Numerical Simulation of Combustion Air Systems for Large Industrial Boilers

2002 ◽  
Author(s):  
Kris L. Jorgensen ◽  
Richard A. Wessel ◽  
Joseph R. Strempek
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Case Studies ◽  
Integral Means ◽  
Performance And Emission ◽  
Wide Range ◽  
Air System ◽  
System 2 ◽  
Industrial Boilers ◽  
System Designs

Combustion air systems are an important aspect of the performance of industrial boilers and are increasingly being used as an integral means of reducing emissions. With the wide range of unique air system designs presently deployed, traditional methods of analyzing performance, based on experience, have become more difficult and less reliable. Numerical simulations are currently being used as a tool to analyze the operation and design of these air systems and how they relate to boiler performance and emission control. A proprietary CFD combustion code has been applied to a wide range of industrial boilers. Recent results from three selected studies are presented. These case studies demonstrate the benefits of using numerical simulation to: 1) analyze and optimize an existing air system, 2) validate an upgrade design, and 3) design and develop a new air system concept.

scholarly journals A Study on the Performance of Combustion in a HCCI Engine Using n-Heptane by a Multi-Zone Model

2009 ◽  
Author(s):  
Hongsheng Guo ◽  
Hailin Li ◽  
W. Stuart Neill
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Chemical Species ◽  
Numerical Data ◽  
Operating Conditions ◽  
Zone Model ◽  
Nox Emissions ◽  
Hcci Engine ◽  
Operation Conditions ◽  
Wide Range

A study of n-heptane combustion in an HCCI engine was carried out by a multi-zone numerical simulation that covers a complete engine cycle. A reaction mechanism that includes 177 chemical species and 1638 reactions was used. The results of the numerical simulations were compared to existing experimental data for a range of air/fuel ratios, compression ratios and engine speeds. It is shown that the numerical simulation is able to reasonably capture the experimental cylinder pressure data over a wide range of operation conditions. It also provides a qualitative trend of CO emissions. The numerical simulation overpredicted the combustion at some operating conditions, such as at extremely high air/fuel ratios and higher engine speeds. Some differences were observed between the experimental and numerical data for NOX emissions. The numerical simulation predicted a monotonic decrease in NOX emissions as air/fuel ratio increased or compression ratio decreased, while an increase in NOX emissions was observed experimentally when combustion became very weak at extremely high air/fuel ratios or low compression ratios. It is suggested that further experiments and numerical simulations should be performed to explain this discrepancy.

scholarly journals NUMERICAL SIMULATION OF THE MOVEMENT OF SMOOTH PARTICLES AT THE ELECTROMAGNETIC SEPARATORS WITH DRUM

2016 ◽  
Vol 21 (3) ◽  
Author(s):  
CĂSĂNDROIU TUDOR ◽  
CIOBANU GABRIELA VALERIA ◽  
VIŞAN LIANA ALEXANDRA
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Case Studies ◽  
Surface Condition ◽  
Separation Process ◽  
Free Flight ◽  
Air Resistance ◽  
Sorting Process

The paper presents the main theoretical elements underlying the seeds separation process after their surface. During the seed cleaning and sorting process according to the surface condition machines with electromagnetic or magnetic separators drums are used. In this paper is made a comparative theoretical analyze of smooth seeds movement on electromagnetic drum surface and trajectory in free flight, neglecting and taking into consideration air resistance, detached from the separation drum and it is evaluated the collection area of detached seeds. On this basis, were carried out several case studies and numerical simulations for three different machines.

scholarly journals NUMERICAL SIMULATION OF THE MOVEMENT OF SMOOTH PARTICLES AT THE ELECTROMAGNETIC SEPARATORS WITH DRUM

2015 ◽  
Vol 21 (3) ◽  
pp. 13-21
Author(s):  
TUDOR CĂSĂNDROIU ◽  
GABRIELA VALERIA CIOBANU ◽  
LIANA ALEXANDRA VIŞAN
Keyword(s):  
Numerical Simulation ◽  
Numerical Simulations ◽  
Case Studies ◽  
Surface Condition ◽  
Separation Process ◽  
Free Flight ◽  
Air Resistance ◽  
Sorting Process

The paper presents the main theoretical elements underlying the seeds separation process after their surface. During the seed cleaning and sorting process according to the surface condition machines with electromagnetic or magnetic separators drums are used. In this paper is made a comparative theoretical analyze of smooth seeds movement on electromagnetic drum surface and trajectory in free flight, neglecting and taking into consideration air resistance, detached from the separation drum and it is evaluated the collection area of detached seeds. On this basis, were carried out several case studies and numerical simulations for three different machines.

Software system for numerical simulation of broadband laser gas analysis of the atmosphere

2018 ◽  
pp. 66-73 ◽  
Author(s):  
S. A. Sadovnikov
Keyword(s):  
Numerical Simulation ◽  
Laser Radiation ◽  
Gas Analysis ◽  
Modular System ◽  
Software System ◽  
Transmission Spectra ◽  
Molecular Absorption ◽  
Molecular Scattering ◽  
Atmospheric Transmission ◽  
Wide Range

Introduction: Successful monitoring of environmental parameters requires the development of flexible software complexes with evolvable calculation functionality. Purpose: Developing a modular system for numerical simulation of atmospheric laser gas analysis. Results: Based on differential absorption method, a software system has been developed which provides the calculation of molecular absorption cross-sections, molecular absorption coefficients, atmospheric transmission spectra, and lidar signals. Absorption line contours are calculated using the Voigt profile. The prior information sources are HITRAN spectroscopic databases and statistical models of the distribution of temperature, pressure and gas components in the atmosphere. For modeling lidar signals, software blocks of calculating the molecular scattering coefficient and aerosol absorption/scattering coefficients were developed. For testing the applicability of various laser sources in the problems of environmental monitoring of the atmosphere, a concentration reconstruction error calculation block was developed for the atmospheric gas components, ignoring the interfering absorption of laser radiation by foreign gases. To verify the correct functioning of the software, a program block was developed for comparing the results of the modeling of atmospheric absorption and transmission spectra by using the standard SPECTRA information system. The discrepancy between the calculation of the atmospheric transmission spectra obtained using the developed system as compared to the SPECTRA results is less than 1%. Thus, a set of the presented program blocks allows you to carry out complex modeling of remote atmospheric gas analysis. Practical relevance: The software complex allows you to rapidly assess the possibilities of using a wide range of laser radiation sources for the problems of remote gas analysis.

Myths of the Underworld in Contemporary Culture

2019 ◽  
Author(s):  
Judith Fletcher
Keyword(s):  
Short Stories ◽  
Case Studies ◽  
Joseph Conrad ◽  
Ezra Pound ◽  
Border Crossing ◽  
First Century ◽  
Contemporary Culture ◽  
Cinematic Adaptation ◽  
Narrative Tradition ◽  
Wide Range

Stories of a visit to the realm of the dead and a return to the upper world are among the oldest narratives in European literature, beginning with Homer’s Odyssey and extending to contemporary culture. This volume examines a series of fictional works by twentieth- and twenty-first century authors, such Toni Morrison and Elena Ferrante, which deal in various ways with the descent to Hades. Myths of the Underworld in Contemporary Culture surveys a wide range of genres, including novels, short stories, comics, a cinematic adaptation, poetry, and juvenile fiction. It examines not only those texts that feature a literal catabasis, such as Neil Gaiman’s Sandman series, but also those where the descent to the underworld is evoked in more metaphorical ways as a kind of border crossing, for instance Salman Rushdie’s use of the Orpheus myth to signify the trauma of migration. The analyses examine how these retellings relate to earlier versions of the mythical theme, including their ancient precedents by Homer and Vergil, but also to post-classical receptions of underworld narratives by authors such as Dante, Ezra Pound, and Joseph Conrad. Arguing that the underworld has come to connote a cultural archive of narrative tradition, the book offers a series of case studies that examine the adaptation of underworld myths in contemporary culture in relation to the discourses of postmodernism, feminism, and postcolonialism.

Explanation Beyond Causation

2018 ◽  
Keyword(s):  
Philosophy Of Science ◽  
Case Studies ◽  
Philosophical Study ◽  
Accurate Information ◽  
Contemporary Philosophy ◽  
Causal Information ◽  
Causal Explanations ◽  
Turn On ◽  
Detailed Case ◽  
Wide Range

Explanations are very important to us in many contexts: in science, mathematics, philosophy, and also in everyday and juridical contexts. But what is an explanation? In the philosophical study of explanation, there is long-standing, influential tradition that links explanation intimately to causation: we often explain by providing accurate information about the causes of the phenomenon to be explained. Such causal accounts have been the received view of the nature of explanation, particularly in philosophy of science, since the 1980s. However, philosophers have recently begun to break with this causal tradition by shifting their focus to kinds of explanation that do not turn on causal information. The increasing recognition of the importance of such non-causal explanations in the sciences and elsewhere raises pressing questions for philosophers of explanation. What is the nature of non-causal explanations—and which theory best captures it? How do non-causal explanations relate to causal ones? How are non-causal explanations in the sciences related to those in mathematics and metaphysics? This volume of new essays explores answers to these and other questions at the heart of contemporary philosophy of explanation. The essays address these questions from a variety of perspectives, including general accounts of non-causal and causal explanations, as well as a wide range of detailed case studies of non-causal explanations from the sciences, mathematics and metaphysics.

scholarly journals The Impact of Initial Conditions in N-Body Simulations of Debris Discs

2015 ◽  
Vol 32 ◽  
Author(s):  
E. Thilliez ◽  
S. T. Maddison
Keyword(s):  
Numerical Simulations ◽  
Initial Conditions ◽  
Parent Body ◽  
Dust Trapping ◽  
Physical Context ◽  
Disc Width ◽  
Wide Range ◽  
Belt Width ◽  
New Generation ◽  
The Impact

AbstractNumerical simulations are a crucial tool to understand the relationship between debris discs and planetary companions. As debris disc observations are now reaching unprecedented levels of precision over a wide range of wavelengths, an appropriate level of accuracy and consistency is required in numerical simulations to confidently interpret this new generation of observations. However, simulations throughout the literature have been conducted with various initial conditions often with little or no justification. In this paper, we aim to study the dependence on the initial conditions of N-body simulations modelling the interaction between a massive and eccentric planet on an exterior debris disc. To achieve this, we first classify three broad approaches used in the literature and provide some physical context for when each category should be used. We then run a series of N-body simulations, that include radiation forces acting on small grains, with varying initial conditions across the three categories. We test the influence of the initial parent body belt width, eccentricity, and alignment with the planet on the resulting debris disc structure and compare the final peak emission location, disc width and offset of synthetic disc images produced with a radiative transfer code. We also track the evolution of the forced eccentricity of the dust grains induced by the planet, as well as resonance dust trapping. We find that an initially broad parent body belt always results in a broader debris disc than an initially narrow parent body belt. While simulations with a parent body belt with low initial eccentricity (e ~ 0) and high initial eccentricity (0 < e < 0.3) resulted in similar broad discs, we find that purely secular forced initial conditions, where the initial disc eccentricity is set to the forced value and the disc is aligned with the planet, always result in a narrower disc. We conclude that broad debris discs can be modelled by using either a dynamically cold or dynamically warm parent belt, while in contrast eccentric narrow debris rings are reproduced using a secularly forced parent body belt.

scholarly journals Wind shear over the Nice Côte d'Azur airport: case studies

2013 ◽  
Vol 13 (9) ◽  
pp. 2223-2238 ◽  
Author(s):  
A. Boilley ◽  
J.-F. Mahfouf
Keyword(s):  
Numerical Simulation ◽  
Numerical Model ◽  
Numerical Simulations ◽  
Wind Shear ◽  
Horizontal Wind ◽  
Wind Profiler ◽  
Measurement Campaign ◽  
Wind Lidar ◽  
Real Time Applications ◽  
Wind Shears

Abstract. The Nice Côte d'Azur international airport is subject to horizontal low-level wind shears. Detecting and predicting these hazards is a major concern for aircraft security. A measurement campaign took place over the Nice airport in 2009 including 4 anemometers, 1 wind lidar and 1 wind profiler. Two wind shear events were observed during this measurement campaign. Numerical simulations were carried out with Meso-NH in a configuration compatible with near-real time applications to determine the ability of the numerical model to predict these events and to study the meteorological situations generating an horizontal wind shear. A comparison between numerical simulation and the observation dataset is conducted in this paper.

scholarly journals Ocean Emission Effects on Aerosol-Cloud Interactions: Insights from Two Case Studies

2010 ◽  
Vol 2010 ◽  
pp. 1-9 ◽  
Author(s):  
Armin Sorooshian ◽  
Hanh T. Duong
Keyword(s):  
Case Studies ◽  
Field Experiments ◽  
Remote Sensing Data ◽  
Anthropogenic Pollution ◽  
Cloud Microphysics ◽  
Marine Aerosols ◽  
Aerosol Cloud ◽  
First Case ◽  
Wide Range ◽  
Aerosol Cloud Interactions

Two case studies are discussed that evaluate the effect of ocean emissions on aerosol-cloud interactions. A review of the first case study from the eastern Pacific Ocean shows that simultaneous aircraft and space-borne observations are valuable in detecting links between ocean biota emissions and marine aerosols, but that the effect of the former on cloud microphysics is less clear owing to interference from background anthropogenic pollution and the difficulty with field experiments in obtaining a wide range of aerosol conditions to robustly quantify ocean effects on aerosol-cloud interactions. To address these limitations, a second case was investigated using remote sensing data over the less polluted Southern Ocean region. The results indicate that cloud drop size is reduced more for a fixed increase in aerosol particles during periods of higher ocean chlorophyll A. Potential biases in the results owing to statistical issues in the data analysis are discussed.

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