摘要

本研究主要探討液態金屬在縫隙型內混式霧化器中不同噴嘴出口長寬比(AR)下之霧化性能。霧化器出口面積為12mm2，噴嘴出口長寬比分別為2.1、3.0、6.9及12.0等。液態金屬噴霧先以液態氮冷卻成金屬粉末，再以INSITEC粒徑分析儀量測金屬粉末粒徑。本實驗所採用之液態金屬為鉛錫合金(錫63%，鉛37%)。實驗結果顯示，在相同操作壓力下液態金屬流量及金屬粉末粒徑隨霧化器噴嘴出口長寬比而有相當大之變化，例如在液態金屬操作壓力為4´105N/m2下，金屬粉末平均粒徑隨噴嘴出口長寬比由AR = 2.1增加到AR = 12.0，其粒徑SMD亦從SMD = 15.0mm增加到SMD = 22.0mm。在長寬比由AR = 2.1增加到AR = 6.9時，在45mm以下的顆粒體積百分比(V45-)由74.2%增加到82.5%，但當AR由6.9再增加到AR = 12.0時V45-則進一步減少到56.8%。實驗結果亦顯示，在長寬比AR = 12.0時，金屬粉末粒徑分布範圍較大，其粒度比為SR = 10.57，而長寬比AR = 6.9時，其粒度比則降至SR = 7.89，故知控制噴嘴長寬比可以有效降低金屬粉末粒徑分布的範圍。液態金屬流量亦隨噴嘴長寬比AR而有顯著之不同，在液態金屬壓力為4´105N/m2時，噴嘴長寬比由AR = 2.1增加到 AR = 6.9時，液態金屬流量由1.54kg/min降到0.7kg/min，但當AR由6.9增加至12.0時液態金屬流量又增加至1.19 kg/min。實驗結果亦顯示在噴嘴長寬比AR = 12下，當液態金屬操作壓力由2´105N/m2增加到3´105N/m2時，SMD由28.93mm降低到22.42mm，但是當液態金屬操作壓力繼續增加到5´105N/m2時，SMD均維持在22mm左右。另外，氣液壓力差亦為霧化之控制參數，實驗結果顯示當氣液壓力差由0.3´105N/m2增加到1.2´105N/m2時，SMD從30.24mm降低到20.94mm。由上述實驗結果顯示噴嘴長寬比為AR = 6.9時有最佳之霧化性能，而且在液態金屬操作壓力3´105N/m2及氣液操作壓力差1.2´105N/m2可以得到較佳之霧化品質。

Abstract
The dependence of performance on aspect ratios of a linear atomizer in the atomization of molten metal is characterized in this paper. The aspect ratio of the atomizer is 2.1, 3.0, 6.9 and 12.0 with the same cross sectional area of 12mm2. The metal powders are first collected in a liquid nitrogen bath. The metal powders are then measured by INSITEC Particle analyzer. The experiments on the atomization of eutectic metal (Sn63%, Pb37%) show that the metal flow rate and the particle size vary significantly under different aspect ratios even with the same operation pressure. For example, the Sauter mean diameter of the powder(SMD) increase from 15.0mm to 22.0mm as the aspect ratio (AR) increase from 2.1 to 12.0 in a test with metal pressure of 4.0´105N/m2. The volume of the powder with the size less than 45mm increases from 74.2% to 82.5% as the AR increases from 2.1 to 6.9, However, when the AR further increases to 12.0, the volume percentage of the powder with size less than 45mm decreases to 62.2%. The result also show that the particle size distribution of the metal powder is wider at AR = 12.0. Size distribution of the metal powder can be narrowed down by reducing the aspect ratio to AR = 6.9. The mass flow rate of molten metal also varies with AR. The molten metal flow rate decreases from 1.54kg/min to 0.7kg/min when AR increases from 2.1 to 6.9. However, The molten metal flow rate increases to 1.19 kg/min when AR further increases to 12.0. On a test with AR = 12.0, SMD decreases from 28.93mm to 22.42mm as metal pressure increases from 2.0´105N/m2 to 3.0´105N/m2. However, SMD remains at 22mm when the metal pressure further increases to 5.0´105N/m2. Results also show that SMD decreases from 30.24mm to 20.94mm as the pressure difference between gas and molten metal increases from 0.3´105N/m2 to 1.2´105N/m2. It can be concluded that the optimization performance of the atomizer can be optimized at AR = 6.9. Moreover, better atomization performance can be obtained at metal pressure of 3.0´105N/m2 and pressure difference between gas and molten metal of 1.2´105N/m2.

摘要
英文摘要
目錄 1
表目錄 IV
圖目錄 V
符號說明 VII
第一章 緒論 1
1-1簡介 1
1-2文獻回顧 2
1-2-1液體碎化過程研究 2
1-2-2金屬噴嘴相關研究 4
1-3研究動機 12
第二章 實驗設備及儀器 14
2-1實驗設備 14
2-2實驗量測儀器 16
2-2-1 INSITEC粒徑分析儀 16
2-2-2攝影器材、顯微影像系統與影像處理系統 17
2-3主要參數簡介 17
第三章 實驗步驟及方法 18
3-1液態金屬溫度控制 18
3-2微粉末之防護 18
3-3液態金屬之霧化及冷卻 19
3-4金屬顆粒之收集 19
3-5液態金屬流量的量測 19
3-6金屬顆粒的顯微鏡量測 19
3-7INSITEC粒徑分析儀的量測 20
3-8量測條件 20
3-9實驗誤差 21
第四章 結果與討論 22
4-1液態金屬噴霧流量-壓力特性 22
4-1-1液態金屬流量隨液態金屬壓力之變化 22
4-1-2噴嘴出口長寬比對金屬流量之影響 23
4-1-3操作壓力差對液態金屬流量之影響 24
4-2噴嘴出口不同長寬比對噴霧性能之影響 24
4-2-1不同噴嘴出口長寬比之噴霧顆粒體積百分比分佈 25
4-2-2金屬顆粒之平均粒徑D32 25
4-2-3 顆粒體積百分比分布粒徑Dv(10)、Dv(50)、Dv(90) 25
4-2-4 粒度比SR 26
4-2-5 顆粒體積百分比V45-、V25-、V15- 27
4-2-6 顆粒體積百分比V25-45 27
4-2-7 顆粒體積百分比V15-25 28
4-3 液態金屬在不同操作壓力下之霧化特性 28
A.液態金屬在液氣壓力差DP = 1.0´105N/m2之霧化特性 28
4-3a-1 金屬顆粒之平均粒徑D32 29
4-3a-2 顆粒體積百分比分布粒徑Dv(10)、Dv(50)、Dv(90) 29
4-3a-3 粒度比SR 30
4-3a-4 顆粒體積百分比V45-、V25-、V15- 30
4-3a-5 顆粒體積百分比V25-45 31
4-3a-6 顆粒體積百分比V15-25 31
B.不同液氣壓差下之霧化特性 32
4-3b-1 金屬顆粒之平均粒徑D32 32
4-3b-2 氣液質量比 32
4-3b-3 顆粒體積百分比分布粒徑Dv(10)、Dv(50)、Dv(90) 33
4-3b-4 粒度比SR 33
4-3b-5 顆粒體積百分比V45-、V25-、V15- 34
4-3b-6 顆粒體積百分比V25-45 34
4-3b-7 顆粒體積百分比V15-25 35
4-4 SEM照相圖 35
第五章 結論 36
參考文獻 38
自述 79

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