Download or read book Characterization of the homogeneous charge compression ignition combustion process written by Anders Hultqvist and published by . This book was released on 2002 with total page 95 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Control and Robustness Analysis of Homogeneous Charge Compression Ignition Using Exhaust Recompression written by Hsien-Hsin Liao and published by Stanford University. This book was released on 2011 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been an enormous global research effort to alleviate the current and projected environmental consequences incurred by internal combustion (IC) engines, the dominant propulsion systems in ground vehicles. Two technologies have the potential to improve the efficiency and emissions of IC engines in the near future: variable valve actuation (VVA) and homogeneous charge compression ignition (HCCI). IC engines equipped with VVA systems are proven to show better performance by adjusting the valve lift and timing appropriately. An electro-hydraulic valve system (EHVS) is a type of VVA system that possesses full flexibility, i.e., the ability to change the valve lift and timing independently and continuously, making it an ideal rapid prototyping tool in a research environment. Unfortunately, an EHVS typically shows a significant response time delay that limits the achievable closed-loop bandwidth and, as a result, shows poor tracking performance. In this thesis, a control framework that includes system identification, feedback control design, and repetitive control design is presented. The combined control law shows excellent performance with a root-mean-square tracking error below 40 [Mu]m over a maximum valve lift of 4 mm. A stability analysis is also provided to show that the mean tracking error converges to zero asymptotically with the combined control law. HCCI, the other technology presented in this thesis, is a combustion strategy initiated by compressing a homogeneous air-fuel mixture to auto-ignition, therefore, ignition occurs at multiple points inside the cylinder without noticeable flame propagation. The result is rapid combustion with low peak in-cylinder temperature, which gives HCCI improved efficiency and reduces NOx formation. To initiate HCCI with a typical compression ratio, the sensible energy of the mixture needs to be high compared to a spark ignited (SI) strategy. One approach to achieve this, called recompression HCCI, is by closing the exhaust valve early to trap a portion of the exhaust gas in the cylinder. Unlike a SI or Diesel strategy, HCCI lacks an explicit combustion trigger, as autoignition is governed by chemical kinetics. Therefore, the thermo-chemical conditions of the air-fuel mixture need to be carefully controlled for HCCI to occur at the desired timing. Compounding this challenge in recompression HCCI is the re-utilization of the exhaust gas which creates cycle-to-cycle coupling. Furthermore, the coupling characteristics can change drastically around different operating points, making combustion timing control difficult across a wide range of conditions. In this thesis, a graphical analysis examines the in-cylinder temperature dynamics of recompression HCCI and reveals three qualitative types of temperature dynamics. With this insight, a switching linear model is formulated by combining three linear models: one for each of the three types of temperature dynamics. A switching controller that is composed of three local linear feedback controllers can then be designed based on the switching model. This switching model/control formulation is tested on an experimental HCCI testbed and shows good performance in controlling the combustion timing across a wide range. A semi-definite program is formulated to find a Lyapunov function for the switching model/control framework and shows that it is stable. As HCCI is dictated by the in-cylinder thermo-chemical conditions, there are further concerns about the robustness of HCCI, i.e., the boundedness of the thermo-chemical conditions with uncertainty existing in the ambient conditions and in the engine's own characteristics due to aging. To assess HCCI's robustness, this thesis presents a linear parameter varying (LPV) model that captures the dynamics of recompression HCCI and possesses an elegant model structure that is more amenable to analysis. Based on this model, a recursive algorithm using convex optimization is formulated to generate analytical statements about the boundedness of the in-cylinder thermo-chemical conditions. The bounds generated by the algorithm are also shown to relate well to the data from the experimental testbed.
Download or read book Inflation Kaufkraft Wechselkurs written by and published by . This book was released on 1986 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design Considerations Modeling and Analysis of Micro homogeneous Charge Compression Ignition Combustion Free piston Engines written by Hans Thomas Aichlmayr and published by . This book was released on 2002 with total page 520 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis of Homogeneous Charge Compression Ignition Engine with Emphasis on Combustion Timing and Reaction Rate written by Arunim Bhattacharya and published by . This book was released on 2017 with total page 39 pages. Available in PDF, EPUB and Kindle. Book excerpt: HCCI engines are a class of engines which use high compression ratio to ignite a charge of air-fuel mixture, essentially eliminating the need for spark plugs. This contrasts with diesel engines (although HCCI can be used for diesel engines) where the fuel is injected near the top dead center of the compression stroke regime. Gasoline HCCI engines are of significance because, it attempts to improve the characteristics of the engine for example the thermal efficiency. High compression ratio comes with higher thermal efficiency, yet the peak temperature remains low enough to have low production rates of harmful oxides of nitrogen and formation of soot. However, there are certain challenges associated with such type of engine, one of which and perhaps the most important of all is how to control the combustion rate. Flow dynamics and chemical-kinetics analysis, is essential to predict combustion timing, duration, and rate. The objective of this study is to analyze a HCCI engine using, simulation analysis models including a three-dimensional CFD simulation model. Simulation analysis is carried out using a generic HCCI engine, initially with simplified chemical kinetics, and then using detailed chemical kinetics and using RANS turbulence CFD model. A sensitivity analysis of the effect of RPM on the combustion time, burn duration, heat release, efficiency and emission concentration are carried out.
Download or read book HCCI Combustion written by and published by . This book was released on 2001 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work. On analysis, we have developed two powerful tools: a single zone model and a multi-zone model. The single zone model has proven very successful in predicting start of combustion and providing reasonable estimates for peak cylinder pressure, indicated efficiency and NOX emissions. This model is being applied to develop detailed engine performance maps and control strategies, and to analyze the problem of engine startability. The multi-zone model is capable of very accurate predictions of the combustion process, including HC and CO emissions. The multi-zone model h as applicability to the optimization of combustion chamber geometry and operating conditions to achieve controlled combustion at high efficiency and low emissions. On experimental work, we have done a thorough evaluation of operating conditions in a 4-cylinder Volkswagen TDI engine. The engine has been operated over a wide range of conditions by adjusting the intake temperature and the fuel flow rate. Satisfactory operation has been obtained over a wide range of operating conditions. Cylinder-to-cylinder variations play an important role in limiting maximum power, and should be controlled to achieve satisfactory performance.
Download or read book HCCI and CAI Engines for the Automotive Industry written by Hua Zhao and published by CRC Press. This book was released on 2007-09-10 with total page 562 pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous charge compression ignition (HCCI)/controlled auto-ignition (CAI) has emerged as one of the most promising engine technologies with the potential to combine fuel efficiency and improved emissions performance, offering reduced nitrous oxides and particulate matter alongside efficiency comparable with modern diesel engines. Despite the considerable advantages, its operational range is rather limited and controlling the combustion (timing of ignition and rate of energy release) is still an area of on-going research. Commercial applications are, however, close to reality. HCCI a.
Download or read book New Generation of Engine written by Pierre Duret and published by Editions OPHRYS. This book was released on with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Homogeneous Charge Compression Ignition HCCI Engines written by Fuquan Zhao and published by SAE International. This book was released on 2003-01-01 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt: The homogeneous charge, compression-ignition (HCCI) combustion process has the potential to significantly reduce NOx and particulate emissions, while achieving high thermal efficiency and the capability of operating with a wide variety of fuels. This makes the HCCI engine an attractive technology that can ostensibly provide diesel-like fuel efficiency and very low emissions, which may allow emissions compliance to occur without relying on lean aftertreatment systems. A profound increase in the level of research and development of this technology has occurred in the last decade. This book gathers contributions from experts in both industry and academia, providing a basic introduction to the state-of-the-art of HCCI technology, a critical review of current HCCI research and development efforts, and perspective for the future. Chapters cover: Gasoline-Fueled HCCI Engines; Diesel-Fueled HCCI Engines; Alternative Fuels and Fuel Additives for HCCI Engines; HCCI Control and Operating Range Extension; Kinetics of HCCI Combustion; HCCI Engine Modeling Approaches.In addition to the extensive overview of terminology, physical processes, and future needs, each chapter also features select SAE papers (a total of 41 are included in the book), as well as a comprehensive list of references related to the subjects. Homogeneous Charge Compression Ignition (HCCI) Engines: Key Research and Development Issues provides a valuable base of information for those interested in learning about this rapidly-progressing technology which has the potential to enhance fuel economy and reduce emissions.
Download or read book An Experimental Characterization of HCCI DI Mixed mode Operation Utilizing External Mixture Formation in a 2 5 Liter Common Rail Diesel Engine written by Joel Michael Cowgill and published by . This book was released on 2007 with total page 338 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: In order to meet future emissions requirements for internal combustion engines, continuing advances in emission reduction techniques are imperative. A method for in-cylinder emissions reduction currently being investigated quite extensively is Homogeneous Charge Compression Ignition (HCCI). An engine operating in pure HCCI combustion is capable of reducing NOx and PM emissions to near zero levels. However, HCCI engines are typically limited to low and mid-load operation due to high cylinder pressure-rise-rates associated with compression ignition of a homogeneous charge. One method of extending this operating range, investigated in this work, is the combination of HCCI combustion with standard CIDI combustion in a mixed-mode operating scheme. This method combines the emissions benefits of HCCI combustion with the high efficiency operation of standard Diesel combustion. Steady-state engine operating conditions are explored in pure HCCI and HCCI/DI mixed-mode operation and compared to baseline operating conditions of standard CIDI in a production 2.5L common rail Diesel engine. In this work, homogeneous mixture preparation is performed utilizing an external atomization device. In preliminary characterization, the effects of HCCI ratio, EGR ratio and DI timing are explored and the advantages of mixed-mode operation is verified over that of standard CIDI Diesel combustion. Following definition of the most important combustion control parameters, a comprehensive sensitivity analysis of EGR ratio, DI timing, engine speed and engine load is also conducted in mixed-mode operation with a focus on the effects of engine out emissions and combustion characteristics. Additionally, the limits of HCCI operation in this particular engine are also explored in order to define a baseline location for the transition to mixed-mode operation. In order to truly ascertain the benefits of mixed-mode combustion, results of mixed-mode operation are contrasted against manufacturer's engine maps for NOx and PM emissions as well as fuel consumption. The results of rough optimization illustrate that significant reduction in NOx emissions are possible with reasonable PM emissions easily eliminated with a current generation DPF. Fuel consumption is also found to be significantly reduced in most mixed-mode cases where up to 15 percent reductions are possible in the operating range considered. This fuel consumption decrease is also found to extend to pure HCCI operation and close to 10 percent reductions are discovered between operating speeds of 1500 and 2500 RPM at slightly more than 2 bar BMEP engine load. To set the stage for further research, basic transient operation is also investigated. With a firm grasp and understanding of steady-state operating conditions, control of the transition between pure HCCI, mixed-mode and pure CIDI combustion schemes can be explored. The basic structure of this control format includes pure HCCI operation at low-loads, mixed-mode operation in mid-loads and standard CIDI operation at high-loads. In this work, HCCI operation is found to be relatively insensitive to engine speed; however, increases in engine speed may affect the load threshold conditions at which these transitions occur.
Download or read book HCCl Combustion written by and published by . This book was released on 2001 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work. On analysis, we have developed two powerful tools: a single zone model and a multi-zone model. The single zone model has proven very successful in predicting start of combustion and providing reasonable estimates for peak cylinder pressure, indicated efficiency and NOX emissions. This model is being applied to develop detailed engine performance maps and control strategies, and to analyze the problem of engine startability. The multi-zone model is capable of very accurate predictions of the combustion process, including HC and CO emissions. The multi-zone model has applicability to the optimization of combustion chamber geometry and operating conditions to achieve controlled combustion at high efficiency and low emissions. On experimental work, we have done a thorough evaluation of operating conditions in a 4-cylinder Volkswagen TDI engine. The engine has been operated over a wide range of conditions by adjusting the intake temperature and the fuel flow rate. Satisfactory operation has been obtained over a wide range of operating conditions. Cylinder-to-cylinder variations play an important role in limiting maximum power, and should be controlled to achieve satisfactory performance.
Download or read book Combustion Characteristics of Turbo Charged DISI engines written by Henrik Hoffmeyer and published by Logos Verlag Berlin GmbH. This book was released on 2012 with total page 193 pages. Available in PDF, EPUB and Kindle. Book excerpt: In spite of progress in the development of alternative powertrain systems and energy sources, the internal combustion and all its derivates still are and will be the main powertrain for automobiles. In SI-engines, several approaches compete with each other like the controlled auto ignition (CAI or HCCI), throttle-free load control using variable valvetrains, stratified mixture formation with lean engine operation or highly turbo charged downsizing concepts all combined with gasoline direct injection. The presented work makes a contribution for a deeper understanding of the combustion process of a turbo charged direct injection engine operating with external EGR as well as lean stratified mixture. Using detailed test bench investigations and introducing a new optical measurement tool, the combustion process is described in detail focusing on the occurrence of non-premixed combustion phenomena. The influence of engine parameters like global and local air-/fuel ratio, external EGR and fuel rail pressure as well as the influence of fuel parameters are discussed giving a characterization of the combustion process of stratified engine operation. Furthermore, the influences of non-inert exhaust gas components on engine knock tendency are investigated using external EGR with an EGR catalyst. Opposing the results to numerical analysis, combustion characteristics of turbo charged DISI-engines are presented.
Download or read book Combustion Diagnostics in Homogeneous Charge Compression Ignition Optical and Thermal Single Cylinder Engines written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The work presented in this thesis is intended to investigate the effects of fuel properties, injection strategy and timing on autoignition and combustion characteristics of a Homogeneous Charge Compression Ignition (HCCI) engine with a negative valve overlap (NVO) strategy. Conventional (pressure-transducer based) measurements and passive optical research have contributed to understanding of the chemical-physical sites of HCCI autoignition and combustion. This experimental work was undertaken on matching thermal and optical single cylinder research engines in configurations derived from a production Jaguar V8 engine. A thermal engine study using a range of fuels including conventional gasoline and primary reference fuels has been performed to gain insight into autoignition and combustion characteristics of various chemically dissimilar blends or components. This was done at different operating conditions by varying the engine speed and the proportion of residuals trapped. These measurements have shown that the autoignition and combustion characteristic of an HCCI operated engine are highly dependent on fuel blend composition and are also affected by engine operating conditions. It was found that the autoignition process type which the mixture undergoes, whether it is one- or two-step, depends very strongly both on fuel blend composition and on engine operating conditions. More specifically the presence and also proportion of particular chemical compounds in a blend could significantly contribute to the alteration of the process type. Similar experiments using the chosen engine operating points were repeated on the optical engine using passive optical diagnostics such as imaging and spectroscopy. Thereby it was possible to gain insight into the chemistry of one-step and two- step ignition processes. The image analysis of the port fuel injected (PFI) HCCI operation have been carried out for stoichiometric and lean conditions. A crank-angle resolved high-speed imaging.
Download or read book Advances in Internal Combustion Engine Research written by Dhananjay Kumar Srivastava and published by Springer. This book was released on 2017-11-29 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book discusses all aspects of advanced engine technologies, and describes the role of alternative fuels and solution-based modeling studies in meeting the increasingly higher standards of the automotive industry. By promoting research into more efficient and environment-friendly combustion technologies, it helps enable researchers to develop higher-power engines with lower fuel consumption, emissions, and noise levels. Over the course of 12 chapters, it covers research in areas such as homogeneous charge compression ignition (HCCI) combustion and control strategies, the use of alternative fuels and additives in combination with new combustion technology and novel approaches to recover the pumping loss in the spark ignition engine. The book will serve as a valuable resource for academic researchers and professional automotive engineers alike.
Download or read book Autoignition and Chemical Kinetic Mechanisms of Homogeneous Charge Compression Ignition Combustion for the Fuels with Various Autoignition Reactivity written by Dongwon Jung and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This work demonstrates the autoignition and chemical-kinetic mechanisms of homogeneous charge compression ignition (HCCI) combustion for the fuels with various autoignition reactivity. This is done for four fuels: methane, dimethyl ether (DME), iso-octane and n-heptane. Methane and iso-octane are selected as the single-stage ignition fuel, and DME and n-heptane are selected as the two-stage ignition fuel. As a tool for understanding the characteristics of autoignition and combustion process in HCCI engine, a zero-dimensional single-zone engine model of 'CHEMKIN' in Chemkin-Pro was used. The complete compression and expansion strokes were modeled using an engine with a connecting-rod length to crank-radius ratio of 3.5 and a compression ratio of 13. A detailed chemical-kinetic mechanism for methane and DME is Mech_56.54 (113 species and 710 reactions). For iso-octane and n-heptane, a detailed chemical-kinetic mechanism from Lawrence Livermore National Laboratory (1034 species and 4236 reactions) is used. The results show that methane and iso-octane exhibit only the main heat release, 'high-temperature heat release (HTHR)' by high-temperature reactions (HTR). In contrast, both DME and n-heptane exhibit the first heat release 'low-temperature heat release (LTHR)' associated with low-temperature reactions (LTR) before HTHR.
Download or read book Study of homogeneous charge compression ignition HCCI combustion and emission characteristics in a multi cylinder engine written by Jacek Waldemar Misztal and published by . This book was released on 2008 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Assessment of Fuel Economy Technologies for Light Duty Vehicles written by National Research Council and published by National Academies Press. This book was released on 2011-06-03 with total page 373 pages. Available in PDF, EPUB and Kindle. Book excerpt: Various combinations of commercially available technologies could greatly reduce fuel consumption in passenger cars, sport-utility vehicles, minivans, and other light-duty vehicles without compromising vehicle performance or safety. Assessment of Technologies for Improving Light Duty Vehicle Fuel Economy estimates the potential fuel savings and costs to consumers of available technology combinations for three types of engines: spark-ignition gasoline, compression-ignition diesel, and hybrid. According to its estimates, adopting the full combination of improved technologies in medium and large cars and pickup trucks with spark-ignition engines could reduce fuel consumption by 29 percent at an additional cost of $2,200 to the consumer. Replacing spark-ignition engines with diesel engines and components would yield fuel savings of about 37 percent at an added cost of approximately $5,900 per vehicle, and replacing spark-ignition engines with hybrid engines and components would reduce fuel consumption by 43 percent at an increase of $6,000 per vehicle. The book focuses on fuel consumption-the amount of fuel consumed in a given driving distance-because energy savings are directly related to the amount of fuel used. In contrast, fuel economy measures how far a vehicle will travel with a gallon of fuel. Because fuel consumption data indicate money saved on fuel purchases and reductions in carbon dioxide emissions, the book finds that vehicle stickers should provide consumers with fuel consumption data in addition to fuel economy information.
