本研究探討二氧化碳雪花產生裝置在改變不同的形成腔體下，會形成不同的機制與效應。所採用為利用側管之側管探討側迴流之設計，也探討不同側管之參數條件下其對雪花粒徑、生成量及機制之影響。雪花粒徑在初級雪花時期，由Malvern粒子分析儀進行量測，而流場以粒子影像測速儀(PIV)量測，進行流場觀察與噴霧品質診斷。之前(Lin,2014)研究發現啟動長度是隨著管徑大小不同，其啟動長度也隨之改變，啟動長度為令二氧化碳產生有效雪花時所需最短長度的形成腔體，當管徑越大，其啟動長度也會越大，(Lin,2014)發現因為雪花團聚為一個迴流的機制，在啟動長度內需要產生一個迴流流場。而結果也顯示出，雪花形成主要是由於雪花團聚現象所產生，而此研究發現當側管加入，會令形成腔體內部再形成第二個迴流場，而第一個迴流場即是雪花產生時的主要機制，然第二迴流場的影響，也改變了出口處的雪花粒徑大小、速度與密度。若側管設置在形成腔體的啟動長度內，且在約三分之一的啟動長度內，結果顯示，若側管為一個與外界接觸非封閉的條件下，會使雪花的啟動機制受到影響，並讓二氧花碳雪花粒徑退回至初級雪花之大小，而若側管在封閉的條件下，側管會產生迴流機制，但同時也破壞了主迴流場，故側管之長度越長，其雪花粒徑與數量會因而減少。結果也顯示，若側管加裝在三分之二的啟動長度，在開放的條件下，其雪花會介於啟動與非啟動的雪花粒徑大小之間，而在封閉的條件下，若其長度越長，也會略影響主迴流場，而令雪花粒徑略下降，但非完全破壞主迴流機制。當側管加裝在啟動長度下時，開放的側管會使雪花粒徑與啟動時之雪花大小相差不大，但若為封閉的條件下，會引起第二迴流場，並讓雪花在第二迴流場發生團聚現象，進而產生塊狀且密度大的雪花，且側管長度越長，會使雪花的粒徑上升。而此研究也顯示，若在形成腔體下，利用第二迴流場與主迴流場的控制，可以有效的控制雪花粒徑甚至是速度與密度。本實驗亦探討傳統式直管形成腔體與此實驗設計之側壁側管迴流裝置下的形成腔體之雪花生成與轉換率比較，在不同位置下之側管封閉產生迴流區時，雪花生成率亦不同，在啟動長度下之側管迴流機制能使雪花生成率上升約1.5倍，同時此實驗也進一步探討內部流場速度與擾動量，進而探討出新的機制與第二迴流模型。

Carbon dioxide (CO2) snow jets are widely used in medical and industrial applications, such as cryogenic therapy, food processing, pharmaceutical granulation, particle removal and surface cleaning. In semiconductor fabrication, CO2 snow cleaning has unique organic and particle removal abilities with eco-friendly that are better than those of traditional surface cleaning methods. A model for the agglomeration of CO2 snow particles is derived by our research team this year, and it provide clear evidence of the agglomeration of CO2 snow inside a tube that has never been published in the literature and indeed providing highly opportunity to advance performance of CO2 cleaning. To prolonging the research results of agglomeration mechanism of primary CO2 snow, this research aim at the controlling-technologies of snow particles, include the onset mechanism, onset length of agglomeration of snow particle and designed chambers. By using the additive manufacturing method by 3D printer, complicated design with opened-air chamber configuration and curved surface can easily be realized. This paper experimentally investigates the agglomeration mechanism of CO2 primary particles inside a tube and lateral jet forming a second recirculation. Results show that a complicated particle motion in the upper portion of the tube is responsible for the formation of large snow. By the change of the condition of the flow recirculation area, the snow particles can be controlled and thus ensure the formation of considerable agglomerated particles. Results also show that the onset condition of agglomeration is influenced by the flow condition, as well as the lateral jet.

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