International audienceNew chemical kinetic reaction mechanisms are developed for two of the five major components of biodiesel fuel, methyl stearate and methyl oleate. The mechanisms are produced using existing reaction classes and rules for reaction rates, with additional reaction classes to describe other reactions unique to methyl ester species. Mechanism capabilities were examined by computing fuel/air autoignition delay times and comparing the results with more conventional hydrocarbon fuels for which experimental results are available. Additional comparisons were carried out with measured results taken from jet-stirred reactor experiments for rapeseed oil methyl ester fuels. In both sets of computational tests, methyl oleate was found to be slightly less reactive than methyl stearate, and an explanation of this observation is made showing that the double bond in methyl oleate inhibits certain low temperature chain branching reaction pathways important in methyl stearate. The resulting detailed chemical kinetic reaction mechanism includes more approximately 3500 chemical species and more than 17,000 chemical reactions

This paper describes a detailed reaction mechanism for Br/Hg/Cl chemistry in coal-derived flue gas and interprets the Hg oxidation performance across a broad range of Br addition rates in recent field tests at plants Miller, Milton R. Young, and Monticello that burn low-rank coals. The dominant channels of the homogeneous Hg chemistry with Br are analogous to those for Cl, whereby a Br atom partially oxidizes Hg 0 into HgBr, which is then oxidized into HgBr 2 by Br 2 . Mercury also oxidizes heterogeneously on unburned carbon (UBC) with Br species. This mechanism is analogous to the surface mechanism for Cl species, except that (i) elemental mercury (Hg 0 ) adsorption is faster on brominated sites and (ii) the higher Br atom concentrations in flue gas promote recombination reactions that maintain very low surface coverages of Hg/Br species. Therefore, the accelerated Hg 0 adsorption rate on brominated UBC promotes Hg 0 oxidation at the hottest gas cleaning temperatures but does not enhance the production of particulate Hg (HgP). The amount of HgP was predicted to increase for progressively greater loss-on-ignition (LOI) levels, although the removals of this form of Hg by electrostatic precipitators (ESPs) are always low for low-rank coals.

The Sydney piloted premixed jet burner (PPJB) experiments are numerically simulated to assess the flamelet generated manifold (FGM) model's ability to predict finite-rate and turbulence/chemistry-interaction effects under low Damköhler number. The results are also compared and assessed with the finite rate eddy-dissipation concept (EDC) model. A reduced CH 4 /air mechanism of 71 species, that considers low-and hightemperature chemistry, is derived from the Model Fuel Library (MFL) and compared with the master MFL mechanism. The same mechanism is used for chemistry closure for both FGM and EDC models. The PPJB simulations are found to be sensitive to the inflow profiles and different power-law profiles are adopted for different centerline jet bulk velocity setups. An overall good match with the experimental data is observed for the non-reactive flow cases, with general under-prediction for the turbulent kinetic energy (TKE). For the PM150 flame conditions presented here, the FGM showed reasonable prediction of the temperature and major species, with under-prediction for OH and over-prediction