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This paper reports the development, validation, and application of the thermophysical and transport properties of coconut, palm, and soy methyl esters for fuel spray and combustion modeling under light-duty diesel engine conditions. The developed fuel library is implemented in an open-source CFD code. The fuel properties are validated for both constant volume combustion chamber and compression ignition (CI) engine operation at a wide range of conditions. Sensitivity analysis on the effects of individual fuel properties is also investigated under both conditions. The properties of interest for the study are density, vapor pressure, heat of vaporization, liquid heat capacity, vapor heat capacity, second-virial coefficient, liquid dynamic viscosity, vapor dynamic viscosity, liquid thermal conductivity, vapor thermal conductivity, surface tension, and vapor diffusivity. From these twelve physical and transport properties, only five have significant effects on fuel spray structure, combustion, and emission characteristics. These are vapor pressure, vapor diffusivity, surface tension, liquid density, and liquid dynamic viscosity. However, only vapor pressure and surface tension have the strongest influence on the mixture preparation process.

The 4th Workshop of the Engine Combustion Network (ECN) was held September 5-6, 2015 in Kyoto, Japan. This manuscript presents a summary of the progress in experiments and modeling among ECN contributors leading to a better understanding of soot formation under the ECN “Spray A” configuration and some parametric variants. Relevant published and unpublished work from prior ECN workshops is reviewed. Experiments measuring soot particle size and morphology, soot volume fraction (fv), and transient soot mass have been conducted at various international institutions providing target data for improvements to computational models. Multiple modeling contributions using both the Reynolds Averaged Navier-Stokes (RANS) Equations approach and the Large-Eddy Simulation (LES) approach have been submitted. Among these, various chemical mechanisms, soot models, and turbulence-chemistry interaction (TCI) methodologies have been considered

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Nowadays, detailed kinetics is necessary for a proper estimation of both flame structure and pollutant formation in compression ignition engines. However, large mechanisms and the need to include turbulence/chemistry interaction introduce significant computational overheads. For this reason, tabulated kinetics is employed as a possible solution to reduce the CPU time even if table discretization is generally limited by memory occupation. In this work the authors applied tabulated homogeneous reactors (HR) in combination with different turbulent-chemistry interaction approaches to model non-premixed turbulent combustion. The proposed methodologies represent good compromises between accuracy, required memory and computational time. The experimental validation was carried out by considering both constant-volume vessel and Diesel engine experiments. First, the ECN Spray A configuration was simulated at different operating conditions and results from different flame structures are compared with experimental data of ignition delay, flame lift-off, heat release rates, radicals and soot distributions. Afterwards, engine simulations were carried out and computed data are validated by cylinder pressure and heat release rate profiles.

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