- 學位論文
數值分析與比較不同回風形式之潔淨室
Numerical study and comparison of different return air systems in cleanroom
摘要
目前一般產業中最常使用的潔淨室回風系統為經由牆壁出口排除至通風管道後再做處理的牆壁回風系統。然而此系統在理論上對於室內有產生高溫及微塵粒子的機台而言，並非擁有最好的效能。搜尋在國內外的文獻中，鮮少有學者探討回風系統設計方式對潔淨室性能之影響，有鑑於此本研究主要目的就是利用數值方法去模擬一般傳統之牆壁回風系統與一新型回風系統之潔淨室之性能比較，此新型回風系統之潔淨室為天花板回風系統(Ceiling return)潔淨室。利用計算流體力學套裝軟體FLUENT以及空調通風專用軟體AIRPAK進行分析。主要研究為不同回風系統設計，再透過各種不同環境情況的條件改變，詳細的去分析與比較，其中環境變數分別為換氣率、發熱機台排放風速與發熱機台排放溫度的不同，由此三種變數去討論其流場、溫度場及微粒運動軌跡，另一環境變數為發熱機台的高度不同，由此去討論溫度的分佈，並且對天花板回風系統的短循環做探討。 經過研究後可以發現，高換氣率能使得兩種回風系統的潔淨室整體效能提升。對於有發熱機台向上排放的情況下，天花板回風系統潔淨室會比牆壁回風系統潔淨室，有更好的廢熱及微粒排除效能。而天花板回風系統之潔淨室比牆壁回風之潔淨室的溫度均勻度較好，意即各高度層的溫差不大。當發熱機台的高度提升，能夠使低溫區的範圍提高。FDCU回風系統會有短循環的產生，尤其是當室內高度提升後，其短循環的範圍會變大，因此在FDCU系統之風機設定上需要嚴加的調整，才能將短循環的影響降至最低，並使得其效能達到最佳狀態。
並列摘要
Non-unidirectional airflow cleanrooms are the most common ventilation system applied in the industries (e.g., semiconductor, medical devices, pharmaceutical, biotech). In a conventional arrangement of the airflow pathway in non-unidirectional airflow cleanrooms, a wall return schemes, the supply air is introduced from ceiling air grilles and the return air is extracted from the wall air grilles close and vertical to floors. However, such wall return ventilation system is theoretically not the optimum resolution at removing the huge amount of heats and particles dissipated from the process tools. Studies related to the effects of return air ventilation system on cleanroom performance were not widely reported. This study is designated to numerically analyze the performance of cleanroom installed with a conventional wall return ventilation system and a newly proposed innovative locally ceiling return ventilation system, respectively, using Computational Fluid Dynamics (CFD) software (FLUENT and Airpak). For each return air ventilation system, the effects of air change rates, heat dissipating air flow velocities and heat discharging temperatures on the air motion characteristics, temperature distributions and particle motion characteristics in the cleanroom are investigated studied. Besides, the effects of the heights of heat dissipating process tool on temperature distribution in the cleanroom is included. Based on the results, for both return air ventilation designs, it is indicated that higher air change rates will lead to better improvement in the overall performance of the cleanroom. As for the heat and particle source which dissipated upwardly from the process tool, the innovative locally ceiling return ventilation system provides better heat and particle removal performance, and temperature distributions compared with those from the conventional wall return ventilation system. Besides, it is also found that coverage of area with lower temperature distribution in the cleanroom will be increased with the increase of the heights of heat dissipating process tool. Nonetheless, the issue of the bypass of clean supply air in the innovative locally ceiling return ventilation system is remarkable in achieving the optimum performance conditions.