On the Formation of Unburned Hydrocarbon Emissions in the Spark Ignition Internal Combustion Engine PDF Download
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Author: J. Otsason
Publisher:
ISBN:
Category :
Languages : en
Pages : 150
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Book Description
Author: J. Otsason
Publisher:
ISBN:
Category :
Languages : en
Pages : 150
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Book Description
Author: George Springer
Publisher: Springer Science & Business Media
ISBN: 1468419838
Category : Science
Languages : en
Pages : 377
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Book Description
In recent years, emissions from transportation engines have been studied widely because of the contribution of such engines to atmospheric pollution. During this period the amounts of pollutants emitted, the mechanism of their formation, and means of controlling emissions have been investigated in industrial and government laboratories, as well as at universities. The results of these investigations have generally been published as individual articles in journals, transactions, meeting proceedings, and, frequently, in company reports. This proliferation of technical information makes it difficult for workers in the field to keep abreast of all developments. For this reason, the editors felt the need for a book which would survey the existing state of knowledge in wide, albeit selected areas, and would provide a guide to the relevant literature. This book is intended to fulfill this function. It is recognized that all aspects of transportation engine emissions cannot be explored in a single volume. In this book attention is focused primarily on sources and mechanisms of emission formation within the combustion process, and on measurement techniques. Beyond this objective, no re strictions were placed on the authors. Within the framework of the general theme each author has been free to treat his subject as he saw fit. The editors have not strived to replace by uniformity the highly personal and attractive divergences of style. Considerable efforts were made, however, to ensure clarity and minimum overlap between the chapters.
Author: K. Song
Publisher:
ISBN:
Category :
Languages : en
Pages : 16
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Book Description
Many recent publications indicate that spark ignition (SI) engines equipped with the conventional port-injection fuel system (PIF) seem to have serious fuel-maldistribution problems, including the formation of liquid layers over the combustion chamber surfaces. It is reasonable to expect that such a maldistribution is an unfavorable condition for the flame propagation in the cylinder. The in-cylinder flame behaviors of a PIF-SI engine as fueled with gasoline are investigated by using the Rutgers high-speed spectral infrared imaging system. These results are then compared with those obtained from the same engine operated by gaseous fuels and other simple fuels. The results from the engine operated by gasoline reveal slowly burning fuel-rich local pockets under both fully warmed and room-temperature conditions. The local pockets seem to stem from the liquid layers formed over the surfaces during the intake period. The (invisible) post-flame oxidation of the rich pockets is observed to continue even after the exhaust valve opens. On the contrary, the same engine run with a gaseous fuel exhibits some predictable and 'clean' flame propagations. The new results obtained from the present study suggest that such a late oxidation of locally fuel-rich liquid pockets may be a significant cause for the emission of the engine-out unburned hydrocarbon (UHC). The sluggish consumption of the fuel there may also be a factor for reducing the thermal efficiency of the engine. A parametric study of this observation is performed to obtain a better understanding of the findings. (AN).
Author: Nobuhiko Ishikawa
Publisher:
ISBN:
Category :
Languages : en
Pages : 226
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Author: Henry Peter Davis
Publisher:
ISBN:
Category : Hydrocarbons
Languages : en
Pages : 222
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Author: Kevin David Cedrone
Publisher:
ISBN:
Category :
Languages : en
Pages : 191
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Book Description
Gasoline consumption and pollutant emissions from transportation are costly and have serious, demonstrated environmental and health impacts. Downsized, turbocharged direct-injection spark ignition (DISI) gasoline engines consume less fuel and achieve superior performance compared with conventional port fuel injected spark ignition (PFI-SI) engines. Although more efficient, turbocharged DISI engines have new emissions challenges during cold start. DISI fuel injection delivers more liquid fuel into the combustion chamber, increasing the emissions of unburned hydrocarbons. The turbocharger slows down activation (warm-up) of the catalytic exhaust after-treatment system. The objective of this research is to find a control strategy that: 1. Accelerates warm-up of the catalyst, and 2. Maintains low emissions of unburned hydrocarbons (UBHCs) during the catalyst warm-up process. This research includes a broad experimental survey of engine behaviour and emission response for a modern turbocharged DISI engine. The study focuses on the idle period during cold-start for which DISI engine emissions are worst. Engine experiments and simulations show that late and slow combustion lead to high exhaust gas temperatures and mass flow rate for fast warm-up. However, late and slow combustion increase the risk of partial-burn misfire. At the misfire limit for each parameter, the following conclusions are drawn: 1. Late ignition timing is the most effective way to increase exhaust enthalpy flow rate for fast catalyst warm-up. 2. By creating a favourable spatial fuel-air mixture stratification, split fuel injection can simultaneously retard and stabilize combustion to improve emissions and prevent partial-burn misfire. 3. Excessive trapped residuals from long valve overlap limit the potential for valve timing to reduce cold-start emissions. 4. Despite their more challenging evaporation characteristics, fuel blends with high ethanol content showed reasonable emissions behaviour and greater tolerance to late combustion than neat gasoline. 5. Higher exhaust back-pressure leads to high exhaust temperature during the exhaust stroke, leading to significantly more post-flame oxidation. 6. Post-flame oxidation in the combustion chamber and exhaust system play a critical role in decreasing the quantity of catalyst-in emissions due to hydrocarbons that escape primary (flame) combustion. A cold start strategy combining late ignition, 15% excess air, and high exhaust backpressure yielded the lowest cumulative hydrocarbon emissions during cold start.
Author: Hans Peter Lenz
Publisher: Springer
ISBN: 148992762X
Category : Technology & Engineering
Languages : en
Pages : 417
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Book Description
Twentyfour years have gone by since the publication of K. Lohner and H. Muller's comprehen sive work "Gemischbildung und Verbrennung im Ottomotor" in 1967 [1.1]' Naturally, the field of mixture formation and combustion in the spark-ignition engine has wit nessed great technological advances and many new findings in the intervening years, so that the time seemed ripe for presenting a summary of recent research and developments. There fore, I gladly took up the suggestion of the editors of this series of books, Professor Dr. H. List and Professor Dr. A. Pischinger, to write a book summarizing the present state of the art. A center of activity of the Institute of Internal-Combustion Engines and Automotive Engineering at the Vienna Technical University, which I am heading, is the field of mixture formation -there fore, many new results that have been achieved in this area in collaboration with the respective industry have been included in this volume. The basic principles of combustion are discussed only to that extent which seemect necessary for an understanding of the effects of mixture formation. The focal point of this volume is the mixture formation in spark-ignition engines, covering both the theory and actual design of the mixture formation units and appropriate intake manifolds. Also, the related measurement technology is explained in this work.
Author: Leonard Kuo-Liang Shih
Publisher:
ISBN:
Category :
Languages : en
Pages : 310
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
The post-flame oxidation of unburned hydrocarbons (HC) released from the ring-pack crevice in spark-ignition engines was investigated. Experimental data was collected in two engines running at steady-state, fully warmed-up condition, fixed load and fixed speed. Nitrogen was injected into the intake manifold to dilute the charge in order to maintain the average burned gas temperature as the equivalence ratio varied. For a given operating condition, similar in-cylinder pressure and burned gas temperature profiles were obtained at different equivalence ratio. Two models for post-flame oxidation were proposed: 1) a mixing-controlled model, based on an empirical correlation of two parameters, and 2) a kinetically controlled model, based on a zero-dimensional model using detailed chemical kinetic. The mixing-controlled model consisted of a linear correlation between the peak mass flow rate of crevice gas returning to the combustion chamber and a post-oxidation metric defined as Global HC Consumption Rate (GCR). Using this correlation, the engine-out HC emissions were estimated. In general, the results were satisfactory, but the main shortcoming of the model was that the constant of the linear correlation needed to be derived empirically for each engine and each air-fuel ratio. A kinetically controlled model was developed to study the effect of the mixture composition and temperature in the post-oxidation process. To account for the mixing between the unburned crevice gas and the burned gas in the cylinder, two approaches were taken: 1) an optimized mixing rate based on a constant (with time) value for the mass of burned gas entrained into an unburned gas parcel, and 2) a time-varying mixing rate, in which the crevice outgassing process was modeled using a self-similarity solution for both a turbulent round jet and a wall jet. Using both approaches, the engine-out HC emissions were calculated. The results were compared to the measured HC emission. In general, satisfactory (or expected) results were found for cases in which the engine was run rich or near stoichiometric. For the lean combustion cases, the results were unsatisfactory (or unexpected) with both mixing approaches. A hypothesis that explain the discrepancy in the lean combustion side was suggested. For a given operating condition, the potential to reduce actual engine-out HC emission was identified. The results showed that during the crevice outgassing process, there was a relatively narrow period of time in which it is feasible to increase the overall rate of post-oxidation. It is suggested that improving the mixing rate during this window of time can boost the level of post-oxidation within the cylinder and subsequently reduce the engine-out HC. This insight can be used to develop strategies for engine-out HC emission reduction by focusing on the period of the engine cycle that matter the most.
Author: Eran Sher
Publisher: Academic Press
ISBN: 0080532756
Category : Technology & Engineering
Languages : en
Pages : 689
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Book Description
This handbook is an important and valuable source for engineers and researchers in the area of internal combustion engines pollution control. It provides an excellent updated review of available knowledge in this field and furnishes essential and useful information on air pollution constituents, mechanisms of formation, control technologies, effects of engine design, effects of operation conditions, and effects of fuel formulation and additives. The text is rich in explanatory diagrams, figures and tables, and includes a considerable number of references. - An important resource for engineers and researchers in the area of internal combustion engines and pollution control - Presents and excellent updated review of the available knowledge in this area - Written by 23 experts - Provides over 700 references and more than 500 explanatory diagrams, figures and tables
