Abstract This study concerns the effect of non-thermal plasma discharges on simulated biogas (mixture of CH4 with 80–20 vol% CO2) combustion at atmospheric pressure in synthetic air or synthetic air enriched by oxygen. The plasma-assisted, premixed combustion was performed in a porous-plate burner with dielectric barrier discharge microplasmas driven by nanosecond high-voltage pulses at 3 kHz and 10 kHz repetition rates in the burner holes. The characteristics of the plasma-assisted flames and the role of reactive oxygen species in the plasma-assisted combustion process supplying various oxidizers were determined using a spatial flame chemiluminescence scanning technique acquiring OH*, C2* and CH* emission intensities. From the obtained results, the pathways of combustion enhancement by the plasma were established. During plasma-assisted combustion, the biogas flame stability has improved. The highest plasma impact on the flame stability was observed for the biogas mixture (CH4-60%/CO2-40%). The flame lift-off for a stoichiometric mixture was reduced by 54% with the discharge at 10 kHz repetition rate, but a decrease of fuel–air ratio φ resulted in reduced effect of plasma and the lift-off was reduced only by 38–10% with 10 kHz discharge and by 22–7% with 3 kHz discharge. The experiments with oxygen-enriched synthetic air showed that the oxygen addition increases the flammability limit of biogas mixtures (CH4 with 50–20 vol% in CO2), and allowed to burn mixtures which were not able to combust under normal conditions. However, the plasma-assisted combustion with oxygen enrichment showed a lower effect on the combustion enhancement than without. During experiments of plasma-assisted combustion, the plasma impact on NOX emissions was also determined, showing that NOX concentrations increased with increasing plasma power.

中文翻译：

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在纳秒 DBD 微等离子体燃烧器中使用各种氧化剂燃烧沼气

摘要 本研究涉及非热等离子体放电对模拟沼气（CH4 与 80-20 vol% CO2 的混合物）在合成空气或富含氧气的合成空气中在大气压下燃烧的影响。等离子体辅助预混燃烧在多孔板燃烧器中进行，介质阻挡放电微等离子体由燃烧器孔中以 3 kHz 和 10 kHz 重复率的纳秒高压脉冲驱动。等离子体辅助火焰的特性和活性氧物质在供应各种氧化剂的等离子体辅助燃烧过程中的作用是使用空间火焰化学发光扫描技术获得的 OH*、C2* 和 CH* 发射强度来确定的。根据所得结果，建立了等离子体增强燃烧的途径。在等离子体辅助燃烧过程中，沼气火焰稳定性得到了提高。观察到沼气混合物 (CH4-60%/CO2-40%) 的等离子体对火焰稳定性的影响最大。以 10 kHz 重复率放电时，化学计量混合物的火焰提升降低了 54%，但燃料空气比 φ 的降低导致等离子体效应降低，并且提升仅降低了 38-10 10 kHz 放电时为 %，3 kHz 放电时为 22–7%。富氧合成空气的实验表明，添加氧气会增加沼气混合物（在 CO2 中含有 50-20 vol% 的 CH4）的可燃性极限，并允许燃烧在正常条件下无法燃烧的混合物。然而，富氧等离子体辅助燃烧对燃烧增强的影响低于没有富氧的影响。