The effects of essential oils (EO) and condensed tannin (CT) on methane production and fermentation were evaluated under in vitro conditions. Experiment one screened the effects of ten different EO at 500 mg/L of culture fluid on methane production in a 24 hr rumen batch culture. Based on the results from experiment one, four EO (clove oil (CLO), cinnamon oil (CNO), white thyme oil (WTO), and anise oil (ANO)) were selected and tested at three different dose levels (125, 250, and 500 mg/L of culture fluid) for their effects on methane production and fermentation in a 24 hr batch culture (experiment two). Methane production was significantly reduced with the four EO at the 500 mg/L dose but at 250 mg/L; only CLO and CNO reduced methane production. The reduction in methane production with the 500 mg/L dose was also associated with reductions in dry matter (DM) digestibility and total volatile fatty acids (VFA). In the third experiment, the effect of CT at 2.5, 5 and 7.5% of diet DM on methane production was also tested in a 24 hr batch culture. Results from this experiment showed no effect of CT on methane production although methane production tended to be lower at 7.5% CT. In conclusion, the reduction in methane production with EO most likely resulted from EO negative effects on DM digestibility and fermentation.

No description available.

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. / Applied Science, Faculty of / Mechanical Engineering, Department of / Graduate

[No abstract available] / Science, Faculty of / Chemistry, Department of / Graduate

Proton magnetic resonance has been studied in methane and its deuterated modifications. Measurements of relaxation time were carried out at a frequency of 30 Mc/sec. using pulse techniques. The spin-lattice relaxation time has been measured in liquid and solid samples of CH₄, CH₃D, CH₂D₂ and CHD₃ between 110°K to 56°K. The simplest possible interpretation of our results in both the liquids and solids is that only one mechanism, that associated with the inter-molecular interactions, is probably predominant in causing relaxation. The spin-rotational and intra-molecular dipolar interactions do not seem to contribute appreciably to relaxation. The effect of dissolved paramagnetic ions has also been studied in samples of CH₄ between 110°K - 78°K and we have developed a very simple and reliable technique for obtaining oxygen-free samples in order to study T₁ in pure samples because T₁ has been found by us to be very sensitive to small, amounts of oxygen. The results verify the invers proportionality of T₁ to the oxygen concentration. The spin-spin relaxation time T₂ has been measured in liquid and solid samples between 110°K and 56°K. The results show that the line shape is predominantly due to inter-molecular interactions. Furthermore the resonance line has a gaussian shape at temperatures below 65°K and changes to a Lorentzlan shape at higher temperatures. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

[No abstract submitted] / Science, Faculty of / Chemistry, Department of / Graduate

The spin-lattice relaxation time T₁ has been measured for the proton and the deuteron resonances in methane -and its deuterated modifications as a function of density ƿ , at low densities where T₁ is proportional to ƿ ; and temperature T, between 110°K and 300°K. For the proton relaxation, plots of log T₁/ƿ versus log T for each of the gases CH₄₌ո Dո, n=0, 1, 2, 3 gave the temperature dependence of T₁/ƿ as T₁/ƿ∝T⁻³ʹ² . The value of T₁/ƿ at constant temperature changed very little with n. This implied that the main interaction contributing to proton spin relaxation was the spin-rotational interaction. For the deuteron results it was found that T₁/ƿ was nearly independent of temperature but differed by a factor of approximately four over the range of isotopic compositions n = 1, 2, 3,4. CD₄ gave the shortest value of T₁ while CHD₃ gave the longest. This was attributed to the dominance of the quadrupolar interaction of the deuteron over the dipolar and spin-rotational interactions. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The spin-lattice relaxation time T₁ has been measured in gaseous CH₄ as a function of density at room temperature. The density region investigated is from 0.006 to 7.0 amagats and T₁ passes through a minimum near 0.04 amagats. The spin-rotation interaction is the dominant relaxation mechanism in gaseous CH₄. Since the spin-rotation constants are accurately known for CH₄, the results provide a check on the existing theory of spin-lattice relaxation for spherical top molecules. An interesting feature was the failure of commonly used theoretical expressions for the density dependence of T₁ to fit the experimental data. A reasonable explanation is that the centrifugal distortion of the CH₄ molecule is indirectly contributing to the spin-lattice relaxation. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

This thesis has studied CO2 reforming of CH4 in atmospheric pressure, non-thermal plasma discharges. The objective of this research was to improve the current understanding of plasma-catalytic interactions for methane reforming. Chapter 1 introduces the existing and potential applications for methane reforming products. The industrial approaches to methane reforming and considerations for catalyst selection are discussed. Chapter 2 introduces non-thermal plasma technology and plasma-catalysis. An introduction to the analytical techniques used throughout this thesis is given. Chapter 3 investigates the effects of packing materials into the discharge gap. The materials were found to influence the reactant conversions for dry reforming of methane in the following order: quartz wool > no packing > Al2O3 > zeolite 3A > BaTiO3 > TiO2. In addition to the dielectric properties, the morphology and porosity of the materials was found to influence the reaction chemistry. The materials also affected the electrical properties of the plasma resulting in surface discharges, as opposed to a filamentary discharge mode. Chapter 4 investigates the effects of variation in CH4/CO2 ratios on plasma-assisted dry reforming of CH4. Differences in the reaction performance for different feed gas compositions are explained in terms of the possible reaction pathways and the electron energy distribution functions. A NiO/Al2O3 catalyst is introduced for plasma-catalytic dry reforming of CH4, which was found to have no significant effect on the reaction performance at low specific input energies. Chapter 5 presents the plasma-assisted reduction of a NiO/Al2O3 catalyst by CH4 and H2/Ar discharges. When reduced in a CH4 discharge, the active Ni/Al2O3 catalyst was effective for plasma-catalytic methane decomposition to produce H2 and solid carbon filaments. A decrease in the breakdown voltage was observed, following the catalyst reduction to the more conductive Ni phase. Chapter 6 investigates the performance of the plasma-reduced Ni/Al2O3 catalysts for plasma-catalytic dry reforming of methane. Whilst the activity towards dry reforming of CH4 was low, the CH4 plasma-reduced catalyst was found to be effective for catalysing the decomposition of CH4 into H2 and solid carbon filaments; both potentially useful products. Chapter 7 discusses further work relevant to this thesis.

The purpose of this study was to examine the possibility of methane as a replacement to traditional fuels. Methane provides several advantages over fuels such as hydrogen. The LABROC VI was used to examine the performance of a small methane and oxygen rocket engine. A theoretical analysis was performed on the LABROC nozzle to compare the effects of changing the mixture ratio and the chamber pressure. The LABVIEW control program was altered to only take data due to problems with the spark plug. The hardware used within the LABROC and the procedure for operation was examined and possible problems are noted. The existing LABVIEW control program was modified to only record data. Experimental data was taken from firing the LABROC and compared to the theoretical values. To check the viability of a methane motor, a nozzle was designed that produces the approximate thrust of small, commercially available, solid rocket motors.