Compact Modeling of Data Center Air Containment Systems

The practice of ducting racks to a dropped ceiling or containing entire cold or hot aisles in data centers is being implemented with more frequency in an attempt to improve reliability and efficiency. While CFD and other numerical modeling tools are widely used to optimize data center cooling, they are not particularly effective at modeling containment systems; the performance of such systems is dominated by small and complex leakage paths (e.g., through, around, and under racks), which are difficult or impossible to include in a practical full-scale model. We propose a compact model which uses a flow network to determine airflow rates inside containment systems while the traditional “parent” numerical model continues to handle predictions in the rest of the facility. The two models are coupled at flow boundaries such as where ducting meets a dropped ceiling and leakage paths cross rack surfaces. The compact-model approach has the opportunity to be much faster and more robust than fully-explicit CFD models since leakage path resistances can be established through experimental measurements. We discuss the characterization of rack leakage paths and demonstrate the use of the compact model in a full data center simulation in which the role of parent numerical model is played by a potential flow model.