Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Diesel Combustion Optimization And Emissions Reduction Using Adaptive Injection Strategies Ais With Improved Numerical Models
Download Diesel Combustion Optimization And Emissions Reduction Using Adaptive Injection Strategies Ais With Improved Numerical Models full books in PDF, epub, and Kindle. Read online Diesel Combustion Optimization And Emissions Reduction Using Adaptive Injection Strategies Ais With Improved Numerical Models ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Diesel Combustion Optimization and Emissions Reduction Using Adaptive Injection Strategies (AIS) with Improved Numerical Models by : Yong Sun
Download or read book Diesel Combustion Optimization and Emissions Reduction Using Adaptive Injection Strategies (AIS) with Improved Numerical Models written by Yong Sun and published by . This book was released on 2007 with total page 234 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :P. A. Lakshminarayanan Publisher :Springer Science & Business Media ISBN 13 :904813885X Total Pages :313 pages Book Rating :4.0/5 (481 download)
Book Synopsis Modelling Diesel Combustion by : P. A. Lakshminarayanan
Download or read book Modelling Diesel Combustion written by P. A. Lakshminarayanan and published by Springer Science & Business Media. This book was released on 2010-03-03 with total page 313 pages. Available in PDF, EPUB and Kindle. Book excerpt: Phenomenology of Diesel Combustion and Modeling Diesel is the most efficient combustion engine today and it plays an important role in transport of goods and passengers on land and on high seas. The emissions must be controlled as stipulated by the society without sacrificing the legendary fuel economy of the diesel engines. These important drivers caused innovations in diesel engineering like re-entrant combustion chambers in the piston, lower swirl support and high pressure injection, in turn reducing the ignition delay and hence the nitric oxides. The limits on emissions are being continually reduced. The- fore, the required accuracy of the models to predict the emissions and efficiency of the engines is high. The phenomenological combustion models based on physical and chemical description of the processes in the engine are practical to describe diesel engine combustion and to carry out parametric studies. This is because the injection process, which can be relatively well predicted, has the dominant effect on mixture formation and subsequent course of combustion. The need for improving these models by incorporating new developments in engine designs is explained in Chapter 2. With “model based control programs” used in the Electronic Control Units of the engines, phenomenological models are assuming more importance now because the detailed CFD based models are too slow to be handled by the Electronic Control Units. Experimental work is necessary to develop the basic understanding of the pr- esses.
Book Synopsis Simulation and Optimization of Internal Combustion Engines by : Zhiyu Han
Download or read book Simulation and Optimization of Internal Combustion Engines written by Zhiyu Han and published by SAE International. This book was released on 2021-12-28 with total page 372 pages. Available in PDF, EPUB and Kindle. Book excerpt: Simulation and Optimization of Internal Combustion Engines provides the fundamentals and up-to-date progress in multidimensional simulation and optimization of internal combustion engines. While it is impossible to include all the models in a single book, this book intends to introduce the pioneer and/or the often-used models and the physics behind them providing readers with ready-to-use knowledge. Key issues, useful modeling methodology and techniques, as well as instructive results, are discussed through examples. Readers will understand the fundamentals of these examples and be inspired to explore new ideas and means for better solutions in their studies and work. Topics include combustion basis of IC engines, mathematical descriptions of reactive flow with sprays, engine in-cylinder turbulence, fuel sprays, combustions and pollutant emissions, optimization of direct-injection gasoline engines, and optimization of diesel and alternative fuel engines.
Book Synopsis Encyclopedia of Automotive Engineering by :
Download or read book Encyclopedia of Automotive Engineering written by and published by John Wiley & Sons. This book was released on 2015-03-23 with total page 3888 pages. Available in PDF, EPUB and Kindle. Book excerpt: Erstmals eine umfassende und einheitliche Wissensbasis und Grundlage für weiterführende Studien und Forschung im Bereich der Automobiltechnik. Die Encyclopedia of Automotive Engineering ist die erste umfassende und einheitliche Wissensbasis dieses Fachgebiets und legt den Grundstein für weitere Studien und tiefgreifende Forschung. Weitreichende Querverweise und Suchfunktionen ermöglichen erstmals den zentralen Zugriff auf Detailinformationen zu bewährten Branchenstandards und -verfahren. Zusammenhängende Konzepte und Techniken aus Spezialbereichen lassen sich so einfacher verstehen. Neben traditionellen Themen des Fachgebiets beschäftigt sich diese Enzyklopädie auch mit "grünen" Technologien, dem Übergang von der Mechanik zur Elektronik und den Möglichkeiten zur Herstellung sicherer, effizienterer Fahrzeuge unter weltweit unterschiedlichen wirtschaftlichen Rahmenbedingungen. Das Referenzwerk behandelt neun Hauptbereiche: (1) Motoren: Grundlagen; (2) Motoren: Design; (3) Hybrid- und Elektroantriebe; (4) Getriebe- und Antriebssysteme; (5) Chassis-Systeme; (6) Elektrische und elektronische Systeme; (7) Karosserie-Design; (8) Materialien und Fertigung; (9) Telematik. - Zuverlässige Darstellung einer Vielzahl von Spezialthemen aus dem Bereich der Automobiltechnik. - Zugängliches Nachschlagewerk für Jungingenieure und Studenten, die die technologischen Grundlagen besser verstehen und ihre Kenntnisse erweitern möchten. - Wertvolle Verweise auf Detailinformationen und Forschungsergebnisse aus der technischen Literatur. - Entwickelt in Zusammenarbeit mit der FISITA, der Dachorganisation nationaler Automobil-Ingenieur-Verbände aus 37 Ländern und Vertretung von über 185.000 Ingenieuren aus der Branche. - Erhältlich als stets aktuelle Online-Ressource mit umfassenden Suchfunktionen oder als Print-Ausgabe in sechs Bänden mit über 4.000 Seiten. Ein wichtiges Nachschlagewerk für Bibliotheken und Informationszentren in der Industrie, bei Forschungs- und Schulungseinrichtungen, Fachgesellschaften, Regierungsbehörden und allen Ingenieurstudiengängen. Richtet sich an Fachingenieure und Techniker aus der Industrie, Studenten höherer Semester und Studienabsolventen, Forscher, Dozenten und Ausbilder, Branchenanalysen und Forscher.
Book Synopsis Investigations of Advanced Injection and Combustion Strategies in Low-emissions Diesel Engines by : Sage L. Kokjohn
Download or read book Investigations of Advanced Injection and Combustion Strategies in Low-emissions Diesel Engines written by Sage L. Kokjohn and published by . This book was released on 2008 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Proceedings of the ... Fall Technical Conference of the ASME Internal Combustion Engine Division by : American Society of Mechanical Engineers. Internal Combustion Engine Division. Technical Conference
Download or read book Proceedings of the ... Fall Technical Conference of the ASME Internal Combustion Engine Division written by American Society of Mechanical Engineers. Internal Combustion Engine Division. Technical Conference and published by . This book was released on 2007 with total page 744 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Development of a Partially Premixed Combustion Model for a Diesel Engine Using Multiple Injection Strategies by : Rene Thygesen
Download or read book Development of a Partially Premixed Combustion Model for a Diesel Engine Using Multiple Injection Strategies written by Rene Thygesen and published by Logos Verlag Berlin GmbH. This book was released on 2012 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to fulfil future emissions legislations, new combustion systems are to be investigated. One way of improving exhaust emissions is the application of multiple injection strategies and conventional or partially premixed combustion conditions to a Diesel engine. The application of numerical techniques as CFD supports and improves the quality of engine developments. Unfortunately, current spray and combustion models are not accurate enough to simulate multiple injection systems, being in this way a topic of research. The goal of this study was the development of a novel simulation method for the investigation of Diesel engines operated with multiple injection strategies and different combustion modes. The first part of this work focused in improving the spray modelling. The inform ation of 3D CFD simulations of the injector nozzle was introduced in the spray simulation as boundary conditions developing coupling subroutines for this issue. The atomisation modelling was also improved using validated presumed droplet size distributions. Moreover, to avoid the simulation of the injector nozzle for every investigated operating point, a novel interpolating tool was developed in order to create spray boundary conditions based on few 3D CFD simulations of the nozzle under certain initial and boundary conditions. The second part of this thesis dealt with the combustion modelling of Diesel engines. For this issue, a laminar flamelet approach called Representative Interactive Flamelet model (RIF) was selected and implemented. Afterwards, an extended combustion model based on RIF was developed in order to take into account multiple injection strategies. Finally, this new model was validated with a wide range of operating points: applying multiple injection strategies under conventional and partially premixed combustion conditions.
Book Synopsis Deisel Engine Modeling and Optimization for Emission Reduction by : Yi Liu
Download or read book Deisel Engine Modeling and Optimization for Emission Reduction written by Yi Liu and published by . This book was released on 2005 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Atomization and Sprays written by and published by . This book was released on 2009 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Droplet Collision Modeling in Multi-dimensional Engine Spray Computation by : Achuth Munnannur
Download or read book Droplet Collision Modeling in Multi-dimensional Engine Spray Computation written by Achuth Munnannur and published by . This book was released on 2007 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Effect of Radiation on Diesel Engine Combustion and Heat Transfer by : Takeshi Yoshikawa
Download or read book Effect of Radiation on Diesel Engine Combustion and Heat Transfer written by Takeshi Yoshikawa and published by . This book was released on 2008 with total page 344 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis COMBUSTION, EMISSIONS, AND PERFORMANCE OPTIMIZATION IN A DI/PFI-RCCI DIESEL/NATURAL GAS TURBOCHARGED ENGINE by :
Download or read book COMBUSTION, EMISSIONS, AND PERFORMANCE OPTIMIZATION IN A DI/PFI-RCCI DIESEL/NATURAL GAS TURBOCHARGED ENGINE written by and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract : Diesel-NG fuel blends are increasingly being used in Reactivity Controlled Compression Ignition (RCCI) applications due to high Brake Thermal Efficiency (BTE), low NOx and PM emissions. But it also has a few disadvantages such as high HC and CO emission and relatively low Exhaust Gas Temperature (EGT). This leads to find out the optimum tradeoff between emissions to meet the regulation and also investigate the cost of operation and find out the minimum liquid consumption (fuel + urea) in RCCI mode. A Cost Function (CF) including Brake Specific Fuel Consumption (BSFC) and Brake Specific Urea Consumption (BSUC) is considered and minimized in this study. This optimization helped to investigate the optimum input parameters between 3 to 12 bar IMEP at 1500 RPM engine speed. This study has been done while all the population in optimization process meet the Tier 3 Bin 20 emission regulations. To increase the number of data points in this optimization, a mathematical (numerical) model is developed to predict (or assess) the Diesel-NG RCCI data. Single fuel diesel only mode is also considered in this optimization, since high BTE of RCCI is limited to medium and high load operating conditions and due to the high HC and low EGT, RCCI may not be an ideal combustion mode at low loads. Parametric models have been developed and validated using experimental data on a light duty 1.9L inline 4 cylinder Compression Ignition (CI) engine as a function of independent input variables including, first and second Start of Injection (SOI1 and SOI2), Manifold Absolute Pressure (MAP), lambda, Exhaust Gas Recirculation (EGR) and Blending Ratio (BR), and validated using RCCI experimental data. In these models, selected emissions - including HC, CO, PM and NOx-, Exhaust Gas Temperature (EGT) and BSFC were computed using correlations as functions of independent input variables. The computed EGT were then used to estimate the Selective Catalyst Reduction (SCR) and Diesel Oxidation Catalyst (DOC) efficiencies to assess the emission data for different input variables by considering after-treatment system to see if they meet the tailpipe emission regulation. Running the engine with this calibrated input parameters not only meet the Tier 3 Bin 20 EPA standard, but also minimized the cost of operation in RCCI mode within 3 to 12 bar IMEP engine load at 1500 RPM engine speed.
Book Synopsis Advanced Direct Injection Combustion Engine Technologies and Development by : H Zhao
Download or read book Advanced Direct Injection Combustion Engine Technologies and Development written by H Zhao and published by Elsevier. This book was released on 2009-12-18 with total page 761 pages. Available in PDF, EPUB and Kindle. Book excerpt: Volume 2 of the two-volume set Advanced direct injection combustion engine technologies and development investigates diesel DI combustion engines, which despite their commercial success are facing ever more stringent emission legislation worldwide. Direct injection diesel engines are generally more efficient and cleaner than indirect injection engines and as fuel prices continue to rise DI engines are expected to gain in popularity for automotive applications. Two exclusive sections examine light-duty and heavy-duty diesel engines. Fuel injection systems and after treatment systems for DI diesel engines are discussed. The final section addresses exhaust emission control strategies, including combustion diagnostics and modelling, drawing on reputable diesel combustion system research and development. Investigates how HSDI and DI engines can meet ever more stringent emission legislation Examines technologies for both light-duty and heavy-duty diesel engines Discusses exhaust emission control strategies, combustion diagnostics and modelling
Book Synopsis Implementation and Control of Stoichiometric Natural Gas Combustion to Enable Low-emission Diesel Engines by : Nathaniel Bryce Oliver
Download or read book Implementation and Control of Stoichiometric Natural Gas Combustion to Enable Low-emission Diesel Engines written by Nathaniel Bryce Oliver and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The expected growth in the heavy-duty transportation sector necessitates the development of engine technologies able to increase efficiency and reduce emissions without sacrificing power output. Previous research has demonstrated that reducing heat transfer losses from the cylinder can enable significant efficiency gains in Diesel engines. The high in-cylinder temperatures generated in this engine architecture enable the use of low-cetane fuels with the potential for low-soot operation. Low soot emissions allow the equivalence ratio to be increased to stoichiometric which increases power, and could allow the existing Diesel aftertreatment system to be replaced with a less-expensive three-way catalyst. Natural gas is a promising candidate for stoichiometric, high-temperature, Diesel-style combustion. Its high hydrogen-to-carbon ratio should be able to reduce both soot and carbon dioxide emissions, and its wide distribution as a commercial and residential fuel provides existing infrastructure to speed deployment in transportation applications. This thesis demonstrates stoichiometric, Diesel-style combustion of neat methane as a single-component surrogate for natural gas. It explores the challenges of injecting a gaseous fuel at high pressures, and demonstrates the fuel's capacity for low emissions. It then provides a preliminary investigation into multiple-injection strategies for controlling combustion behavior and emissions in a stoichiometric, high-temperature engine architecture. First, fuel system hardware is developed to enable gaseous operation and preliminary experimentation is accomplished with methane. A fuel compression system is designed to supply methane at pressures suitably high to achieve good mixing and short injection durations, and a solenoid-actuated Diesel fuel injector is modeled and modified to inject methane at these pressures. This fuel injection system is then implemented on a single-cylinder engine. An insulated piston face, air cooled head, and intake preheating achieve suitable start of injection temperatures to ignite methane. Intake preheating is varied at low equivalence ratios to determine the sensitivity of engine performance to temperature at the lowest-load, lowest-temperature conditions of interest. A sweep of equivalence ratio demonstrates soot emissions roughly four times the current EPA limit for heavy-duty vehicles and combustion efficiencies of approximately 92% at stoichiometric fuel loading. High soot levels and low combustion efficiencies are also seen at the lowest equivalence ratios investigated. This suggests poorly mixed combustion, and poor injector performance. Second, injector dynamics are examined in greater detailed, and emissions performance is characterized with improved injector performance. High-speed Schlieren imaging is able to determine the injection dynamics contributing to high low-load emissions. A parametric modeling investigation suggests that reducing the injector plunger length is able to remove flow rate oscillations seen at long injection durations, and that the addition of dry friction is able to reduce the magnitude of low-momentum post injections occurring after injector closing. Dry friction is implemented using PTFE O-rings installed between the injector body and plunger. Imaging is used to confirm that a shortened plunger is able to remove long-duration oscillations, and to determine the number of O-rings necessary to suitably reduce post injection magnitude. The improved injector is used to repeat the sweep of equivalence ratios and demonstrates improved soot emissions at all operating conditions. Most notably, low-load soot emissions are reduced by more than a factor of ten, demonstrating the effectiveness of improved injector performance for improving emissions. Techniques for further improving injector performance and potential changes to injector design are discussed. Finally, the prospects for controlling combustion in a stoichiometric, low heat rejection Diesel engine using multiple injections are discussed and experimentally investigated. The applications and effects of multiple injection strategies in traditional Diesel engines are explored, and their potential extension to stoichiometric engines is discussed. Methanol engine operation enables the use of a fast-actuating piezoinjector and the realization of short injection pulses. A range of two-injection strategies are implemented in order to determine the sensitivity of engine operation to pilot, split-main, and post-injection timing and duration. Small pilot injections are found to have control authority over rate of pressure rise and peak pressure and show some promise for improving combustion efficiency. Post injections demonstrate authority over peak pressure and combustion efficiency. All of these effects are accomplished with minimal impact on engine work output. The experiments of this thesis demonstrate that, even with course control of injection, high-temperature, stoichiometric combustion of methane is able to greatly reduce soot emissions over traditional Diesel engines. Improved injector dynamics and the implementation of multiple injection strategies further improve emissions and combustion performance, suggesting substantial room for refinement of the technology and motivating the continued development of injector hardware and injection strategies. The ability to operate a Diesel engine at stoichiometric fueled only by natural gas and to employ a three-way catalyst for emissions abatement makes this strategy a clean, efficient, high-torque, and low-cost solution for heavy-duty transportation.
Book Synopsis Optimization Methods for the Mixture Formation and Combustion Process in Diesel Engines by : Jost Weber
Download or read book Optimization Methods for the Mixture Formation and Combustion Process in Diesel Engines written by Jost Weber and published by Cuvillier Verlag. This book was released on 2008-09-02 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: The optimization of the combustion and mixture formation process in Diesel engines by CFD simulations requires a reliable model approach as a pre-requisite in order to predict combustion and emissions. A general and commonly used model for the liquid spray is the discrete droplet model. Sub-models for droplet breakup, collision and coalescence, and evaporation are available in the CFD code. With regard to combustion, the flamelet model approach is interactively coupled with the CFD code, known as RIF model. It benefits from a one-dimensional description of the thin reaction zone in the flame. By this approach, a detailed reaction mechanism for the model fuel can be used. Sub-mechanisms for NOx formation and a soot model are included. The reaction mechanism has been modified in this work to account for a correct ignition delay and heat-release at low-temperature conditions e.g. in the PCCI combustion. The modeling of the mixture formation in a spray contains uncertainties in the model constants and initial conditions. Spray data is required to calibrate the spray model. At least, the spray penetration has to be measured under engine like conditions as performed in a spray chamber. The spray penetration is interpreted as a criterion for the mass and momentum exchange between the spray and the surrounding gas on a macroscopic level. Finding a good agreement for the spray penetration between simulation and experiment defines an optimization problem. That agreement is expressed in an Euclidean norm as a merit function. The objective is to minimize this merit function. The search for an appropriate set of spray model parameters and initial conditions is denoted here as calibration of the spray model. Six parameters have been identified, spanning a six dimensional parameter space. A manual search is not feasible anymore but the implemented Genetic Algorithm is suitable to find a global optimum where a good agreement between measured and simulated spray penetration is obtained. If the same spray parameters are applied to a virtual engine case, a similar good agreement is achieved although the mesh resolution is much finer and the mesh topology is different than for the spray chamber simulation. From this result, spray data for engine simulations should be provided and be used for sake of calibration before the engine simulation is conducted. Additionally data is obtained by PDA measurements at discrete points in the spray. That measurement technique is, however, limited to less dense areas. Nevertheless, it shows that also local data is in agreement with the simulation data. Agreement with spray penetration is thus a relatively good choice and accounts also for the physics on a local or microscopic level. That hypothesis is well supported by the data from the ethanol spray calibration. The excellent agreement with regard to the global spray penetration is reflected by the 2D comparison of liquid and vapor fuel concentrations and temperature, respectively. Furthermore, a similar good agreement in spray penetration is obtained if the breakup and collision model is not used. In that case, the spray penetration is only controlled by the evaporation process. The Genetic Algorithm finds a point in the parameter space with an initial SMR that is of the order of size of the outcome of the secondary droplet breakup. However in engine simulations, spray data is not always available. In that case the spray parameters have to be adjusted. That adjustment is carried out following a methodology that is presented in this work. Mainly, SOI and EGR variations have to be used to calibrated the spray and combustion model. That approach has been investigated for three different engine data sets for conventional and PCCI combustion mode. On the Cummins QSX engine, a conventional combustion has been studied. Spray parameters are subject of adjustment. On the Duramax 6600 Diesel engine, a conventional and PCCI combustion mode are investigated. For the PCCI combustion mode, the reaction mechanism is modified in order to account for a correct ignition delay in the low temperature combustion regime. The comparison between engine data and results from the simulation indicates a good agreement for the combustion and engineout emissions. On the Duramax full load case, most uncertainties are addressed to the spray-wall interaction. Uncertainties from physical not well based models will always occur in the engine simulation. Therefore, calibration of these models is a mean to quantify its influence and minimize the discrepancies.
Book Synopsis Investigations of Advanced Injection and Combustion Strategies on DI Diesel Engine Performance and Emissions by : Raouf Mobasheri
Download or read book Investigations of Advanced Injection and Combustion Strategies on DI Diesel Engine Performance and Emissions written by Raouf Mobasheri and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The main driving force behind this research was the need for cleaner and more efficient engines to meet the ever-increasing demands on the modern automobile's emissions. In recent years different studies have been carried out to analyze the combined effects of high-pressure injection, boost pressure, multiple injections, included spray angle and combustion chamber geometry. Though considerable research has shown these technologies can meet the low emission regulations, the careful optimization of the engine operating conditions is still required in order to get the full benefit of the different strategies. With these issues as motivation, the first important objective of this study was to gain a detailed understanding of the mechanisms through which fuel injection interacts with other engine parameters and influences diesel combustion and emissions, and hence to attempt to generalize the adoption of multiple injection strategies with regards to improving diesel engine performance. For this purpose, a modified parameter called "Homogeneity Factor of in-cylinder charge" (HF) was introduced and proposed as a new measure in combustion theory to analyze the combustion characteristics and air-fuel mixing process of diesel engines in more detail. The second part of this research builds upon a detail investigation on the included spray cone angle concept and explores further their use in conjunction with multiple-injection strategies in diesel engines. In addition, an investigation was performed in third phase of this research to analyze the effects of piston geometry on combustion, performance and exhaust emission characteristics. The results showed that employing a post-injection combined with a pilot injection results in reduced soot formation from diffusion combustion and enhances the soot oxidation process during the expansion stroke, resulting in decreased soot emissions, while the NOx concentration is maintained in low levels. It was also found that spray targeting is very effective for controlling the in-cylinder mixture distributions especially when it accompanied with advanced injection strategies. Moreover, the results confirmed that a narrower width of piston bowl has a higher unburned fuel air mixture region and hence results in higher soot emissions but with slightly larger piston surface area the optimum operating point could be obtained.
Book Synopsis Adaptive Engine Injection for Emissions Reduction by :
Download or read book Adaptive Engine Injection for Emissions Reduction written by and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: NOx and soot emissions from internal combustion engines, and in particular compression ignition (diesel) engines, are reduced by varying fuel injection timing, fuel injection pressure, and injected fuel volume between low and greater engine loads. At low loads, fuel is injected during one or more low-pressure injections occurring at low injection pressures between the start of the intake stroke and approximately 40 degrees before top dead center during the compression stroke. At higher loads, similar injections are used early in each combustion cycle, in addition to later injections which preferably occur between about 90 degrees before top dead center during the compression stroke, and about 90 degrees after top dead center during the expansion stroke (and which most preferably begin at or closely adjacent the end of the compression stroke). These later injections have higher injection pressure, and also lower injected fuel volume, than the earlier injections.
