A methodology for the design of perforated tiles in raised floor data centers using computational flow analysis

Abstract

Data centers are used to house multiple servers, mainframes, supercomputer systems, and storage systems used in business data processing and scientific analysis. Typically, data processing (DP) equipment is cooled using forced flow of air. Modular chillers are commonly used to cool the hot air exhausted from the DP equipment and a raised floor to recirculate the conditioned air back into the room. Therefore, data centers need well-designed ventilation systems, appropriate placement of the DP equipment, and modular chillers to ensure that the air used for cooling the processing equipment is within the desired temperature range. An important aspect of the design of data centers involves sizing of the perforated floor tiles for return of cold air, the size of the space under the raised floor, and placement of the DP equipment and modular chillers. The flow through individual perforated tiles needs to fulfil the cooling requirements of the computer equipment placed adjacent to them. The novelty of the paper lies in the treatment of the volume under the raised floor as a uniformly pressurized plenum. The accuracy of the Pressurized Plenum model is demonstrated with reference to a Computational Fluid Dynamics (CFD) analysis of the recirculating flow under the raised floor and the limits of its validity are also identified. The simple model of the volume under the raised floor enables use of the technique of Flow Network Modeling (FNM) for the prediction of the distribution of flow rates exiting from the various tiles. An inverse design method is proposed for one-step design of the perforated tiles and flow balancing plates for individual chillers. Subsequent use of the FNM technique enables assessment of the performance of the actual system. Further, modifications to an existing system design needed to accommodate the changes in the cooling requirements can also be evaluated using the FNM analysis in a simple, quick, and accurate manner. The resulting design approach is very simple and efficient, and is well suited for the design of modern data centers.