A novel reduced i-propanol-n-butanol-ethanol (IBE)/diesel mechanism for engine combustion and emissions prediction

Abstract

The direct application of i-propanol-n-butanol-ethanol (IBE) as an assuring alternative biofuel of internal combustion engines to get rid of the high recovery cost and extra energy consumption associated with n-butanol production has been gaining popularity, the research on performance and emissions of engines fueled with IBE are starting to be carried out. However, the available chemical reaction mechanism of IBE for engine combustion model is rarely reported. Therefore, a reduced mechanism named HT-IBE including 151 species and 775 reactions to track the combustion and emissions behavior of engine fueled with IBE/diesel blends was proposed in the present research. It was first meticulously developed based on the coupling of the reduced mechanisms of i-propanol, n-butanol, ethanol and diesel surrogates and the simplified NOx and soot formation models using combined reduction methods of directed relation graph with error propagation and sensitivity analysis (DRGEPSA), computational singular perturbation (CSP) and reaction path analysis (RPA) methods. To improve the predictive power of the mechanism, the sensitive reactions to ignition delay were identified and optimized based on sensitivity analysis. The mechanism was validated against ignition delay, laminar flame speed, and species mole fractions over a wide range of engine relevant conditions. The 3D engine simulation was further carried out using KIVA-3V2-CANTERA coupled with the mechanism to simulate the in-cylinder pressure, heat release rate, NOx and the soot emissions. Results show that the HT-IBE mechanism can reliably predict the combustion characteristics and emissions characteristics of IBE/diesel blends in the CI engine.