Integrating Laminar Burning Velocity into an Empirical Kinetic Model for Predicting the Ignition Delay of Biodiesel Blends

Abstract Accurate prediction of ignition delay time is fundamental for optimizing combustion phasing in compression ignition engines. Classical empirical models often fail to capture the complex auto-ignition behavior of oxygenated fuels like biodiesel due to the omission of flame propagation characteristics. This study proposes a novel empirical kinetic model that integrates the maximum laminar burning velocity (uL, max) and cetane number (CN) to represent the synergy between physical transport and chemical kinetics. The model was developed using a robust experimental dataset derived from a Cooperative Fuel Research (CFR-F5) engine and a constant-volume bomb. Five primary parameters—CN, uL, max, in-cylinder pressure (pinj), temperature (Tinj) at injection, and equivalence ratio were incorporated into a power-law formulation. Validation against 330 experimental data points demonstrates high predictive capability, achieving a coefficient of determination of 0.742 and a mean absolute percentage error of 6.75%. The integration of uL, max significantly enhances the model's sensitivity to the thermodynamic state, providing a reliable kinetic-based tool for advanced combustion simulations.