Vortex-enhanced thermal environment for air-cooled data center: An experimental and numerical study

Abstract

Poor airflow management attributed to hot air recirculation and cold air by-pass adds massive thermal inefficiencies to air-cooled data center’s cooling system. The containment system usually was adopted to mitigate such drawbacks by isolating the space using a physical partition wall, such as hot aisle containment. Although the recirculation and by-pass can be effectively suppressed, the consequent high backpressure built up in the containment reducing the server air flowrate and possibly increasing the server temperature beyond the acceptable limit. This study presents a new enclosure mechanism for air-cooled data center using a vortex flow as an alternative to the conventional hot aisle containment to reduce the hot recirculation and, at the same time to retain the server air flowrate. The experiments conducted in a half-scale test cell (2-times smaller than a typical data center hall in length scale) examined vortex containment's effectiveness. The experiment results revealed that the average Supply Heat Index (SHI) in vortex hot aisle containment could be reduced to 0.11. Although vortex hot aisle containment did not enclose all hot recirculation compared to the full containment deployed in the benchmark layout, the relieved backpressure (the high pressure in the hot aisle) retains the rack flowrate by 42% (2.1 m/s in the vortex hot aisle containment with a diameter 1.2 m (VFL1200) layout compared to 1.2 m/s in full containment) and results in a 4.3% lower normalized server temperature (1.03 in VFL1200 layout compared to 1.076 in full containment CL). In the end, the validated CFD model provides more insights on vortex containment characteristics, such as the vortex strength and pressure distribution.