Every generation of computing hardware increases the power of your devices to do amazing things every day – run your favourite games, bring powerful videography and post-production capabilities to your pocket, or even take the brunt of your never-ending array of open browser tabs. What also increases at the same time is the ease with which your device can heat up, thanks to more components like transistors being crammed into smaller areas, thus building up the heat they give off due to resistance. But then, shouldn’t all kinds of devices become increasingly prone to overheating with every generation? The answer is no, thanks to the several types of cooling technology that is used across your devices and gadgets with an objective to cool them as efficiently as possible. Some rely on purely passive cooling, which uses natural convection and dissipation, while some opt for active cooling, which uses an external device to enhance cooling. But beyond this broad classification, there are numerous ways it’s done across gadgets.
Even the most rudimentary smartphones today boast of quite a few capabilities. And all those abilities come at the cost of heating up the device when overused. There are quite a few advanced ways in which smartphone manufacturers are dealing with overheating, and some are yet to be applied to actual devices:
Using pipes to dissipate heat in smartphones is not new. NEC did it way back in 2013 with the Medias X. The design involved a pipe that contained water (in minuscule quantities) that ran from the CPU to other areas of the smartphone. Once heated, the water drop would turn into water vapour, travel to other, cooler areas of the body and condense back into the water, thus dispersing the heat before it travelled back to the CPU again. Some designs can skip water altogether and use dissipation to turn your entire smartphone into a heatsink. But it was Samsung that revolutionised the technology for its Galaxy S7 and S7 edge by designing a new pipe based cooling system that was 50 times more efficient than pure copper in terms of thermal conductivity.
They were able to achieve this by experimenting with alloys and metal mesh inside the pipe. Even in 2018, despite the availability of other types of tech Samsung has announced that they’ll be using heat pipes in their 2018 models as well. The gaming-centric Razor Phone also comes with a massive copper heat pipe in its design. Right now, if one were to bet, heat pipes are likely to stay for another couple of years or at least until vapour chambers (explained later) become affordable.
Working on the same principle of two-phase cooling as heat pipes, vapour chambers are different from heat pipes because they have, you guessed it, chambers instead of pipes for the water to evaporate and travel from a heated up area to a colder region and condense, releasing the heat externally.
While smartphone manufacturers have stayed away from vapour chambers due to the additional cost and the bulk they would add to a smartphone, recent advancements have made them both cheap and sleek enough to not put much additional bulk into the design. Expect to see them hit mainstream phones soon enough, as the cooling with vapour chambers is more effective than the heat pipe counterpart.
Employing the electrocaloric effect that uses electric fields to change the temperature of a material, scientists at UCLA and SRI International have devised a thin, flexible polymer material that can be used to reduce the temperature of devices significantly. The polymer transports the heat from the source to the sink when needed by alternating contacts between them. Think of it like this – when a piece of metal is heated on one end, the constituent particles on that end are in a higher state of excitement than the particles on the other end.
An electric field that makes these particles flow from the hot end to the cold end would inevitably spread out the heat evenly and reduce the temperature further. A simple way to visualise this is how, after you’ve added some cold water to a bucket of hot water, mixing it manually with your hand makes it cool faster. This is the principle that makes this technology work. Due to the flexibility of the polymer field, this device will work with smartphones that are curved and flexible as well.
This one is a little more obvious to us geeks. If you’re a veteran of the master race, who has wrangled with the flaming beasts that lie within your cabinet during a session of the latest AAA game or a 4K video render, you know important it is to keep a PC cool. And the future might have some interesting developments in cooling tech!
Cooling centric design
One of the first places where manufacturers look to improve the cooling capabilities of PCs is the build itself. And when we say build, we are referring to the material of choice, the cabinet design and more. Take, for instance, the Streacom DB6 that was revealed at Computex in 2017. The fanless tower case is a microATX (340 x 360 x 245mm) chassis that will be able to passively cool a 125W CPU and a 125W GPU. We say ‘will’ as the product hasn’t been listed commercially yet.
The design features side panels made of aluminium that push the weight of the case to a whopping 18kgs but it does an exceptional job of keeping the system cool. The loop heat pipe system on the interior, also made of metal, is technology that is used in satellites and industrial applications and hasn’t yet been brought to mainstream PC applications. Although, similar aluminium builds are also available from other manufacturers.
It is one thing to liquid cool your system the usual way, and a whole different ball game to immerse it completely in a liquid. Sounds crazy? It actually isn’t, unless you plan on using water as the liquid of choice. In a two-phase immersion cooling system, the media of choice for immersion are generally dielectric heat transfer liquids, which are much better heat conductors than air, water or oil. The electronic components are submerged into a bath of the same.
With their various low boiling points (ie, 49°C vs. 100°C in water), the fluids rapidly boil on the surface of the heat generating components and rising vapour passively takes care of heat transfer. One example of such a liquid is the 3M Novec 649 Engineered Fluid. It offers some direct advantages over other such media by being environment-friendly and clean – oil isn’t exactly ideal if you would like to keep your system neat.
Advanced liquid cooling
There are a few ways in which the usual liquid cooling methods can be taken up a notch. Phase-change cooling essentially converts your PC into a refrigerator. A vapour compression phase-change cooler is a unit which usually sits underneath the PC, with a tube leading to the processor. Inside the unit is a compressor of the same type as in an air conditioner. As in a fridge, the compressor compresses the gas into a liquid which is then pumped to the processor, at which point it passes through a condenser then an expansion device which evaporates it again, thus dispersing the heat. This type of a cooling system can be expensive and is hence not found in mainstream implementations.
Slightly more mainstream among enthusiasts is the use of liquid nitrogen to cool overclocked machines. Due to its extremely low boiling point of -196°C, it is highly effective coolant for short overclocking sessions. In a typical setup, a copper or aluminium pipe is installed over the processor or graphics card that is to be overclocked. After proper insulation, the liquid nitrogen is poured into the pipe. While there are devices to hold the poured liquid nitrogen, once it evaporates it has to be refilled. Additionally, although it is not flammable, it condenses oxygen quite rapidly from the atmosphere, which is highly flammable itself.
When it comes to designing cooling solutions for laptops, both the portability and the computing power have to be taken into account. It wouldn’t be too wrong to say that laptops have the constraints of both smartphones and PCs when it comes to thermal management. In fact, that is one of the main reasons why laptops, except for a few high-end ones, still offer mostly rudimentary thermal management capabilities and are often designated as lap burners, While they do employ fans and heat pipes, we are looking at something more effective for the future.
One of the first problems with laptops is that adding something externally to it or increasing its bulk defeats the purpose of the device. So, it is understandable that manufacturers have focussed heavily on improving the design of the inbuilt fan as a way to target overheating issues. Acer’s AeroBlade 3D fan technology changes the typical laptop fan in a number of ways to improve cooling.
Using thinner fan blades to incorporate more blades with a curved axial fin on the top of each blade lets it provide 35% more airflow than a typical laptop fan. Another example of a cooling centric design is the Asus ROG Zephyrus that features an ‘Active Aerodynamics System’ which raises a section of the bottom of the laptop when the lid is opened. This creates a wide, rear open vent through which the fans can push the heat being generated. There are several other examples where the design of a laptop has played an important role in its thermal management.
If you’re willing to sacrifice on mobility up to some extent, there are quite a few doors that open up for laptops. Cooling pads are an alternative that has been used for a while now and have faced considerable debate regarding their effectiveness. Typically, cooling pads feature additional fans and are USB powered to improve airflow across the bottom of your laptop.
On the liquid cooling side of things, some manufacturers like Asus have gone all the way and incorporated a detachable liquid cooling setup with their ROG GX lineup of laptops. The setup is found in a bulky attachment at the rear of these devices.
There are few cooling technologies that are applicable and effective across devices. Take graphene, for instance. Due to its high conductivity, thin structure and inexpensive nature, it forms an ideal candidate as a thermoelectric cooling medium. Additionally, scientists at Duke University, along with Intel, have come up with an improved vapour chamber design that incorporates ‘jumping droplets’ that jump off hydrophobic surfaces. The chamber has a super-hydrophobic floor on one side and a sponge-like ceiling on the other. As the heat increases due to the surrounding electronics, tiny water droplets are formed due to condensation, which falls onto the super-hydrophobic floor. There, they join together into bigger droplets, releasing a small amount of energy that is enough to make it jump off the surface. The water is then soaked back up by the sponge-like ceiling and the whole process starts over.
Similar improvements across all kinds of gadgets are going to keep them from heating up – at least until the next major computational power growth happens. Until then, keep it cool!