systems and refrigerators all have one thing in common: they have bulky, noisy, highly mechanical or complex cooling systems. These systems consume large amounts of power and – in the case of refrigerants especially – often release harmful greenhouse gases into the atmosphere.

As computer chips, or CPUs, become more powerful, they also generate higher amounts of heat, too. Some pundits argue that if new cooling techniques are not found, thus creating a new, lower temperature working environment, then the regular increases in CPU speeds we have become accustomed to will continue to slow.

The breakthrough in laser cooling (aka optical refrigeration) technology could lead to compact, cost effective, vibration-free and cryogen-less cooling systems in many different applications. CPUs could reduce their reliance on external cooling systems like fans and incorporate built-in laser controlled systems instead. The potential for minimized heat and prolonged battery life in items such as tablets and smartphones is another example.

Or as Professor Xiong Qihua says, “If we are able to harness the power of laser cooling, it would mean that medical devices which require extreme cooling, such as MRI which uses liquid helium, could do away with bulky refrigerant systems with just an optical refrigeration device in its place.” And adding to that, “it would also remove the need for compressors and coolants in air-conditioning and refrigerators used in our homes and automobiles, saving space, energy and greenhouse gases.”

In theory, semiconductors can be cooled much further in temperature than minus 20 degrees Celsius. The research team is now looking to bring the laser cooling technique down to liquid helium temperature, at minus 269° Celsius. This is something that researchers at the Niels Bohr Institute managed to achieve with their own laser cooling method.

The experiment was funded by the NTU, Professor Xiong’s National Research Foundation Fellowship grant and the Ministry of Education Academic Research Fund. It took three years complete.

The study was published in January edition of the journal Nature.

Source: Nanyang Technological University


So the optical LASER causes the substance to "cool" or transfer heat from one side to the other. This heat will still be inside the computer case and still needs fans to pull it out...right? Additionally, any LASER case that Ive ever touched is hot (reference their heat sinks), so where is the added efficiency? This sounds like the once vaulted sonic refrigeration that never managed to materialize.

14th February, 2013 @ 04:21 am PST

While I understand the criticism posted here of the technology, I do think this is a a great way to move heat away from sensitive components. In some respects it is a more complicated system than just a fan but it does allow cooling beyond ambient air temp.

And it is just as complicated or less so than a liquid cooling system.
14th February, 2013 @ 05:37 am PST

>>more energy efficient air conditioners and refrigerators that don't produce greenhouse gases.

Really? I didn't know my fridge emitted any greenhouse gases.

Now, if what is meant is that it would reduce the amount of greenhouse gases produced by a greenhouse-gas-producing power generating plant, I disagree again. Assuming it works to remove heat from one place, it will only move it to another place. Valuable? Yes. But it cannot be >100% efficient, so the overall effect will be to burn MORE fossil fuels.

14th February, 2013 @ 08:46 am PST

jBar, so the laser over here is Hot, yes, but the cooling target is way over there... That's revolutionary. No more need to wrap your coper pipes in foam.

And MikeG... their not talking about Carbon:

Yes, your refrigerator will eventually loose its refrigerant poke it's own little hole in the Ozone.

Matthew Bailey
14th February, 2013 @ 11:30 am PST

Is this like the wonders of Graphine ?

The wonder substance that still isn't in one Real product.

Or the new batteries that last ten time longer ? Been talking about that one for twenty years.

Brian Mcc
14th February, 2013 @ 11:43 am PST

Oy, we got us a bunch of fun people here...

Guys, all cooling systems move heat around, the question is how efficiently they do it. We aren't talking about defying entropy here, just about being a lot more efficient than compressors and fans, which would mean less electricity used, plus all the other benefits mentioned. And Jbar, your dvd player has a laser in it, does it get hot? Ever seen a laser pointer? Brian, waiting on the wonders of graphene? Patience, young Padawan. Let's enjoy contemplating the future, people, that's what this is about.

Kim Holder
14th February, 2013 @ 04:28 pm PST

It makes me wonder if there might be an application in future hydrogen powered vehicles as hydrogen is best stored in cryo tanks and vehicle weight is always an issue.

Kerry Callinan
14th February, 2013 @ 05:02 pm PST

Am I missing something? FREON in refrigerators was outlawed years (decades?) ago - there are no more ozone-depleting gasses used in refrigeration nowadays that I'm aware of. Not sure what gasses they *do* use now, but again, I would be very surprised if whatever-it-is turns out to be "harmful". Like, seriously, why go to all the effort to establish international bans on one bad-ass-gas, only to replace it with another?

14th February, 2013 @ 05:11 pm PST

christopher yes Freon was banned years ago, but new refrigerants are Azeotropic and Zeotropic blends of new refrigerants classified by their ODP (Ozone depleting Potential) and GWP (Global Warming Potential) all of which do not score a O in both classifications or are as energy efficient as Freon(R12) or R22 (being phased out of production) and now newer blends (R404a, R134a etc.) The current alternative to these are natural refrigerants such as ammonia and CO2 which do have 0 odp/gwp but carry other risks such as flammability and are toxic to humans.

So the potential for this technology could be enormous in the refrigeration industry and the environment.

14th February, 2013 @ 07:37 pm PST

I'd love to finally see a new method being brought to computer cooling. If the laser removes the heat to a higher heat reservoir, then a fan is needed to remove that heat although you can use a bigger and more quiet fan as with water cooling (no subzero cooling).

Adjusting how much you cool is important when your system can reach subzero temperatures, because that's when water condensation can become a serious problem for your components.

CFC's (chlorofluorocarbons) have high retention time and have CO2 equivalent emissions of in the thousands.

Fretting Freddy the Ferret pressing the Fret
24th February, 2013 @ 06:07 am PST

Cooling a computer has certain real world issues to consider. Any form of cooling that causes condensation inside a computer case is a breakdown in progress. So there are very real limits on how cool the cooled part of the component can get as the dew point is too easily reached by very low temperatures. The other issue is the spread of cadmium as the units are builT. Being cadmium free is a really good idea and we certainly do not want the county dump oozing cadmium.

Jim Sadler
18th March, 2013 @ 09:48 am PDT
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