Numerical investigation of underfloor obstructions in open-contained data center with fan curves

The purpose of under floor plenum in a typical raised floor data center is to route the supply of cold air to perforated tiles in the cold aisles, and hence, to the racks. However, the presence of under floor chiller piping and various wiring may have an adverse effect on flow rates if not placed based on physical considerations; the pressure drop caused by chiller piping and under floor blockages has not been investigated thoroughly in modeling of a fully representative real life data center, and in particular, in applications where some or all of the cold aisles may be contained. This effect on flow rate is expected to be even more profound in contained systems; this study aims to address the effect of under floor obstructions on data center performance. It was shown that when having blockages in critical locations, containment can act as a solution for the inlet temperatures at the racks, however, the blockage effect can still be seen on the racks outlet and the CRAC return temperatures. It was also observed that inadequate distribution of those blockages led to a change in the operating point of both the CRAC and severs fan curve reducing the flow being fed to the IT equipment, and hence the chiller cooling load is expected to increase, which results in a thermal deficiency of the data center.