How Data Center Cooling Has Evolved

In the recent years, we have witnessed a change in the data center cooling strategies which are deployed by the data centers. Data center knowledge has expanded considerably and with it, the innovation in the cooling systems being used in these facilities. For years, there has been a reliance on the “chaos” cooling methodologies which have been deployed in most of these centres. In these systems, perimeter CRAC units were designed in which pumped volumes of cooled air into the facility. This chilled air served a dual purpose. On the one hand, it cooled the IT equipment while also pushing out the hot server exhaust air via the return air ducts of the installation.

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This kind of “chaos” air distribution system had several inefficiencies. These included the following:

Re-circulation: In some cases, the hot server exhaust air can find its way back into the facility via the server air intakes and in the process raising the temperatures of the facility and heating equipment to dangerous temperatures. This was mainly caused by poor rack hygiene or in situations where the cool air available was insufficient.

Air stratification:  There is a natural tendency of air to mass in different layers based on the temperature. If you have precision cooling equipment in your installation, this stratification of air is going to cause the set points to be lower than is recommended. In an effort to re-mediate this, technicians may increase the CRAC fan speeds and this may in turn cause bypass air.

Bypass air: The bypass air occurs when the cool air stream velocity is greater than the ability of the server fans to take in the cool air and as a result, the cool air stream will shoot past the IT racks. The bypass air will weaken the cooling efficiency of the data center.

To combat these inefficiencies in the data center facility, businesses have adopted newer cooling strategies such as the hot aisle/cold aisle orientation for the racks. In this orientation, the cool air intakes face the hot air exhausts in rows. This helps to maximize the cooling efficiency of the data center facility.

This kind of orientation will lead to the formation of the convection air currents which will in turn improve the air flow in the facility. Even though these have been an improvement over the “chaos” strategy, they are still not very efficient in providing optimal cooling for the data centers.

The Cooling Containment Strategies

Plagued by these datacenter cooling inefficiency problems and as data center knowledge increases, engineers have been cracking their heads in order to come up with even more innovative and efficient cooling strategies. One of these has been the cooling containment strategy. This has been designed such that they enclose the server racks in the centre in sealed structures which will capture the hot exhaust server air. The hot air is then vented to the CRAC units while the chilled air is delivered directly to the server units instead of relying on convection to make this happen. This cooling technique unlocks numerous benefits such as improved cooling efficiency, increased reliability of the centre and lower energy spending. It also provides for greater floor plan flexibility. Check out Data Center Journal for more details.

Trends in Data Center Cooling

The containment strategies and data center knowledge have also impacted the way data centers are designed around the world for the best cooling. Today, the facilities are designed around server racks. The company chooses the ideal racks that it needs and then builds around them based on their specifications. This kind of design allows them to install optimal infrastructure in their facility. This results in a facility that is easy to cool and more reliable.

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