Experimental and numerical analyses of nitrogen oxides formation in a high ammonia-low hydrogen blend using a tangential swirl burner
Experimental and numerical analyses of nitrogen oxides formation in a high ammonia-low hydrogen blend using a tangential swirl burner
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DOI：
10.1007/s43979-022-00021-9
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发表时间：
2022-06
期刊：
影响因子：
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通讯作者：
A. Alnasif;S. Mashruk;M. Kovaleva;P. Wang;A. Valera-Medina
中科院分区：
文献类型：
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作者：
A. Alnasif;S. Mashruk;M. Kovaleva;P. Wang;A. Valera-Medina
氨被认为是一种新型的脱碳燃料。然而，来自燃烧系统的排放仍然是一个问题。因此，已经进行了实验和数值模拟以研究来自燃烧氨/氢（NH3/H2）混合物85/15（体积%）的废气排放物（一氧化氮“NO”、一氧化二氮“N2 O”）的浓度。在不同的热功率范围为10至20千瓦和不同的雷诺数从20，000 - 40，000测量的效果。在Ansys CHEMKIN-Pro环境中采用文献中的七种化学动力学机制对实验点进行了数值研究。所有实验都是在标准大气条件下进行的。实验结果表明，当雷诺数从20，000增加到40，000时，NO和N2 O浓度均逐渐增加。沿着，当Re = 20，000时，由于较低的反应性自由基形成，排气中的NO排放浓度报告为最低水平，所有这些都导致火焰特性的劣化。此外，随着Re从20，000增加到40，000，NO*、OH*、NH* 和NH 2 * 的积分自由基强度表现出增加的趋势。在热功率方面，当热功率增加到15 kW时，N2 O突然下降，而NO则相反。此外，OH*，NH* 和NH 2 * 的自由基强度图显示，当热功率增加到15 kW时，它们的浓度增加，然后随着热强度的增加而下降，达到20 kW，反映为NO产生增加和N2 O水平降低。数值分析表明，Stagni，Bertolino，和Bowen Mei是最准确的机制，因为这些给了一个很好的预测NO和N2 O。化学反应（HNO + O2参与NO + HO 2）是NO生成的主要来源。而化学反应（NH + NO参与N2 O + H）则负责消耗NO生成N2 O，此时NH自由基会大量生成。最后，处理高氨浓度的混合燃料促使氨化学在火焰中变得更占主导地位。它降低了火焰温度，从而降低了火焰与周围环境之间的热损失。
Ammonia has been considered as a novel fuel for decarbonization purposes. However, emissions from combustion systems are still posing a problem. Therefore, experimental and numerical simulations have been conducted to study the concentration of exhaust emissions (Nitric oxide “NO”, Nitrous oxide “N2O”) from burning the ammonia/hydrogen (NH3/H2) blend 85/15 (vol%). The effects were measured at various thermal powers ranging 10 to 20 kW and with different Reynolds numbers from 20,000—40,000. The experimental points were numerically investigated in the Ansys CHEMKIN-Pro environment employing seven chemical kinetic mechanisms taken from the literature. All experiments have been undertaken at standard atmospheric conditions. The experimental results showed that both NO and N2O gradually increased when the Reynolds number increased from 20,000 to 40,000. Along with that, the concentration of NO emissions at the exhaust reported minimum level when the Re = 20,000 due to lower reactivity radical formation, all that led to a deterioration of the flame characteristics. Also, the integrated radical intensities of NO*, OH*, NH*, and NH2* demonstrate an increasing trend as Re increased from 20,000 to 40,000. In terms of thermal power, N2O suffered an abrupt decrease when the thermal power increased up to 15 kW, while the opposite occurs for NO. In addition, the radicals intensity of OH*, NH*and NH2* figures show an increase in their concentration when the thermal power increased up to 15 kW then decreased with increasing thermal intensity to reach 20 kW, reflecting into increased NO productions and decreased N2O levels. The numerical analysis showed that Stagni, Bertolino, and Bowen Mei were the most accurate mechanisms as these give a good prediction for NO and N2O. The study also showed that the chemical reaction (HNO + O2↔ NO + HO2) is the main source of NO formation. While the chemical reaction (NH + NO ↔ N2O + H) is responsible for the formation of N2O by consuming NO and when there will be abundance in NH radicals. Finally, dealing with a blended fuel of high ammonia concentration encourages ammonia chemistry to become more dominant in the flame. It decreases the flame temperature, hence lowering heat loss between the flame and the surrounding.