Does Samsung's Note 9 Carbon-Water cooling system work?



Whenever I hear the word "water cooling system", I remember the classic example of an automobile radiator. Such a fine piece of art preventing so many engines across the globe from getting damaged. Only if that was the case with mobile phones. Nope, the cooling systems inside smartphones don't exactly work like the ones in your car. Don't let all the advertising jargons tell you otherwise.

Since the launch of Note 9, youtuber JerryRigEverything has opened up the new note 9 to see if there is water inside. It seemed like his NASA mission was successful because there was water inside, just not big enough to make a tea. But, hey, we found water.

It seems like the cooling system inside a smartphone (or at least that of note 9) is a copper sink that transfers heat from the hot part of the phone (processor) to a colder region. We aren't exactly sure how carbon applies to the entire process (jargons maybe).

Anyways, the real question is, does it work?

It's not that easy to say. A conclusion from tests published in Tom's guide is that the cooling system does not necessarily bring the temperature down, but it has been able to maintain the performance. That's good news for a heavy user. You cannot expect the temperature of the phone to go down because what these systems do is to distribute heat from higher temperature points to lower temperature points inside the phone itself. There is little option to dissipate heat to the atmospheric air.

According to Samsung's official blog post, the heat absorption achieved by Note 9 is 3 times that of Galaxy 8 and thermal conductivity is about 3.5 times that of the Galaxy 8. But what exactly are the heat absorption rate of the Galaxy 8's cooling system and thermal conductivity of the same remains an unanswered question.

How much of the absorbed heat is dissipated to air? Or to other components in the phone? Because the meaning of the terms heat absorption and thermal conductivity is rather vague as per the context applied in Samsung's blog.

The thermal conductivity of copper is about 401W/mK and thermal conductivities are often a function of temperature difference between the two ends. Which effectively means that when the temperature rises, the temperature difference between the two ends of the copper sink will be about the same that no heat transfer is going to occur. This probably explains why when the phone was operating at a consistently high temperature, the performance difference was barely noticeable.

Keeping that in mind, remember there is water inside (and carbon, but we don't know what it does). According to Samsung, the water absorbs heat and becomes water vapor. It then goes through a thermal spreader (aka copper sink) transferring the heat absorbed to its body. This condenses the water and the cycle continues.

Looks like carbon is a big loser in this whole game without a particular job, maybe integrating carbon would have a positive effect on heat convection. Which is not something Samsung has been talking about.

The performance of any cooling system depends on the amount of heat it can liberate to the surrounding. But there is no mention of heat convection rate by Samsung, oddly enough. So we should be sticking to natural convection rates of copper, which is not going to be that great inside a closed cabin. Just think about how easily will your copper plate utensil loose heat to surrounding? The same thing has to happen while the plate (sink) is constantly being heated.

In conclusion, this cooling system cannot be game-changing technology, but it is rather the beginning of the end to our heat problems inside a smartphone. Performance improvement do is noted with this system in place, but the value for cost is debatable. We somehow need to integrate forced convection into our small devices to achieve consistent heat dissipation ability. So far, creating a mini radiator inside a smartphone will be subjected to size and energy constrains. We don't have enough space to jam big demanding batteries, let alone cooling systems. Let the big companies sort that out for now.