INDUSTRY INTELLIGENCE POWERED BY THE DCA
Industry expert discusses getting holistic with air-cooling control
Dr Jon Summers , DCA Advisory Board and Scientific Lead in Data Centres at Research Institutes of Sweden , offers his best practice advice and discusses holistic air-cooling control in depth .
When it comes to data centre operation , the control system and strategy that is adopted to keep all the IT systems humming within their desired environmental envelope is the prime focus . It is therefore not surprising that the providers of cooling equipment for data centres highlight their control systems as one of their most important and unique selling points . Digital control of the cooling systems has grown to become elaborate but can be seen as the differentiator when acquiring a supplier .
Data centres draw power from the electrical grid that is transformed and propagated to ultimately be ‘ pumped ’ into very many small volumes at up to 200A of current , only to be converted into the thermal energy at the rate of up to 1MW per square metre , where the heat is required to be transferred away from these small volumes and ultimately rejected or used to displace other sources of primary thermal energy generation . Principally , for data centres , heat is transferred by convection – where the thermal energy is picked up by a fluid ( liquid or gas ) and propagated by a flow .
The heat transfer has three parts to it : first , from the small volumes ( OK , let ' s just call them servers ) to the edge of the data hall and then secondly , through the walls of the hall , again this is done using a fluid to the point where the heat is transferred for the third time into the environment . This is also achieved by the convection of the external air or alternatively the heat can be carried away by convection to another heat transfer point for thermal energy applications .
In the north of Sweden , the three highlighted heat transfer processes can be performed using an approach called direct fresh air cooling , where the outside air – which is usually cool – is carried directly into the data hall via convection , using large cooling fans , where it is pushed towards the entrance of the air-cooled servers . The server fans then draw this air over their internal hot surfaces ( where the electrical current stops in its tracks ) by convection to the back of the servers , where the ( now hot ) air is pulled out of the data hall by extract fans with some of the air being drawn back to the cooling units and mixed with the incoming air to warm up outside air that , during part of the year , is too cold to operate with the servers .
Of course , warm outside air can be cooled using water and very low relative humidity outside air can be humidified with water , so the cooling system requires an evaporative function that serves to both humidify and cool . As part of an EU www . intelligentdatacentres . com
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