Data Centres have become a vital part of our worldwide infrastructure, but they are vulnerable technological organisms creating their own weaknesses. One of the weaknesses is brought about by the large rate of electricity consumption needed to run a data centre 24/7. That electricity leads to exceptionally hot environments and due to their nature, data centres can not simply be shut down to rest and cool down. If not mitigated against, performance can be greatly reduced and with frequent failures and increased downtime.
Dealing with heat in a data centre can be even more challenging in tropical countries. To maintain a Tier IV status, a data centre, it is imperative that a facility has a world class cooling system.
In a colocation data centre, such as that of Onix in Accra, Ghana, as more and more servers are added to the racks, the temperature increases. As the temperature rises, servers will stop performing at their peak levels and are susceptible to burning out entirely. There are various methods used to cool large colocation data centres, such as water-cooled chiller plant, air cooled chiller plant and direct evaporating cooling. In this article we will discuss the direct expansion, cold aisle system used by Onix in Accra.
The facility in Accra, a city with an average daily temperature of 30°C (86°F), currently houses 170 racks in its initial data room. It uses a technique called Cold Aisle Containment (CAC) as its main defence against the immense heat caused by this number of servers in a tropical climate.
With CAC the cold aisle is enclosed between the server racks, which face each other, with doors at either end of the aisle. The floor tiles running down the aisle, in front of both racks, are perforated. Cold air is blown through these tiles and contained within the aisle, and therefore delivered directly to the server equipment air intakes. The containment aisle means that the cold air does not mix with warm air and reaches the servers without obstruction. This is termed ‘focus cooling.
The question now is, where does all the warm air from the servers go? Well, the heated air from the servers is forced out of the back and then recycled into the Computer Room Air conditioning (CRAC) unit. From here it is cooled and passes back into the system to cool the room and the CAC.
The direct expansion CRAC units work in a similar manner to those you may have in your homes or have experienced in hotels. The difference is these devices can function continuously for a year without a pause. The cooling function is provided by blowing cool air over a cooling coil, filled with a refrigerant, which is kept cool by a compressor within the unit.
This then completes the cycle by pumping the air through the raised floor and through the perforated tiles into the CAC. The system also monitors the temperature, air distribution and humidity in the data centre to maintain a balanced climate throughout the day. With the raised floor, which was built into the architecture, and the CAC, cooling can be made for 30kW heat load per rack. Each CRAC in our Data Hall has a heat energy of 104kW.
Want to see our direct expansion cold aisle containment technology in action? Take a video tour of our data centre’s Tier IV cooling system, where we use this cutting-edge technique to keep our servers cool and operating at peak efficiency in the hot and humid climate of Accra, Ghana. Watch the video below to see how our innovative cooling system works, and how we maintain a 99.995% uptime for our clients. Contact us if you want any further information.
