供風量與發熱量對小型數據中心之熱管理實驗研究

Abstract

本實驗研究利用美國冷凍空調學會所訂定之機櫃冷卻指標參數(RCI, Rack cooling index)，來評定天花板供風之數據中心內部氣流狀況，並藉由改變不同發熱量分佈等不同參數組合下，探討其數據中心內部氣流狀況及溫度場尋求最佳化設計，研究顯示，改變發熱量分布使高發熱量區域位於機櫃底部，相較均勻發熱時過熱程度也獲得改善，RCI最高提升至64%。若在抽風量等於供風量的情況下，增加機櫃頂部三排風扇之抽風量，其機櫃內部熱回流程度大幅降低，RCI增至47%。在空調方面，供風口溫度降低，RCI最高增加21%。若改變開啟的供風口，在熱回流較嚴重的回風口附近增開編號一的供風口，會降低機櫃側邊熱回流的溫度，RCI上升至63%；在熱通道AB機櫃間安裝擋板可降低A機櫃入口溫度，RCI增至54%，且在鄰近回風口的區域裝設單一塊擋板，與在後方安裝多塊擋板的效果相同，同時提高頂部三排風扇之抽風量、AB機櫃間加入擋板及額外開啟最鄰近回風口之供風口的的結果，RCI最高可增加至66%。

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%.