| The flourishing development of data center construction and its high energy consumption have aroused widespread concern of society, experts and scholars at home and abroad. Energy-saving transformation or constructing energy-efficient data center is of great significance for energy-saving work. The air conditioning system as the main energy consumption of the data center accounts for about 45%. With the increasing integration level of electronic products, unit area heat dissipation increases significantly per year, and enormous heat of high heat flux density equipment brings a serious test to the air conditioning system. At the same time,factors such as unreasonable airflow and unmatched equipment caused to the cold quantity waste and local overheating phenomenon. In order to ensure the safe and stable operation of the equipment, to create a well data center thermal environment is particularly important.At present, in the data center energy-saving research,experts and scholars at home and abroad pay more concentration on the thermal environment improvement and airflow optimization. The effect of the air distribution in the data center is presented by thermal environment. Optimizing the form of airflow structure is not only can reduce the local hotspots and improve the thermal environment, but also to improve the utilization of cooling capcity and reduce the energy consumption of air conditioning system in data center.Cold / hot channel layout, under-floor air supply as effective airflow is widely used in data center. For the raised-floor data center,the airflow of the under-floor plenum plays a key role in the effective operation of the data center. Therefore, the key to modify the airflow distribution in the data center is to influence the flow field of under-floor plenum.The flow field of the under-floor plenum is a complex function of a large number of variables, including the plenum height, the open area of the perforated tiles, the locations and flow rates of the computer room air conditioner (CRAC) units, and the size and location of the under-floor obstructions like cables and pipes. In order to improve the thermal environment quality of the raised-floor data center, optimize the distribution of airflow and improve the utilization of cold energy, the main researches at home and abroad are the following two aspects: firstly, closing the cold channel or the hot channel; secondly,optimize the air duct structure. And research methods are mostly numerical simulation.Large data centers are usually expanded with arrays of odd-numbered columns or even-numbered columns data center sub-module. To improve the thermal environment of the data center and reduce the energy consumption of the air conditioning system are our fundamental goal. In this paper,the data center sub-module (four-row cabinet as a sample choose from a large-scale data center) with the cold channel closed in the array of even-numbered columns is selected as the research object, and the temperature field and velocity field of the raised-floor data center sub-module are comprehensively analyzed.According to the analysis, the thermal environment problems are summarized. Furthermore,the influence of plenum height, open area of perforated tile and baffle angle on the airflow is studied by numerical simulation. The recommended range of plenum height and open area of perforated tile are 700mm～500mm and 20%～30% respectively, and gradually optimizing plenum height and open area of perforated tile of the raised-floor data center sub-module. On the basis of this, a baffle is erected in the pleuum at 4 angles from -15° to 45° to obtain the most satisfying cooling effect. Finally, the optimal airflow model of the data center sub-module is obtained and tested,which effectively improves the thermal environment quality of the data center and provides a reference for the thermal environment optimization of large data center. |
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