DATA CENTRE COOLING
Optimal control with hybrid dry coolers
Cooling technologies are available that work in different ways, however operating costs can also be reduced simply by changing operating parameters and using intelligent system technology. Here, Jan Ballandt, sales director Europe of Jaeggi, explains.
O
ptimal temperature control in a data centre is a balancing act, with the commercial considerations of keeping the power usage effectiveness value (PUE = quota of all energy consumption and that of IT) as low as possible on one side and the need to provide optimal working conditions for the server technology on the other.
On average, 50% of power consumption in data centres is attributable to air-conditioning, heat dissipation and ensuring an uninterruptible power supply (UPS).
The ASHRAE TC9.9 guidelines -
recommendations and guide values for room air temperature and humidity - provide a good guide to achieving an optimal server room climate. In addition to budgetary restrictions on investment and operating costs as well as building regulations, it is in principle the technical specifications applicable to the supply and exhaust air and the local climate that decide the optimal cooling technology for computer centres.
34 November 2019
Six different cooling technologies Theoretically, there are six different cooling technologies to choose from: dry, sprayed, adiabatic and hybrid dry coolers as well as closed and open cooling towers – the technical range thus extends from dry to purely ‘wet’ cooling. In air-cooled cooling systems, physical limits are defined for the return temperatures. For dry systems, a cooling limit interval of around 6K to 8K is still considered economical, meaning that at an ambient air temperature of 34°C a return temperature of around 40°C can be realised. Wet cooling towers, however, incur high operating costs.
It is significantly more efficient to combine free cooling when external temperatures rise, with the use of evaporative cold, in particular to prolong the free cooling operation. This technical alternative is becoming increasingly interesting by the further development of IT server hardware, as nowadays this can tolerate supply air temperatures of up to 32°C; temperatures of 18 – 27°C are recommended for server rooms in the
2011 ASHRAE Handbook. With that, depending on the system technology, cold water temperatures of only around 24°C would be necessary. In contrast, very low temperatures in data centres are not economically sensible, as these cause enormous demand for cooling and the dissipation of heat from the server room into the environment.
Additionally, if one minimises or eliminates temperature differences for free cooling operation, for example at the plate heat exchanger for system separation between the water cycles of the computer centre/cooling, the potential of free cooling is further improved and, in otherwise unfavourable climatic conditions, free cooling is actually made possible. Under certain circumstances, and given suitable climate prerequisites, it is therefore possible to dispense entirely with the installation of a compression refrigeration chiller.
Careful needs analysis Within the framework of project planning and
www.acr-news.com
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 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60 |
Page 61 |
Page 62 |
Page 63 |
Page 64
