M. Fathi, D. Roekaerts, S. Hickel (2025)
Applications in Energy and Combustion Science 24: 100398. doi: 10.1016/j.jaecs.2025.100398
A comprehensive unified framework of high-fidelity physical models and numerical simulation techniques for transcritical dual-fuel combustion systems is presented and applied for the analysis of three configurations, each involving injection of an n-dodecane jet into a 6 MPa, 1000 K environment. The cases differ in ambient composition: (1) a single-fuel baseline consisting of air mixed with combustion products, and (2–3) two dual-fuel cases with either methane or a 90:10 (by volume) methane/ethane blend added to the ambient.
A central challenge in dual-fuel combustion applications is the successful ignition of low-reactivity ambient fuel by the high-reactivity pilot fuel jet. The interaction of the radical pools associated with both fuels is known to be an important characteristic. This study captures the evolution of this interaction across both the low-temperature combustion (LTC) and high-temperature combustion (HTC) regimes.
Insights on ignition and flame structure are gained from homogeneous reactor simulations, transcritical counterflow diffusion flames, and large-eddy simulation (LES). Combustion modes are defined by threshold levels of key species and temperature. The flame volume is subdivided according to the modes and for each mode the ignition delay and the temporal evolution of heat release rate (HRR) are obtained. The differences in the radical pools of SF and DF combustion are demonstrated. LTC ignition is shown to start in the multiphase region near the base of the jet. The high accuracy of the proposed methods provides a firm basis for modeling prospective dual-fuel systems using alternative fuels.