Numerical Investigation on Laminar Burning Velocity and Flame Temperature Characteristics of Dedicated EGR SI Engine Fueled with Methane and Propane Under Different Equivalence Ratio

The laminar flame velocity is a significant metric in premixed combustion modeling of spark ignition (SI) engines. The present investigation was conducted to determine the chance of a dedicated EGR (d-EGR) system being added to a four-cylinder SI engine to increase thermal efficiency, which might be reduced owing to the high EGR ratio for reducing in-cylinder NOx generation by lowering the combustion temperature. Methane and propane were chosen as the test fuels. The numerical findings predicted by the PREMIX algorithm in CHEMKIN-PRO were used to determine flame temperature (Tf\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${T}_{\text{f}}$$\end{document}) and laminar burning velocity (SL\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${S}_{\text{L}}$$\end{document}). The laminar burning velocities acquired at varied beginning pressures are required for conducting a thorough kinetic investigation of the combustion reaction and testing the actual reaction mechanisms. Thermal efficiency was calculated using the Wocshni's heat transfer coefficient and Wiebe function. The findings reveal that the d-EGR mechanism boosted thermal efficiency, surpassing that of the typical SI engine's stoichiometric combustion due to the low flame temperature and fast laminar burning velocity. These findings give essential theoretical references for enhancing the thermal efficiency of SI engines powered by methane and propane fuel.