Author: K. Seshadri Publisher: ISBN: Category : Languages : en Pages :
Book Description
A study was performed to elucidate the chemical-kinetic mechanism of combustion of toluene. The research was performed in collaboration Dr. Charles Westbrook and Dr. William Pitz at Lawrence Livermore National Laboratory (LLNL). A detailed chemical-kinetic mechanism for toluene developed at LLNL was employed. Numerical calculations were performed using this mechanism and the results were compared with experimental data obtained from premixed and nonpremixed systems. Under premixed conditions, predicted ignition delay times were compared with new experimental data obtained by I. Da Costa, R. Fournet, F. Billaud, F. Battin-Leclerc at Departement de Chime Physique des Reactions, CNRS-ENSIC, BP. 451, 1, rue Grandville, 51001 Nancy, France. Also, calculated species concentration histories were compared to experimental flow reactor data from the literature. Under nonpremixed conditions, critical conditions of extinction and autoignition were measured in strained laminar flows in the counterflow configuration. Numerical calculations were performed using the chemical-kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and autoignition are predicted and compared with the experimental data. Comparisons between the model predictions and experimental results of ignition delay times in shock tube, and extinction and autoignition in nonpremixed systems show that the chemical-kinetic mechanism predicts that toluene/air is overall less reactive than observed in the experiments. The principal objective of this research is to obtain a fundamental understanding of the physical and chemical mechanisms of autoignition and combustion of Diesel in nonpremixed systems. The major components of Diesel are straight-chain paraffins, branched-chain paraffins, cycloparaffins, and aromatics. The results of this research on toluene are expected to be useful in understanding the role of aromatics in combustion of Diesel.
Author: Publisher: ISBN: Category : Languages : en Pages : 53
Book Description
The objective of the research was to obtain a fundamental understanding of the physical and chemical mechanisms of autoignition and combustion of diesel and JP-8 in non-premixed systems. Diesel and JP-8 are comprised of hundreds of aliphatic and aromatic hydrocarbon compounds. The major components of these fuels are straight chain paraffins, branched chain paraffins, cycloparaffins, aromatics, and alkenes. Detailed chemical kinetic mechanisms that describe combustion of many of the components in diesel and JP-8 are not available and are unlikely to be developed in the near future. As a consequence, it is necessary to develop surrogate fuels. The research was focused on developing the necessary scientific knowledge for developing these surrogate fuels. The experimental part of the research was performed employing the counterflow configuration. The fuels tested were n-heptane, n-decane, n-dodecane, n-hexadecane, cyclohexane, methylcyclohexane, toluene, and o-xylene because they represent the types of fuels in diesel and JP-8. Critical conditions of autoignition and extinction were measured. Flame structures were measured for non-premixed n-heptane flames and n-decane flames. For n-heptane and n-decane flames, numerical calculations were performed using detailed chemistry and the results were compared with experiments.
Author: Goutham Kukkadapu Publisher: ISBN: Category : Electronic dissertations Languages : en Pages :
Book Description
The design process for development of engines could be made faster and less expensive with the help of computations which help understanding the processes prevalent in internal combustion engines. Running engine simulations are challenging as they need to accurately capture the fluid dynamic and chemical kinetic processes that occur in an engine. A major challenge in simulating chemical kinetic processes is the complexity of the fuel chemistry: real fuels are complex mixtures whose composition determines their physical properties and reactivity. The behavior of these real fuels can be conveniently represented using simpler mixtures often called â€surrogates mixtures†that match the key properties of the real fuels. Successful modeling of the ignition of real fuel first requires the formulation of an appropriate surrogate mixture whose compositions are carefully chosen in order to best emulate the combustion properties of the targeted real fuel. Then a comprehensive chemical kinetic model developed based on the surrogate fuel is used to simulate the combustion process of the real fuel. The work presented in the current dissertation intends to systematically study the surrogate modeling of diesel fuels. The study has been conducted to understand the ignition of surrogate fuel constituents and fully blended diesel fuels. Autoignition of tetralin, 1-methylnaphthalene, iso-cetane, and n-dodecane, the constituents of diesel surrogates, are investigated in the current dissertation. Besides, ignition of binary blends of the surrogate constituents has also been studied to investigate the effects of blending on ignition when neat components are blended to formulate a surrogate fuel. Furthermore, the ignition of two fully blended research grade diesel fuels has also been conducted inorder to provide quality ignition delay data for development and validation of chemical kinetic models of kinetic fuels.
Author: Mengyuan Wang Publisher: ISBN: Category : Languages : en Pages : 0
Book Description
Because of increasingly stringent engine emissions and fuel economy standards, there is an urgent need for developing future diesel engines with higher efficiency and lower emissions. Therefore, low temperature combustion is currently being pursued to develop new types of advanced diesel engines. Since low temperature combustion is more sensitive to chemical kinetics, the understanding of the autoignition characteristics of diesel fuels under low-to-intermediate temperatures becomes important. In order to achieve the goal of higher efficiency and lower emissions diesel engines, both experimental and computational investigations of diesel fuels at low-to-intermediate temperatures need to be conducted, as the experimental autoignition results help develop a comprehensive understanding of diesel ignition and provide a validation database for model development, and a comprehensive chemical kinetic model of diesel is also imperative for accurate prediction of ignition and emissions characteristics of diesel engines. Because diesel fuels contain hundreds, even thousands of species, and the composition of diesel is too complex to model, it is also necessary to develop surrogate fuels, which are simpler mixtures that include fuel components representative of hydrocarbon classes found in diesel fuels, and can capture the essential chemical/physical properties and performance characteristics of the target diesel fuel to sufficient accuracy. Therefore, the work presented in the current dissertation aims to gain better understandings and fill in gaps in fundamental combustion data of diesel-surrogate components and surrogate fuel mixtures relevant to diesel fuels. Autoignition of trans-decalin at low-to-intermediate temperatures has been investigated first to get a better understanding of its autoignition characteristics, and the development of a detailed chemical kinetic model of diesel surrogates has been benefited from the results of trans-decalin. The agreements of the developed diesel surrogate model have been tested by comparing with the current autoignition results of diesel surrogates, and possible sources of discrepancies between experimental and simulated results have also been investigated. Based on that, binary blends of iso-cetane and tetralin are further chosen for autoignition investigation to help find out possible reasons causing those discrepancies and to further benefit the refinement and development of comprehensive diesel surrogate models.
Author: Chunsham Song Publisher: CRC Press ISBN: 1000158667 Category : Technology & Engineering Languages : en Pages : 320
Book Description
This edited work covers diesel fuel chemistry in a systematic fashion from initial fuel production to the tail pipe exhaust. The chapters are written by leading experts in the research areas of analytical characterization of diesel fuel, fuel production and refining, catalysis in fuel processing, pollution minimization and control, and diesel fuel additives.
Author: Publisher: ISBN: Category : Languages : en Pages : 17
Book Description
In this study, the primary objectives of this work were to formulate, blend, and characterize a set of four ultralow-sulfur diesel surrogate fuels in quantities sufficient to enable their study in single-cylinder-engine and combustion-vessel experiments. The surrogate fuels feature increasing levels of compositional accuracy (i.e., increasing exactness in matching hydrocarbon structural characteristics) relative to the single target diesel fuel upon which the surrogate fuels are based. This approach was taken to assist in determining the minimum level of surrogate-fuel compositional accuracy that is required to adequately emulate the performance characteristics of the target fuel under different combustion modes. For each of the four surrogate fuels, an approximately 30 L batch was blended, and a number of the physical and chemical properties were measured. This work documents the surrogate-fuel creation process and the results of the property measurements.
Author: Varun Anthony Davies Publisher: ISBN: Category : Chemical kinetics Languages : en Pages : 72
Book Description
Practical fuels are a complex mixture of thousands of hydrocarbon compounds, making it challenging and difficult to study their combustion behavior. It's generally agreed that in order to study these complex practical fuels a much simpler approach of studying simple fuel surrogates containing limited number of components is more feasible. Ethanol and n-heptane have been studied as primary reference fuels in the surrogate study of gasoline and diesel over the past few decades. The objective of the following thesis has been to study the autoignition characteristics of ethanol and n-heptane and validate chemical kinetic mechanisms. The validation of a chemical kinetic mechanism provides a deeper insight into the combustion behavior of the fuels which can be further used to study advanced combustion concepts. Experiments have been conducted on the rapid compression machine (RCM) and validated against mechanisms from literature study. Rapid compression machines have been primarily used to study chemical kinetics at low to intermediate temperatures and high pressures for their accuracy and reproducibility. For the following study experiments span over a range of temperature (650-1000 K), pressure (10, 15 and 20 bar) and equivalence ratio ([phi]=0.3, 0.5, 1). Experimental data based on the adiabatic volumetric expansion approach have been modeled numerically using the Sandia SENKIN code in conjunction with CHEMKIN. Experiments have been primarily focused on validating kinetic mechanisms at low to intermediate temperatures and elevated pressures. Ignition delay time data from experiments have been deduced based on the pressure and time histories. A brute sensitivity and flux analysis has been performed to reveal the key sensitive reactions and the dominant reaction pathways followed under the present experimental conditions. Improvements have been suggested and discrepancies noted in order to develop a valid chemical kinetic mechanism. Under the present experimental conditions for the study of ethanol, reactions involving hydroperoxyl radicals, namely C2H5OH+HȮ2 and CH3CHO+ HȮ2 as well as the formation of H2O2 from HȮ2 radical and its subsequent decomposition have been found to be sensitive. Based on the following, improvements and developements have been suggested to increase the accuracy and predictability of the mechanisms studied. Ignition delay data from experiments have been compared against those obtained from the mechanism used in the study for n-heptane. Discrepancies have been found in the low temperature region, with the mechanism under predicting the first ignition delay. The causes for the discrepancy have been noted to be due to the NTC behaviour exhibited during the two stage ignition of n-heptane. At low temperatures the reaction pathway proceeded by chain branching mainly due to the ketohydroperoxide species reaction pathway has been analysed. As the temperature of the reaction increases the reaction pathway is dominated by the ȮOH species propagation resulting in the formation of conjugate olefins and [Beta]-decomposition products, a further investigation of which can help improve the predictability of the mechanism.
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: Publisher: ISBN: Category : Languages : en Pages :
Book Description
Diesel and biodiesel combustion in a multi-cylinder light duty diesel engine were simulated during a closed cycle (from IVC to EVO), using a commercial computational fluid dynamics (CFD) code, CONVERGE, coupled with detailed chemical kinetics. The computational domain was constructed based on engine geometry and compression ratio measurements. A skeletal n-heptane-based diesel mechanism developed by researchers at Chalmers University of Technology and a reduced biodiesel mechanism derived and validated by Luo and co-workers were applied to model the combustion chemistry. The biodiesel mechanism contains 89 species and 364 reactions and uses methyl decanoate, methyl-9- decenoate, and n-heptane as the surrogate fuel mixture. The Kelvin-Helmholtz and Rayleigh-Taylor (KH-RT) spray breakup model for diesel and biodiesel was calibrated to account for the differences in physical properties of the fuels which result in variations in atomization and spray development characteristics. The simulations were able to capture the experimentally observed pressure and apparent heat release rate trends for both the fuels over a range of engine loads (BMEPs from 2.5 to 10 bar) and fuel injection timings (from 0° BTDC to 10° BTDC), thus validating the overall modeling approach as well as the chemical kinetic models of diesel and biodiesel surrogates. Moreover, quantitative NOx predictions for diesel combustion and qualitative NOx predictions for biodiesel combustion were obtained with the CFD simulations and the in-cylinder temperature trends were correlated to the NOx trends.
Author: K. Seshadri
Author: 
Author: Goutham Kukkadapu
Author: Mengyuan Wang
Author: 
Author: Chunsham Song
Author: 
Author: Varun Anthony Davies
Author: Rakesh Kumar Maurya
Author: