LAUSR

Abstract The energy consumptions of data centers are increasing dramatically and cooling systems using for controlling the operating temperature usually consume more than half of these energy. Thus, effective strategies on thermal management in data centers may have benefit on energy savings. In order to improve the power usage effectiveness (PUE) of data centers, the effects of air supply flowrate by computer room air handler (CRAH), intake flowrate of rack cooling fans, air supply grilles and heat load distribution on the cooling performance of a typical small container data center having overhead air supply system are investigated in this paper. The rack cooling index (RCI) and supply heat index (SHI) are incorporated to evaluate the local and average cooling performance of data racks. It is found that the intake flowrate of rack cooling fans plays dominant role, which is suggested to be greater than the air supply flowrate in normal operation. Meanwhile, the volumetric flowrate distribution of grilles is studied. The additional front grille before entering the cold aisle may improve the RCI and SHI of front rack (rack A), in which severe hot-air recirculation may occur in typical operation. Conversely, additional rear grille at the exit of cold aisle has negative effect on cooling performance of the last rack (rack E). Based on the measurement of local temperature distribution, the non-uniform heat load distribution in racks is proposed. Result shows that the RCI can be improved to 64% if more power is placed at lower half part, which is eligible for energy saving. However, the non-uniform heat load distribution shows limited improvement on the rear rack (rack E).