Immersion Cooling Systems

  Yes, those servers are in a bathtub - this is how immersion cooling works

 Hot. The worst enemy, what limits a processor the most is the heat it generates when it works at full capacity. It's what makes your laptop sound like a plane about to take off when you open a game, and what causes one of the biggest expenses in a data center is its cooling.

The solution to mitigate this heat has almost always been ducted ventilation, with some more advanced examples using liquid cooling ducts. But what if we could go further and directly submerge the servers in containers filled with liquid? That is precisely what immersion refrigeration achieves, and there are already several companies that offer it as an alternative. 

  Dipping servers in liquid is no longer crazy 

  No, you are not getting it wrong: immersion cooling consists of submerging entire servers in liquid, so that the heat they generate is easily transferred to that liquid and cooled more efficiently. Microsoft has tested this by submerging servers in the sea with positive results, but in this case we are talking about sinking data center servers in liquid-filled tanks large enough for them to be completely submerged. 

 The liquid used in these cases is dielectric, which means that it is capable of isolating the electrical current that electronic devices need (unlike water, a conductive liquid). That liquid can be a mineral oil, deionized water, or a solution created specifically for this use.

 We can generally classify immersion refrigeration into two broad types: single phase immersion and double phase immersion. Simple phase immersion uses a cooling liquid that receives heat from the submerged servers and passes through a circuit to another tank where a water circuit cools it again.

 Once cooled, the liquid returns to the servers to perform its function again. In this case, the coolant never boils or evaporates, nor does it freeze. Thanks to this, too complex installations are not required.

 Two-phase immersion goes further: it uses a dielectric liquid with a low boiling point compared to 100ºC for water) and allows it to boil and evaporate due to the heat generated by submerged servers. The vapor that rises from the tank passes through some condensers, so that there it returns to a liquid state and "rains" on top of the tank, being able to start the process again. 3M has a video in live action where we can see one of these tanks filled with boiling coolant:

 

 This process has the advantage of requiring fewer circuits and valves, but the steam escaping from the condensers causes liquid losses. Still, companies like Top Video advertise energy cost savings of up to 95%.