A computer model is used to examine oxidation of hydrocarbon fuels in a rapid compression machine. For one of the fuels studied, n-heptane, significant fuel consumption is computed to take place during the compression stroke under some operating conditions, while for the less reactive n-pentane, no appreciable fuel consumption occurs until after the end of compression. The third fuel studied, a 60 PRF mixture of iso-octane and n-heptane, exhibits behavior that is intermediate between that of n-heptane and n-pentane. The model results indicate that computational studies of rapid compression machine ignition must consider fuel reaction during compression in order to achieve satisfactory agreement between computed and experimental results.

In this work, numerical and experimental techniques are used to investigate the effect of the position of the double bond on the ignition properties of pentene and hexene linear isomers. A wide-range kinetic model for the oxidation of C5-C6 linear alkenes has been developed. Literature rapid compression machine data were used to validate the model at low temperatures and new shock tube experiments were performed in order to assess the behavior of the considered alkenes in the high temperature region. Some interesting inversions in the relative reactivity of the isomers were detected. The model successfully reproduced the measured behavior and allowed to explain the reason of these reactivity changes. The information gathered will be applied to the development of the kinetic mechanisms of larger unsaturated surrogate components.

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 and CAI engines for the automotive industry presents the state-of-the-art in research and development on an international basis, as a one-stop reference work. The background to the development of HCCI / CAI engine technology is described. Basic principles, the technologies and their potential applications, strengths and weaknesses, as well as likely future trends and sources of further information are reviewed in the areas of gasoline HCCI / CAI engines; diesel HCCI engines; HCCI / CAI engines with alternative fuels; and advanced modelling and experimental techniques. The book provides an invaluable source of information for scientific researchers, R&D engineers and managers in the automotive engineering industry worldwide. - Presents the state-of-the-art in research and development on an international basis - An invaluable source of information for scientific researchers, R&D engineers and managers in the automotive engineering industry worldwide - Looks at one of the most promising engine technologies around

Detailed kinetic models of pyrolysis and combustion of hydrocarbon fuels are nowadays widely used in the design of internal combustion engines and these models are effectively applied to help meet the increasingly stringent environmental and energetic standards. In previous studies by the combustion community, such models not only contributed to the understanding of pure component combustion, but also provided a deeper insight into the combustion behavior of complex mixtures. One of the major challenges in this field is now the definition and the development of appropriate surrogate models able to mimic the actual features of real fuels. Real fuels are complex mixtures of thousands of hydrocarbon compounds including linear and branched paraffins, naphthenes, olefins and aromatics. Their behavior can be effectively reproduced by simpler fuel surrogates containing a limited number of components. Aside the most commonly used surrogates containing iso-octane and n-heptane only, the so called Primary Reference Fuels (PRF), new mixtures have recently been suggested to extend the reference components in surrogate mixtures to also include alkenes and aromatics. It is generally agreed that, including representative species for all the main classes of hydrocarbons which can be found in real fuels, it is possible to reproduce very effectively in a wide range of operating conditions not just the auto-ignition propensity of gasoline or Diesel fuels, but also their physical properties and their combustion residuals [1]. In this work, the combustion behavior of several components relevant to gasoline surrogate formulation is computationally examined. The attention is focused on the autoignition of iso-octane, hexene and their mixtures. Some important issues relevant to the experimental and modeling investigation of such fuels are discussed with the help of rapid compression machine data and calculations. Following the model validation, the behavior of mixtures is discussed on the basis of computational results.

The use of gasoline in homogeneous charge compression ignition engines (HCCI) and in duel fuel diesel - gasoline engines, has increased the need to understand its compression ignition processes under engine-like conditions. These processes need to be studied under well-controlled conditions in order to quantify low temperature heat release and to provide fundamental validation data for chemical kinetic models. With this in mind, an experimental campaign has been undertaken in a rapid compression machine (RCM) to measure the ignition of gasoline mixtures over a wide range of compression temperatures and for different compression pressures. By measuring the pressure history during ignition, information on the first stage ignition (when observed) and second stage ignition are captured along with information on the phasing of the heat release. Heat release processes during ignition are important because gasoline is known to exhibit low temperature heat release, intermediate temperature heat release and high temperature heat release. In an HCCI engine, the occurrence of low-temperature and intermediate-temperature heat release can be exploited to obtain higher load operation and has become a topic of much interest for engine researchers. Consequently, it is important to understand these processes under well-controlled conditions. A four-component gasoline surrogate model (including n-heptane, iso-octane, toluene, and 2-pentene) has been developed to simulate real gasolines. An appropriate surrogate mixture of the four components has been developed to simulate the specific gasoline used in the RCM experiments. This chemical kinetic surrogate model was then used to simulate the RCM experimental results for real gasoline. The experimental and modeling results covered ultra-lean to stoichiometric mixtures, compressed temperatures of 640-950 K, and compression pressures of 20 and 40 bar. The agreement between the experiments and model is encouraging in terms of first-stage (when observed) and second-stage ignition delay times and of heat release rate. The experimental and computational results are used to gain insight into low and intermediate temperature processes during gasoline ignition.

Mathematical Modelling of Gas-Phase Complex Reaction Systems: Pyrolysis and Combustion, Volume 45, gives an overview of the different steps involved in the development and application of detailed kinetic mechanisms, mainly relating to pyrolysis and combustion processes. The book is divided into two parts that cover the chemistry and kinetic models and then the numerical and statistical methods. It offers a comprehensive coverage of the theory and tools needed, along with the steps necessary for practical and industrial applications. - Details thermochemical properties and "ab initio" calculations of elementary reaction rates - Details kinetic mechanisms of pyrolysis and combustion processes - Explains experimental data for improving reaction models and for kinetic mechanisms assessment - Describes surrogate fuels and molecular reconstruction of hydrocarbon liquid mixtures - Describes pollutant formation in combustion systems - Solves and validates the kinetic mechanisms using numerical and statistical methods - Outlines optimal design of industrial burners and optimization and dynamic control of pyrolysis furnaces - Outlines large eddy simulation of turbulent reacting flows