Effect of Under Floor Blockages on Data Center Performance

In a typical raised floor data center, under floor plenum supplies cold air to the computer room via perforated floor tiles. Thermal management of any data center primarily depends on air flow rates through the tiles. These tile flow rates are a function of several factors that govern the flow pattern under the raised floor. CFD analyses of an ideal raised floor can often be misleading as they may not incorporate the effect of under floor blockages such as cables, ducts, pipes and other random blockages. In this paper, the effect of under floor blockages on data center performance is discussed. A raised floor data center with 8 kW racks is considered. There are four rows of racks with six racks per row. Two air conditioning units supply chilled air to the data center through a 2 ft. deep plenum. Blockages are included in the model and are shown to have significant impact on tile flow rates and eventually the rack inlet temperatures. Parameters like blockage size and locations are investigated to come up with a set of broad guidelines which will help the facility designer to rearrange the blockages and improve the thermal performance without altering the layout or cold air supply