- 期刊
- OpenAccess
具流動聚焦霧化機制之內衝式微霧化器性能研究
Atomization Performance of Internal-Impinging Type Micro-Atomizer with Flow Focusing Mechanism
摘要
本研究應用微機電(MEMS)技術製作具流動聚焦機制之內衝式微霧化器(MMA)，其噴口水力直徑(D(下標 h))?45及78μm，由邊鞘之層流氣流以48度角衝擊並推送此液束至噴口外碎化成噴霧流。結果顯示，低氣液質量比下，出現氣泡爆破(bubble bursting)、單液滴噴流及分岔之液滴噴流現象，在較高之氣液質量比下則出現紊流霧化模態。當D(下標 h)=45μm，液體流率?1.0mL/min，霧化氣體壓力?2bar時，可產生平均粒徑(SMD)3μm之噴霧，其中有50%之噴霧液滴小於5μm，77%液滴小於10μm。其霧化品質優於市售之醫用霧化器(NE-C21V)，適合運用在ICP質譜儀之液體樣本導入及氣霧給藥等領域。
並列摘要
This paper describes the atomization mechanisms and performance of a twin-fluid micro atomizer with flow focusing. The micro atomizer is fabricated via MEMS bulk micro-machining processes. The orifice hydraulic diameters (D(subscript h)) of the micro atomizers are 45 and 78 μm, respectively. The liquid streams are pushed by the sheath gas flows by an angle of 48 degree in the mixing chamber and are impinged each other at the exit. They are disintegrated into droplets at the exit of the micro-atomizer. Observations of the disintegration of liquid in the near field of the atomizer show that the breakup phenomena involved the mechanisms of bubble bursting, mono-dispersed droplet formation, and flow branching of the liquid jet under lower gas-to-liquid mass ratio. On the other hand, the mechanism of turbulent breakup mode can be observed under higher gas-to-liquid mass ratio. It turns out that the micro-atomizer generates a fine stream with 50% volume fraction less than 5μm and 77% volume fraction of droplets less than 10μm. Furthermore, the mean droplet size of the micro spray is lowered to 3μm under the gas pressure of 2bar and liquid flow rate of 1.0mL/min. The performance of the micro-atomizer compares favorably better than the commercial pneumatic nebulizer. It is very useful in the applications of sample introduction in inductively coupled plasma mass spectrometry (ICP-MS) and medical inhalation devices.