Abstract Recent trends among automotive manufacturers towards downsized, boosted engines make it imperative to understand specific fuel chemistry interactions encountered in this new operating regime. At these elevated pressure conditions a phenomenon called pre-spark heat release has recently been discovered, and is characterized by kinetically controlled heat release before spark, with resultant changes in end-gas thermodynamic state and composition. These reactions typically occur in the end-gas during normal operation, but are obscured by the deflagration heat release and therefore cannot be easily studied. A 2-zone spark-ignition engine model was utilized to determine whether chemical kinetic mechanisms are able to predict this phenomenon, and whether they accurately capture end-gas thermodynamic history. Experimental engine data at a range of boosted operating conditions demonstrating pre-spark heat release were compared with simulations using mechanisms representing the latest developments in gasoline kinetic modeling. The results demonstrated significant discrepancies between mechanisms, and between experimental and simulated results in terms of low-temperature heat release magnitude, end-gas thermodynamic state, and autoignition propensity. The results highlight shortcomings in low-temperature reaction pathways, and indicate the necessity of simultaneously matching first-stage ignition delay and heat release magnitude, in addition to second-stage ignition delay, in order to accurately predict end-gas thermodynamics and autoignition.

中文翻译：

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增压火花点火发动机中异辛烷的预火花放热和低温化学建模

摘要 汽车制造商最近趋向于小型化、增压发动机的趋势使得了解在这种新操作制度中遇到的特定燃料化学相互作用势在必行。在这些高压条件下，最近发现了一种称为预火花放热的现象，其特征在于火花前动力学控制的放热，从而导致尾气热力学状态和成分发生变化。这些反应通常发生在正常运行期间的尾气中，但由于爆燃放热而被掩盖，因此不容易研究。使用 2 区火花点火发动机模型来确定化学动力学机制是否能够预测这种现象，以及它们是否准确地捕获了尾气热力学历史。在一系列提升操作条件下的实验发动机数据证明了火花前放热，与使用代表汽油动力学建模最新发展的机制的模拟进行了比较。结果表明，在低温放热幅度、尾气热力学状态和自燃倾向方面，机制之间以及实验和模拟结果之间存在显着差异。结果突出了低温反应途径的缺点，并表明除了第二阶段点火延迟外，还需要同时匹配第一阶段点火延迟和放热量，以准确预测尾气热力学和自燃。