Natural gas direct injection and glow plug ignition assist technologies were implemented in a single-cylinder, optically-accessible engine. Initial experiments studied the effects of injector and glow plug shield geometry on ignition quality. Injector and shield geometric effects were found to be significant, with only two of 20 tested geometric combinations resulting in reproducible combustion. Further experiments explored the effects of equivalence ratio and intake pressure on ignition delay, engine performance, and exhaust emissions. Combustion was found to proceed in a stratified-premixed mode at lower equivalence ratios, and a free-mixing mode at the higher equivalence ratios. Both combustion modes resulted in high NOx emissions. Stratified-premixed combustion produced higher hydrocarbon emissions, and lower levels of particulate matter and carbon monoxide, when compared to free-mixing combustion. Higher intake pressure was found to reduce all emissions levels. This effect was largely attributed to better charge mixing achieved from pressure-driven increase in engine swirl momentum.

The direct-injection of natural gas into the compression-ignition engines is attractive, due to its emission advantage and diesel-equivalent efficiency. The computational simulation of this next-generation heavy-duty engine can provide deep insights of the gas injection and ignition characteristics and help understand the emission formation process, and hence, a KIVA-3v based three-dimensional computational model was developed and improved to represent the configuration of a glow plug assisted direct-injection natural gas engine. This thesis presents the important conclusions about the numerical studies of the natural gas ignition and emissions by using this engine computational model. Preliminary simulations revealed that the shield for a glow plug, an ignition assist for natural gas in compression-ignition engines, can highly improve the natural gas ignition stability compared to an unshielded glow plug, and the design of the glow plug shield has great potential for the further improvement of the natural gas ignition. The different shield designs, characterized by the parameters such as shield opening shape, number and distribution, were evaluated by using the improved KIVA model. The simulated results clearly demonstrated the three key functions of a good shield design. A multi-opening shield, consisting of four small openings in a diamond shape, can achieve all three requirements and hence highly reduce the natural gas ignition delay and improve the ignition stability, compared to the original single-opening shield. The proper emission models are critical for the numerical simulations of natural gas engine emissions. For the gaseous species, a kinetic package, CANTERA, is coupled to KIVA CFD code to simulate the formation of important emissions, such as C2H2 and NOx. However, the available detailed mechanisms, such as GRI-3.0, will over-predict the ignition delay at low temperature (

Direct injection enables precise control of the fuel/air mixture so that engines can be tuned for improved power and fuel economy, but ongoing research challenges remain in improving the technology for commercial applications. As fuel prices escalate DI engines are expected to gain in popularity for automotive applications. This important book, in two volumes, reviews the science and technology of different types of DI combustion engines and their fuels. Volume 1 deals with direct injection gasoline and CNG engines, including history and essential principles, approaches to improved fuel economy, design, optimisation, optical techniques and their applications. - Reviews key technologies for enhancing direct injection (DI) gasoline engines - Examines approaches to improved fuel economy and lower emissions - Discusses DI compressed natural gas (CNG) engines and biofuels

The process of fuel injection, spray atomization and vaporization, charge cooling, mixture preparation and the control of in-cylinder air motion are all being actively researched and this work is reviewed in detail and analyzed. The new technologies such as high-pressure, common-rail, gasoline injection systems and swirl-atomizing gasoline fuel injections are discussed in detail, as these technologies, along with computer control capabilities, have enabled the current new examination of an old objective; the direct-injection, stratified-charge (DISC), gasoline engine. The prior work on DISC engines that is relevant to current GDI engine development is also reviewed and discussed. The fuel economy and emission data for actual engine configurations have been obtained and assembled for all of the available GDI literature, and are reviewed and discussed in detail. The types of GDI engines are arranged in four classifications of decreasing complexity, and the advantages and disadvantages of each class are noted and explained. Emphasis is placed upon consensus trends and conclusions that are evident when taken as a whole; thus the GDI researcher is informed regarding the degree to which engine volumetric efficiency and compression ratio can be increased under optimized conditions, and as to the extent to which unburned hydrocarbon (UBHC), NOx and particulate emissions can be minimized for specific combustion strategies. The critical area of GDI fuel injector deposits and the associated effect on spray geometry and engine performance degradation are reviewed, and important system guidelines for minimizing deposition rates and deposit effects are presented. The capabilities and limitations of emission control techniques and after treatment hardware are reviewed in depth, and a compilation and discussion of areas of consensus on attaining European, Japanese and North American emission standards presented. All known research, prototype and production GDI engines worldwide are reviewed as to performance, emissions and fuel economy advantages, and for areas requiring further development. The engine schematics, control diagrams and specifications are compiled, and the emission control strategies are illustrated and discussed. The influence of lean-NOx catalysts on the development of late-injection, stratified-charge GDI engines is reviewed, and the relative merits of lean-burn, homogeneous, direct-injection engines as an option requiring less control complexity are analyzed.

Alternative Fuels and Advanced Vehicle Technologies for Improved Environmental Performance: Towards Zero Carbon Transportation, Second Edition provides a comprehensive view of key developments in advanced fuels and vehicle technologies to improve the energy efficiency and environmental impact of the automotive sector. Sections consider the role of alternative fuels such as electricity, alcohol and hydrogen fuel cells, as well as advanced additives and oils in environmentally sustainable transport. Other topics explored include methods of revising engine and vehicle design to improve environmental performance and fuel economy and developments in electric and hybrid vehicle technologies. This reference will provide professionals, engineers and researchers of alternative fuels with an understanding of the latest clean technologies which will help them to advance the field. Those working in environmental and mechanical engineering will benefit from the detailed analysis of the technologies covered, as will fuel suppliers and energy producers seeking to improve the efficiency, sustainability and accessibility of their work. - Provides a fully updated reference with significant technological advances and developments in the sector - Presents analyses on the latest advances in electronic systems for emissions control, autonomous systems, artificial intelligence and legislative requirements - Includes a strong focus on updated climate change predictions and consequences, helping the reader work towards ambitious 2050 climate change goals for the automotive industry

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.