Guidelines on Managing Under Floor Blockages for Improved Data Center Performance

Due to the increase in computer rack equipment power in recent years, thermal management of data centers has become a challenging problem. Data center facilities with raised floor plenums are the most popular configuration from a thermal management perspective. Considerable ongoing research efforts focus on optimizing the room layouts and equipment design in order to achieve the desired cooling. However, the detrimental impact of under floor blockages, which occur widely, is seldom addressed. These blockages often take the form of chiller pipes, cabling, and wires. They impede the flow of cold air from the air conditioning units and yield unpredictable air flow patterns. This results in highly maldistributed tile flow rates which can create additional hot spots above the raised floors. In this paper the effect of such under floor blockages on data center performance is characterized in detail. A representative data center is modeled using commercial CFD code, with typical under floor blockages. Blockages are shown to have a significant impact on tile flow rates and rack inlet temperatures. A detailed parametric study is presented, to identify the locations under the floor, where blockages if installed, have minimal effect on data center performance. Case studies are presented to show that blockages, if installed with prior consideration, have a positive effect on overall data center performance. Finally guidelines are presented on how to rearrange existing blockages or to install new blockages, and still achieve an improvement in thermal performance, without any change to the room layout or cold air supply.