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| Author | : Alessandro Parente |
| Publisher | : Frontiers Media SA |
| Total Pages | : 160 |
| Release | : 2021-11-26 |
| Genre | : Technology & Engineering |
| ISBN | : 2889717003 |
| Author | : Jeffrey Labahn |
| Publisher | : |
| Total Pages | : 161 |
| Release | : 2016 |
| Genre | : Combustion engineering |
| ISBN | : |
Conditional Source-term Estimation (CSE) is a turbulent combustion model which uses conditional averages to provide closure for the mean chemical source term and is based on the same ideas as the Conditional Moment Closure (CMC) approach. CSE applies first order closure for the conditional averages which are obtained by inverting an integral equation and has been used to simulate a range of premixed, non-premixed and partially premixed flames. In the present study, CSE is applied to investigate a high efficient, low emission combustion process called Moderate and Intense Low Oxygen Dilution (MILD) combustion. This work represents the first application of CSE for MILD combustion, the first application of a multi-stream CSE formulation and the first doubly-conditioned CSE formulation applied in the Large Eddy Simulation (LES) framework. The objectives of the present study are to i) investigate the CSE combustion model for turbulent non-premixed combustion, ii) develop a CSE formulation for MILD combustion problems, iii) implement CSE for MILD combustion problems in Reynolds-Averaged Navier-Stokes (RANS) and LES and iv) compare the CSE predictions to experimental and previous numerical results for well documented MILD combustion flames. Numerical simulations of a confined non-premixed methane flame are completed using the CSE non-premixed approach. This study investigates the sensitivity to various CSE model parameters and shows CSE is able to accurately predict non-premixed methane combustion. A detailed study of the inversion problem encountered in CSE is also investigated using the Bayesian framework. The origin of the perturbation seen in the unconditional mass fraction in CSE and the impact of a smoothing prior on the recovered solution and credible intervals are discussed. Different regularization methods are studied and it is shown that both zeroth and first order Tikhonov are promising regularization methods for CSE. In the present work, the non-premixed CSE formulation is extended to include the impact of radiation of the conditional reaction rates and is applied to a semi-industrial furnace. This study demonstrates that a RANS-CSE simulation is able to accurately predict the temperature and species concentration, including NOx, for large scale realistic furnace configurations. Finally, a multi-stream CSE formulation is developed and applied to the DJHC burners in the RANS and LES framework. This new CSE formulation is able to predict the temperature and velocity profiles in very good agreement with the experimental data. Further, the LES multi-stream CSE formulation is able to predict the time-dependent nature of the DHJC burners.
| Author | : Norbert Peters |
| Publisher | : Cambridge University Press |
| Total Pages | : 322 |
| Release | : 2000-08-15 |
| Genre | : Science |
| ISBN | : 1139428063 |
The combustion of fossil fuels remains a key technology for the foreseeable future. It is therefore important that we understand the mechanisms of combustion and, in particular, the role of turbulence within this process. Combustion always takes place within a turbulent flow field for two reasons: turbulence increases the mixing process and enhances combustion, but at the same time combustion releases heat which generates flow instability through buoyancy, thus enhancing the transition to turbulence. The four chapters of this book present a thorough introduction to the field of turbulent combustion. After an overview of modeling approaches, the three remaining chapters consider the three distinct cases of premixed, non-premixed, and partially premixed combustion, respectively. This book will be of value to researchers and students of engineering and applied mathematics by demonstrating the current theories of turbulent combustion within a unified presentation of the field.
| Author | : Tarek Echekki |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 496 |
| Release | : 2010-12-25 |
| Genre | : Technology & Engineering |
| ISBN | : 9400704127 |
Turbulent combustion sits at the interface of two important nonlinear, multiscale phenomena: chemistry and turbulence. Its study is extremely timely in view of the need to develop new combustion technologies in order to address challenges associated with climate change, energy source uncertainty, and air pollution. Despite the fact that modeling of turbulent combustion is a subject that has been researched for a number of years, its complexity implies that key issues are still eluding, and a theoretical description that is accurate enough to make turbulent combustion models rigorous and quantitative for industrial use is still lacking. In this book, prominent experts review most of the available approaches in modeling turbulent combustion, with particular focus on the exploding increase in computational resources that has allowed the simulation of increasingly detailed phenomena. The relevant algorithms are presented, the theoretical methods are explained, and various application examples are given. The book is intended for a relatively broad audience, including seasoned researchers and graduate students in engineering, applied mathematics and computational science, engine designers and computational fluid dynamics (CFD) practitioners, scientists at funding agencies, and anyone wishing to understand the state-of-the-art and the future directions of this scientifically challenging and practically important field.
| Author | : Nedunchezhian Swaminathan |
| Publisher | : Cambridge University Press |
| Total Pages | : 447 |
| Release | : 2011-04-25 |
| Genre | : Technology & Engineering |
| ISBN | : 1139498584 |
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 | : W.C., Jr. Gardiner |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 564 |
| Release | : 1999-12-10 |
| Genre | : Science |
| ISBN | : 9780387988610 |
Superseding Gardiner's "Combustion Chemistry", this is an updated, comprehensive coverage of those aspects of combustion chemistry relevant to gas-phase combustion of hydrocarbons. The book includes an extended discussion of air pollutant chemistry and aspects of combustion, and reviews elementary reactions of nitrogen, sulfur and chlorine compounds that are relevant to combustion. Methods of combustion modeling and rate coefficient estimation are presented, as well as access to databases for combustion thermochemistry and modeling.
| Author | : Anna Schwarz |
| Publisher | : Springer Science & Business Media |
| Total Pages | : 304 |
| Release | : 2009-06-17 |
| Genre | : Technology & Engineering |
| ISBN | : 3642020380 |
November, 2008 Anna Schwarz, Johannes Janicka In the last thirty years noise emission has developed into a topic of increasing importance to society and economy. In ?elds such as air, road and rail traf?c, the control of noise emissions and development of associated noise-reduction techno- gies is a central requirement for social acceptance and economical competitiveness. The noise emission of combustion systems is a major part of the task of noise - duction. The following aspects motivate research: • Modern combustion chambers in technical combustion systems with low pol- tion exhausts are 5 - 8 dB louder compared to their predecessors. In the ope- tional state the noise pressure levels achieved can even be 10-15 dB louder. • High capacity torches in the chemical industry are usually placed at ground level because of the reasons of noise emissions instead of being placed at a height suitable for safety and security. • For airplanes the combustion emissions become a more and more important topic. The combustion instability and noise issues are one major obstacle for the introduction of green technologies as lean fuel combustion and premixed burners in aero-engines. The direct and indirect contribution of combustion noise to the overall core noise is still under discussion. However, it is clear that the core noise besides the fan tone will become an important noise source in future aero-engine designs. To further reduce the jet noise, geared ultra high bypass ratio fans are driven by only a few highly loaded turbine stages.
| Author | : Annemie Bogaerts |
| Publisher | : MDPI |
| Total Pages | : 248 |
| Release | : 2019-04-02 |
| Genre | : Technology & Engineering |
| ISBN | : 3038977500 |
Plasma catalysis is gaining increasing interest for various gas conversion applications, such as CO2 conversion into value-added chemicals and fuels, N2 fixation for the synthesis of NH3 or NOx, methane conversion into higher hydrocarbons or oxygenates. It is also widely used for air pollution control (e.g., VOC remediation). Plasma catalysis allows thermodynamically difficult reactions to proceed at ambient pressure and temperature, due to activation of the gas molecules by energetic electrons created in the plasma. However, plasma is very reactive but not selective, and thus a catalyst is needed to improve the selectivity. In spite of the growing interest in plasma catalysis, the underlying mechanisms of the (possible) synergy between plasma and catalyst are not yet fully understood. Indeed, plasma catalysis is quite complicated, as the plasma will affect the catalyst and vice versa. Moreover, due to the reactive plasma environment, the most suitable catalysts will probably be different from thermal catalysts. More research is needed to better understand the plasma–catalyst interactions, in order to further improve the applications.
| Author | : Hiroshi Tsuji |
| Publisher | : CRC Press |
| Total Pages | : 425 |
| Release | : 2002-12-03 |
| Genre | : Nature |
| ISBN | : 1420041037 |
Maximize efficiency and minimize pollution: the breakthrough technology of high temperature air combustion (HiTAC) holds the potential to overcome the limitations of conventional combustion and allow engineers to finally meet this long-standing imperative. Research has shown that HiTAC technology can provide simultaneous reduction of CO2 and nitric
| Author | : Timothy C. Lieuwen |
| Publisher | : Cambridge University Press |
| Total Pages | : 385 |
| Release | : 2013-07-08 |
| Genre | : Science |
| ISBN | : 052176405X |
The development of clean, sustainable energy systems is a preeminent issue in our time. Gas turbines will continue to be important combustion-based energy conversion devices for many decades to come, used for aircraft propulsion, ground-based power generation, and mechanical-drive applications. This book compiles the key scientific and technological knowledge associated with gas turbine emissions into a single authoritative source.
