Detection and Onset Determination of End-Gas Autoignition on Spark-Ignited Natural Gas Engines Based on the Apparent Heat Release Rate
2022-01-0563
03/29/2022
- Event
- Content
- Natural Gas used in high-efficiency engines holds promise as a low-cost intermediate solution to reduce Greenhouse Gases and particulate matter. However, to achieve high engine efficiencies, engines need to be operated at higher power levels and increased Brake Mean Effective Pressures (BMEP), which is limited by destructive, engine damaging knock. Alternatively, if controlled, the same End-Gas Autoignition (EGAI) process responsible for knock can boost efficiencies and consume unburned methane while leveraging low-cost traditional exhaust aftertreatment technologies, such as a three-way catalyst, to minimize environmental impact. For this reason, this work has developed a method to detect the presence of EGAI and to determine its onset location (or crank angle). This method is based on the characteristic shape of the Apparent Heat Release Rate (AHRR) curve under four levels of EGAI, where, by searching for the presence and location of inflection points one can determine the onset location and intensity of EGAI. Results show a remarkably good agreement in determining the onset of EGAI for various engine operating conditions, e.g. engine speed, IMEP, Exhaust Gas Recirculation (EGR) levels, and engine sizes, especially in the light/low EGAI levels that are highly important for a Controlled EGAI (C-EGAI) operation. Additionally, the method can also successfully determine if a cycle is autoigniting or not and run under 2 milliseconds on a standard workstation, which can allow it to be implemented on a cycle-by-cycle real-time engine control setup.
- Citation
- Bernardi Bestel, D., Rodriguez, J., Marchese, A., Olsen, D. et al., "Detection and Onset Determination of End-Gas Autoignition on Spark-Ignited Natural Gas Engines Based on the Apparent Heat Release Rate," SAE Technical Paper 2022-01-0563, 2022, .