Author: Tommy Tzanetakis
Publisher:
ISBN: 9780494161692
Category :
Languages : en
Pages : 252
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Book Description
Homogeneous charge compression ignition (HCCI) is a viable alternative to current internal combustion modes. HCCI engines exhibit high thermal efficiencies and produce near-zero NOx and soot emissions. In this study, a numerical multi-zone model has been developed in order to predict experimental data from an HCCI engine fuelled with PRF20. The experimental study used dilution to indirectly control combustion and map out the knocking and misfire engine operating limits. These operating limits were examined with the multi-zone model and the trends based on dilution with EGR and excess air ratio were reproduced. Results also indicated that small changes of initial temperature within the reported experimental variance were able to capture the cyclic variability observed in the data. Two PRF chemical kinetic mechanisms of varying detail were contrasted and did not show significant differences in predicted results. Introducing trapped residual gases also did not drastically change the modeled trends.
Author: Pablo Mendoza Villafuerte
Publisher:
ISBN:
Category :
Languages : en
Pages : 251
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Author: Roy Ogink
Publisher:
ISBN:
Category :
Languages : en
Pages : 61
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Author: Volker M. Sohm
Publisher:
ISBN:
Category :
Languages : en
Pages : 344
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Book Description
Author: Luigi Del Re
Publisher: Springer Science & Business Media
ISBN: 1849960704
Category : Technology & Engineering
Languages : en
Pages : 291
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Book Description
Automotive control has developed over the decades from an auxiliary te- nology to a key element without which the actual performances, emission, safety and consumption targets could not be met. Accordingly, automotive control has been increasing its authority and responsibility – at the price of complexity and di?cult tuning. The progressive evolution has been mainly ledby speci?capplicationsandshorttermtargets,withthe consequencethat automotive control is to a very large extent more heuristic than systematic. Product requirements are still increasing and new challenges are coming from potentially huge markets like India and China, and against this ba- ground there is wide consensus both in the industry and academia that the current state is not satisfactory. Model-based control could be an approach to improve performance while reducing development and tuning times and possibly costs. Model predictive control is a kind of model-based control design approach which has experienced a growing success since the middle of the 1980s for “slow” complex plants, in particular of the chemical and process industry. In the last decades, severaldevelopments haveallowedusing these methods also for “fast”systemsandthis hassupporteda growinginterestinitsusealsofor automotive applications, with several promising results reported. Still there is no consensus on whether model predictive control with its high requi- ments on model quality and on computational power is a sensible choice for automotive control.
Author: Nedunchezhian Swaminathan
Publisher: Cambridge University Press
ISBN: 1139498584
Category : Technology & Engineering
Languages : en
Pages : 447
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Book Description
A work on turbulent premixed combustion is important because of increased concern about the environmental impact of combustion and the search for new combustion concepts and technologies. An improved understanding of lean fuel turbulent premixed flames must play a central role in the fundamental science of these new concepts. Lean premixed flames have the potential to offer ultra-low emission levels, but they are notoriously susceptible to combustion oscillations. Thus, sophisticated control measures are inevitably required. The editors' intent is to set out the modeling aspects in the field of turbulent premixed combustion. Good progress has been made on this topic, and this cohesive volume contains contributions from international experts on various subtopics of the lean premixed flame problem.
Author: Varun Tandra
Publisher:
ISBN:
Category :
Languages : en
Pages : 218
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Book Description
With growing environmental concern, energy consumption has become a key element in the current debate on global warming. Over the past two decades, Homogeneous Charge Compression Ignition (HCCI) engine technology has aroused a great deal of interest in the automotive sector owing to its fuel flexibility and ability to generate ultra-low exhaust emissions. One of the strategies to achieve ultra-low emissions in HCCI engines is to retain some exhaust gas/burnt products in the cylinder by dynamically actuating/varying valve opening and closing timings and lifts. This can be achieved by recent advancements in microprocessor, actuators and controller technologies. The first step in the synthesis of control algorithms involves developing simple system-level mathematical models. This thesis presents two such mathematical models of HCCI combustion. In the first part of this thesis, a control-oriented two-zone thermo-kinetic model of a single cylinder HCCI engine is presented. Earlier control laws were derived using single zone mathematical models of HCCI combustion; however, such models fail to accurately capture the combustion dynamics of an HCCI engine owing to the assumption of homogeneous composition and temperature in the cylinder. Certain multi-zone models of HCCI engines emphasizing the shortcomings of these single zone models have also been reported in literature. However, such models are far too complex and unwieldy for the development of fast and efficient controllers for HCCI engines. The present work outlines the modeling approach of a physics based two-zone model of a single-cylinder HCCI engine by incorporating the first law of thermodynamics and the temperature and concentration inhomogeneities within the cylinder in order to better predict emissions, peak pressures, and timing. A comparative analysis between the single zone and two-zone models is also discussed. The nonlinear model was linearized about an operating point to facilitate the development of an effective LQR regulator. The model inputs include variable valve timing to effectively control peak pressures, exhaust temperatures and ignition timing. In the second part of the thesis we address the shortcomings of control analysis which to date has been done by developing models that are engine specific, such models often rely on extensive parameters which are to be experimentally identified. Moreover, further investigation revealed that these models were valid only for a narrow operating range. Therefore, a detailed mathematical model of an HCCI engine, which is fuel flexible and valid for transitions in engine speed, is developed based on ideal gas laws and basic thermodynamics and conservation principles. The different engine subsystems and engine phenomena discretized into eight stages are modeled in a "control-oriented sense" to address the combustion timing, peak pressure and heat release rate control issues. The model has been implemented in MATLAB® to facilitate simulation studies and requires minimum tuning parameters to be experimentally recognized. Model validation is based on three sets of engine data, obtained from literature. The validation suggests that the model, once tuned properly, shows a fair agreement between the simulation and experimental data for a given engine and operating conditions.
Author: Carsten Baumgarten
Publisher: Springer Science & Business Media
ISBN: 3540308369
Category : Technology & Engineering
Languages : en
Pages : 312
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Book Description
A systematic control of mixture formation with modern high-pressure injection systems enables us to achieve considerable improvements of the combustion pr- ess in terms of reduced fuel consumption and engine-out raw emissions. However, because of the growing number of free parameters due to more flexible injection systems, variable valve trains, the application of different combustion concepts within different regions of the engine map, etc., the prediction of spray and m- ture formation becomes increasingly complex. For this reason, the optimization of the in-cylinder processes using 3D computational fluid dynamics (CFD) becomes increasingly important. In these CFD codes, the detailed modeling of spray and mixture formation is a prerequisite for the correct calculation of the subsequent processes like ignition, combustion and formation of emissions. Although such simulation tools can be viewed as standard tools today, the predictive quality of the sub-models is c- stantly enhanced by a more accurate and detailed modeling of the relevant pr- esses, and by the inclusion of new important mechanisms and effects that come along with the development of new injection systems and have not been cons- ered so far. In this book the most widely used mathematical models for the simulation of spray and mixture formation in 3D CFD calculations are described and discussed. In order to give the reader an introduction into the complex processes, the book starts with a description of the fundamental mechanisms and categories of fuel - jection, spray break-up, and mixture formation in internal combustion engines.
Author: Allen Charles Ernst
Publisher:
ISBN:
Category : Diesel motor
Languages : en
Pages : 170
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Book Description
"Homogeneous Charge Compression Ignition (HCCI) may be the next leap of improvement to internal combustion engines due to its decreased emissions and improved engine efficiencies. However, such a jump possesses challenges owing to its strict reliance on the inherent physics that dictate start of combustion and limit the reach of stable operation. This work investigates the role and fundamental influence of carbon monoxide on the cycle-to-cycle combustion dynamics present in the region of incomplete combustion that frames the limited HCCI operating region. An improved understanding will open doors to enhanced control methodologies and an expanded stable operating envelope. A constant volume chemical kinetics simulation was developed utilizing an established skeletal PRF mechanism in order to predict product species evolution in an HCCI engine under incomplete combustion conditions. The predicted product species amounts were harnessed to determine internally trapped residual carbon monoxide mass amounts that would be carried to the next engine cycle. These amounts became the basis for an experimental investigation on a single cylinder HCCI engine running on a high octane primary reference fuel. Cyclically resolved, in-cylinder active-specie injections were employed at partial burn operation to explore the effects of carbon monoxide on engine performance and its resultant cyclic dynamics. Observations made through detailed cyclic performance data, return maps, and symbol sequencing analysis help to expose a significant impact of carbon monoxide on HCCI combustion development and the potential it may possess to drive HCCI combustion as a future dynamic control mechanism"--Abstract, page iii.
Author: Paitoon Kongsereeparp
Publisher:
ISBN: 9780768016369
Category : Engines
Languages : en
Pages :
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