Making use of opti­mi­sa­tion poten­tial for cooling

The catch­word “Green IT” is on everyone’s lips now – energy-conscious behav­iour is indis­pens­able these days precisely in conjunc­tion with the indis­pens­able cooling in data centres. Partic­u­larly in light of ever-increasing computing power, it pays off to switch to energy-effi­cient fans. State-of-the-art EC tech­nology can contribute a lot to this, for example, by sparing the envi­ron­ment and the operator’s wallet. There is no end in sight to the growth of data centres. Trends such as mobile internet, cloud computing and internet TV require ever-higher outputs, since the volume of data is contin­u­ously rising. As a result, data centres have turned into consid­er­able energy consumers. As early as 2008, commer­cial data centres in Germany were using around 10 terawatt-hours of elec­tricity, which corre­sponded to just under 2 % of the overall energy consump­tion. This value will increase even more in future if data centre oper­a­tors and people respon­sible for facil­i­ties and IT depart­ments do not invest in thermal opti­mi­sa­tion. Real-world appli­ca­tions show that 35 to 50 %, thus about half of the energy demand of a data centre, is required for the cooling alone. Herein lie enor­mous poten­tial energy savings, espe­cially for air-condi­tioning tech­nology. Now there are state-of-the-art data centres that operate with a PUE (power usage effec­tive­ness) value of approx­i­mately 1.1. The PUE value describes the ratio of energy demand by the actual IT hard­ware and the overall energy consump­tion of a data centre. Thus this key figure is a measure for the effi­ciency of the non-IT-rele­vant envi­ron­ment, in partic­ular, of air-condi­tioning tech­nology. In the case of conven­tion­ally oper­ated data centres, the PUE value should be about 1.9, that is, nearly half of the overall energy consump­tion is not used for the computing power and there­fore does not serve the actual purpose of a data centre.

Low energy consump­tion by means of free cooling

Figure 1: Free cooling in the data centre. The central compo­nent is called a FanGrid; this is a trade fair exhibit.

The palette of cooling options for data centres is wide-ranging. This is neces­sary because there will be no universal solu­tion in the future either. After all, struc­tural condi­tions have just as much influ­ence on the selec­tion as the tech­nology used or the climatic condi­tions at the loca­tion. There­fore local cooling concepts, such as a direct server cooling system in the rack, are just as appro­priate as concepts for cooling entire data centre areas or even the entire building complex with a central unit. To do this, oper­a­tors of data centres are increas­ingly relying on what is called free cooling. It oper­ates without energy-inten­sive chillers and uses the data centre’s ambient air. An impor­tant role is played, for example, by multiple fans oper­ating in parallel, which provide for the defined intake and exhaust air flows within the building. Such “FanGrids” can be put together in prac­ti­cally any size and arrange­ment to achieve an ideal adap­ta­tion to the respec­tive condi­tions (figure 1). The modular design makes the systems scal­able, and the user can choose whether to use multiple small fans or fewer large fans.

EC tech­nology brings advan­tages

Figure 2: The RadiPac series is avail­able with a drive output from 500 watts to 12 kilo­watts in outer diam­eter sizes from 250 mm to 1,250 mm.

ebm-papst is the world market leader in the field of EC tech­nology and has been repre­sented for many years in the area of data centre cooling. The fan specialist has propelled this field forward and, on this basis, is offering solu­tions for energy-effi­cient concepts with a wide selec­tion of suit­able fans. The new “radiPac” product line (figure 2) combines high flex­i­bility provided by the frame design with maximum output, precisely for appli­ca­tions requiring a moderate oper­ating pres­sure.

Figure 3: The “radiCal” centrifugal fan for appli­ca­tions in venti­lation and air-condi­tioning tech­nology. The impellers of the fans are matched perfectly to the motor and elec­tronics to attain a high-effi­ciency total solu­tion.

Flow rates of up to 35,000 m³/h per fan are possible here. Depending on the desired oper­ating point, however, other fans from the compre­hen­sive product range of the Mulfingen-based specialist lend them­selves to the task. The “RadiCal” series (figure 3), for example, was devel­oped based on the core compe­ten­cies in fluid mechanics, motor tech­nology and elec­tronics. The RadiCal centrifugal fans feature partic­u­larly low noise emis­sions and reveal their strengths espe­cially well in the low pres­sure range. These centrifugal fans are currently avail­able in the sizes 133 to 630 with drive outputs between 35 W and 3 kW. The attain­able flow rates reach up to 15,000 m³/h per fan. Whether oper­ating under full load or espe­cially under partial load, both fan series operate with high effi­ciency and are excep­tion­ally quiet.

Control­la­bility, bus networking, redun­dancy and long service life

Another advan­tage is the compact dimen­sions of the fans. The elec­tron­i­cally commu­tated external rotor motor is directly inte­grated into the impeller, which dramat­i­cally reduces the instal­la­tion dimen­sions. The elec­tronics inte­grated in the drives are not only ideally matched to the EC motors used, they can also be controlled with either a 0-10 V analogue signal or digi­tally with a MODBUS inter­face. For the FanGrids in which many fans are used in parallel, the bus networking offers advan­tages: from making config­u­ra­tions during commis­sioning to performing service, alarm diag­nosis and main­te­nance, dealing with the tech­nology becomes substan­tially easier if the tech­ni­cian can use a central computer to access the fans. More­over, by means of the MODBus inter­face the fans from ebm-papst can be inte­grated into a BMS (Building Manage­ment System) or DCIM (Data Center Infra­struc­ture Manage­ment). This inter­face makes the motor speeds contin­u­ously vari­able, which provides a very conve­nient option for demand-oriented perfor­mance adap­ta­tion. Thus the air perfor­mance of the FanGrids can be perfectly matched to the specific ambient and oper­ating condi­tions of the data centre. At the same time, it is easy to incor­po­rate the neces­sary redun­dancy in the event of a fan failure. The speed of the “neigh­bouring fans” is increased so that the same air flow is main­tained.