應用STAR-CD軟體模擬渦卷式壓縮機排氣室流場與微功率反應器廠房通風系統之排氣效率

Abstract

本論文應用STAR-CD 套裝軟體來進行流體力學之數值計算。論文內容主要分為兩部分：第一部份是模擬渦卷式壓縮機排氣室內的流場，第二部分則是模擬微功率反應器廠房通風系統之排氣狀況。 第一部份的研究結果顯示，冷媒由渦卷吐出口進入排氣室空間中，高速氣流衝擊頂蓋的中央部位而形成高壓區域，而後轉由排氣管流出排氣室。若在排氣室中加入逆止閥，則主氣流直接衝擊逆止閥頂部，並在閥座空間中形成高壓區域，之後再由閥座出口流至排氣室空間，頂蓋因不受高壓氣流的直接衝擊，故壓力值較未加入逆止閥前為低，且分佈也較均勻。再透過暫態流場的模擬，更可以觀察流場的連續變化。 第二部分的研究結果顯示，於原始廠房設計的空間中，在各角落處容易有小渦流產生。現有廠房加蓋三間實驗室後，流道空間受到限制，在多處角落或加蓋的實驗室壁面都發生氣流轉向的現象，使得流速有略微減緩的趨勢。三樓大部份空間的流速極低，流動性不如一、二樓的空間，其壓力分佈極為均勻。最後，由四個案例的比較，可以推論：在5000~10000 cfm此一流量範圍內，系統總流量的改變並不至於對流場結構產生明顯的變化，而流場空間的改變則明顯改變流場結構。

This thesis utilizes a commercial code, SATR-CD, to simulate the flow field for two subjects. The first one is the flow field inside an exhaust chamber of a scroll compressor, the other is the ventilation flow inside a building of ZPRL (Zero Power Reactor at Lungtan). The computed results of the first part show that the refrigerant from discharge port enters the exhaust chamber, and the center of top cover becomes the high-pressure area due to the main flow direct impingement. After that, it flows out the chamber through the exhaust pipe. If a check valve is placed in the chamber, then, the main stream will directly impinge its top surface, resulting in a high pressure inside the check valve. The stream then flows out the check valve to the exhaust chamber. Not subjected to the flow impingement directly, the pressure of top cover becomes lower and its distribution more uniform. Finally, a successive flow variation history can be observed by an animation by using the transient flow simulation of STAR-CD. In the second part, the simulation results find that there exist many small vortices at corners in the building for its original design. After three additional experimental rooms are set up in the original building, the space of flow path is limited. Therefore, the re-circulation flows are occurred at the corners and wall surfaces along these additional experiment rooms. The velocities of flow are slightly decreased accordingly. The flow velocities in the third floor are found relatively small and its pressure distribution becomes more uniform. Comparing the results obtained from the four case studies, it can be concluded that the arrangement of space has a much greater influence on the flow structure than that of the total ventilation flow rate in the range of 5000 to 10000 cfm.