Experimental study of airflow designs for data centers

Growth in ICT has led to increased demands on data centers. Highly reliable operations of data centers require an efficient and robust air-conditioning system. In most data centers, circulating air enters at the floor level, and returns at the ceiling level (floor supply design). However, the authors have developed an airflow design in which air is both supplied and returned at the ceiling level (ceiling supply design). To compare the cooling characteristics of both designs, temperatures were measured in a full-scale model of a data center. For both designs, changes in cooling characteristics were evaluated in response to changes in heat density, supply-air volume, and supply-air temperature. In addition, the authors studied the effects of separating cold and hot aisles by hanging walls from the ceiling between aisles. Dimensionless indices, dimensionless rack-temperatures, and values of the rack-cooling index (RCI) were used to compare the cooling characteristics of the two designs. The authors confirm that ceiling supply design is more robust regarding changes in major design parameters compared to floor supply design.