Heavy-duty natural gas engines offer air pollution and energy diversity benefits. However, current homogeneous-charge lean-burn engines suffer from impaired efficiency and high unburned fuel emissions. Natural gas direct-injection engines offer the potential of diesel-like efficiencies, but require further research. To improve understanding of the autoignition and emission characteristics of natural gas direct-injection compression-ignition combustion, the effects of key operating parameters (including injection pressure, injection duration, and pre-combustion temperature) and gaseous fuel composition(including the effects of ethane, hydrogen and nitrogen addition) were studied. An experimental investigation was carried out on a shock tube facility. Ignition delay, ignition kernel location, and NOx emissions were measured. The results indicated that the addition of ethane to the fuel resulted in a decrease in ignition delay and a significant increase in NOx emissions. The addition of hydrogen to the fuel resulted in a decrease in ignition delay and a significant decrease in NOx emissions. Diluting the fuel with nitrogen resulted in an increase in ignition delay and a significant decrease in NOx emissions. Increasing pre-combustion temperature resulted in a significant reduction in ignition delay, and a significant increase in NOx emissions. Modest increase in injection pressure reduced the ignition delay; increasing injection pressure resulted in higher NOx emissions. The effects of ethane, hydrogen, and nitrogen addition on the ignition delay of methane were also successfully predicted by FlameMaster simulation. OH radical distribution in the flame was visualized utilizing Planar Laser Induced Fluorescence (PLIF). Single-shot OH-PLIF images revealed the stochastic nature of the autoignition process of non-premixed methane jets. Examination of the convergence of the ensemble-averaged OH-PLIF images showed that increasing the number of repeat experiments was the most effective way to achieve a more converged result. A combustion model, which incorporated the Conditional Source-term Estimation(CSE) method for the closure of the chemical source term and the Trajectory Generated Low-Dimensional Manifold (TGLDM) method for the reduction of detailed chemistry, was applied to predict the OH distribution in a combusting non-premixed methane jet. The model failed to predict the OH distribution as indicated by the ensemble-averaged OH-PLIF images, since it cannot account for fluctuations in either turbulence or chemistry.

No description available.

No description available.

The formation of gas hydrates in the oil and gas industry causes numerous problems that require costly solutions and operation downtime. A great deal of hydrate research has focused on their prevention either through kinetic or thermodynamic inhibitors. Recently, antifreeze proteins (AFPs) produced by cold adapted organisms have been found to have a kinetic inhibitory effect on clathrate hydrates. / Kinetic experiments were conducted on the methane-water system in the presence of AFPs by measuring the gas uptake during the formation of methane hydrate in a 610 cc high pressure crystallizer. These experiments were performed at temperatures ranging from 277.15 K to 280.65 K, pressures of 5800 KPa to 8100 KPa and at an AFP concentration of 0.01 mM. / The results of these experiments showed that the presence of AFPs affect methane hydrate formation in multiple ways. They were shown to increase the nucleation time, reduce the initial growth rate of methane hydrate at the time of nucleation and there was evidence to suggest that they also have an anti-agglomerating effect on hydrate crystals.

The use of off-farm materials as amendments in anaerobic digestion of manure is an interesting option due to the benefits of boosting biogas production, and making the process more economical for the farmer. The addition of varying amounts of glycerol, which is a by-product of biodiesel production, was used as an amendment to anaerobic digestion of hog manure in lab-scale tests. The use of 2% glycerol produced the greatest amount of methane and biogas, however stabilization time was high, and the digestion of nutrients in the manure decreased. The addition of 4% glycerol resulted in an overloading of COD and digester failure. The addition of 1% glycerol resulted in a doubling of the methane and biogas production and the acclimation period was quite short, while the effluent quality remained good. There were no detrimental effects of using crude glycerol observed compared to using pure glcyerol. Batch tests also showed that smaller additions of glycerol (0.5%, 1%) produced the highest methane yields and were recommended as good co-substrates for anaerobic digestion with hog manure.

No description available.

The use of off-farm materials as amendments in anaerobic digestion of manure is an interesting option due to the benefits of boosting biogas production, and making the process more economical for the farmer. The addition of varying amounts of glycerol, which is a by-product of biodiesel production, was used as an amendment to anaerobic digestion of hog manure in lab-scale tests. The use of 2% glycerol produced the greatest amount of methane and biogas, however stabilization time was high, and the digestion of nutrients in the manure decreased. The addition of 4% glycerol resulted in an overloading of COD and digester failure. The addition of 1% glycerol resulted in a doubling of the methane and biogas production and the acclimation period was quite short, while the effluent quality remained good. There were no detrimental effects of using crude glycerol observed compared to using pure glcyerol. Batch tests also showed that smaller additions of glycerol (0.5%, 1%) produced the highest methane yields and were recommended as good co-substrates for anaerobic digestion with hog manure.

Graduation date: 1950

Cleats are natural fractures in coal that serve as permeability avenues for darcy flow of gas and water to the well bore during production. Theoretically, the development of cleat and coal-seam permeability is related to the rank, type and grade of the coal concerned. The permeability of a coal seam, moreover, may change during gas production, due to either matrix shrinkage, cleat closure or both. Matrix shrinkage and cleat closure are also affected by numerous geological factors, including coal rank, desorption character and geological setting. A method integrating geochemical and petrographic analysis, reservoir engineering diagnosis, geophysical data and production characteristics has been developed, and used to determine the initial permeability of coal seam on a metre by metre scale. This overcomes the constraint of conventional well test by refining the test intervals. The effect of coal rank, grade and type on the initial permeability of coal seams was also investigated, with the special reference to the coals of the Galilee Basin. The permeability was estimated using analytical equations based on the permeability data obtained from well tests and from cleat descriptions within the seam section. This aspect of the study showed that the coal type, rank and grade strongly influence the initial permeability of individual coal seams. Increase in ash content has negative effect on cleat development and permeability. On contrast, increasing coal rank and proportion of bright coal lead to reduction in cleat spacing and increase in permeability. Twenty three core samples collected from the Qinshui Basin in China were evaluated in the laboratory to investigate the effects of coal grade, rank and type on the change in permeability during pressure depletion. The experimental factors included the coal's geochemical properties, the permeability against changing pressure, and strain with pore pressure depletion. This part of the study fund that permeability changes with pore pressure depletion in relation to coal rank, grade and type. The strain values determined by the experiments with pressure depletion were used to identify the mechanical principles associated with changes in permeability during pressure depletion in relation to the rank, grade and type of the coal concerned. A reservoir simulation study was used to investigate the effects of desorption pressure, geological setting and coal rank on the variation in permeability under in-situ conditions during coalbed methane production, based on a study in the Hedong area, Ordos Basin, China. The simulations allowed history matching of gas and water production from 12 wells with the actual well conditions specified as the model pressure. Good agreement was achieved between the model yields and the actual production data, suggesting that the changing permeability interpreted from the simulation is a realistic representation of the in-situ reservoir properties. The reservoir simulation study found that the decreases in permeability with production exceeded the increase in permeability caused by matrix shrinkage for nearly all wells in the Hedong area. The magnitude of the decrease in permeability increases as the gap between initial pressure and desorption pressure increases. The decrease in permeability is slower in the zone closest to the fault. The reservoir simulation has demonstrated that coal rank influences significantly the change in permeability during coalbed methane production.

Thesis (M.S.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Greg Johnson. Includes bibliographical references (leaves 85-95).