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The simulation of a diesel natural gas dual fuel combustion process is the topic of this paper. Based on a detailed chemical reaction mechanism, which was applied for such a dual fuel combustion, the complete internal combustion engine process was simulated. Two single fuel combustion reaction mechanisms from literature were merged, to consider the simultaneous reaction paths of diesel and natural gas. N-heptane was chosen as a surrogate for diesel. The chemical reaction mechanisms are solved by applying a tabulation method using the software tool AVL Tabkin™. In combination with a Flamelet Generated Manifold (FGM) combustion model, this leads to a reduction of computational effort compared to a direct solving of the reaction mechanism, because of a decoupling of chemistry and flow calculations. Turbulence was modelled using an unsteady Reynolds-Averaged Navier Stokes (URANS) model. In comparison to conventional combustion models, this approach allows for detailed investigations of the complex ignition process of the dual fuel combustion process. The unexpected inversely proportional relationship between start of injection (SOI) and start of combustion (SOC), a later start of injection makes for an earlier combustion of the main load, is only one of these interesting combustion phenomena, which can now be analyzed in detail. Further investigations are done for different engine load points and multiple pilot injection strategies. The simulation results are confirmed by experimental measurements at a medium speed dual fuel single cylinder research engine.

Thermophysical properties of 1-butyl-3-methylimidazolium dicyanamide [BMIM][DCA] {(p, ρ, T) data at T = (283.15 to 393.15) K, pressures up to p =100 MPa, and viscosity at T = (283.15 to 373.15) K and p = 0.101 MPa} are reported with an estimated experimental relative combined standard uncertainty of Δρ/ρ = ±(0.01 to 0.08) % in density and Δη/η = ±0.35 % in dynamic viscosity. The measurements were carried out with a recently constructed Anton-Paar DMA HPM vibration-tube densimeter and a fully automated SVM 3000 Anton-Paar rotational Stabinger viscometer. The vibration-tube densimeter was calibrated using doubledistilled water, methanol, toluene and aqueous NaCl solutions. An empiric equation of state for fi tting of the (p, ρ, T) data of [BMIM][DCA] has been developed as a function of pressure and temperature. This equation was used for the calculation of thermomechanical properties of the IL, such as isothermal compressibility, isobaric thermal expansibility, differences in isobaric and isochoric heat capacities, thermal pressure coeffi cient and internal pressure. Viscosity measurements were fi tted to the polynomial equation.