ABSTRACT In this study, the combustion pressure of pure methane-air mixture, with 99.99% purity, and a mixture of air with Natural Gas (NG) consisted of 84.2% Methane, 9.5% Ethane, and 3.7% Propane was investigated, while both mixtures had an initial pressure of 10 bar. In this study, the combined effect of initial turbulence, pressure, and ignition energy on the combustion characteristics of each mixture was investigated. The fuel concentration in the methane-air and NG-air mixture varied between 4.98% and 17.3%. The flammability limits of the NG were 4.41% and 14.47%, whereas they were 5% and 15% for pure methane. To investigate the effect of rich or lean mixture on the combustion pressure, experiments were conducted with equivalence ratios of 0.50, 0.75, 1.00, 1.50, and 2.00. For both sets of experiments, the maximum combustion pressure occurred at the equivalence ratio of 1.00. The results showed that the lower methane concentration and the presence of other hydrocarbons such as Ethane and Propane in NG, do not cause the maximum combustion pressure to occur in a ratio other than the equivalence ratio of 1.00. Also, the study showed that the igniter energy had a significant effect on the combustion pressure, where an increase in the spark energy dramatically increased the combustion pressure for both pure methane and NG. The experiments were expended to demonstrate the effect of initial turbulence created via the mixer, on the combustion pressure for both fuels. The results suggest that the use of the mixer has a significant effect on the combustion pressure, so that experiments performed with the mixer significantly increased the combustion pressure in both fuels. Also, the study showed that the combustion pressure is influenced more than initial turbulence rather than ignition energy. The results of this study can be used in different fields from preventing unwanted combustion and detonation in engines or at places with High-risk environments such as mines and storage facilities for these gases.

中文翻译：

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初压升高纯甲烷与天然气燃烧压力对比试验研究

摘要 在这项研究中，研究了纯度为 99.99% 的纯甲烷-空气混合物的燃烧压力，以及由 84.2% 甲烷、9.5% 乙烷和 3.7% 丙烷组成的空气与天然气 (NG) 的混合物的燃烧压力，而两者均混合物的初始压力为 10 巴。在这项研究中，研究了初始湍流、压力和点火能量对每种混合物燃烧特性的综合影响。甲烷-空气和天然气-空气混合物中的燃料浓度在 4.98% 和 17.3% 之间变化。NG 的可燃极限为 4.41% 和 14.47%，而纯甲烷为 5% 和 15%。为了研究浓或稀混合气对燃烧压力的影响，进行了当量比为 0.50、0.75、1.00、1.50 和 2.00 的实验。对于两组实验，最大燃烧压力出现在当量比为 1.00 时。结果表明，天然气中较低的甲​​烷浓度和其他碳氢化合物（如乙烷和丙烷）的存在不会导致最大燃烧压力以当量比 1.00 以外的比例出现。此外，研究表明点火器能量对燃烧压力有显着影响，其中火花能量的增加显着增加了纯甲烷和天然气的燃烧压力。实验用于证明通过混合器产生的初始湍流对两种燃料的燃烧压力的影响。结果表明，混合器的使用对燃烧压力有显着影响，因此使用混合器进行的实验显着增加了两种燃料的燃烧压力。此外，研究表明，燃烧压力的影响不仅仅是初始湍流，而是点火能量。这项研究的结果可用于不同领域，以防止发动机或具有高风险环境的地方（如矿山和这些气体的储存设施）发生不必要的燃烧和爆炸。