The continuous increase of data center usage is leading the industry to increase the load density per square foot of existing facilities. High density (HD) IT load per rack demands bringing the cooling source closer to the heat load in contrast to room level air cooling. For high density racks, the use of in-row cooling systems is becoming increasingly popular. In-row cooling can be the main source of cooling for a data center or work jointly with perimeter cooling in what is called a hybrid cooled room level system. Also, hot or cold aisle containment can be integrated with perimeter cooling and used throughout the data center to reduce the mixing of hot and cold air. Currently, there has not been much work comparing the performance of in-row cooling in open versus contained environments.

The present work builds on a previous study where the interaction of perimeter and row-based cooling was evaluated for a cold-aisle containment (CAC) environment. Previously, the benefit of using row-based cooled in an aisle has not been compared with an aisle in open conditions. Here, we numerically investigate the performance of in-row coolers in both opened and cold-aisle contained environments. Groups of IT equipment that differ in air flow strength are used to provide the heat load. Empirically measured flow curves for common IT equipment are employed to provide simplified models of the IT equipment in the CFD software used. The steady state analysis includes information provided in the manufacturer’s specifications such as heat exchanger performance characteristics. The model was validated using a new data center laboratory with perimeter cooling. A single aisle of the data center is modeled to reduce the computational time, and the results are generalized. The cold aisle contains 16 racks of IT equipment distributed on both sides. In addition, the aisle contains 2 power distribution units. Full details are incorporated in the computational model. A single Liebert® CW114 CRAC unit provides the perimeter cooling in the data center. The model captures the particular air flow behavior in the cold aisle when row-based cooling is utilized. Correlations are derived to predict the ability of air cooling units to maintain set points at different air flow rates. The effect of leakage is also considered.

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