Effect of H2 addition on laminar burning velocity of NH3/DME blends by experimental and numerical method using a reduced mechanism
Effect of H2 addition on laminar burning velocity of NH3/DME blends by experimental and numerical method using a reduced mechanism
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DOI：
10.1016/j.combustflame.2023.113000
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发表时间：
2023-11
影响因子：
4.4
通讯作者：
Huizhen Li;Huahua Xiao
中科院分区：
文献类型：
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作者：
Huizhen Li;Huahua Xiao
在氨（NH3）中掺入二甲醚（DME）可以有效地促进纯氨的燃烧，已受到越来越多的关注。NH3的部分解离可以将NH3/DME转化为NH3/DME/ h2混合物。在φ = 0.7-1.7、0.1 MPa和298 K条件下，采用球形等体积燃烧法测量了不同配比（100/0、80/20、40/60和0/100）、不同h2添加量（0%、20%和40%）下NH3/DME/空气混合物的Markstein长度和层状燃烧速度。在已有详细机理的基础上，建立并优化了简化动力学机理。该模型对NH3、DME、NH3/DME和NH3/DME/ h23的层流燃烧速度、点火延迟时间和物质浓度的预测比以往的模型更准确。实验和建模结果表明，NH3/DME/ h2共混物的Markstein长度随当量比的变化呈现出不同的状态。h2的存在可以有效地提高NH3/二甲醚/空气混合物的层流燃烧速度。不同h2添加量的层流燃烧速度（ESL）随当量比的增加呈非单调增长趋势。NH3/DME/空气混合物的esl峰值出现在φ = 1.5左右。这可以归因于含碳和含氮反应的主导作用，而不是在富燃烧侧的单键do反应。与esl类似，主导层流燃烧速度的自由基可能在φ = 1.3 ~ 1.6左右从H、O和OH转移到c单键H和n单键H自由基。热效应对富燃料的esland层流燃烧速度也有贡献。
Blending dimethyl ether (DME) into ammonia (NH3) can efficiently enhance the combustion of pure NH3, and has attracted increasing attention. Partial dissociation of NH3can convert NH3/DME to NH3/DME/H2mixtures. This work measured the Markstein length and laminar burning velocity of NH3/DME/air mixtures for different blend ratios (100/0, 80/20, 40/60, and 0/100) with various H2additions (0%, 20%, and 40%) atϕ= 0.7–1.7, 0.1 MPa, and 298 K using a spherical constant-volume combustion method. A reduced kinetics mechanism was developed and optimized based on own prior detailed mechanism. This model gives more accurate predictions for NH3, DME, NH3/DME, and NH3/DME/H2compared to previous models in terms of laminar burning velocity, ignition delay time, and species concentration. The experimental and modeling results show that the measured Markstein length of NH3/DME/H2blends as a function of equivalence ratio presents different states for different NH3/DME blend ratios. The existence of H2can effectively increase the laminar burning velocity of NH3/DME/air mixtures. Relative increase in laminar burning velocity (ESL) shows a non-monotonic tendency with increasing equivalence ratio for different H2additions. The peak value ofESLfor NH3/DME/air mixtures with various H2additions appears at aroundϕ= 1.5. This can be attributed to the dominant effect of C-contain and N-contain reactions rather than Hsingle bondO reactions at the rich burn side. Similar toESL, the free radicals that dominate laminar burning velocity may transit from H, O, and OH to Csingle bondH and Nsingle bondH radicals at aroundϕ= 1.3 ∼ 1.6. The thermal effect also contributes to theESLand laminar burning velocity for rich fuel.