Alcohols with carbon numbers ranging from C1 to C5 were individually blended with unleaded test gasoline. All the alcohol-gasoline blends had the same oxygen mass content. The performance characteristics of the blends were quantified using a single-cylinder spark ignition engine. The knock-limiting spark timing was determined by analysis of the third derivative of the measured in-cylinder gas pressure versus crank angle. The engine operating conditions were optimized for each (C1-C5) blend with two different values of matched oxygen mass content (2.5 and 5.0 per cent). Emission mass rates of carbon monoxide (CO), nitric oxides (NOx), total unburned hydrocarbons (THCs), alcohols and aldehydes were quantified. The brake power specific rate emissions were compared with that of neat gasoline. Adding lower alcohols (C1, C2 and C3) to gasoline improved the knock resistance. Further improvement was achieved by increasing the oxygen content of the fuel blend. Blends with higher alcohols (C4 and C5) showed degraded knock resistance when compared with neat gasoline. Generally, all alcohol-gasoline blends showed reduction in CO emissions. Higher alcohol-gasoline blends with an oxygen mass content of 5.0 per cent showed a pronounced increase in NOx emission rates when operating at high compression ratios and 5° before top dead centre timing. This is attributed to their lower enthalpy of vaporization and higher flame temperature. All blends tested at optimized operating conditions showed reduction in THC emission rates. Unburned alcohol emission rates were higher for blends with higher content of alcohol, and aldehyde emissions were higher for all blends with formaldehyde as the main constituent.
Methods for sampling aldehyde and ketone using 2,4-dinitrophenylhydrazine (DNPH) are reviewed with emphasis on the type of trapping media, the absorbing solution composition and stability and the sample flowrate. Pre- and post-sampling procedures are discussed as well as collected sample stability, detection range, contamination and interference. Different methods for generating standard atmospheres are discussed as well as collection efficiency and standards recovery. Aldehyde emissions measured using DNPH in engine exhaust are briefly reviewed with an overview of the effects of fuel type, engine concept and operation and exhaust gas aftertreatment. Finally, practices and recommendations are proposed to ensure the integrity of the sampling process and appropriateness to different applications.
Rapid Control Prototyping (RCP) tools are becoming an essential part of the development process of modern automotive control strategies. The interface between the RCP real-time hardware and the existing electronic control unit (ECU) can be established via Controller Area Network (CAN). In a typical production ECU, the limited availability of unused message objects and the rate of data transfer on the CAN bus are limiting factors which influence the mechanism used for communication between the ECU and the RCP system. This document outlines the details involved in a CAN-based selective bypass approach. A data transfer mechanism is proposed which makes use of only two message objects to establish communication. The introduced time delays and the synchronization of the time driven main tasks are discussed. The proposed mechanism is validated through engine testing and the implementation details are described as well. A standard realization of the proposed mechanism is presented based on the CAN Calibration Protocol (CCP) standard. The CAN-based approach to RCP is shown to be a viable alternative to a Dual Port RAM (DPRAM)-based approach, especially in light of the fact that the hardware flexibility is maintained when the original ECU is being upgraded.
Increasingly stringent emissions legislation and demands for improved fuel economy have mandated the need for advanced control algorithms and complicated the diesel engine calibration procedure. To this end, a neural networkbased mean value model of a modern turbocharged direct injection diesel engine has been developed and validated. For a pre-specified engine speed schedule and control vector trajectory, the engine model was shown to produce accurate predictions of the turbocharger manifold charging dynamics and combustion efficiency through engine brake torque predictions. The mean value model was coupled with several sub-models to predict exhaust gaseous and particulate emissions and satisfactory predictions were reported over highly transient engine test schedules. The mean value model was used to develop and validate through simulation a neural network-based engine torque controller for both non-governed as well as governed engine operation. Two types of proportional governors were considered where one governor employed a more aggressive fueling strategy than the other. The engine performance and exhaust gas emissions for both strategies were quantified through simulation, showing steeper rises in torque and larger excursions in transient emissions for the more aggressive fueling strategy. The controller was adapted online using the standard back-propagation algorithm. For a pre-specified engine speed schedule and desired engine torque trajectory, excellent torque tracking was predicted using the neural network (NN) controller over transient operation compared to a classical proportional plus integral (PI) controller, which was tuned heuristically. The mean value model was also used to develop and validate through simulation a neural network-based all-speed governor. For a pre-specified engine load schedule and accelerator position trajectory, accurate tracking was predicted for the desired engine speed for both classical and NN-based controllers under high load transients. For the test engine used, it was shown through simulation that tighter control of engine torque over the Federal Test Procedure (FTP) cycle resulted in higher brake specific emissions of carbon dioxide, oxides of nitrogen, and particulate matter. Also, the EPA validation criteria for the prescribed engine torque over the FTP cycle allow for significant variations in brake specific emissions, especially particulate matter, total hydrocarbons, and carbon monoxide emissions, while still meeting the legal requirements for a valid engine certification test. iii ACKNOWLEDGEMENTS The author wishes to express his gratitude to his thesis advisor, Dr. Chris Atkinson, for the invaluable opportunity he has given him to work on this very interesting subject. Thanks for many unlimited office hours of sincere discussions on engine controls, a subject greatly complicated by confidentiality agreements and propriety information. The author wishes to thank his committee members, specifically Dr. Napolitano for accepting him as a 'guest' in his advanced con...
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