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The implementation of techniques aimed at improving engine performance and reducing particulate matter (PM) pollutant emissions is strongly influenced by the limited understanding of the polycyclic aromatic hydrocarbons (PAH) formation chemistry, in combustion devices, that produces the PM emissions. New experimental results which examine the formation of multi-ring compounds are required. The present investigation focuses on two techniques for such an experimental examination by recovery of PAH compounds from a typical combustion oriented experimental apparatus. The online technique discussed constitutes an optimal solution but not always feasible approach. Nevertheless, a detailed description of a new online sampling system is provided which can serve as reference for future applications to different experimental set-ups. In comparison, an offline technique, which is sometimes more experimentally feasible but not necessarily optimal, has been studied in detail for the recovery of a variety of compounds with different properties, including naphthalene, biphenyl, and iodobenzene. The recovery results from both techniques were excellent with an error in the total carbon balance of around 10% for the online technique and an uncertainty in the measurement of the single species of around 7% for the offline technique. Although both techniques proved to be suitable for measurement of large PAH compounds, the online technique represents the optimal solution in view of the simplicity of the corresponding experimental procedure. On the other hand, the offline technique represents a valuable solution in those cases where the online technique cannot be implemented. [ABSTRACT FROM AUTHOR]

Abstract: The high pressure oxidation of dilute CO mixtures doped with 150–200ppm of H2 has been studied behind reflected shock waves in the UIC high pressure single pulse shock tube. The experiments were performed over the temperature range from 1000 to 1500K and pressures spanning 21–500bars for stoichiometric (Φ =1) and fuel lean (Φ =0.5) oxidation. Stable species sampled from the shock tube were analyzed by standard GC, GC/MS techniques. The experimental data obtained in this work were simulated using a detailed model for H2/CO combustion that was validated against a variety of experimental observables/targets that span a wide range of conditions. These simulations have shown that within experimental error the model is able to capture the experimental trends for the lower pressure data sets (average nominal pressures of 24 and 43bars). However the model under predicts the CO and O2 decay and subsequent CO2 formation for the higher pressure data sets (average nominal pressures of 256 and 450bars). The current elevated pressure data sets span a previously unmapped regime and have served to probe HO2 radical reactions which appear to be among the most sensitive reactions in the model under these conditions. With updated rate parameters for a key HO2 radical reaction OH+HO2 =H2O+O2, the model is able to reconcile the elevated pressure data sets thereby extending its capability to an extreme range of conditions. [Copyright &y& Elsevier]

Abstract: Part 1 of this two part series presented a chemical kinetic model for the simulation of high pressure shock tube pyrolysis and oxidation data of two representative biodiesel surrogate components and the application of this model for predicting prompt NO at practical diesel combustion conditions. The present work discusses in greater detail the model’s development, structure, and rate parameters as well as expands the model’s validation range to include complementary 10atm jet stirred reactor (JSR) oxidation experiments conducted at lower temperatures (550–1200K) and longer reaction times of 0.7s. In addition, shock tube ignition delay measurements of 1-heptene and 1,6-heptadiene, analogs of the hydrocarbon side chains of the methyl esters, have also been performed and are presented to further constrain the model. [Copyright &y& Elsevier]