Smartphone chip sets keep getting faster year by year, but despite the constant improvement in silicon nodes, they keep getting hotter. That is why cooling solutions have become an important element in which vapor chambers (aka heat pipes) are a common part of the cooling stack.
Xiaomi has developed Loop LiquidCool technology that improves core heat pipes in two ways, resulting in doubling cooling efficiency. The technology is expected to appear in Xiaomi’s products in the second half of 2022.
Here’s how it works (see chart above). The heat from the chip set evaporates the liquid (this is the evaporator segment), it travels under a pipe to cool in a hot gas condenser (for example using a metal frame as a heat sink) and Turns into liquid again. This liquid then goes to the refill chamber which feeds the evaporator, so that the cycle can start anew.
It’s like being in a normal heat pipe, but as we said, there are some big differences. First, hot gas and cold liquid are kept separate. This is not the case with heat pipes – the wick that carries the liquid and the chamber through which the gas passes are all in the same metal pipe, reducing the connection between the two.
Another major change is the use of Tesla valves to ensure that the circulation is correct. Yes, these valves were invented by Tesla and have no moving parts, instead they rely on their clever design to ensure that the liquid flows easily from one direction to the other. Flows from (they are easy to recognize by the shape of the teardrops).
That’s the theory of how Loop LiquidCool works, now here’s some practice. While the first phones are months away, Xiaomi customized a Mix 4 by replacing its original vapor chamber with a Loop LiquidCool system.After 30-minutes of Genshin Impact at 60 fps (max video settings),
the maximum temperature recorded was 47.7ºC, 8.6ºC cooler than an unmodified Mix 4. Note that the video above gives a more conservative target – 5ºC lower than “typical Snapdragon 888 smartphones”.
Xiaomi says its design is flexible and can be made to accommodate other components, such as a square loop that will leave more room for batteries, camera modules and other components.