Ma Junrong, Wang Cheng, Zhang Changsuo
College of Energy Engineering, Shanxi Institute of Science and Technology, Shanxi 048000, China.
State Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, Beijing 100081, China.
ACS Omega. 2024 Oct 1;9(41):42289-42296. doi: 10.1021/acsomega.4c04879. eCollection 2024 Oct 15.
An optimal ignition criterion must be selected for the numerical prediction of the ignition parameters for mechanical spark ignition of near-limit methane-air fuel mixtures based on fuel mixture equivalency ratio; wherein, the vast majority of ignition criteria can be used for stoichiometric fuel mixtures. However, the viability of each criterion must be individually determined for near-limit fuel mixtures. This study developed a high-resolution algorithm that can be used to model the mechanical spark ignition and combustion of methane-air fuel mixtures of varying equivalence ratios. Three ignition criteria, Van't Hoff, reaction heat release rate, and -OH concentration, were evaluated at varying equivalence ratios based on their respective distributions at varying times. The widely used Van't Hoff criterion cannot be used to predict near-limit fuel mixtures due to a high required ignition temperature and low rates of combustion. -OH concentration criterion is significantly affected by the rate of combustion and reaction temperature; therefore, it tends to erroneously overestimate ignition parameters for near-limit fuel mixtures. This study has found that reaction heat release rate criterion can be used at all equivalence ratios and faithfully produces ignition parameter trends for fuel mixture reaction schemes of varying simplifications. Reaction heat release rate is a valid ignition criterion because the location of peaks in reaction released heat at varying times corresponds to flame front location, which is its physical counterpart.
必须基于燃料混合物当量比，为近极限甲烷 - 空气燃料混合物机械火花点火的点火参数数值预测选择最佳点火准则；其中，绝大多数点火准则可用于化学计量燃料混合物。然而，对于近极限燃料混合物，必须分别确定每个准则的可行性。本研究开发了一种高分辨率算法，可用于模拟不同当量比的甲烷 - 空气燃料混合物的机械火花点火和燃烧。基于不同时刻各自的分布，在不同当量比下对范特霍夫、反应热释放率和 -OH 浓度这三个点火准则进行了评估。由于所需点火温度高且燃烧速率低，广泛使用的范特霍夫准则不能用于预测近极限燃料混合物。 -OH 浓度准则受燃烧速率和反应温度的显著影响；因此，它往往会错误地高估近极限燃料混合物的点火参数。本研究发现，反应热释放率准则可用于所有当量比，并能忠实地得出不同简化程度的燃料混合物反应方案的点火参数趋势。反应热释放率是一个有效的点火准则，因为不同时刻反应释放热峰值的位置与火焰前沿位置相对应，而火焰前沿位置是其物理对应物。
