CFD-Simulation of the Flow Patterns and Optimization of the Air-Conditioning in a Server Room

In cooperation with the Austrian National Bank a server-room should be optimized for maximum utilization of available cooling energy.

In the server-room typical air-conditioning through a double-floor with directly cooled racks is installed. The racks have different packing densities and expell hot air, according to the installed electrical power, to the top. This yields an inhomogenious temperature distribution in the server-room and a lower than optimal temperature difference between cool air from the air-condition and hot air from the racks. Some of the cold air is directly returned to the air-condition which unnecessarily raises the energy consumption of the re-cooling.
Through optimized flow regimes inside the racks and and improvements of the set-up and increase of the hot air temperature the energy consumption of the air-condition should be lowered. TU Vienna accompanied the optimization with measurements, calculations and numerical simulations (CFD).

Through measurements and simulations of the present-state non-optimal zones in the room were found and the positioning of power hungry servers was optimized. The set-up of new racks was simulated and a complete heat-balance of the computer centre was calculated. This clearly showed the savings potential for re-cooling of the hot air.

Figure : Cross section through a server-rack showing temperatures in °C