Effect of raised floor height on different arrangement of under-floor air distribution performance in data center

In the more and more expanding and complicated data center, requirements on air conditioning system and the air distribution arrangement are getting higher and higher. One of the resolutions is improving the airflow uniformity and cooling the local over-hot area by raising the floor in the data center. With a typical mode of four rows of cabinets in the data center as a sample. This paper uses Computational fluid dynamic (CFD) to investigate the influence of the six raised floor heights (0.2m, 0.4m, 0.6m, 0.8m, 1m and 1.2m) on the airflow distribution of three types of under-floor air distribution (the open aisle, the cold aisle containment and the hot aisle containment). Optimization is done on performance indexes, including supply/return heat index (SHI/RHI), return cooling index (RCI) and return temperature index (RTI), with which the condition of subcooling / overheating of all cabinets and the characteristics of the airflow organization in the data center are reflected and the thermal environment in the data center is revealed. Normally, the cooling effect and the uniformity of the airflow can be improved by raising the floor height. However, this won't work well when the floor height reaches a certain level. Therefore, based on the comparative analysis on the 18 different cases in this investigation, the recommended range of raised floor height in data centers of different construction can be obtained and verified in the experimental tests. The experimental results turn out to be in accordance with the simulation results, which proves the range recommended in this investigation is valuable.