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A comprehensive experimental and modelling study of the ignition delay time (IDT) characteristics of some single prominent C1-C2 hydrocarbons including methane, ethane, and ethylene have been performed over a wide range of temperatures (~800-2000 K), pressures (~1-80 bar), equivalence ratios (~0.5-2.0), and dilutions (~75-90%). An extensive literature review was conducted, and available data were extracted to create a comprehensive database used in our simulations. Based on existing literature data, an experimental matrix was designed using the Taguchi approach (L9) in order to identify and complete the experimental matrix required to generate a comprehensive validation set necessary for validation of a chemical kinetic model. The required IDTs were recorded using a high-pressure shock tube for shorter IDTs and a rapid compression machine for longer times, which encompass high-and low-temperature ranges, respectively. The predictions of a C 3 -NUIG mechanism have been compared with all of the available experimental data including those from the current study using the IDT simulations and the correlation technique. Moreover, individual and total effects of the studied parameters including pressure, equivalence ratio, and dilution on IDT have been studied over a wide temperature range. Moreover, correlations which were developed based on the NUIG mechanism are presented for each specific fuel over the conditions studied. These correlations show acceptable performance versus the experimental Taguchi matrix data.

Dual fuel combustion exhibits a high degree of complexity due to the presence of different fuels like diesel and natural gas in initially different physical states and a spatially strongly varying mixing ratio. Optimizing this combustion process on an engine test bench is costly and time consuming. Cost reduction can be achieved by utilizing simulation tools. Although these tools cannot replace the application of test benches completely, the total development costs can be reduced by an educated combination of simulations and experiments. A suitable model for describing the reactions taking place in the combustion chamber is required to correctly reproduce the dual fuel combustion process. This is why in the presented study, four different reaction mechanisms are benchmarked to shock tube (ST) and rapid compression machine (RCM) measurements of ignition delay times (IDTs) at pressures between 60 and 100 bar and temperatures between 671 and 1284 K. To accommodate dual fuel relevant diesel-natural gas mixtures, methane–propane–n-heptane mixtures are considered as the surrogate. Additionally, the mechanisms AramcoMech 1.3, 2.0 and 3.0 are tested for methane–propane mixtures. The influence of pressure and propane/n-heptane content on the IDT based on the measurements is presented and the extent to which the mechanisms can reflect the IDT-changes discussed.

The oxidation of CH4 and CH4/C2H6 mixtures were studied at pressures relevant to knocking in large bore natural gas engines. The experiments were carried out in a rapid compression machine (RCM) at end of compression (EOC) temperatures ranging between 885-940 K at compressed gas pressures of 105, 125, 150, and 160 bar at varying equivalence ratios (0.417, 0.526, and 1.0) and dilution percentages (0, 10, and 30% Exhaust Gas Recirculation-EGR) that were defined in a test matrix. This study describes the method and limitations of performing high-pressure experiments of this magnitude in an RCM, modeling, and validation of the kinetic mechanism against experimental data. While the recently published AramcoMech 2.0 could well predict the ignition delay times (IDTs) for CH4 within the uncertainty ranges at comparatively higher pressures and lower temperatures (885-940 K), the predicted reactivity is, in general, lower than that of AramcoMech 1.3 as shown in our previous screening study. Based on the comparison between both mechanisms as well as sensitivity analysis on the predicted IDTs, the reaction rate constant for Ḣ-atom abstraction from CH4 by HȮ2 radical was optimized in order to achieve better agreement with the new data while maintaining the agreement to the previous data sets. The modified mechanism predicts well the IDTs and the trend of their variation caused by the change in pressure, equivalence ratio, dilution percentage, and mixture variation with C2H6.

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A comprehensive experimental and kinetic modelling study of the ignition delay time (IDT) characteristics of some binary-blends of C1-C2 gaseous hydrocarbons such as methane/ethylene, methane/ethane, and ethane/ethylene were performed over a wide range of composition (90%/10%, 70%/30%, 50%/50%), temperature (~800-2000 K), pressure (~1-40 bar), equivalence ratio (~0.5-2.0), and dilution (~75-90%).An extensive literature review was conducted, and available data were extracted to create a comprehensive database for our simulations. Based on existing literature data, an experimental matrix was designed using the Taguchi approach (L9) in order to identify and complete the experimental matrix required to generate a comprehensive experimental IDT set necessary for the validation of a chemical kinetic model. The required high-and low-temperature IDTs were collected using low/high-pressure shock tubes and rapid compression machines, respectively. The predictions of NUIGMech1.0 are examined versus all of the available experimental data, including those taken in the current study using the IDT simulations and a correlation technique. Moreover, the individual effect of the studied parameters, including mixture composition, pressure, equivalence ratio, and dilution on IDT is investigated over the studied temperature range. Correlations that were developed based on NUIGMech1.0 are presented for each specific blended fuel over the conditions studied. These correlations show an acceptable performance versus the experimental data.

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