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.
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
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.
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.
Randy