Electronics

Fujitsu tech could bring us liquid-cooled smartphones

Fujitsu tech could bring us li...
A prototype of the loop heat pipe (Photo: Fujitsu)
A prototype of the loop heat pipe (Photo: Fujitsu)
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A prototype of the loop heat pipe (Photo: Fujitsu)
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A prototype of the loop heat pipe (Photo: Fujitsu)
A diagram of the loop heat pipe principle (Image: Fujitsu)
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A diagram of the loop heat pipe principle (Image: Fujitsu)
The loop heat pipe, as integrated into a smartphone (Image: Fujitsu)
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The loop heat pipe, as integrated into a smartphone (Image: Fujitsu)
A thermal image of a loop heat pipe prototype (Image: Fujitsu)
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A thermal image of a loop heat pipe prototype (Image: Fujitsu)
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Although there definitely are liquid-cooled PCs, there just isn't room for such cooling systems within smartphones – or at least, there hasn't been until now. Fujitsu recently announced development of a loop heat pipe that's less than one millimeter thick, which could help future mobile devices to keep their cool.

Currently, heat is drawn away from hot spots in smartphones using sheets of thermally-conductive solid materials such as graphite. According to Fujitsu, however, those materials won't be sufficient as phones continue to process data faster, and run more integrated devices such as cameras. Not only that, but phones will likely also continue getting slimmer, so they'll be generating more heat which will be concentrated in a smaller space.

That's where the loop heat pipe enters the picture.

Containing an unspecified liquid, it's a closed system that consists of an evaporator located near a hot spot (such as a CPU) and a condenser in a cooler section of the phone. The two are linked together in a loop, by two tiny pipes.

A diagram of the loop heat pipe principle (Image: Fujitsu)
A diagram of the loop heat pipe principle (Image: Fujitsu)

The evaporator contains six 0.1-mm-thick stacked sheets of copper, each one perforated with an array of pores. The liquid climbs up through these pores (which are offset from one another), with the heat from the hot spot causing it to vaporize as it does so.

That vapor then travels along the "vapor line" pipe to the condenser, where the cooler temperature causes it to condense back into liquid, releasing its payload of heat energy in the process. That liquid subsequently travels back along the "liquid line," returning to the evaporator to continue the process.

Because the liquid moves throughout the system via capillary action, it works regardless of the orientation of the phone.

Fujitsu is aiming at introducing the first practical implementations of the loop heat pipe in 2017.

Source: Fujitsu via IEEE Spectrum

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7 comments
The Skud
Pure genius! I wonder if sewing these into a jacket (ala B/P vest) would work for us overheated peons?
Fretting Freddy the Ferret pressing the Fret
Very -cool- use of evaporation/condensation in such a tiny format. As more of our technology is shrinking to a handheld size, solutions are needed for keeping them cool without leaving a large footprint.
Perhaps with some modifications and scaling, this could be used in notebooks as well? Adding a fan to the evaporator would boost condensation and do away with the dreaded loud fans. It is a kinda hard idea to implement however, because you need a large surface area of the evaporator and there is not a lot of room inside a notebook case. More importantly, capillary action could prove to have an unsatisfactory flow rate to keep everything chilly for except the least power hungry notebooks.
Regardless, this is very nice tech.
VirtualGathis
So their solution is to spread the heat to the entire phone rather than develop a less thermally wasteful processor?
My Samsung already gets too hot on the processor side when under heavy use. I can't imaging how bad it would be if the entire phone got hot as well, and yes I'm aware of the idea that spreading the heat will allow it to dissipate, but that operates under the assumption that a cooling fluid can flow over thermally conductive heat exchangers. Smartphones do not have power or room for an active fan so that concept is useless in a device that will be shrouded by the users hand most of the time.
It's neat science, but I foresee it being useless for the intended market.
PAV
Is there a way too use the heat to generate electricity to power the phone? Heat absorbed and converted to power? Now the waste heat is cycled back into power and the battery can be smaller to make room for the cooling device. I seem to remember some new alloy being created that does exactly that, it under went a phase change where the nonmagnetic material became magnetic and imposed a current in a coil. Perhaps it would be a hybrid where Fujitsu's items condenser is made up of the alloy, the liquid moves the heat away from the effected area and the water condenses as the alloy converts the heat into energy.
Dustin Cowles
@Freddy There has been cooling like this for laptops for well over a decade. Getting it small enough to use in a phone is the only thing new here.
Expanded Viewpoint
YAAWWWNNNN, call me when they get the DNA and cell damaging microwave radiation problem fixed, then I might be interested in having one of those currently dangerous devices near me. The president of Nokia reportedly never carries a cell phone on his body. How can a device that emits a blast of RF energy every 2 to 3 seconds be a safe thing to carry in your pockets or bra? Women who carry their cell phone in their bra cup develop breast cancer right in that spot. How much more proof is needed?? I never use one except in an emergency, and I keep the conversation SHORT! Over in Wally World a few years ago, I was behind a guy at the registers who had lost about 1/4th of his left ear lobe and a good portion of his scalp and neck skin. The scar tissue was not helping with his looks at all. And there he had a Bluetooth device on his right side! Hellooo! Time to wake up there Chum!!
Randy
Charl.H.Schul
16-04-2015 Another Electronic Cooling Possibility : What about using nano motors in a fan configuration integrated in the microprocessor circuits with nano ducts in order to cool off the system using an evacuation type of principle . The nano motor armature fan could be initiated by the electric pulses that travel along the digital lines which are digitally activated according to the different message demand so that they are only activated according to electronic traffic in that evacuated zone .