| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 105 === This study evaluates the effect of supplying airflow on the efficiency index of computer racks. Tests are performed in a ten-rack data center having a capacity of 50 kW. The effect of non-uniform heat loading and rack arrangement on the efficiency index is also reported. The cooling system is a 30 RT system, and the supplied air ranges from 0 m3/s to 4m3/s while the supplied temperature changes from 7.5 ℃ to room temperature . The results indicate that it is essential to place the higher power parts at the bottom of the rack, which may improve the RCI (rack cooling index) to 64%, and slightly reduces degree of overheating as compared to that of uniform heating. In the condition of supplied flow rate equals the rack flow rate, the hot air recirculation inside the rack can be offset by increasing the fan revoltion to have a higher flowrate on top of the rack, and the RCI is improves to 47%. For the influence of temperature of the CRAH (computer room air handler), as the supplied temperature drops, the highest of the RCI is raised to 21%. Regarding the change the open grills, by opening the first grill can significantly reduce the hot air re-circulation of the first rack. Yet the corresponding RCI rises to 63%. Install the baffle between A rack and B rack in the hot aisle decreases inlet temperature of A rack and improves the RCI to 54%. A similar effect is seen for just installing one baffle in the closest CRAH as compared to multiple baffles. Also, raising the fan flowrate of the first part of computer rack on top of the rack and installing the baffle between A rack and B rack subject to opening the first grill could improve RCI to 66%.
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