Video tour to the data center: Free-cooling

Good day, habrayuzer! We continue the series of articles and videos dedicated to
Intel’s Russian Data Center and are considering a system today
free cooling or free-cooling.

The entire cooling system of the data center consists of 2 circuits: internal and external.
To the internal - chiller, pumping stations and precision air conditioners.
The principle of the internal circuit is as follows: cold water (its temperature
is 7-8 degrees) from the chiller using pumping stations comes to
precision air conditioners that cool the air directly in the room
Datacenter. The heat removed from the data center is fed back through pumping stations to
chiller in the form of water heated to 13-14 degrees. There this water cools again and the cycle
repeats again.

Since the chiller is in itself a very heat-consuming device for its
cooling requires the presence of an external circuit, which includes heat exchangers,
directly on the street. Each heat exchanger itself is
fairly complex device, but for his work almost does not require
electricity than it is fundamentally different from the chiller. He is not just
coil (as it may seem from the video), there is still a mass of levers, valves, etc.
With their help, the flow is regulated depending on the temperature outside and inside
data center. So this is quite a “smart” device. It is also worth noting that
coolant in the outer circuit through which heat is exchanged between
chiller and the street is glycol (since in winter the water in it simply froze
would).
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For a complete understanding of the entire free-cooling system, it is worth remembering that there is
two technologies of free cooling (we talked about this in the very first review,
dedicated data center) - direct and indirect. Recall with direct cooling
air from the street is chased directly to the cooling servers. With indirect free-
The cooling system with the system included the same chillers that we talked about above.

The implementation of a direct free-cooling system is justified only in rare cases.
For example, an experiment was conducted in the state of New Mexico in the USA - they built
the data center was about 900 servers and was just cooled by air from the street. Air there
dry enough, it's desert. With air humidity control to prevent
corrosion of metal in the cooled equipment, there were no special problems. In the same
places like England or St. Petersburg, for example, direct free-cooling technology
it is almost impossible to use, because there they will very quickly go out of
building elements of data center equipment.

In general, for the Central European climate, as, for example, in Germany or in
France, where it is too warm in summer and too cold in winter, it is necessary
the use of devices that will drive the temperature of the supplied air to
limits for the data center range. Not to mention Russia, where the temperature difference
during the year reaches 80 degrees and the dependence on such devices is even higher. Obviously
that when from the street in the summer come 30 degrees and above, it is necessary to cool further
air. Similarly, it is not good when the air in winter comes too cold. Therefore,
it's almost impossible to do without a chiller in the summer, and often in the winter (no one
in her right mind she will not give air cooled down to -30 degrees into the room with
servers). At least 3-5 months a year, the chiller is simply necessary, and therefore, the system
indirect free-cooling is justified in most cases.

To summarize the overall implementation of the free-cooling'a. Water Chillers
in the warm season, when the temperature is low enough, they are turned off and instead of
In the system, they begin to use heat exchangers in which heat from the internal
contour is given to the outside. This whole system works in automatic mode. Chiller
it turns on itself when current conditions require it. In addition, there is
water supply (in large barrels) and when its temperature exceeds a predetermined limit,
the chiller automatically turns on and starts cooling this water. When will be reached
A sufficient level of its temperature, the chiller will automatically shut down. That's it
this water also comes in precision air conditioners. Usually manually interfere
In the process of starting the chiller is not required, except, of course, situations where it is not
starts automatically due to any abnormal situations.
In general, during the implementation of free cooling in the cold season, the cooling system of the data center
somewhat complicated, but the savings in electricity justifies these costs. Exemplary
The payback period in our Russian climate (of course, it depends on the weather, how much
winters will be cold and long, etc.) averages 2.5 years.

Ask a question to Leonid Shishlov here .