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Author: Publisher: ISBN: Category : Languages : en Pages : 416
Book Description
Detailed and highly time resolved experimental measurements were used to characterize the effects of transient operation on the performance of a light duty diesel engine, and to identify the physical processes responsible for transient-specific combustion behavior. The engine response to transient events varied with the size and type of transition and the combustion strategy used, but the underlying processes were similar in all cases. Differences in the response rate of the fuel and air systems caused large variations in the equivalence ratio of the combustion charge during transient events. For moderate to low load conditions, this was primarily due to the discrepancy between the instantaneous intake air flow rate and the composition of the intake charge caused by storage of exhaust gas in the EGR system. This effect was particularly significant for early injection LTC operation due to higher EGR rates and greater dependence of combustion phasing on intake charge composition. Individual combustion cycles during transient events were compared to steady state operation at the same speed and load to quantify the differences in physical conditions. The greatest effect on combustion and emissions was due to differences in intake charge composition, which varied significantly between transient and steady state operation. The response time of the common rail pressure also contributed to transient behavior in situations where the target pressure varied with changes in speed or load. During larger load transitions, thermal inertia of the engine system had a significant effect on emissions, particularly UHC, but did not influence the combustion phasing or heat release rate. The characteristic rates of change of the charge gas, fluid, and physical component temperatures in response to speed or load transitions were much slower than those of other variables such as pressures or flow rates, and were consistent with concurrent variations in engine-out emissions levels. Numerous mechanisms by which thermal inertia could affect emissions formation were identified, including variation of the intake manifold charge gas temperature, in-cylinder heat transfer, and changing physical properties of the fuel.
Author: Publisher: ISBN: Category : Languages : en Pages : 416
Book Description
Detailed and highly time resolved experimental measurements were used to characterize the effects of transient operation on the performance of a light duty diesel engine, and to identify the physical processes responsible for transient-specific combustion behavior. The engine response to transient events varied with the size and type of transition and the combustion strategy used, but the underlying processes were similar in all cases. Differences in the response rate of the fuel and air systems caused large variations in the equivalence ratio of the combustion charge during transient events. For moderate to low load conditions, this was primarily due to the discrepancy between the instantaneous intake air flow rate and the composition of the intake charge caused by storage of exhaust gas in the EGR system. This effect was particularly significant for early injection LTC operation due to higher EGR rates and greater dependence of combustion phasing on intake charge composition. Individual combustion cycles during transient events were compared to steady state operation at the same speed and load to quantify the differences in physical conditions. The greatest effect on combustion and emissions was due to differences in intake charge composition, which varied significantly between transient and steady state operation. The response time of the common rail pressure also contributed to transient behavior in situations where the target pressure varied with changes in speed or load. During larger load transitions, thermal inertia of the engine system had a significant effect on emissions, particularly UHC, but did not influence the combustion phasing or heat release rate. The characteristic rates of change of the charge gas, fluid, and physical component temperatures in response to speed or load transitions were much slower than those of other variables such as pressures or flow rates, and were consistent with concurrent variations in engine-out emissions levels. Numerous mechanisms by which thermal inertia could affect emissions formation were identified, including variation of the intake manifold charge gas temperature, in-cylinder heat transfer, and changing physical properties of the fuel.
Author: Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Low Temperature Combustion (LTC) is currently being researched as a way to reduce problematic emissions (i.e., NOx and PM) from compression-ignition engines while maintaining high fuel efficiency. One of the primary types of LTC is Premixed Compression Ignition (PCI), with some examples of PCI being homogeneous charge compression ignition (HCCI), premixed charge compression ignition (PCCI), reactivity controlled compression ignition (RCCI) and partially premixed combustion (PPC). These LTC strategies use early fuel injections to allow sufficient time for air/fuel mixing before combustion. By increasing the amount of air/fuel premixing, NOx and PM emissions can be lowered due to the reduced local and global equivalence ratios. The lean nature of PCI also maintains high thermal efficiency due to the reduced heat transfer losses from the reduced peak combustion temperatures. However, too much air/fuel premixing can lead to rapid energy release rates, limiting the operation space for PCI. To combat this problem, the combustion strategy of interest for the study, RCCI, uses fuel reactivity gradients to increase combustion duration (i.e., reduce the energy release rate) and phasing control, thereby increasing the engine operating space for PCI operation. Previous tests [1-7] have shown promising results for petroleum-based fuels with RCCI. Recent work at Oak Ridge National Laboratory (ORNL) has shown how blends of biofuels with petroleum fuels can improve RCCI combustion performance [8,9] The work sets out to examine biofuel performance over a wide engine operating space both at steady-state and transient operating conditions with RCCI combustion. It is hoped to demonstrate the capability and effects of using bio-derived fuels in place of conventional petroleum-derived fuels for advanced combustion strategies under real-world operating conditions. In RCCI operation, blends of biodiesel and ethanol fuels will be investigated to examine the fuel effects on the combustion event.
Author: Constantine D. Rakopoulos Publisher: Springer Science & Business Media ISBN: 1848823754 Category : Technology & Engineering Languages : en Pages : 408
Book Description
Traditionally, the study of internal combustion engines operation has focused on the steady-state performance. However, the daily driving schedule of automotive and truck engines is inherently related to unsteady conditions. In fact, only a very small portion of a vehicle’s operating pattern is true steady-state, e. g. , when cruising on a motorway. Moreover, the most critical conditions encountered by industrial or marine engines are met during transients too. Unfortunately, the transient operation of turbocharged diesel engines has been associated with slow acceleration rate, hence poor driveability, and overshoot in particulate, gaseous and noise emissions. Despite the relatively large number of published papers, this very important subject has been treated in the past scarcely and only segmentally as regards reference books. Merely two chapters, one in the book Turbocharging the Internal Combustion Engine by N. Watson and M. S. Janota (McMillan Press, 1982) and another one written by D. E. Winterbone in the book The Thermodynamics and Gas Dynamics of Internal Combustion Engines, Vol. II edited by J. H. Horlock and D. E. Winterbone (Clarendon Press, 1986) are dedicated to transient operation. Both books, now out of print, were published a long time ago. Then, it seems reasonable to try to expand on these pioneering works, taking into account the recent technological advances and particularly the global concern about environmental pollution, which has intensified the research on transient (diesel) engine operation, typically through the Transient Cycles certification of new vehicles.
Author: Publisher: ISBN: Category : Languages : en Pages :
Book Description
The engine industry is currently facing severe emissions mandates. Pollutant emissions from mobile sources are a major source of concern. For example, US EPA mandates require emissions of particulate and nitrogen oxides (NOx) from heavy-duty diesel engine exhaust to drop at least 90 percent between 1998 and 2010. Effective analysis of the combustion process is required to guide the selection of technologies for future development since exhaust after-treatment solutions are not currently available that can meet the required emission reduction goals. The goal of this project is to develop methods to optimize and control Low Temperature Combustion Diesel technologies (LTC-D) that offers the potential of nearly eliminating engine NOx and particulate emissions at reduced cost over traditional methods by controlling pollutant emissions in-cylinder. The work was divided into 5 Tasks, featuring experimental and modeling components: 1.) Fundamental understanding of LTC-D and advanced model development, 2.) Experimental investigation of LTC-D combustion control concepts, 3.) Application of detailed models for optimization of LTC-D combustion and emissions, 4.) Impact of heat transfer and spray impingement on LTC-D combustion, and 5.) Transient engine control with mixed-mode combustion. As described in the final report (December 2008), outcomes from the research included providing guidelines to the engine and energy industries for achieving optimal low temperature combustion operation through using advanced fuel injection strategies, and the potential to extend low temperature operation through manipulation of fuel characteristics. In addition, recommendations were made for improved combustion chamber geometries that are matched to injection sprays and that minimize wall fuel films. The role of fuel-air mixing, fuel characteristics, fuel spray/wall impingement and heat transfer on LTC-D engine control were revealed. Methods were proposed for transient engine operation during load and speed changes to extend LTC-D engine operating limits, power density and fuel economy. Low emissions engine design concepts were proposed and evaluated.
Author: Rakesh Kumar Maurya Publisher: Springer ISBN: 3319685082 Category : Technology & Engineering Languages : en Pages : 553
Book Description
This book deals with novel advanced engine combustion technologies having potential of high fuel conversion efficiency along with ultralow NOx and particulate matter (PM) emissions. It offers insight into advanced combustion modes for efficient utilization of gasoline like fuels. Fundamentals of various advanced low temperature combustion (LTC) systems such as HCCI, PCCI, PPC and RCCI engines and their fuel quality requirements are also discussed. Detailed performance, combustion and emissions characteristics of futuristic engine technologies such as PPC and RCCI employing conventional as well as alternative fuels are analyzed and discussed. Special emphasis is placed on soot particle number emission characterization, high load limiting constraints, and fuel effects on combustion characteristics in LTC engines. For closed loop combustion control of LTC engines, sensors, actuators and control strategies are also discussed. The book should prove useful to a broad audience, including graduate students, researchers, and professionals Offers novel technologies for improved and efficient utilization of gasoline like fuels; Deals with most advanced and futuristic engine combustion modes such as PPC and RCCI; Comprehensible presentation of the performance, combustion and emissions characteristics of low temperature combustion (LTC) engines; Deals with closed loop combustion control of advanced LTC engines; State-of-the-art technology book that concisely summarizes the recent advancements in LTC technology. .
Author: National Research Council Publisher: National Academies Press ISBN: 0309373913 Category : Science Languages : en Pages : 812
Book Description
The light-duty vehicle fleet is expected to undergo substantial technological changes over the next several decades. New powertrain designs, alternative fuels, advanced materials and significant changes to the vehicle body are being driven by increasingly stringent fuel economy and greenhouse gas emission standards. By the end of the next decade, cars and light-duty trucks will be more fuel efficient, weigh less, emit less air pollutants, have more safety features, and will be more expensive to purchase relative to current vehicles. Though the gasoline-powered spark ignition engine will continue to be the dominant powertrain configuration even through 2030, such vehicles will be equipped with advanced technologies, materials, electronics and controls, and aerodynamics. And by 2030, the deployment of alternative methods to propel and fuel vehicles and alternative modes of transportation, including autonomous vehicles, will be well underway. What are these new technologies - how will they work, and will some technologies be more effective than others? Written to inform The United States Department of Transportation's National Highway Traffic Safety Administration (NHTSA) and Environmental Protection Agency (EPA) Corporate Average Fuel Economy (CAFE) and greenhouse gas (GHG) emission standards, this new report from the National Research Council is a technical evaluation of costs, benefits, and implementation issues of fuel reduction technologies for next-generation light-duty vehicles. Cost, Effectiveness, and Deployment of Fuel Economy Technologies for Light-Duty Vehicles estimates the cost, potential efficiency improvements, and barriers to commercial deployment of technologies that might be employed from 2020 to 2030. This report describes these promising technologies and makes recommendations for their inclusion on the list of technologies applicable for the 2017-2025 CAFE standards.
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Author: Constantine D. Rakopoulos
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Author: Daniel Ryan Williams
Author: Richard Michael Opat
Author: Rakesh Kumar Maurya
Author: Metin Korkmaz
Author: Jonathan L. Burton
Author: National Research Council