Comparison Between Numerical and Experimental Temperature Distributions in a Small Data Center Test Cell

Abstract

Information Technology equipment is continuing to increase in power, leading to significant challenges from the room air conditioning perspective. Numerical models are the dominant techniques for designing new data centers and optimizing existing ones. It is thus critical to understand the inherent error in the model prediction of flow and temperature distributions in the data center, with emphasis on the vicinity of the server rack. This study uses a simulated server rack in a small room where detailed temperature (3D), flow, and power measurements were carried out for a single scenario under steady state conditions. A numerical model was constructed to represent the data center cell for this case. Model results were then compared with three dimensional experimentally obtained temperature maps and the discrepancy between the two was quantified as an error in temperature. The difference between test data and model results was found to be the highest in the exhaust air path from the rear of the simulated server rack to the inlet of the air conditioning unit. The dominant sources of error are likely to be in the use of the standard k-ε turbulence model, and the simplistic rack representation in which rack exhaust airflow is assumed uniform. Both modeling limitations tend to pronounce hot and cold spots and inhibit the mixing of hot and cold air streams within the data center. This is the first study on comparison between three dimensional temperature distributions obtained via modeling and from actual data collection.