臺灣博碩士論文加值系統

近年來網路資料中心(IDC)機房擴展迅速，造成機房內熱密度的急遽上升，以及消耗大量的能源。本文將針對機房內密閉式機櫃之主要影響機櫃散熱效率的設計參數，以計算流體力學(CFD)方法模擬其氣流分布和進行研究。本文探討之參數變化大致分為(一)密閉式機櫃內下方伺服器最小底部高度之可行性研究，(二)密閉式機櫃之入出風口最佳方位研究，(三) 密閉式機櫃氣流出口風量對機櫃散熱效率的影響。機櫃內伺服器散熱效率取決在伺服器風扇是否能在機櫃內靜壓之不均勻情況下順利出風。由改變伺服器距底部距離之模擬結果發現，密閉式機櫃內之靜壓會隨著伺服器與底部距離減少而逐漸降低，當伺服器與底部距離10cm時，機櫃內呈現負壓，造成伺服器出風不易，故在機櫃設計中，密閉式機櫃內伺服器距底部應至少20cm以上。由改變機櫃氣流出入口相關位置之模擬結果發現，當機櫃氣流入口位置與伺服器氣流入口位置同側時，最下方伺服器內幾乎毫無散熱效果，因此在機櫃設計上，應避免伺服器之氣流入口位置偏於機櫃氣流入口位置。由改變機櫃氣流出口風扇風量之模擬結果發現，在過度風量情況下，當降低機櫃氣流出口風扇風速，可增加伺服器氣流出口風速，提升散熱效率，並且減少風扇所需電力負荷，以達節約能源功效。

In recent years due to wide applications of network, internet data center (IDC) is fast growing. The increase of power consumption of servers causes the rapid rising of the power density in the IDC; also consume a large amount of energy. This thesis used the CFD method to simulate the closed type cabinet rack. The design parameters of thermal efficiency of the closed cabinet rack were studied. The parameters studied in this thesis consist of, (1) the feasibility study of the minimum height of the lowest server in the closed cabinet rack, (2) the study of best positions of the air inlet and outlet in the closed cabinet rack, (3) the influence of thermal efficiency to the flow rate of the cabinet outlet. Servers’ heat dissipation thermal efficiency depends on the fan capability under the asymmetrical static pressure in the cabinet. From the simulation results of changing the height between the server and the cabinet bottom, it was found that the static pressure of the closed cabinet rack reduces gradually as the height of the lowest server reduces. When the height was 10cm, the interior of the cabinet became negative pressure. It would cause the servers to have decreased flow rate. It was found that for the closed cabinet rack design, the height of the lowest server should be at least 20cm. From the simulation results of changing the related positions of the air inlet and the air outlet, it is shown that when the air inlet position of the servers and cabinet are the same side, there is not enough heat dissipation for the lowest server in the cabinet rack. Therefore, in the cabinet design, it should prevent the air inlet of the server being at the side of the air inlet of the cabinet. From the simulation results of changing the fan flow rate of the air oulet on the cabinet, it is shown that in the situation of over design of air flowrate, decreasing the fan speed of the air outlet on the cabinet could increse the air flow rate through the servers. It would improve the efficiency of the heat dissipation, and decrease the fan power so to save fan energy.

摘 要 i
ABSTRACT ii
誌 謝 iv
目 錄 v
表目錄 viii
圖目錄 ix
第一章 緒論 1
1.1 研究背景與動機 1
1.2 文獻回顧與探討 3
1.3 研究目的 10
第二章 數值模擬分析方法 11
2.1 統御方程式 11
2.2 數值方法 14
2.2.1 對流–擴散方程式的差分形式 14
2.2.2 壓力–速度耦合關係的處理 18
2.3 鬆弛因子離散方式 22
2.4 計算流體力學電腦程式說明 23
2.4.1 目前現有計算流體力學商用套裝軟體 23
2.4.2 計算流體力學軟體執行數值模擬之步驟 23
第三章 伺服器機櫃之熱流模型 25
3.1 機櫃電腦模型 25
3.2 伺服器電腦模型 26
3.3 起始條件與邊界條件 27
3.4 格點獨立分析 28
第四章 伺服器機櫃散熱改善 29
4.1 影響伺服器機櫃性能之參數 29
4.2 密閉式機櫃內下方伺服器最小底部高度之模擬分析(Case1) 30
4.2.1 編號1伺服器距底部60cm 32
4.2.2 編號1伺服器距底部50cm 36
4.2.3 編號1伺服器距底部40cm 40
4.2.4 編號1伺服器距底部30cm 44
4.2.5 編號1伺服器距底部20cm 48
4.2.6 編號1伺服器距底部10cm 52
4.2.7 改變伺服器距底部距離之結果與討論 56
4.3 密閉式機櫃之入出風口最佳方位之模擬分析(Case2) 57
4.3.1 機櫃氣流出入口位置皆向-X方向偏移(LL) 60
4.3.2 機櫃氣流出口位置向-X方向偏移，機櫃氣流入口位置向+X方向偏移(LR) 63
4.3.3 機櫃氣流出口位置向+X方向偏移，機櫃氣流入口位置向-X方向偏移(RL) 66
4.3.4 機櫃氣流出入口位置皆向+X方向偏移(RR) 69
4.3.5 改變機櫃氣流入出口方位之結果與討論 72
4.4 密閉式機櫃氣流出口風量對機櫃散熱效率的影響之模擬分析(Case3) 74
4.4.1 機櫃氣流出口風扇風速為6m/s(RL) 75
4.4.2 機櫃氣流出口風扇風速為4m/s(RL) 77
4.4.3 機櫃氣流出口風扇風速為6m/s(RR) 79
4.4.4 機櫃氣流出口風扇風速為4m/s(RR) 81
4.4.5 改變機櫃氣流出口風扇風量之結果與討論 83
第五章 結論與建議 86
5.1 結論 86
5.2 建議 87
參考文獻 88
符號彙編 90

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