Skeletal CH₃OH/NO Kinetic Model for Simulating Spark-Ignition and Turbulent Jet Ignition Engines

Area of Science:

• Combustion Chemistry
• Chemical Kinetics
• Engine Combustion

Background:

• Methanol is a key renewable fuel for improving engine efficiency and lowering emissions.
• Nitrogen oxides (NOx) significantly influence methanol oxidation and ignition under exhaust gas recirculation conditions.
• A lack of skeletal kinetic models hinders accurate computational fluid dynamics (CFD) simulations of methanol/NOx interactions.

Purpose of the Study:

• To develop a reduced skeletal kinetic model for methanol (CH3OH) and nitrogen oxides (NOx) interactions.
• To validate the model using new experimental data and existing literature.
• To apply the model in 3D CFD simulations for spark-ignition (SI) and turbulent jet ignition (TJI) engines.

Main Methods:

• Development of a skeletal kinetic model with 25 species and 82 reactions (55 irreversible, 27 reversible).
• Experimental ignition studies of methanol with 200 ppmv NO/NO2 in a rapid compression machine (RCM) at 20-30 bar and 850-950 K.
• Validation against literature data and new experimental results across various conditions.
• Application in 3D CFD simulations for SI and TJI engine combustion.

Main Results:

• Experimental data showed that NO/NO2 notably enhances methanol ignition.
• The proposed skeletal mechanism accurately predicted methanol and methanol/NOx combustion over a wide range of conditions.
• CFD simulations using the skeletal mechanism showed good agreement with experimental pressure traces and engine metrics for SI and TJI engines.

Conclusions:

• The developed skeletal kinetic model is suitable and sufficient for CFD simulations of methanol combustion with NOx.
• Accurate modeling of CH3OH/NOx interactions is crucial for predicting engine combustion performance.
• The model aids in optimizing renewable fuel combustion for enhanced efficiency and reduced emissions.