Intelligent Data Centres Issue 09 | Page 49

END USER INSIGHT purchase three Liebert Smart Rack PDUs MPX from Vertiv and to test the DCD air-water cooling doors in a two-month trial period. The result of the proof-of-concept was clear: with 20 to 25 kW per rack, the new solution had still not exceeded the power limit. Another benefit was the huge space saving. The price was also unbeatable which meant the decision was quickly made and the new data centre was equipped with just under 30 racks. The results: Higher performance densities for the servers, cost reductions, space saving and greater energy efficiency in addition to the high-performance computers, the EPFL uses racks where output amounts to a maximum of 10 kW. The initial plan was to use the CoolTherm solution for high density (up to 30kW) and hot-air containment for lower needs (up to 10kW). After consulting with Vertiv’s experts in depth, it was decided that the Knürr DCD Water Cooled Rack Doors from Vertiv were the best cooling solution for all the racks. The air-water cooling door from Vertiv is an air-water heat exchanger integrated in the rear door of the server rack. The cold water is used in a closed heat exchanger system directly behind the servers in the rear door of the rack. All the heat of the integrated IT equipment is dissipated via the water circuit which feeds the rack door with cold water and carries away warmer water. The water cooling solution has also resulted in a lower risk of failure, greater system reliability and fewer error sources than with a solution based purely on air cooling. This type of cooling also reduces energy consumption through electrical loss and the cooling process. The optimised heat exchanger structure and short air paths without diversions also mean there is no need for additional fans in the cooling unit. Cooling via the DCD air-water cooling door achieves power usage effectiveness (PUE) values of 1.06. The same pipes are used for the new water cooling system as those previously deployed for the transport of water from Leman Lake, thus reducing investment costs. As the water is used directly in the DCD air-water cooling rear door rack exchanger, the EPFL used 30% to 50% less space compared to conventional air cooling systems despite integrating more servers. The cooling effect occurs when the warm outgoing air flows through the heat exchanger in the rear section of the server cabinet. The cooling air flow is driven solely by the server fans. Today, up to 90 DCD Cooling Doors carry out the cooling of the 300 m2 data centre. The temperature is regulated via thermostatic valves which control the water flow in the heat exchanger depending on the current load in the rack. Additional fans in the cooling door are not required. Boisseau initially decided to This means the water volume can be adjusted to the power density in the www.intelligentdatacentres.com racks and vice-versa – the DCD Cooling Doors can be deployed as the sole cooling solution in the entire data centre regardless of the various performance densities in the racks. “When it comes to cooling servers and racks with different power densities or high-performance servers, Vertiv’s water cooling solution with the DCD air-water cooling doors is an outstanding solution,” said Aristide Boisseau Data Center Architect and Operations at the EPFL. “It stands out due to its low PUE values, higher energy efficiency, lower costs and easy installation compared to conventional air-cooling systems. If the volumes of data to be processed and power densities at data centres increase, data centre managers should definitely consider this innovative and future-oriented method of cooling.” Looking ahead In 2015, Boisseau realised that the capacity of the new data centre commissioned in 2012 was running short. One of the older data centres also had to be completely upgraded to meet the increasing requirements. He therefore began planning a new data centre which is set to be put into operation by 2021 at the latest and to upgrade the old data centre. In accordance with WTO guidelines, the EPFL as a government-run university has to put out a new invitation to tender for the construction of the new data centre. Vertiv will take part in the tender process with its innovative and application- oriented water cooling solutions. ◊ TODAY, UP TO 90 DCD COOLING DOORS CARRY OUT THE COOLING OF THE 300 M2 DATA CENTRE. Issue 09 0 49