臺灣博碩士論文加值系統

本文主要探討不同的幾何尺寸及入口速度，水蒸氣是否有回流的現象而影響氣態鋅粒子的形成，在不考慮化學反應條件下觀察兩種高溫氣體混合後的流場與溫度場。
在模型設計上，分別固定反應爐出口直徑與氣體出口直徑、固定反應爐出口直徑與改變氣體出口直徑、改變反應爐出口直徑與固定氣體出口直徑，再藉由改變氣態鋅入口速度，探討其混合區流場與溫度場。
本文結果顯示在低的入口速度，反應爐出口直徑超過16mm，水蒸氣會隨著直徑增加而回流趨勢越明顯；當入口速度為2.192m/s，反應爐出口直徑小於18mm，氣體出口直徑增加或減少，水蒸氣都不有回流現象；若速度增加為4.384m/s，固定反應爐出口直徑或固定氣體出口直徑，都會有大量的水蒸氣往反應爐回流現象，造成產氫效率會大幅降低。

The present thesis tends to investigate the influence of mixing chamber’s geometries, incoming gaseous speeds and the circulations of flow on the forming of the gaseous state Zinc particle. Without the consideration of chemical reaction condition, both high-temperatures gas flow field and temperature field after mixing are investigated in detail.
In the numerical simulations, different combinations of furnace exit diameter and gas exit diameter, as well as the gaseous zinc entrance velocity, are taken to see the influence of furnace’s geometry on the thermal and fluid distributions.
Results show as the entrance speed is low and the furnace exit diameter is larger than 16mm, the water steam will flow backward into the furnace. The trend will be more obvious as the diameter increases. While the inlet Zinc velocity is 2.192m/s and the furnace exit diameter is smaller than 18mm, no matter what the gas exit diameter is, the water steam will never flow backward into the furnace. If the inlet velocity increases to 4.384m/s, regardless of fixed furnace exit diameter or fixed gas exit diameter, there always has a large amount of steam flows backward into the furnace. The backflow of the steam will surely reduce the efficiency of hydrogen production.

摘要 I
英文摘要 II
目錄 III
表目錄 VI
圖目錄 VII
符號說明 XI
第一章 序論 1
1-1 前言 1
1-2 產氫方法簡介 2
1-3 熱化學產氫之介紹與文獻回顧 6
1-4 研究動機與目的 13
第二章 理論模式 14
2-1物理模型與基本假設 14
2-2 統御方程式 15
2-2-1 多種物質混合後的流體性質 15
2-2-2 動量方程式 16
2-2-3 能量方程式 17
2-3 模型設計 17
2-4 邊界條件 17
第三章 數值方法 19
3-1 使用軟體 19
3-1-1 Gambit模組 19
3-1-2 Fluent模組 20
3-2 格點設定 21
3-3 計算流程與收斂條件 21
第四章 結果與討論 22
4-1 與文獻結果之比較 22
4-2 固定反應爐出口直徑（d1）與氣體出口直徑（d2） 23
4-3固定反應爐出口直徑（d1）與改變氣體出口直徑（d2） 26
4-4改變反應爐出口直徑（d1）與固定氣體出口直徑（d2） 28
第五章 結論 30
5-1 結論 30
5-2 未來展望 32
參考文獻 33
附錄A 36
I. 成核理論模式 36
II. 分子數量濃度、粒子數量濃度、粒子體積 37
III. 模擬之過程 40

1.A. Kogan, “Direct Solar Thermal Splitting of Water and on Site Separation of the Products. Ι. Theoretical Evaluation of Hydrogen Yield,” International Journal of Hydrogen Energy, 1997, Vol. 22, Issue 5, pp. 481-486.
2.A. Steninfeld, “Solar Thermochemical Production of Hydrogen—A Review,” Solar Energy, 2005, Vol. 78, Issue 5, pp. 603-615.
3.J. E. Funk, “Thermochemical Hydrogen Production: Past and Present,” International Journal of Hydrogen Energy, 2001, Vol. 26, Issue 3, pp. 185-190.
4.A. Kogan, “Direct Solar Thermal Splitting of Water and on Site Separation of the Products. II. Experimental Feasibility Study,” International Journal of Hydrogen Energy, 1998, Vol. 23, Issue 2, pp. 88-98.
5.M. Sakurai, A. Tsutsumi, and K. Yoshida, “Improvement of Ca-pellet Reactivity in UT-3 Thermochemical Hydrogen Production Cycle,” International Journal of Hydrogen Energy, 1995, Vol. 20, Issue 4, pp. 297-301.
6.P. Zhang, B. Yu, J. Chen, and J. M. Xu, “Study on the Hydrogen Production by Thermochemical Water Splitting,” Progress in Chemistry, 2005, Vol. 17, Issue 4. pp. 643-650.
7.A. Steinfeld, P. Kuhn, A. Reller, R. Palumbo, J. Murray and Y. Tamaura, “Solar-Processed Metals as Clean Energy Carriers and Water-Splitters,” International Journal of Hydrogen Energy, 1998, Vol. 23, Issue 9, pp. 767-774.
8.T. Nakamura, “Hydrogen Production From Water Utilizing Solar Heat at High Temperatures,” Solar Energy, 1977, Vol. 19, Issue 5, pp. 467-475.
9.A. Steninfeld, S. Sanders, and R. Palumbo, “Design Aspects of Solar Thermochemical Engineering—A Case Study:Two-Step Water- Splitting Ccycle Using the Fe3O4/FeO Redox System,” Solar Energy, 1999, Vol. 65, Issue 1, pp. 43-53.
10.R. Palumbo, A. Rouanet, and G. Pichelin, “The Solar Thermal Decomposition of TiO2 at Temperatures above 2200K and Its Use in the Production of Zn From ZnO,” Energy, 1995, Vol. 20, Issue 9, pp. 857-868.
11.M. Sturzenegger, and P. Nüesch, “Efficiency Analysis for a Manganese-Oxide-Based Thermochemical Cycle,” Energy, 1999, Vol. 24, Issue 11, pp. 959-970.
12.M. Forster, “Theoretical Investigation of the System SnOx/Sn for the Thermochemical Storage of Solar Energy,” Energy, 2004, Vol. 29, pp. 789-799.
13.K. Wegner, H. C. Lya, R. J.Weissa, S. E. Pratsinisa, and A. Steinfeld, “In Situ Formation and Hydrolysis of Zn Nanoparticles for H2 Production by the 2-Step ZnO/Zn Water-Splitting Thermochemical Cycle,” International Journal of Hydrogen Energy, 2006, Vol. 31, Issue 1, pp. 55-61.
14.S. Tsantilis, S. E. Pratsinis, and V. Haas, “Simulation of Synthesis of Palladium Nanoparticles in a Jet Aerosol Flow Condenser,” Journal of Aerosol Science, 1999, Vol. 30, Issue 6, pp. 785-803.
15.S. L. Girshick, and C. Chiu, “Kinetic Nucleation Theory: A New Expression for the Rate of Homogeneous Nucleation from an Ideal Supersaturated Vapor,” Journal of Chemical Physics, 1990, Vol. 93, Issue 2, pp. 1273-1277.
16.S. K. Friedlander, Smoke Dust and Haze, Fundamentals of Aerosol Behaviour, Wiley, New York, 1977.
17.K. Wegner, B. Walker, S. Tsantilis, and S. E. Pratsinis, “Design of Metal Nanoparticle Synthesis by Vapor Flow Condensation,” Chemical Engineering Science, 2002, Vol. 57, Issue 10, pp. 1753-1762.
18.R. J. Weiss, H. C. Ly, K. Wegner, S.E. Pratsinis, and A. Steinfeld, “H2 Production by Zn Hydrolysis in a Hot-Wall Aerosol Reactor,” American Institute of Chemical Engineers, 2005, Vol. 57, Issue 7, pp. 1966-1970.
19.FLUENT 6.0 Users Guide Documentation, Fluent Inc., Lebanon, New Hampshire, 2001.
20.J. Garai, “Physical model for the latent heat of fusion,” Chemical Physics Letters, 2004, Vol. 398, Issues 1-3, pp. 98-101.
21.R. Hultgren, R.L. Orr, P. D. Anderson, and K. K. Kelley, Selected Values of the Thermodynamic Properties of Metals and Alloys., Wiley, New York, 1963.
22.D. R. Warren, and J. H. Seinfeld, “Nucleation and growth of aerosol from a continuously reinforced vapor,” Aerosol Sci. Technol. 1984, Vol. 3, pp.135.
23.R. Reid, J. Prausnitz, and B. Poling, The Properties of Gases and liquids, Mc Graw-Hill Inc., New York, 1987, 4th Edition.
24.S. Panda, and S. E. Pratsinis, “Modeling the synthesis of aluminum particles by evaporation-condensation in an aerosol flow reactor,” Nanostructured Materials, 1995, Vol. 5, Issues 7-8, pp. 755-767.
25.J. H. Seinfeld, Atmospheric Chemistry and Physics of Air Pollution, Wiley, New York, 1986.