Abstract
The use of natural gas in pure or in a blended form with hydrogen and syngas in spark ignition (SI) engines has received much attention in recent years. They have higher diffusion coefficient and laminar flame speed, a small quenching distance and wider flammability limit which compensate the demerits of the lean-burn natural gas combustion. Therefore, a careful examination of the chemical kinetics of combustion of gaseous fuel blends is of great importance. In this paper, performance of the various chemical kinetics mechanisms is compared against experimental data, accumulated for methane-based fuel blends under engine-relevant conditions to find the most appropriate mechanism in engine simulations. Pure methane, methane/syngas, and methane/propane blends are mainly studied at various temperatures, pressures, and equivalence ratios. The ignition delay time and laminar flame speed are used as quantitative metrics to compare the simulation results with the data from experiments. The mechanisms were shown to be mainly consistent with the experimental data of lean and stoichiometric mixtures at high pressures. It was also shown that the GRI-3.0 and 290Rxn mechanisms have high compatibility with the ignition delay times and laminar flame speed at high pressures and lean conditions, and they can be utilized for simulations of SI engine combustion due to their lower computational cost. The results of present research provide an important contribution to the methane-based fuel blends combustion simulation under SI engine-relevant conditions.
Highlights
Lee at al. [24] used Cantera to conduct a comprehensive comparison of Davis2005, GRI1999, USC2007, NUIG2013, Sun2007, and Li2007 chemical kinetics mechanisms and published experimental results for mixture compositions that are pertinent to biogas/syngas mixtures
The predicted ignition delay time for CH4 as a function of temperature is indicated in Figures 1 and 2 for different pressures and equivalence ratios
For laminar flame speed due to the lack of data, just low-pressure case (p = 1 atm) pressures and lean mixtures corresponding to spark ignition (SI) engine-like conditions for methane/synwas studied and the simulation results were satisfactory at lean conditions
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. [24] used Cantera to conduct a comprehensive comparison of Davis2005, GRI1999, USC2007, NUIG2013, Sun2007, and Li2007 chemical kinetics mechanisms and published experimental results for mixture compositions that are pertinent to biogas/syngas mixtures They discovered that the NUIG2013 mechanism is the best fit for reproducing the calculated laminar flame speed and ignition delay time of biogas/syngas fuel blends. There is no detailed analysis of various pathways for assessing ignition delay times and laminar flame speeds of methane-based fuels under lean-burn natural gas SI engine conditions, according to the literature (i.e., for initial pressures between 10 and 40 bar, temperatures between 900 and 1600 K, and air–fuel equivalence ratios from 0.5 to 0.8). The best mechanism that could serve as suitable candidate for future natural gas SI engine simulations is suggested
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