Investigating the effect of hydrogen addition on cyclic variability in a natural gas spark ignition engine: Wavelet multiresolution analysis
Investigating the effect of hydrogen addition on cyclic variability in a natural gas spark ignition engine: Wavelet multiresolution analysis
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DOI：
10.1016/j.apenergy.2011.06.030
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发表时间：
2011-12
期刊：
影响因子：
11.2
通讯作者：
A. Sen;Jinhua Wang;Zuo-hua Huang
中科院分区：
文献类型：
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作者：
A. Sen;Jinhua Wang;Zuo-hua Huang
利用小波多分辨分析，研究了天然气火花点火发动机中氢气添加对循环变动性的影响。发动机在3000 rpm下运转，并使用过量空气比为1.4的贫可燃混合气。研究了三种情况：不添加氢气的天然气，以及添加23%和40%体积氢气的天然气。分析了192个发动机循环的平均指示压力时间序列。采用最大重叠离散小波变换的方法，将时间序列分解为5个不同频带的层次，每一层次由“细节”信号和“近似”信号组成。在每个级别的细节信号的均方根幅度被用作循环可变性的度量。结果表明，加入23%的氢气后，5个波段的细节信号均方根值均小于100%天然气。当氢添加量增加到40%时，五个谱带中的每一个谱带中的均方根值进一步减小。换句话说，氢添加对降低指示平均有效压力的循环可变性具有显著效果。
Using wavelet-based multiresolution analysis, this study investigates the effect of hydrogen addition on cyclic variability in a natural gas spark ignition engine. The engine is operated at 3000rpm, and a lean combustible mixture with excess air ratio of 1.4 is used. Three cases are examined: natural gas with no hydrogen added, and natural gas with the addition of 23% and 40% hydrogen by volume. The time series of the indicated mean effective pressure are analyzed over 192 engine cycles. The method of maximal overlap discrete wavelet transform is used to decompose the time series into five levels with different frequency bands, each level consisting of a “detail” signal and an “approximation” signal. The root mean square amplitude of the detail signal at each level is used as a measure of cyclic variability. The results reveal that with the addition of 23% hydrogen, the root mean square value of the detail signal in each of the five bands is less than that for 100% natural gas. When the amount of hydrogen addition is increased to 40%, the root mean square value in each of the five bands is further reduced. In other words, hydrogen addition has a pronounced effect on reducing the cyclic variability of the indicated mean effective pressure.