Ethanol-diesel fuel blends -- a review.

Soot processes in compression ignition engines

A detailed chemical kinetic modeling approach is used to examine the phenomenon of suppression of sooting in diesel engines by the addition of oxygenated hydrocarbon species to the fuel. This suppression, which has been observed experimentally for a few years, is explained kinetically as a reduction in concentrations of soot precursors present in the hot products of a fuel-rich diesel ignition zone when oxygenates are included. The kinetic model is also used to show how different oxygenates, ester structures in particular, can have different soot-suppression efficiencies due to differences in the molecular structure of the oxygenated species.

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Chemical kinetic modeling study of the effects of oxygenated hydrocarbons on soot emissions from diesel engines.

This paper proposes a structure for the diesel combustion process based on a combination of previously published and new results Processes are analyzed with proven chemical kinetic models and validated with data from production-like direct injection diesel engines The analysis provides new insight into the ignition and particulate formation processes, which combined with laser diagnostics, delineates the two-stage nature of combustion in diesel engines Data are presented to quantify events occurring during the ignition and initial combustion processes that form soot precursors A framework is also proposed for understanding the heat release and emission formation processes

/pdf/diesel-combustion-an-integrated-view-combining-laser-4mmxkq11dz.pdf

Diesel combustion: an integrated view combining laser diagnostics, chemical kinetics, and empirical validation

Thermodynamic properties and detailed chemical kinetic models have been developed for the combustion of two oxygenates: methyl butanoate, a model compound for biodiesel fuels, and methyl formate, a related simpler molecule. Bond additivity methods and rules for estimating kinetic parameters were adopted from hydrocarbon combustion and extended. The resulting mechanisms have been tested against the limited combustion data available in the literature, which was obtained at low temperature, subatmospheric conditions in closed vessels, using pressure measurements as the main diagnostic. Some qualitative agreement was obtained, but the experimental data consistently indicated lower overall reactivities than the model, differing by factors of 10 to 50. This discrepancy, which occurs for species with wellestablished kinetic mechanisms as well as for methyl esters, is tentatively ascribed to the presence of wall reactions in the experiments. The model predicts a region of weak or negative dependence of overall reaction rate on temperature for each methyl ester. Examination of the reaction fluxes provides an explanation of this behavior, involving a temperature-dependent competition between chain-propagating unimolecular decomposition processes and chain-branching processes, similar to that accepted for hydrocarbons. There is an urgent need to obtain more complete experimental data under well-characterized conditions for thorough testing of the model.

/pdf/detailed-chemical-kinetic-mechanisms-for-combustion-of-3dafq43bt9.pdf

Nabi Md. Nurun

Papers

Smokeless, Low NOx, High Thermal Efficiency, and Low Noise Diesel Combustion with Oxygenated Agents as Main Fuel