DATA CENTRES M


any of the refrigerants that used to be in common


all, if you remove the heat with air, then it becomes harder to recover at any useful ‘grade’ of heat. So, perhaps that will have the effect of driving us back to water-based heat recovery systems.


With water-based system, at least the mechanical energy used to drive a vapour compression cycle can be recovered at useful temperatures via total heat recovery chillers. Plant replacement activities also have to involve local planners, who will often now insist on a heat recovery strategy. The question is, what do you do with the recovered heat?


There are, of course, obvious uses. You can, for example, heat the building and pre-heat domestic hot water demand. But data centres don't have any DHW, or very little unless the development is mixed-use.


In fact, the government’s environmental strategy does indeed point towards mixed mode or mixed-use buildings or estates. This involves creating areas that, as well as data centres, might also include residential, leisure, healthcare, offices, and industrial facilities. This will mean that, effectively, every level of heat an be used via a heat network.


A heat network is a system for distributing heat generated in a centralised location through a system of


T


he refrigeration equipment that cools computers housed in data centres is typically protected from power outages by an uninterrupted power supply (UPS). In the event of a power cut, this is designed to supply the systems continuously with power until the emergency power generators have been connected.


However, many companies underestimate the fact that, despite the UPS, it often takes up to 10 minutes for the refrigeration technology to start up again.


Some chillers, such as the Engie Quantum


insulated pipes for residential and commercial heating requirements such as space and water heating. This sort of heat network or district heating arrangement was discussed in a landmark report – the LETI guide published a few years ago.


LETI (the London Energy Transformation Initiative) comprises a network of more than 1,000 built environment professionals including developers, engineers, housing association professionals, architects, planners, academics, sustainability professionals, contractors, and facilities managers, with support and input provided by the Greater London Authority and London boroughs.


They are working together to support the transition of London’s built environment to net zero carbon. The guide maps a path to zero carbon and defines what ‘good’ looks like for new buildings in the context of the climate emergency.


Part of its strategy involves prescribing the capture of waste heat (for example, air conditioning heat rejection) to make it available to other buildings (such as for difficult- to-upgrade existing stock) via heat sharing (ambient loop) networks.


X www.klima-therm.co.uk


models available from Klima-Therm, counteract this situation and ensure that server cooling can restart as quickly as possible after a blackout. Quantum chillers, for example, are equipped with special fast restart (FRS) technology. This is a software function that reduces the time it takes to test starting conditions in the event of a blackout. It also activates the default load control of the machines in response to demand. The chillers have a double connection that combines two technological measures: Q The chiller can be connected directly to a UPS via the double connection and therefore be


Download the ACR News app today supplied with power continuously.


Q The installed fast restart function ensures that start-up after a power outage is very quick.


Fast restart is a software function that lowers the restarting time of chillers by up to half. “It reduces the time it takes to check the starting conditions, and it activates standard load control in response to demand,” explains Jörn Stiegelmeier, head of technology and development at Engie Refrigeration. “That means our magnetic bearing turbo compressors reach their full capacity much quicker.”


www.acr-news.com • November 2021 27


use in data centre applications are affected by usage bans in the Montreal Protocol and by the phase-down specified in the F-gas Regulation. This is because such refrigerants had an ozone depletion potential and/or are environmentally harmful greenhouse gases that contribute to global warming. But there are alternatives: the group of synthetic hydrofluoroolefin (HFO) refrigerants, such as R-1234ze, which are now also used in various blends with traditional HFC refrigerants to create low GWP options, and the group of natural refrigerants, such as ammonia (R-717), propane (R-290) or carbon dioxide (R- 744), for example. Eco-friendly refrigerants


significantly reduce the direct emissions and thus the equivalent carbon dioxide emissions from chillers and heat pumps. Furthermore, HFOs combine low direct emissions with low indirect emissions if highly efficient oil-free radial turbo compressors are used. Each refrigerant has its own specific chemical and physical properties that distinguish it for its particular area of application, so the old ‘one size fits (almost) all’ days are basically behind us.


Page 1  |  Page 2  |  Page 3  |  Page 4  |  Page 5  |  Page 6  |  Page 7  |  Page 8  |  Page 9  |  Page 10  |  Page 11  |  Page 12  |  Page 13  |  Page 14  |  Page 15  |  Page 16  |  Page 17  |  Page 18  |  Page 19  |  Page 20  |  Page 21  |  Page 22  |  Page 23  |  Page 24  |  Page 25  |  Page 26  |  Page 27  |  Page 28  |  Page 29  |  Page 30  |  Page 31  |  Page 32  |  Page 33  |  Page 34  |  Page 35  |  Page 36  |  Page 37  |  Page 38  |  Page 39  |  Page 40  |  Page 41  |  Page 42  |  Page 43  |  Page 44  |  Page 45  |  Page 46  |  Page 47  |  Page 48