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A new combustion zone analytical model has been developed in which the combustion front temperature may be calculated. The model describes in the combustion zone, the amount of fuel burned based on reaction kinetics, the fuel concentration and produced gas composition based on combustion stoichiometry, and the amount of heat generated based on a heat balance. Six runs were performed in a 3-inch diameter, 40-inch long steel combustion tube with Jobo crude oil (9-11°API) from the Orinoco Belt in Venezuela. These runs were carried out with air containing three values of oxygen concentration, 21%, 30%, and 40%. The weight percentage of sand, clay, water, and oil in the sand mix was kept constant in all runs at 86.6%, 4.7%, 4.0%, and 4.7% respectively. Injection air rates (3 L/min) as well as the production pressure (300 psig) were kept constant in all runs. The results indicate that the calculated combustion zone temperatures and temperature profiles are in good agreement with the experimental data, for the range of oxygen concentration in the injected air. The use of oxygen-enriched air slightly increased the combustion front temperature from 440°C in a 21 mole % O2 concentration to a maximum of 475°C for air with 40 mole % O2 concentration. Oxygen-enriched air injection also increased the combustion front velocity from 13.4 cm/hr (for 21% oxygen) to 24.7 cm/hr (for 40% oxygen), thus reducing the start of oil production from 3.3 hours (for 21% oxygen) to 1.8 hours (for 40% oxygen). In the field, the use of oxygen-enriched air injection could translate into earlier oil production compared to with not-enriched air injection. The new analytical model for the combustion zone developed in this study will be beneficial to future researchers in understanding the effect of oxygen-enriched in-situ combustion and its implications on the combustion front temperature and combustion front thickness.

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The design of combustion devices is very important to society today. They need to be highly efficient, while reducing emissions in order to meet strict environmental standards. These devices, however, are currently not being designed effectively. The most common method of improving them is through parametric studies, where the design parameters are altered one at a time to try and find the best operating point. While this method does work, it is not very enlightening as it neglects the non-linear interactions between the design parameters, requires a large amount of time, and does not guarantee that the best operating point is found. As the environmental standards continue to become stricter, a more robust method of optimizing combustion devices will be required. In this work a robust design optimization algorithm is presented that is capable of mathematically accounting for all of the interactions between the parameters and can find the best operating point of a combustion device. The algorithm uses response surface modeling to model the objective function, thereby reducing computational expense and time as compared to traditional optimization algorithms. The algorithm is tested on three case studies, with the goal of improving the radiant efficiency of a two stage porous radiant burner. The first case studied was one dimensional and involved adjusting the pore diameter of the second stage of the burner. The second case, also one dimensional, involved altering the second stage porosity. The third, and final, case study required that both of the above parameters be altered to improve the radiant efficiency. All three case studies resulted in statistically significantly changes in the efficiency of the burner.

Bioalcohols, such as bioethanol and biobutanol, are suitable replacements for gasoline, while biodiesel can replace petroleum diesel. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This study's contribution is experimentally validated chemical kinetic combustion mechanisms for biobutanol and biodiesel. Fundamental combustion data and chemical kinetic mechanisms are presented and discussed to improve our understanding of biofuel combustion. The net environmental impact of biobutanol (i.e., n-butanol) has not been studied extensively, so this study first assesses the sustainability of n-butanol derived from corn. The results indicate that technical advances in fuel production are required before commercializing biobutanol. The primary contribution of this research is new experimental data and a novel chemical kinetic mechanism for n-butanol combustion. The results indicate that under the given experimental conditions, n-butanol is consumed primarily via abstraction of hydrogen atoms to produce fuel radical molecules, which subsequently decompose to smaller hydrocarbon and oxygenated species. The hydroxyl moiety in n-butanol results in the direct production of the oxygenated species such as butanal, acetaldehyde, and formaldehyde. The formation of these compounds sequesters carbon from forming soot precursors, but they may introduce other adverse environmental and health effects. Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents high quality experimental data for one large fatty acid methyl ester, methyl decanoate, and models its combustion using an improved skeletal mechanism. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which ultimately lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene, thereby reducing the production of soot precursors. The study concludes that the oxygenated molecules in biofuels follow similar combustion pathways to the hydrocarbons in petroleum fuels. The oxygenated moiety's ability to sequester carbon from forming soot precursors is highlighted. However, the direct formation of oxygenated hydrocarbons warrants further investigation into the environmental and health impacts of practical biofuel combustion systems.

Bioalcohols, such as bioethanol and biobutanol, are suitable replacements for gasoline, while biodiesel can replace petroleum diesel. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This study's contribution is experimentally validated chemical kinetic combustion mechanisms for biobutanol and biodiesel. Fundamental combustion data and chemical kinetic mechanisms are presented and discussed to improve our understanding of biofuel combustion. The net environmental impact of biobutanol (i.e., n-butanol) has not been studied extensively, so this study first assesses the sustainability of n-butanol derived from corn. The results indicate that technical advances in fuel production are required before commercializing biobutanol. The primary contribution of this research is new experimental data and a novel chemical kinetic mechanism for n-butanol combustion. The results indicate that under the given experimental conditions, n-butanol is consumed primarily via abstraction of hydrogen atoms to produce fuel radical molecules, which subsequently decompose to smaller hydrocarbon and oxygenated species. The hydroxyl moiety in n-butanol results in the direct production of the oxygenated species such as butanal, acetaldehyde, and formaldehyde. The formation of these compounds sequesters carbon from forming soot precursors, but they may introduce other adverse environmental and health effects. Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents high quality experimental data for one large fatty acid methyl ester, methyl decanoate, and models its combustion using an improved skeletal mechanism. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which ultimately lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene, thereby reducing the production of soot precursors. The study concludes that the oxygenated molecules in biofuels follow similar combustion pathways to the hydrocarbons in petroleum fuels. The oxygenated moiety's ability to sequester carbon from forming soot precursors is highlighted. However, the direct formation of oxygenated hydrocarbons warrants further investigation into the environmental and health impacts of practical biofuel combustion systems.

Over the past few decades, combustion of fossil fuels has released greenhouse gases such as CO2 and NOx into the atmosphere. It has been realized that a mean temperature increase of the Earth, also known as global warming, has resulted from the increase of CO2 concentration in the air. Hence, there is a growing tendency to establish novel methods of burning fossil fuels in order to mitigate CO2 concentration. Chemical Looping Combustion (CLC) is a method of burning fuel with inherent separation of CO2 while curbing the formation of NOx, typically by circulating an oxygen carrier between an air (oxidation) reactor and a fuel (reduction) reactor. An oxygen carrier, mainly a metal oxide, circulates between the reactors providing the oxygen for conversion of fuel to CO2 and H2O. Thus, having a pure CO2 stream, CO2 sequestration becomes economically feasible. Fe2O3, due to its availability and properties, could be an apposite oxygen carrier for CLC. Reaction kinetics of reduction of Hematite with methane, in the absence of gaseous oxidant, was studied. Temperature Program Reduction (TPR) experiments were carried out in a fixed bed tubular reactor. Reduction gas was composed of 15% methane and 85% argon. Thermogravimetric Analysis (TGA) was carried out on TPR products using air as the oxidant. Iron oxide samples were analyzed through X-ray diffraction (XRD) analysis and scanning electron microscopy. Two-stage reduction of iron oxide was observed: Fe2O3 reduced to Fe3O4 and then reduced to FeO. The activation energy of each stage was calculated from Kissinger’s method. For the first and second stage of reduction the activation energies were 10.58±0.86 and 25.77±0.83 kJ/mol, respectively. In addition, different kinetic models were assumed and compared to the actual data. A random nucleation mechanism can be assigned to the first stage and a two-dimensional diffusion mechanism can be assigned to the second stage of the reduction.

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No description available.