Dynamic thermal characterization of raised floor plenum data centers: Experiments and CFD

Abstract

World over, power consumption by “server farms” or data centers is a growing concern. With time dependent job arrival rates at the servers, the power dissipation, and concomitantly the cooling requirements are dynamic. However, due to the lack of more efficient control algorithms, cooling systems are set to conservatively pre-determined set points, which result in sub-optimal energy consumption. An important step in the development of smarter control algorithms is detailed knowledge about the dynamic behavior of the data center system, which is missing in the open literature. In this paper, we have conducted transient experiments and CFD modeling to understand data center behavior for a broad range of time-varying input parameters such as CPU utilization, cooling air temperature and flow rates. Experiments at the server, rack, and facility level of raised floor plenum data centers were designed to record system responses to these input variable perturbations. The output responses were rack inlet-outlet air temperatures & CPU temperatures. A transient CFD model was validated with experiments. We foresee that these experimental results and the validated CFD model can be used in designing smarter control algorithms as a next step.