Hydrogen is an attractive fuel source not only because it is abundant and renewable but also because it produces almost zero regulated emissions. Internal combustion engines fueled by compressed natural gas (CNG) are operated throughout a variety of industries in a number of mobile and stationary applications. While CNG engines offer many advantages over conventional gasoline and diesel combustion engines, CNG engine performance can be substantially improved in the lean operating region. Lean operation has a number of benefits, the most notable of which is reduced emissions. However, the extremely low flame propagation velocities of CNG greatly restrict the lean operating limits of CNG engines. Hydrogen, however, has a high flame speed and a wide operating limit that extends into the lean region. The addition of hydrogen to a CNG engine makes it a viable and economical method to significantly extend the lean operating limit and thereby improve performance and reduce emissions. Drawbacks of hydrogen as a fuel source, however, include lower power density due to a lower heating value per unit volume as compared to CNG, and susceptibility to pre-ignition and engine knock due to wide flammability limits and low minimum ignition energy. Combining hydrogen with CNG, however, overcomes the drawbacks inherent in each fuel type. Objectives of the current study were to evaluate the feasibility of using blends of hydrogen and natural gas as a fuel for conventional natural gas engines. The experiment and data analysis included evaluation of engine performance, efficiency, and emissions along with detailed in-cylinder measurements of key physical parameters. This provided a detailed knowledge base of the impact of using hydrogen/natural gas blends. A four-stroke, 4.2 L, V-6 naturally aspirated natural gas engine coupled to an eddy current dynamometer was used to measure the impact of hydrogen/natural gas blends on performance, thermodynamic efficiency and exhaust gas emissions in a reciprocating four stroke cycle engine. The test matrix varied engine load and air-to-fuel ratio at throttle openings of 50% and 100% at equivalence ratios of 1.00 and 0.90 for hydrogen percentages of 10%, 20% and 30% by volume. In addition, tests were performed at 100% throttle opening, with an equivalence ratio of 0.98 and a hydrogen blend of 20% to further investigate CO emission variations. Data analysis indicated that the use of hydrogen/natural gas fuel blend penalizes the engine operation with a 1.5 to 2.0% decrease in torque, but provided up to a 36% reduction in CO, a 30% reduction in NOX, and a 5% increase in brake thermal efficiency. These results concur with previous results published in the open literature. Further reduction in emissions can be obtained by retarding the ignition timing.

Progress in a 3 year research program to evaluate the performance and emission characteristics of hydrogen-fueled internal combustion engines is reported. Fifteen hydrogen engine configurations will be subjected to performance and emissions characterization tests. During the first two years, baseline data for throttled and unthrottled, carburetted and timed hydrogen induction, Pre IVC hydrogen-fueled engine configurations, with and without exhaust gas recirculation (EGR) and water injection, were obtained. These data, along with descriptions of the test engine and its components, the test apparatus, experimental techniques, experiments performed and the results obtained, are given. Analyses of other hydrogen-engine project data are also presented and compared with the results of the present effort. The unthrottled engine vis-a-vis the throttled engine is found, in general, to exhibit higher brake thermal efficiency. The unthrottled engine also yields lower NOx emissions, which were found to be a strong function of fuel-air equivalence ratio. (LCL).

Biofuels such as ethanol, butanol, and biodiesel have more desirable physico-chemical properties than base petroleum fuels (diesel and gasoline), making them more suitable for use in internal combustion engines. The book begins with a comprehensive review of biofuels and their utilization processes and culminates in an analysis of biofuel quality and impact on engine performance and emissions characteristics, while discussing relevant engine types, combustion aspects and effect on greenhouse gases. It will facilitate scattered information on biofuels and its utilization has to be integrated as a single information source. The information provided in this book would help readers to update their basic knowledge in the area of "biofuels and its utilization in internal combustion engines and its impact Environment and Ecology". It will serve as a reference source for UG/PG/Ph.D. Doctoral Scholars for their projects / research works and can provide valuable information to Researchers from Academic Universities and Industries. Key Features: • Compiles exhaustive information of biofuels and their utilization in internal combustion engines. • Explains engine performance of biofuels • Studies impact of biofuels on greenhouse gases and ecology highlighting integrated bio-energy system. • Discusses fuel quality of different biofuels and their suitability for internal combustion engines. • Details effects of biofuels on combustion and emissions characteristics.

Summary: This book contains the papers presented at the IMechE's Internal Combustion Engines: Performance, fuel economy and emissions conference, held at the IMechE, London, 8-9 December 2009. This conference, the latest in the successful biannual series on internal combustion engines, addresses drivers of change, technological developments and advances in the latest research. It examines developments for personal transport applications, though many of the drivers of change apply to light and heavy-duty, on and off-highway, transport and other sectors. The conference focuses on spark ignition engine technology for fuel economy, engine downsizing design and analysis, diesel engine design and analysis, and fuels. About the editors: The Institution of Mechanical Engineers (IMechE) is one of the leading professional engineering institutions in the world. Contents: SI ENGINES: TECHNOLOGY FOR FUEL ECONOMY A comparison of inlet valve operating strategies in a single cylinder spark ignition engine Future gasoline engine downsizing technologies - CO2 improvements and engine design considerations SI ENGINES: DOWNSIZING, DESIGN AND ANALYSIS Variable valve actuation enabled high efficiency gasoline engine A variable compression opposed-piston SI engine Application of high-precision absolute pressure sensors for gas exchange analysis DIESEL ENGINES: DESIGN AND ANALYSIS Effects of cooled and super-cooled low pressure EGR systems on the LD diesel engine performances Effect of compression ratio on combustion stability and performance of a DI diesel engine under cold conditions Effect of charge density on emissions in a HD-LTC diesel engine by retarding intake valve timing and rising boost pressure EMISSIONS CONTROL: NOx AND PARTICULATES Measures to improve the NOx-PM trade off for passenger car Diesel engines at elevated engine load Low particulate combustion development of the JCB Dieselmax mid-range off highway engine Exhaust inorganic nanoparticle emissions from internal combustion engines FUELS AND DIESEL ENGINES In-cylinder fuel injection and combustion analysis on 2nd generation bio-fuels in a single cylinder CR DI diesel optical engine Low NOx, low smoke operation of a diesel engine using a gasoline fuel Dual-fuel and low-carbon HGVs using bio methane Investigation of fuel properties and characterization of new generation alternative fuel for diesel engine LOW-TEMPERATURE COMBUSTION Hydrogen homogeneous charge compression ignition (HCCI) engine with DME as an ignition promoter HCCI simulation of a non reciprocating internal combustion engine The effects of exhaust back pressure on conventional and low temperature diesel combustion FUELS AND SI ENGINES Omnivore: an automotive flex-fuel 2-stroke engine with variable compression ratio, variable charge trapping and direct fuel injection A study of gasoline-alcohol blended fuels in a turbocharged DISI engine The nature of "superknock" and its origins in SI engines