In the formation process of soot in the flames of even-carbon-numbered fuels, acetylene and its derivatives are suspected to be dominant. The addition of an odd-carbon-numbered fuel into these flames introduces methyl radicals and/or C3 chemistries, which are believed to (de)activate certain chemical pathways towards the production of soot. The resultant soot formation rate of the mixture could be higher than the sum of the respective rates of the mixture components, i.e., synergistic eff ect. In this work, the mixtures of butane isomers, ethylene-butane isomers, and propane-butane isomers were studied on a co-flow and a counterflow burner. Chemical effects were isolated from those of thermal and dilution by mixing isomers and comparing the mixtures including one isomer to those including the counterpart. Line of sight attenuation (LOSA) and laser-light extinction techniques were used for measuring soot volume fraction. The results provide information on synergistic effects in soot formation for the fuels used.

The effects of pressure on various properties of ten different syngas fueled flames were analyzed using one and two dimensional simulations. One-dimensional premixed flames were modeled in CANTERA. Flame speed, adiabatic flame temperature and thermal diffusivity as functions of equivalence ratio and pressure were quantified for the fuels using four chemical kinetic mechanisms. Data from the different mechanisms displayed good agreement with data from previous experimental benchmarks. Two-dimensional axisymmetric co-flow flames were simulated in a state of the art computational framework for modeling laminar flames. Flame structure comparisons were made with past experimental and numerical results as well as with theoretical predictions. Good agreement in stoichiometric flame height was observed with past theoretical and numerical flame height measurements. Visible flame heights had little correlation with the stoichiometric flame heights. The flame radius was also noted to be proportional to p^-0.35 at high pressures instead of p^-0.5 as predicted by theory.

In the formation process of soot in the flames of even-carbon-numbered fuels, acetylene and its derivatives are suspected to be dominant. The addition of an odd-carbon-numbered fuel into these flames introduces methyl radicals and/or C3 chemistries, which are believed to (de)activate certain chemical pathways towards the production of soot. The resultant soot formation rate of the mixture could be higher than the sum of the respective rates of the mixture components, i.e., synergistic eff ect. In this work, the mixtures of butane isomers, ethylene-butane isomers, and propane-butane isomers were studied on a co-flow and a counterflow burner. Chemical effects were isolated from those of thermal and dilution by mixing isomers and comparing the mixtures including one isomer to those including the counterpart. Line of sight attenuation (LOSA) and laser-light extinction techniques were used for measuring soot volume fraction. The results provide information on synergistic effects in soot formation for the fuels used.

The effects of pressure on various properties of ten different syngas fueled flames were analyzed using one and two dimensional simulations. One-dimensional premixed flames were modeled in CANTERA. Flame speed, adiabatic flame temperature and thermal diffusivity as functions of equivalence ratio and pressure were quantified for the fuels using four chemical kinetic mechanisms. Data from the different mechanisms displayed good agreement with data from previous experimental benchmarks. Two-dimensional axisymmetric co-flow flames were simulated in a state of the art computational framework for modeling laminar flames. Flame structure comparisons were made with past experimental and numerical results as well as with theoretical predictions. Good agreement in stoichiometric flame height was observed with past theoretical and numerical flame height measurements. Visible flame heights had little correlation with the stoichiometric flame heights. The flame radius was also noted to be proportional to p^-0.35 at high pressures instead of p^-0.5 as predicted by theory.

Combustion is responsible for providing energy for many applications, especially in propulsion and rocket propellants. Shock tubes provide a controlled, repeatable means of studying combustion characteristics; although, most of these studies require the fuel in a mixture to exist in pure gas-phase. This makes it challenging to test low-vapor-pressure fuels that tend to remain in condensed form. Low-vapor-pressure fuels are commonly used in many combustion applications, making combustion studies of these fuels important. A method to study low-vapor-pressure fuels using a shock tube approach is to inject the fuel into the shock tube as tiny, uniformly-sized aerosol droplets. The sub-micron-sized aerosol droplets remain uniformly suspended in the shock tube prior to running the experiment. An incident shock wave vaporizes the liquid fuel droplets, then the reflected shock wave initiates ignition of the mixture. This study presents the characterization of an aerosol fuel injection method to the shock tube to study the combustion of low-vapor-pressure fuels. An aerosol generator was used to produce repeatable, uniformly-sized fuel droplets, and flow controllers were used to control and measure oxygen and argon dilution gas injected into the shock tube. A technique was developed to ensure consistent and repeatable aerosol fuel production rates over which calibration curves were found. This study presents the ignition delay times for C7H16 (ϕ = 1.0) at a pressure of 2.0 atm for temperatures from 1220 - 1427 K, C7H8 (ϕ = 1.0) at 1.9 atm over a temperature range of 1406 – 1791 K, and C12H26 (ϕ = 0.3) at 3.0 atm for the temperature range of 1293 – 1455 K. The ignition delay times for heptane and toluene were compared to the literature values at the same conditions and were found to be in good agreement. Laser extinction (visible laser at 632nm) was used to verify the presence of aerosol fuel droplets inside the shock tube for dodecane, but showed the heptane aerosol vaporized upon injection into the shock tube. Initial laser absorption (3.39 µm) measurements were also taken. This aerosol technique was found to successfully evaluate combustion effects of low-vapor-pressure fuels; however, was limited by the range of possible fuel concentrations. Further work needs to be performed on the verification of aerosol spatial uniformity and obtaining higher fuel concentrations.

Thesis (M.S.)--University of Hawaii at Manoa, 2007. / Includes bibliographical references (leaves 59-63). / x, 63 leaves, bound ill. 29 cm

Thesis (MEngineering (Research)) -- University of South Australia, 1991

No description available.

High-intensity pyrolysis, rapid heating in an inert gas atmosphere at up to 20 atm pressure, of 6 Australian coals was examined to gain further insight into high-intensity processes such as Integrated Gasification Combined Cycles (IGCC). Experiments focussed on pyrolysis in a specially developed Wire Mesh Reactor (WMR). The particle temperature lagged that of the mesh by 0.2 seconds at a heating rate of 100??~C s -1 and was predicted by modelling. This is part of the reason the volatile yield (VY) results for 10 s hold-time at ???b1.7 wt% daf of coal, is much more reproducible than 1 s hold-time experiments at ???b4.2 wt% daf of coal. Four coals of the same rank did not behave identically when heated. Three of the coals had a pyrolysis VY the same as the proximate VM when heated to 100??~C at 1 atm but the fourth, higher inertinite coal had a 1 atm pyrolysis VY 90% of its proximate VM. All four coals of similar rank had a significant decrease in VY, between 10 and 20 wt% daf of coal, with pressure increasing from 1 to 20 atm. The two lower rank coals showed less decrease in VY with increasing pressure than the higher rank and higher inertinite coals. The lower decrease in VY with increased pressure was mostly attributed to the lower inertinite levels for both the coals of similar rank and VM, and the coals of lower rank. Char characteristics examined focussed on pore Surface Area (SA). For high intensity WMR and Drop Tube Furnace (DTF) pyrolysis experiments CO2 SA for char from a particular coal was similar but the BET SA different. This was due to the char in the WMR experiments having longer to form larger pores determined by BET N2 SA. Both the N2 and CO2 SA was more than an order of magnitude greater than for low intensity pyrolysis char. This highlights that the WMR can be used to attain char with similar CO2 SA characteristics as other high intensity pyrolysis experiments and to provide a more meaningful insight into char reactivity than low intensity chars do.

Bibliography: leaves 272-286. / xxix, 286 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Uses different experimental techniques to study the spontaneous combustion behaviour of Victorian brown coal. In such a way, the influence of system conditions involved the different techniques can be understood with confidence, thus providing an improved understanding of the spontaneous combustion. / Thesis (Ph.D.)--University of Adelaide, Dept. of Chemical Engineering, 1999