The effects of NH3 pre-cracking and initial temperature on the intrinsic instability and NOx emissions of NH3/bio-syngas/air premixed flames

IF 5.6 2区 工程技术 Q2 ENERGY & FUELS
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Abstract

The study of the combustion characteristics of NH₃/bio-syngas/air under NH₃ partial cracking and elevated initial temperatures can enhance its feasibility as a practical fuel. The effects of NH₃ cracking rates (ζ) and initial temperature (T0) on the laminar burning velocity (SL), instability, and NO emissions of NH₃/bio-syngas/air premixed flames under different equivalence ratios are investigated. The results indicate that increasing ζ and T0 enhances the SL of the premixed flame, with ζ having a more pronounced effect on combustion enhancement. Virtual gas analysis reveals that pre-cracking primarily strengthens combustion through chemical effect. An increase in ζ significantly shifts the peak SL towards the fuel-rich region, while at any T0, the peak SL consistently occurs around Φ = 1.1. Increasing ζ and T0 reduces the critical radius (rc) and the critical Peclet number (Pec) of the premixed fuel, with rc decreasing more rapidly when ζ is below 30 %. The dimensionless growth rate () increases with the rise in ζ and T0, consistently remaining positive, indicating an unstable state. Additionally, varies more significantly with T0 when T0 is below 450 K. When ζ is below 60 %, the NO mole fraction increases with the increase in ζ. However, at ζ = 80 %, the NO mole fraction is lower than at ζ = 40 %. Increasing T0 continually increases the NO mole fraction. Analysis of the NH3 reaction pathways indicates that NHi (i = 0, 1, 2) is closely related to the NO → N2 reduction reactions.
NH3 预裂解和初始温度对 NH3/生物合成气/空气预混合火焰内在不稳定性和氮氧化物排放的影响
研究 NH₃部分裂解和初始温度升高条件下 NH₃/生物合成气/空气的燃烧特性可提高其作为实用燃料的可行性。研究了不同当量比下 NH₃ 裂解率 (ζ)和初始温度 (T0) 对 NH₃/生物合成气/空气预混合火焰的层燃速度 (SL)、不稳定性和氮氧化物排放的影响。结果表明,增加 ζ 和 T0 会增强预混合火焰的 SL,其中 ζ 对燃烧增强的影响更为明显。虚拟气体分析表明,预裂解主要通过化学效应增强燃烧。ζ的增大会使SL峰值明显偏向富燃料区,而在任何T0下,SL峰值始终出现在Φ = 1.1附近。增加 ζ 和 T0 会降低预混燃料的临界半径(rc)和临界佩克莱特数(Pec),当 ζ 低于 30% 时,rc 下降得更快。无量纲增长率(∑)随着 ζ 和 T0 的增加而增加,但始终保持正值,表明处于不稳定状态。此外,当 T0 低于 450 K 时,∑ 随 T0 的变化更为显著。当 ζ 低于 60 % 时,NO 分子分数随 ζ 的增加而增加。然而,当 ζ = 80 % 时,NO 分子分数低于 ζ = 40 %。增加 T0 会持续增加 NO 分子分数。对 NH3 反应路径的分析表明,NHi(i = 0、1、2)与 NO → N2 还原反应密切相关。
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来源期刊
Journal of The Energy Institute
Journal of The Energy Institute 工程技术-能源与燃料
CiteScore
10.60
自引率
5.30%
发文量
166
审稿时长
16 days
期刊介绍: The Journal of the Energy Institute provides peer reviewed coverage of original high quality research on energy, engineering and technology.The coverage is broad and the main areas of interest include: Combustion engineering and associated technologies; process heating; power generation; engines and propulsion; emissions and environmental pollution control; clean coal technologies; carbon abatement technologies Emissions and environmental pollution control; safety and hazards; Clean coal technologies; carbon abatement technologies, including carbon capture and storage, CCS; Petroleum engineering and fuel quality, including storage and transport Alternative energy sources; biomass utilisation and biomass conversion technologies; energy from waste, incineration and recycling Energy conversion, energy recovery and energy efficiency; space heating, fuel cells, heat pumps and cooling systems Energy storage The journal''s coverage reflects changes in energy technology that result from the transition to more efficient energy production and end use together with reduced carbon emission.
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