碩士生: 黎明心
畢業年分: 2025年7月
論文名稱: 氨氣/空氣火焰與傾斜甲烷/空氣火焰交互作用之火焰行為與排放特性研究(中文) / A study on flame behaviors and emissions of ammonia/air flames interacting with inclined methane/air flames (英文)
中文摘要:
氨氣 (NH₃)/甲烷 (CH₄) 雙火焰燃燒被視為提升 NH₃ 利用效率並降低 NOx 排放的潛力途徑。然而，單獨火焰當量比對火焰穩定性與污染物生成的影響仍未充分理解，特別是在化學計量與富 CH₄ 條件下。本研究利用具傾斜側噴流的三槽燃燒器，建立一穩定、準二維且具光學可視化的火焰，並可獨立控制 Φ_(CH₄) 與 Φ_(NH₃)。
火焰影像顯示，NH₃ 火焰行為（包括尖端開口、連續與膨脹三種模式）受 CH₄ 火焰條件顯著影響。富 CH₄ 當量比促進 NH₃ 反應速率，縮短火焰高度並降低尖端開口閾值。雖然 PIV 量測顯示局部回流，但主導穩定機制為自由基擴散（由 NH₂* 與 CH* 化學發光驗證）及 CH₄ 運輸，改變了 NH₃ 火焰的局部當量比與成分。
排放分析顯示，在偏貧 Φ_(NH₃) 條件下，富 Φ_(CH₄) 可顯著降低 NO 與 CO 排放，但過度富化則可能透過 fuel-NO 路徑促進 NO 生成。CO–CO₂ 關係進一步指出涉及 HCN 生成與氧化的碳路徑。綜合上述，本研究凸顯當量比配對在控制雙火焰燃燒動態與污染物生成中的關鍵角色，為發展低排放氨基燃燒系統提供實驗依據。
英文摘要:
Ammonia (NH₃)/methane (CH₄) dual-flame combustion offers a promising pathway to improve NH₃ utilization while mitigating NOx emissions. Yet, the role of individual flame equivalence ratios in flame stabilization and pollutant formation remains poorly understood, particularly under stoichiometric and fuel-rich CH₄ conditions. This study employs a triple-slot burner with inclined side jets to establish a stable, quasi-two-dimensional, optically accessible flame, enabling independent control of Φ_(CH₄) and Φ_(NH₃) over a wide operating range.
Direct flame imaging shows that NH₃ flame behavior—transitioning between tip-opening, continuous, and blooming regimes—is strongly influenced by CH₄ flame conditions. Higher Φ_(CH₄) enhances NH₃ reaction rates, reduces flame height, and lowers the tip-opening threshold. While particle image velocimetry reveals localized recirculation, the dominant stabilization mechanisms are radical diffusion, observed through NH₂* and CH* chemiluminescence imaging, and CH₄ transport, which modify the NH₃ flame’s local equivalence ratio and composition.
Post-flame emission analysis indicates that NO and CO emissions at lean Φ_(NH₃) decrease significantly under rich Φ_(CH₄). However, excessive enrichment promotes NO formation through fuel-NO pathways. Furthermore, CO–CO₂ relationships suggest alternative carbon routes involving HCN formation and oxidation.
Overall, this study highlights the importance of equivalence ratio pairing in governing dual-flame combustion dynamics and pollutant formation. The results provide valuable insights into reducing emissions while maintaining flame stability, supporting the development of advanced low-emission NH₃-based combustion systems.
