Fundamentals of Air Pollution Engineering


Book Description

A rigorous and thorough analysis of the production of air pollutants and their control, this text is geared toward chemical and environmental engineering students. Topics include combustion, principles of aerosol behavior, theories of the removal of particulate and gaseous pollutants from effluent streams, and air pollution control strategies. 1988 edition.Reprint of the Prentice-Hall, Inc., Englewood Cliffs, New Jersey, 1988 edition.




Utilizing a Cycle Simulation to Examine the Use of Exhaust Gas Recirculation (EGR) for a Spark-ignition Engine


Book Description

The exhaust gas recirculation (EGR) system has been widely used to reduce nitrogen oxide (NOx) emission, improve fuel economy and suppress knock by using the characteristics of charge dilution. However, previous studies have shown that as the EGR rate at a given engine operating condition increases, the combustion instability increases. The combustion instability increases cyclic variations resulting in the deterioration of engine performance and increasing hydrocarbon emissions. Therefore, the optimum EGR rate should be carefully determined in order to obtain the better engine performance and emissions. A thermodynamic cycle simulation of the four-stroke spark-ignition engine was used to determine the effects of EGR on engine performance, emission characteristics and second law parameters, considering combustion instability issues as EGR level increases. A parameter, called 'Fuel Fraction Burned, ' was introduced as a function of the EGR percentage and used in the simulation to incorporate the combustion instability effects. A comprehensive parametric investigation was conducted to examine the effects of variations in EGR, load and speed for a 5.7 liter spark-ignition automotive engine. Variations in the thermal efficiencies, brake specific NOx emissions, average combustion temperature, mean exhaust temperature, maximum temperature and relative heat transfer as functions of exhaust gas recycle were determined for both cooled and adiabatic EGR configurations. Also effects of variations in the load and speed on thermal efficiencies, relative heat transfers and destruction of availability due to combustion were determined for 0% EGR and 20% EGR cases with both cooled and adiabatic configurations. For both EGR configurations, thermal efficiencies first increase, reach a maximum at about 16% EGR and then decrease as the EGR level increases. Thermal efficiencies are slightly higher for cooled EGR configuration than that for adiabatic configuration. Concentration of nitric oxide emissions decreases from about 2950 ppm to 200 ppm as EGR level increases from 0% to 20% for cooled EGR configuration. The cooled EGR configuration results in lower nitric oxide emissions relative to the adiabatic EGR configuration. Also second law parameters show the expected trends as functions of EGR. Brake thermal efficiency is higher for the 20% EGR case than that for the no EGR case over the range of load (0 to WOT) and speed (600 rpm to 6000 rpm). Predictions made from the simulation were compared with some of the available experimental results. Predicted thermal efficiencies showed a similar trend when compared to the available experimental data. Also, percentage of unused fuel availability increases as the EGR level increases, and it can be seen as one of the effects of deteriorating combustion quality as the EGR level increases.




The Effects of Cycle-to-cycle Variations on Nitric Oxide (NO) Emissions for a Spark-ignition Engine


Book Description

The objectives of this study were to 1) determine the effects of cycle-to-cycle variations (ccv) on nitric oxide (NO) emissions, and 2) determine if the consideration of ccv affects the average NO emission as compared to the mean cycle NO emission. To carry out the proposed study, an engine simulation model was used. The simulation determines engine performance and NO emissions as functions of engine operating conditions, engine design parameters, and combustion parameters. An automotive, spark-ignition engine at part load and 1400 rpm was examined in this study. The engine cycle simulation employed three zones for the combustion process: (1) unburned gas, (2) adiabatic core region, and (3) boundary-layer gas. The use of the adiabatic core region has been shown to be especially necessary to capture the production of nitric oxides which are highly temperature dependent. Past research has shown that cyclic variations in combustion cause ccv of burn duration, ignition delay and equivalence ratio. Furthermore, literature has shown that variations of these three input parameters may be approximated by a normal frequency distribution. Using the mean and standard deviation, and a random number generator, input values were tabulated for the ignition delay, burn duration and equivalence ratio. These three input parameters were then used to simulate cyclic variations in the combustion process. Calculated results show that cyclic variations of the input parameters cause the cycle-by-cycle NO emissions to increase and decrease by as much as 59% from the mean cycle NO of 3,247 ppm. The average NO emission resulting from ccv was 4.9% less than the mean cycle NO emission. This result indicates that cyclic variations must be considered when calculating the overall NO emissions.







Fossil Energy


Book Description

The word sustainability shares its root with sustenance. In the context of modern society, sustenance is inextricably linked to the use of energy. Fossil Energy provides an authoritative reference on all aspects of this key resource, which currently represents nearly 85% of global energy consumption. Gathering 16 peer-reviewed entries from the Encyclopedia of Sustainability Science and Technology, the chapters provide comprehensive, yet concise coverage of fundamentals and current areas of research. Written by recognized authorities in the field, this volume represents an essential resource for scientists and engineers working on the development of energy resources, fossil or alternative, and reflects the essential role of energy supplies in supporting a sustainable future.




Quasi-Dimensional Simulation of Spark Ignition Engines


Book Description

Based on the simulations developed in research groups over the past years, Introduction to Quasi-dimensional Simulation of Spark Ignition Engines provides a compilation of the main ingredients necessary to build up a quasi-dimensional computer simulation scheme. Quasi-dimensional computer simulation of spark ignition engines is a powerful but affordable tool which obtains realistic estimations of a wide variety of variables for a simulated engine keeping insight the basic physical and chemical processes involved in the real evolution of an automotive engine. With low computational costs, it can optimize the design and operation of spark ignition engines as well as it allows to analyze cycle-to-cycle fluctuations. Including details about the structure of a complete simulation scheme, information about what kind of information can be obtained, and comparisons of the simulation results with experiments, Introduction to Quasi-dimensional Simulation of Spark Ignition Engines offers a thorough guide of this technique. Advanced undergraduates and postgraduates as well as researchers in government and industry in all areas related to applied physics and mechanical and automotive engineering can apply these tools to simulate cyclic variability, potentially leading to new design and control alternatives for lowering emissions and expanding the actual operation limits of spark ignition engines




Combustion Engineering, Second Edition


Book Description

Combustion Engineering, Second Edition maintains the same goal as the original: to present the fundamentals of combustion science with application to today’s energy challenges. Using combustion applications to reinforce the fundamentals of combustion science, this text provides a uniquely accessible introduction to combustion for undergraduate students, first-year graduate students, and professionals in the workplace. Combustion is a critical issue impacting energy utilization, sustainability, and climate change. The challenge is to design safe and efficient combustion systems for many types of fuels in a way that protects the environment and enables sustainable lifestyles. Emphasizing the use of combustion fundamentals in the engineering and design of combustion systems, this text provides detailed coverage of gaseous, liquid and solid fuel combustion, including focused coverage of biomass combustion, which will be invaluable to new entrants to the field. Eight chapters address the fundamentals of combustion, including fuels, thermodynamics, chemical kinetics, flames, detonations, sprays, and solid fuel combustion mechanisms. Eight additional chapters apply these fundamentals to furnaces, spark ignition and diesel engines, gas turbines, and suspension burning, fixed bed combustion, and fluidized bed combustion of solid fuels. Presenting a renewed emphasis on fundamentals and updated applications to illustrate the latest trends relevant to combustion engineering, the authors provide a number of pedagogic features, including: Numerous tables with practical data and formulae that link combustion fundamentals to engineering practice Concise presentation of mathematical methods with qualitative descriptions of their use Coverage of alternative and renewable fuel topics throughout the text Extensive example problems, chapter-end problems, and references These features and the overall fundamentals-to-practice nature of this book make it an ideal resource for undergraduate, first level graduate, or professional training classes. Students and practitioners will find that it is an excellent introduction to meeting the crucial challenge of engineering sustainable combustion systems in a cost-effective manner. A solutions manual and additional teaching resources are available with qualifying course adoption.