• 沒有找到結果。

本研究是利用現有的氣相擴散方程式與液相擴散方程式來求得氣液介 面上的氣相通量與液相通量,且在質傳過程中,氣相通量、分子動力理論 所提出之介面通量式以及液相通量必須相等,利用上述關係求得污染物在 氣液介面上的氣相分壓ps與液相莫耳濃度Cs並代入介面通量式後,得到單 顆液滴吸收污染物之通量式,進而模擬得到液滴濃度與時間的關係。

由模擬結果發現,「液滴內部濃度均勻」之模式的之模擬值遠大於實驗 值,誤差約4 倍,故該假設不適用於預測液滴濃度;「液滴內部只有擴散機 制」則需加上環流修正倍數才會比較接近實驗值,但仍有 25%~40%的誤 差,只有在液滴與氣體的接觸距離約0.6 m (約 0.35 秒)以內才會符合實驗 值;「污染物有水解反應」之模式亦需要加上環流修正係數才會接近實驗 值,且此模式所預測之液滴平衡濃度與實驗值符合,誤差約17%。

另外以「污染物有水解反應」之模式模擬了不同液滴初始 pH 值與不 同液滴粒徑大小對於液滴濃度的影響,結果發現,液滴初始 pH 值愈低,

液滴平衡濃度愈低;液滴粒徑愈大,液滴平衡濃度愈高,且達到平衡濃度 所需時間愈長。此外,利用水解模式計算攝入係數γ值,發現γ會隨時間 變化,並非固定值,但是不論液滴粒徑大小,γ最後仍會趨於一致。

總括來說,本研究所推導出來的理論式雖然可以接近其他學者的實驗 值,但是仍有部份誤差,有待改進。未來可針對液滴內部環流增加質傳通 量這部份加以修正改進,或是針對水解部份能夠更加詳細推導,也許能得 到更合用的理論模式,此外液滴在運動狀態中會產生變形也是影響質傳的 因素之ㄧ。

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