Comparison of air and EGR with different water fractions dilutions on the combustion of hydrogen-air mixtures
Comparison of air and EGR with different water fractions dilutions on the combustion of hydrogen-air mixtures
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DOI：
10.1016/j.fuel.2022.124686
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发表时间：
2022
期刊：
影响因子：
7.4
通讯作者：
Shuofeng Wang;Yifan Zhai;Zhe Wang;Ruifeng Hou;Tianyue Zhang;C. Ji
中科院分区：
文献类型：
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作者：
Shuofeng Wang;Yifan Zhai;Zhe Wang;Ruifeng Hou;Tianyue Zhang;C. Ji
稀薄燃烧和废气再循环（EGR）是控制氢发动机NOx和放热过程的关键策略。本文首先比较了这两种策略在0~50%稀释比范围内氢气-空气混合物的燃烧行为。然后，进一步研究了EGR中的水蒸气对氢气-空气混合物燃烧的影响。所有测试均在初始温度为 373 K、压力为 1 bar 的恒容燃烧容器中进行。采用CHEMKIN PRO，利用一维预混绝热规划火焰模型来预测不同条件下氢气-空气混合物的燃烧行为。测量最终产品中未燃烧的氢气浓度和NO摩尔分数。结果表明，与空气稀释率相比，层流燃烧速度随EGR比例的降低更为明显。 EGR稀释对降低最终产品中NO摩尔分数有非常明显的影响。然而，两种稀释策略都会不利地导致不完全燃烧的氢气增加。为了平衡 NO 控制和未燃 H2 排放，根据本研究的测试范围，建议采用 30% EGR 率和 20% 水蒸气分数。
Lean combustion and exhaust gas recirculation (EGR) are key strategies for controlling NO and heat release process of hydrogen engines. This paper firstly compared these two strategies on combustion behaviors of hydrogen-air mixtures within dilution ratio ranges from 0 to 50%. Then, the water vapor effects in EGR on combustion of hydrogen-air mixtures are further investigated. All tests are conducted in a constant volume combustion vessel at the initial temperature of 373 K and pressure of 1 bar. CHEMKIN PRO is adopted to predict the hydrogen-air mixtures combustion behaviors under different conditions with one-dimensional premixed adiabatic planner flame model. The unburnt hydrogen concentration and the NO mole fraction in the final products were measured. The results show that laminar burning velocity decreases more obviously with the EGR ratio than air dilution ratio. EGR dilution has much obvious influence on reducing NO mole fraction in the final products. However, both dilution strategies adversely cause the increase of incompletely combusted H2. To balance the NO control and unburned H2emission, 30% EGR rate with 20% water vapor fraction is recommended based on the testing ranges of this study.