Improvement in airflow and temperature distribution with an in-rack UFAD system at a high-density data center

This paper introduced and analyzed a new concept where an under-floor air supply (UFAD) system with cold aisle containment (CAC) is replaced by a new in-rack UFAD system called an in-rack cold aisle (IR-CA). The IR-CA system is analyzed using CFD simulation, and on-site measurement was carried out to validate the feasibility and reliability of simulation models. The study is divided into eight cases with seven different dimensions for the rack air inlet (2.2 m × 0.6 m, 0.2 m × 0.6 m, 0.3 m × 0.6 m, 0.4 m × 0.6 m, 0.5 m × 0.6 m, 0.6 m × 0.6 m, and 0.7 m × 0.6 m), while an additional partition plane is placed in Case 8 with a 0.6 m × 0.6-m in-rack air inlet. The thermal distribution is compared and analyzed in the eight cases, while cooling efficiency and energy saving is compared between the original and optimal cases. The results showed that the optimal thermal distribution is achieved in Case 8 with a 0.6 m × 0.6 m IR-CA and partition plane, while the thermal distribution in Case 8 with SAT of 23 °C is still much better than that in the original DC. The application of a 0.6 m × 0.6 m IR-CA and partition plane can save approximately 98 kW h/day in electricity consumption in the studied DC. A new evaluation index named the MS index is proposed to evaluate the optimization effects of the optimization model based on the original model.