Room Level Modeling of Air Flow in a Contained Data Center Aisle

Abstract

Cold aisle containment is used in air cooled data centers to minimize direct mixing between cold and hot air. Here, we present room level air flow field investigation for open, partially and fully contained cold aisles. Our previous investigation for rack level modeling has shown that consideration of momentum rise above the tile surface, due to acceleration of air through the pores, significantly improves the predictive capability as compared to the generally used porous jump model. The porous jump model only specifies a step pressure loss at the tile surface without any influence on the flow field. The momentum rise could be included by either directly resolving the tile's pore structure or by artificially specifying a momentum source above the tile surface. In the present work, a modified body force model is used to artificially specify the momentum rise above the tile surface. The modified body force model was validated against the experimental data as well as with the model resolving the tile pore geometry at the rack level and then implemented at the room level. With the modified body force model, much higher hot air entrainment and higher server inlet temperatures were predicted as compared to the porous jump model. Even when the rack air flow requirement is matched with the tile air flow supply, considerable hot air recirculation is predicted. With partial containment, where only a curtain at the top of the cold aisle is deployed and side doors are opened, improved cold air delivery is suggested.