Mashruk Syed, Shi Hao, Mazzotta Luca, Ustun Cihat Emre, Aravind B, Meloni Roberto, Alnasif Ali, Boulet Elena, Jankowski Radoslaw, Yu Chunkan, Alnajideen Mohammad, Paykani Amin, Maas Ulrich, Slefarski Rafal, Borello Domenico, Valera-Medina Agustin
College of Physical Sciences and Engineering, Cardiff University, Cardiff, Wales CF24 3AA, U.K.
Reaktive Strömungen und Messtechnik (RSM), TU Darmstadt, 64287 Darmstadt, Germany.
Energy Fuels. 2024 Oct 2;38(20):19253-19292. doi: 10.1021/acs.energyfuels.4c03381. eCollection 2024 Oct 17.
Climate change and global warming necessitate the shift toward low-emission, carbon-free fuels. Although hydrogen boasts zero carbon content and high performance, its utilization is impeded by the complexities and costs involved in liquefaction, preservation, and transportation. Ammonia has emerged as a viable alternative that offers potential as a renewable energy storage medium and supports the global economy's decarbonization. With its broader applicability in large power output applications, decentralized energy sources, and industrial locations off the grid, ammonia is increasingly regarded as an essential fuel for the future. Although ammonia provides a sustainable solution for future low-carbon energy fields, its wide-scale adoption is limited by NO emissions and poor combustion performance under certain conditions. As research on ammonia combustion expands, recent findings reveal factors impacting the chemical reaction pathways of ammonia-based fuels, including the equivalence ratio, fuel mixture, pressure, and temperature. Investigations into ammonia combustion and NO emissions, at both laboratory and industrial scales, have identified NO production peaks at equivalence ratios of 0.8-0.9 for ammonia/hydrogen blends. The latest studies about the NO emissions of the ammonia flame at different conditions and their generating pathways are reviewed in this work. Effective reduction in NO production from ammonia-based flames can be achieved with richer blends, which generate more NH radicals. Other advanced NO mitigation techniques such as plasma-assisted combustion have been also explored. Further research is required to address these challenges, reduce emissions, and improve efficiencies of ammonia-based fuel blends. Finally, the extinction limit of ammonia turbulent flame, its influential factors, and different strategies to promote the ammonia flame stability were discussed. The present review contributes to disseminating the latest advancements in the field of ammonia combustion and highlights the importance of refining reaction mechanisms, computational models, and understanding fundamental phenomena for practical implications.
气候变化和全球变暖使得向低排放、无碳燃料的转变成为必要。尽管氢气碳含量为零且性能优异，但其利用受到液化、储存和运输过程中的复杂性和成本的阻碍。氨已成为一种可行的替代方案，具有作为可再生能源存储介质的潜力，并支持全球经济的脱碳。由于氨在大功率输出应用、分散能源和离网工业场所具有更广泛的适用性，它越来越被视为未来的重要燃料。尽管氨为未来的低碳能源领域提供了可持续的解决方案，但其大规模应用受到氮氧化物排放以及在某些条件下燃烧性能不佳的限制。随着氨燃烧研究的扩展，最近的研究结果揭示了影响氨基燃料化学反应途径的因素，包括当量比、燃料混合物、压力和温度。在实验室和工业规模上对氨燃烧和氮氧化物排放的研究已经确定，氨/氢混合物在当量比为0.8 - 0.9时氮氧化物产生峰值。本文综述了关于不同条件下氨火焰氮氧化物排放及其生成途径的最新研究。使用更富的混合物可以有效减少氨基火焰中氮氧化物的产生，因为更富的混合物会产生更多的NH自由基。还探索了其他先进的氮氧化物减排技术，如等离子体辅助燃烧。需要进一步研究来应对这些挑战、减少排放并提高氨基燃料混合物的效率。最后，讨论了氨湍流火焰的熄火极限、其影响因素以及促进氨火焰稳定性的不同策略。本综述有助于传播氨燃烧领域的最新进展，并强调完善反应机理、计算模型以及理解实际应用中的基本现象的重要性。
