High-Load Engine Simulation of Renewable Diesel Fuel Using A Reduced Mechanism

According to the Annual Energy Outlook 2022 (AEO2022) report, almost 30% of the transport sector will still use internal combustion engines (ICE) until 2050. The transportation sector has been actively seeking different methods to reduce the CO2 emissions footprint of fossil fuels. The use of lower carbon-intensity fuels such as Renewable Diesel (RD) can enable a pathway to decarbonize the transport industry. This suggests the need for experimental or advanced numerical studies of RD to gain an understanding of its combustion and emissions performance.

This work presents a numerical modeling approach to study the combustion and emissions of RD. The numerical model utilized the development of a reduced chemical kinetic mechanism for RD’s fuel chemistry. The final reduced mechanism for RD consists of 139 species and 721 reactions, which significantly shortened the computational time from using the detailed mechanism. Both zero-dimensional (0D) and three-dimensional (3D) computational fluid dynamics (CFD) simulations showed comparable auto-ignition chemistry of RD between reduced and detailed mechanisms. Moreover, the reduced mechanism was successfully validated with the collected single-cylinder engine (SCE) experiment on both combustion and emissions performance. The characteristics uniquely associated with RD compared to conventional diesel were also relatively well captured. Results from CFD simulation showed significantly lower soot emissions with RD compared to diesel, which was in agreement with the engine experimental findings. All simulations were carried out under a high engine load condition (19 bar gIMEP at 1200 RPM). This study shows CFD results for the simulation of RD fuel at both stock and high compression ratio (CR=17:1 and CR=22:1) combustions systems. The currently developed model can be used to guide further development of the combustion system using RD fuel.