Modern trends in the heat removal from highly loaded racks
Let’s remind that even 15 years ago racks were considered to be high-loaded with heat dissipation more than 5-7 kWh. Then for quite a long time racks with heat dissipation exceeded 15 kWh were treated as the same. What do we see today?
Actually no one who works in the field of data centers construction is surprised and not afraid of racks with heat dissipation more than 50 kilowatts. And if we talk about supercomputers, here the equipment with 100-kilowatt and even much higher dissipation is found.
In reviewing the modern equipment used for heat removal from highly loaded racks, inside air conditioning, cooling systems mounted directly on the door racks, and racks with freon system with closed cycle integrated directly into them are worth mentioning.
Here I want to share my idea, maybe seditious from the point of view of such a specialist. For several years I am getting the impression that the creators and developers of electronic and computer technology have aimed (and successfully achieved) to refuse the services of specialists in the field of refrigeration equipment. To back up my words with statistics I will say that there is already not one, not two, but dozens of data centers, which don’t use refrigeration equipment for the removal of heat excess from the equipment at all in the world. Modern processors are quite capable of safely and steadily to work with its own temperature of 65—85ºC and more by only air with the temperature up to 45º C for heat sink. There are no refrigerators at all. The heat sink is operated only through the air into the environment. To design such data centers specialists in ventilation are needed. And there will be more and more such objects.
And because of its thermal properties or for some other reasons, for example due to architectural solutions of the object, the air can’t be refrigerant/heat-transfer agent, the other natural refrigerant — water intervenes in proceedings. The use of not chilled water for heat removal from the racks with the excess heat of more than 150 kWh is already a fait accompli! And soon, believe me, none of the experts-will not be scared of the fact that water is circulating in the processor, in the center of the rack. Technology, as we know, doesn’t rest on its laurels and the effect of the usage of direct water cooling, especially at normal and elevated temperatures outweigh fears and prejudices. Of course, hydraulic power packs, intermediate heat exchangers and liquid chillers are needed outside the data center for water cooling. But it is a challenge for hydraulic and heating engineers, not refrigerationists.
Identifying current trends of the heat sink from racks with a high density of the heat flow, we did not set out to «bury» traditional cooling systems that use certain refrigeration cycles with refrigerants-freons and the profession of conditioningmaker and refrigerationist. These systems (and professions) will exist and be in demand, and will find its adherents and applications in IT. But we feel compelled to point it out that the trend of rejection from refrigeration equipment for data centers is growing with each passing year.