This document summarizes a study on the effects of local carbon-to-oxygen (C/O) ratio and scalar dissipation rate on the sooting limits of spherical non-premixed ethylene flames. The study used detailed chemistry modeling to analyze 17 microgravity flame experiments. It identified a critical local C/O ratio of 0.51 for soot formation and found that flames with scalar dissipation rates below 2 s-1 at this location had average temperatures of 1400K, regardless of stoichiometry, while higher rates required higher temperatures to form soot.
The document refers to Black Saturday on 7 February 2009 in Kinglake, Victoria, Australia. A devastating bushfire occurred on that date, known as Black Saturday, where large areas of Victoria were engulfed in fire. Kinglake was one of the towns significantly impacted by the Black Saturday bushfires in Victoria, Australia in 2009.
This document provides website analytics statistics for the Archdiocese of Philadelphia's Licensed GradeConnect site from November 19th, 2008 to December 19th, 2008. It includes the number of visits to the site, unique visitors, average pages viewed per visit, and breakdowns of the statistics by world region, country, state, and city within Pennsylvania.
Nevmug Martins Point Health Care J Anuary 2009csharney
Martin's Point Health Care implemented a highly virtualized storage and computing environment using 3PAR storage and VMware to address the limitations and management challenges of their previous monolithic architecture. The new solution provides unlimited scalability, high availability, advanced disaster recovery, and a 75% reduction in storage administration. It allows over 50 hosts to connect to Microsoft SQL databases and has realized a 25% cost savings and 85% reduction in provisioning time.
American Recovery and Reinvestment Conference Report Division Afinance3
This document is a conference report on a bill making supplemental appropriations for job creation, infrastructure investment, assistance to the unemployed, and state fiscal stabilization for fiscal year 2009. It appropriates funds to numerous federal agencies and programs, including:
- $24 million to the Department of Agriculture for construction and repairs
- $500 million to the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC)
- Over $6 billion to rural housing and community development programs
- $2.5 billion to expand broadband internet access in rural areas
- $100 million to provide school lunch equipment grants to states
The report provides funding to support economic recovery through job preservation, assistance programs, infrastructure
The document presents a metaphor comparing one's life to a bank account that is credited each day with 86,400 seconds (24 hours) but any unused time is lost at the end of the day. It encourages the reader to make the most of their time each day by investing in their health, happiness, and success as wasted time cannot be reclaimed. It emphasizes appreciating the value of even small amounts of time by considering what those who have missed opportunities would think.
A person is unsure what to get their partner for Valentine's Day and lists some expensive gift ideas like a car, diamond, or gadget. They also suggest an inexpensive lingerie option worth £4.8 million.
2008 Fourth Quarter Real Estate Commentaryalghanim
The global real estate market suffered in 2008 due to the financial crisis and economic downturn. U.S. REITs rebounded in the 4th quarter of 2008 and may lead a recovery in 2009 if the U.S. economy rebounds. Credit markets remain largely frozen, which is impacting commercial mortgage backed securities and new lending. Defensive investment strategies focused on liquidity and balance sheet strength are positioned to perform best in 2009 until economic and market conditions stabilize further. Opportunities may arise in undervalued REITs and direct commercial real estate if accessed with a long/short hedge fund strategy.
The document refers to Black Saturday on 7 February 2009 in Kinglake, Victoria, Australia. A devastating bushfire occurred on that date, known as Black Saturday, where large areas of Victoria were engulfed in fire. Kinglake was one of the towns significantly impacted by the Black Saturday bushfires in Victoria, Australia in 2009.
This document provides website analytics statistics for the Archdiocese of Philadelphia's Licensed GradeConnect site from November 19th, 2008 to December 19th, 2008. It includes the number of visits to the site, unique visitors, average pages viewed per visit, and breakdowns of the statistics by world region, country, state, and city within Pennsylvania.
Nevmug Martins Point Health Care J Anuary 2009csharney
Martin's Point Health Care implemented a highly virtualized storage and computing environment using 3PAR storage and VMware to address the limitations and management challenges of their previous monolithic architecture. The new solution provides unlimited scalability, high availability, advanced disaster recovery, and a 75% reduction in storage administration. It allows over 50 hosts to connect to Microsoft SQL databases and has realized a 25% cost savings and 85% reduction in provisioning time.
American Recovery and Reinvestment Conference Report Division Afinance3
This document is a conference report on a bill making supplemental appropriations for job creation, infrastructure investment, assistance to the unemployed, and state fiscal stabilization for fiscal year 2009. It appropriates funds to numerous federal agencies and programs, including:
- $24 million to the Department of Agriculture for construction and repairs
- $500 million to the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC)
- Over $6 billion to rural housing and community development programs
- $2.5 billion to expand broadband internet access in rural areas
- $100 million to provide school lunch equipment grants to states
The report provides funding to support economic recovery through job preservation, assistance programs, infrastructure
The document presents a metaphor comparing one's life to a bank account that is credited each day with 86,400 seconds (24 hours) but any unused time is lost at the end of the day. It encourages the reader to make the most of their time each day by investing in their health, happiness, and success as wasted time cannot be reclaimed. It emphasizes appreciating the value of even small amounts of time by considering what those who have missed opportunities would think.
A person is unsure what to get their partner for Valentine's Day and lists some expensive gift ideas like a car, diamond, or gadget. They also suggest an inexpensive lingerie option worth £4.8 million.
2008 Fourth Quarter Real Estate Commentaryalghanim
The global real estate market suffered in 2008 due to the financial crisis and economic downturn. U.S. REITs rebounded in the 4th quarter of 2008 and may lead a recovery in 2009 if the U.S. economy rebounds. Credit markets remain largely frozen, which is impacting commercial mortgage backed securities and new lending. Defensive investment strategies focused on liquidity and balance sheet strength are positioned to perform best in 2009 until economic and market conditions stabilize further. Opportunities may arise in undervalued REITs and direct commercial real estate if accessed with a long/short hedge fund strategy.
The document presents a numerical investigation of spherical diffusion flames. It summarizes past work on spherical diffusion flames and outlines the objectives of studying soot formation in ethylene flames and weak hydrogen micro-flames. For ethylene flames, the investigation finds that soot formation requires a local C/O ratio of at least 0.51 and temperature of around 1400K. For hydrogen micro-flames, it characterizes flames near the quenching limit and finds flame structure is similar to microgravity flames.
This study investigated the sooting limits of spherical diffusion flames of ethylene fuel in microgravity conditions. Numerical simulations using detailed chemistry models were performed to analyze the effects of local carbon-to-oxygen ratio, temperature, and residence time on 17 limit flames identified in previous experiments. The results show that for flames with residence times over 0.2 seconds, the critical temperature for sooting at a carbon-to-oxygen ratio of 0.6 is approximately 1200K, regardless of strain rate. For very short residence times under 0.1 seconds, higher temperatures are required at this carbon-to-oxygen ratio for sooting to occur.
The document investigates the effects of carbon-to-oxygen (C/O) ratio and temperature on the sooting limits of spherical diffusion flames of ethylene. It finds that soot formation requires a local C/O ratio of at least 0.51 where the local temperature is 1400 K or higher. These critical values of C/O ratio and temperature for soot formation are independent of factors like convection direction, fuel/oxidizer concentrations, residence time, and scalar dissipation rate (except at very high dissipation rates).
This document provides answers and solutions to physics, chemistry, and mathematics questions for an AIEEE exam from 2010. It includes 10 multi-part chemistry questions with explanations of the answers. The questions cover topics such as ionization constants, solubility products, ionic radii, chemical reactions, phase equilibria, spectroscopy, and organic compound analysis.
Answer key with detailed explanations for the AIEEE Code A PCM, Code B - PCM, Code C - PCM and Code D - PCM papers solved by the coaching experts at Sri Chaitanya. Set your sights on the IITJEE, AIEEE Entrance exams and start your test preps for IITJEE Physics, IITJEE Chemistry and IITJEE Maths today for the IITJEE 2014 and 2015 entrance examinations
This document provides an overview of organic chemistry concepts including bonding, molecular structure, and common functional groups. It begins with a brief history of the field and then covers topics such as ionic and covalent bonding, Lewis structures, resonance, and the shapes of molecules determined by valence electron repulsion. Key figures mentioned include Gilbert Lewis, who developed Lewis structures to represent covalent bonding in molecules.
This document provides an overview of organic chemistry concepts including bonding, functional groups, and reactions. It begins with Lewis structures which use octet rules to distribute valence electrons between atoms to form single, double or triple bonds in order to achieve noble gas configurations. Resonance forms are discussed which show that molecules may be represented by multiple equivalent structures. The document then discusses how molecular shape is controlled by valence electron repulsion. Basic reactions like substitution and elimination are also mentioned.
ADVANTAGES Nuclear power generation does emit relatively low amounts of carbon dioxide (CO2). The emissions of green house gases and therefore the contribution of nuclear power plants to global warming is therefore relatively little. This technology is readily available, it does not have to be developed first. It is possible to generate a high amount of electrical energy in one single plant
Nitrogen oxides (NOx) are produced during combustion processes and can harm human health and the environment. Selective catalytic reduction (SCR) is a process that uses a catalyst to convert NOx in exhaust gases into less harmful nitrogen and water. SCR systems inject ammonia or urea into exhaust to facilitate the reaction on the catalyst. Proper operation of SCR systems and monitoring of emissions helps control NOx and improve air quality.
Ppt 13 R1.2 Energy cycles in reactions.pptxNeera16
the ppt is on energy cycles in reactions and deal with Hess's law of constant heat summation where the law of conservation of mass is obeyed. The enthalpy change can be calculated no matter whatever path the reaction has taken place as long as reactants and products are same the enthalpy change can be determined. Thus if enthalpy change of reaction is to be calculated than we can use enthalpy of combustion and formation to calculate it.
The document provides a list of questions that will be covered on a final exam for Grade 11. The questions cover a range of chemistry topics including:
- Le Chatelier's principle, molarity, disproportionation, orbital shapes, aromaticity, oxidation numbers, structural formulas.
- Metamerism, inverse of an equilibrium constant, law of multiple proportions, nucleophiles and electrophiles.
- Differences between orbitals and orbits, position-velocity uncertainty principle.
- Bronsted-Lowry acid/base theory and conjugate pairs.
- Uses of x-rays including in airports for luggage screening and their approximate wavelength.
- Inductive effects, resonance structures, identification
This document provides an overview of thermodynamics and entropy. It discusses how the second law of thermodynamics predicts the spontaneous direction of chemical reactions based on entropy changes. Entropy refers to the disorder of a system, and tends to increase over time as reactions proceed in the direction of greater disorder. The change in entropy of a reaction (ΔS°rxn) can be calculated from standard entropy values. While entropy changes alone cannot predict spontaneity, the Gibbs free energy (G) combines both entropy and enthalpy to determine whether reactions will proceed spontaneously.
1. The document discusses various properties of light including its speed, wavelength, frequency, and energy as it relates to different types of electromagnetic radiation such as x-rays, radio waves, and visible light.
2. Key concepts around the behavior of light are covered like reflection, refraction, and how light interacts with lenses to cause vision corrections for nearsightedness and farsightedness.
3. The particle-wave duality of light is examined through experiments like the photoelectric effect which provided evidence that light behaves as quantized packets of energy called photons.
This document discusses spontaneity, entropy, and free energy in thermodynamics. It explains that spontaneous processes are driven by an increase in entropy of the universe according to the second law of thermodynamics. Entropy is a measure of disorder and randomness, and spontaneous reactions favor a higher entropy state. The free energy change of a reaction can predict spontaneity, with a negative value corresponding to a spontaneous process. Temperature affects spontaneity by influencing the entropy changes of both the system and surroundings.
Entropy is a measure of disorder or randomness in a system. It increases as a reaction progresses from reactants to products. Nuclear reactions like fission and fusion release large amounts of energy and can be spontaneous or non-spontaneous depending on whether the products have lower or higher energy than the reactants. Nuclear reactions involve the emission of particles like alpha, beta, or gamma rays and must balance atomic and mass numbers.
Direct measurement of vinoxy radicals from ozonolysis of 2-butenes using Cavity Ring-Down Spectroscopy. The document outlines the experimental setup using CRDS to directly measure vinoxy radicals, as well as results from ozonolysis of trans-2-butene and cis-2-butene. Key findings include direct measurement of vinoxy radicals, the effect of oxygen on decreasing glyoxal while not significantly impacting formaldehyde, and lower OH radical and formaldehyde yields from cis-2-butene ozonolysis likely due to decreased vinoxy radical formation.
1. The document discusses metamaterials, which are composite materials that can have negative effective electrical permittivity and magnetic permeability over certain frequency bands.
2. It provides an overview of the historical background of metamaterials and left-handed media. Maxwell's equations are also derived for these types of materials.
3. Unique optical properties arise from negative refractive index materials, including reversed Snell's law and a reversed Poynting vector. Energy flow is in the opposite direction of phase velocity.
The document discusses various topics relating to states of matter and gas laws. It defines the three common states of matter and phase transitions. It also explains the different types of intermolecular forces and how they relate to boiling points. Several gas laws are defined, including Boyle's, Charles', and Gay-Lussac's Laws. The ideal gas law and concepts like molar mass, density, diffusion, and partial pressures are also covered.
Contoso helps organizations foster collaborative thinking and workplace innovation through closing feedback loops and agile frameworks. Their pitch deck outlines problems in the market like a lack of easy-to-use products that fully address consumer needs, as well as their solution to create a simple, stylish, and niche product for Gen Z. The product will be uniquely designed with consumer input and testing to be the first beautiful and functional option that saves costs. The company's research-based business model develops minimalist products dedicated to underserved markets.
This document summarizes an experiment that measured the yields of stabilized Criegee intermediates (sCIs) produced from the ozonolysis of trans-2-butene and 2,3-dimethyl-2-butene. The experiment used cavity ring-down spectroscopy to monitor the reaction of sCIs with SO2, allowing the sCI yields to be determined from changes in SO2 and O3 levels. The nascent sCI yields were found to be 0 for trans-2-butene and 0.15 for 2,3-dimethyl-2-butene.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
The document presents a numerical investigation of spherical diffusion flames. It summarizes past work on spherical diffusion flames and outlines the objectives of studying soot formation in ethylene flames and weak hydrogen micro-flames. For ethylene flames, the investigation finds that soot formation requires a local C/O ratio of at least 0.51 and temperature of around 1400K. For hydrogen micro-flames, it characterizes flames near the quenching limit and finds flame structure is similar to microgravity flames.
This study investigated the sooting limits of spherical diffusion flames of ethylene fuel in microgravity conditions. Numerical simulations using detailed chemistry models were performed to analyze the effects of local carbon-to-oxygen ratio, temperature, and residence time on 17 limit flames identified in previous experiments. The results show that for flames with residence times over 0.2 seconds, the critical temperature for sooting at a carbon-to-oxygen ratio of 0.6 is approximately 1200K, regardless of strain rate. For very short residence times under 0.1 seconds, higher temperatures are required at this carbon-to-oxygen ratio for sooting to occur.
The document investigates the effects of carbon-to-oxygen (C/O) ratio and temperature on the sooting limits of spherical diffusion flames of ethylene. It finds that soot formation requires a local C/O ratio of at least 0.51 where the local temperature is 1400 K or higher. These critical values of C/O ratio and temperature for soot formation are independent of factors like convection direction, fuel/oxidizer concentrations, residence time, and scalar dissipation rate (except at very high dissipation rates).
This document provides answers and solutions to physics, chemistry, and mathematics questions for an AIEEE exam from 2010. It includes 10 multi-part chemistry questions with explanations of the answers. The questions cover topics such as ionization constants, solubility products, ionic radii, chemical reactions, phase equilibria, spectroscopy, and organic compound analysis.
Answer key with detailed explanations for the AIEEE Code A PCM, Code B - PCM, Code C - PCM and Code D - PCM papers solved by the coaching experts at Sri Chaitanya. Set your sights on the IITJEE, AIEEE Entrance exams and start your test preps for IITJEE Physics, IITJEE Chemistry and IITJEE Maths today for the IITJEE 2014 and 2015 entrance examinations
This document provides an overview of organic chemistry concepts including bonding, molecular structure, and common functional groups. It begins with a brief history of the field and then covers topics such as ionic and covalent bonding, Lewis structures, resonance, and the shapes of molecules determined by valence electron repulsion. Key figures mentioned include Gilbert Lewis, who developed Lewis structures to represent covalent bonding in molecules.
This document provides an overview of organic chemistry concepts including bonding, functional groups, and reactions. It begins with Lewis structures which use octet rules to distribute valence electrons between atoms to form single, double or triple bonds in order to achieve noble gas configurations. Resonance forms are discussed which show that molecules may be represented by multiple equivalent structures. The document then discusses how molecular shape is controlled by valence electron repulsion. Basic reactions like substitution and elimination are also mentioned.
ADVANTAGES Nuclear power generation does emit relatively low amounts of carbon dioxide (CO2). The emissions of green house gases and therefore the contribution of nuclear power plants to global warming is therefore relatively little. This technology is readily available, it does not have to be developed first. It is possible to generate a high amount of electrical energy in one single plant
Nitrogen oxides (NOx) are produced during combustion processes and can harm human health and the environment. Selective catalytic reduction (SCR) is a process that uses a catalyst to convert NOx in exhaust gases into less harmful nitrogen and water. SCR systems inject ammonia or urea into exhaust to facilitate the reaction on the catalyst. Proper operation of SCR systems and monitoring of emissions helps control NOx and improve air quality.
Ppt 13 R1.2 Energy cycles in reactions.pptxNeera16
the ppt is on energy cycles in reactions and deal with Hess's law of constant heat summation where the law of conservation of mass is obeyed. The enthalpy change can be calculated no matter whatever path the reaction has taken place as long as reactants and products are same the enthalpy change can be determined. Thus if enthalpy change of reaction is to be calculated than we can use enthalpy of combustion and formation to calculate it.
The document provides a list of questions that will be covered on a final exam for Grade 11. The questions cover a range of chemistry topics including:
- Le Chatelier's principle, molarity, disproportionation, orbital shapes, aromaticity, oxidation numbers, structural formulas.
- Metamerism, inverse of an equilibrium constant, law of multiple proportions, nucleophiles and electrophiles.
- Differences between orbitals and orbits, position-velocity uncertainty principle.
- Bronsted-Lowry acid/base theory and conjugate pairs.
- Uses of x-rays including in airports for luggage screening and their approximate wavelength.
- Inductive effects, resonance structures, identification
This document provides an overview of thermodynamics and entropy. It discusses how the second law of thermodynamics predicts the spontaneous direction of chemical reactions based on entropy changes. Entropy refers to the disorder of a system, and tends to increase over time as reactions proceed in the direction of greater disorder. The change in entropy of a reaction (ΔS°rxn) can be calculated from standard entropy values. While entropy changes alone cannot predict spontaneity, the Gibbs free energy (G) combines both entropy and enthalpy to determine whether reactions will proceed spontaneously.
1. The document discusses various properties of light including its speed, wavelength, frequency, and energy as it relates to different types of electromagnetic radiation such as x-rays, radio waves, and visible light.
2. Key concepts around the behavior of light are covered like reflection, refraction, and how light interacts with lenses to cause vision corrections for nearsightedness and farsightedness.
3. The particle-wave duality of light is examined through experiments like the photoelectric effect which provided evidence that light behaves as quantized packets of energy called photons.
This document discusses spontaneity, entropy, and free energy in thermodynamics. It explains that spontaneous processes are driven by an increase in entropy of the universe according to the second law of thermodynamics. Entropy is a measure of disorder and randomness, and spontaneous reactions favor a higher entropy state. The free energy change of a reaction can predict spontaneity, with a negative value corresponding to a spontaneous process. Temperature affects spontaneity by influencing the entropy changes of both the system and surroundings.
Entropy is a measure of disorder or randomness in a system. It increases as a reaction progresses from reactants to products. Nuclear reactions like fission and fusion release large amounts of energy and can be spontaneous or non-spontaneous depending on whether the products have lower or higher energy than the reactants. Nuclear reactions involve the emission of particles like alpha, beta, or gamma rays and must balance atomic and mass numbers.
Direct measurement of vinoxy radicals from ozonolysis of 2-butenes using Cavity Ring-Down Spectroscopy. The document outlines the experimental setup using CRDS to directly measure vinoxy radicals, as well as results from ozonolysis of trans-2-butene and cis-2-butene. Key findings include direct measurement of vinoxy radicals, the effect of oxygen on decreasing glyoxal while not significantly impacting formaldehyde, and lower OH radical and formaldehyde yields from cis-2-butene ozonolysis likely due to decreased vinoxy radical formation.
1. The document discusses metamaterials, which are composite materials that can have negative effective electrical permittivity and magnetic permeability over certain frequency bands.
2. It provides an overview of the historical background of metamaterials and left-handed media. Maxwell's equations are also derived for these types of materials.
3. Unique optical properties arise from negative refractive index materials, including reversed Snell's law and a reversed Poynting vector. Energy flow is in the opposite direction of phase velocity.
The document discusses various topics relating to states of matter and gas laws. It defines the three common states of matter and phase transitions. It also explains the different types of intermolecular forces and how they relate to boiling points. Several gas laws are defined, including Boyle's, Charles', and Gay-Lussac's Laws. The ideal gas law and concepts like molar mass, density, diffusion, and partial pressures are also covered.
Contoso helps organizations foster collaborative thinking and workplace innovation through closing feedback loops and agile frameworks. Their pitch deck outlines problems in the market like a lack of easy-to-use products that fully address consumer needs, as well as their solution to create a simple, stylish, and niche product for Gen Z. The product will be uniquely designed with consumer input and testing to be the first beautiful and functional option that saves costs. The company's research-based business model develops minimalist products dedicated to underserved markets.
This document summarizes an experiment that measured the yields of stabilized Criegee intermediates (sCIs) produced from the ozonolysis of trans-2-butene and 2,3-dimethyl-2-butene. The experiment used cavity ring-down spectroscopy to monitor the reaction of sCIs with SO2, allowing the sCI yields to be determined from changes in SO2 and O3 levels. The nascent sCI yields were found to be 0 for trans-2-butene and 0.15 for 2,3-dimethyl-2-butene.
Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptxEduSkills OECD
Iván Bornacelly, Policy Analyst at the OECD Centre for Skills, OECD, presents at the webinar 'Tackling job market gaps with a skills-first approach' on 12 June 2024
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
This slide is special for master students (MIBS & MIFB) in UUM. Also useful for readers who are interested in the topic of contemporary Islamic banking.
Chapter wise All Notes of First year Basic Civil Engineering.pptxDenish Jangid
Chapter wise All Notes of First year Basic Civil Engineering
Syllabus
Chapter-1
Introduction to objective, scope and outcome the subject
Chapter 2
Introduction: Scope and Specialization of Civil Engineering, Role of civil Engineer in Society, Impact of infrastructural development on economy of country.
Chapter 3
Surveying: Object Principles & Types of Surveying; Site Plans, Plans & Maps; Scales & Unit of different Measurements.
Linear Measurements: Instruments used. Linear Measurement by Tape, Ranging out Survey Lines and overcoming Obstructions; Measurements on sloping ground; Tape corrections, conventional symbols. Angular Measurements: Instruments used; Introduction to Compass Surveying, Bearings and Longitude & Latitude of a Line, Introduction to total station.
Levelling: Instrument used Object of levelling, Methods of levelling in brief, and Contour maps.
Chapter 4
Buildings: Selection of site for Buildings, Layout of Building Plan, Types of buildings, Plinth area, carpet area, floor space index, Introduction to building byelaws, concept of sun light & ventilation. Components of Buildings & their functions, Basic concept of R.C.C., Introduction to types of foundation
Chapter 5
Transportation: Introduction to Transportation Engineering; Traffic and Road Safety: Types and Characteristics of Various Modes of Transportation; Various Road Traffic Signs, Causes of Accidents and Road Safety Measures.
Chapter 6
Environmental Engineering: Environmental Pollution, Environmental Acts and Regulations, Functional Concepts of Ecology, Basics of Species, Biodiversity, Ecosystem, Hydrological Cycle; Chemical Cycles: Carbon, Nitrogen & Phosphorus; Energy Flow in Ecosystems.
Water Pollution: Water Quality standards, Introduction to Treatment & Disposal of Waste Water. Reuse and Saving of Water, Rain Water Harvesting. Solid Waste Management: Classification of Solid Waste, Collection, Transportation and Disposal of Solid. Recycling of Solid Waste: Energy Recovery, Sanitary Landfill, On-Site Sanitation. Air & Noise Pollution: Primary and Secondary air pollutants, Harmful effects of Air Pollution, Control of Air Pollution. . Noise Pollution Harmful Effects of noise pollution, control of noise pollution, Global warming & Climate Change, Ozone depletion, Greenhouse effect
Text Books:
1. Palancharmy, Basic Civil Engineering, McGraw Hill publishers.
2. Satheesh Gopi, Basic Civil Engineering, Pearson Publishers.
3. Ketki Rangwala Dalal, Essentials of Civil Engineering, Charotar Publishing House.
4. BCP, Surveying volume 1
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
1. Effects of local C/O ratio and scalarEffects of local C/O ratio and scalar
dissipation rate on sooting limits of sphericaldissipation rate on sooting limits of spherical
non-premixed flamesnon-premixed flames
V.R. LecoustreV.R. Lecoustre11
, B.H. Chao, B.H. Chao22
, P.B. Sunderland, P.B. Sunderland11
,,
D.L. UrbanD.L. Urban33
, D.P. Stocker, D.P. Stocker33
, R.L. Axelbaum, R.L. Axelbaum44
11
University of Maryland, College Park, MD ;University of Maryland, College Park, MD ; 22
University of Hawaii, Honolulu, HI ;University of Hawaii, Honolulu, HI ;
33
NASA Glenn Research Center, Cleveland, OH ;NASA Glenn Research Center, Cleveland, OH ; 44
Washington University, St. Louis, MOWashington University, St. Louis, MO
This work was supported by NASA.This work was supported by NASA.
2007 Fall Technical Meeting2007 Fall Technical Meeting
October 22nd
, 2007
2. BackgroundBackground
• Experiments: local critical C/O ratio of about 0.6 has been
identified for ethylene spherical diffusion flames. Agrees with
the global C/O ratio for premixed flames (Haynes and Wagner,
1981, Glassman, 1988).
• The critical soot formation T is 1250 – 1650 K (Glassman, 1998)
in diffusion flames.
• Short tres can prevent soot formation.
• Microgravity offers strain-free 1D diffusion flames (Law,
Axelbaum, Atreya, co-workers).
• 17 sooting limit microgravity flames were identified by
Sunderland et al. (2004).
3. ObjectivesObjectives
• Investigate sooting limits of microgravity C2H4
diffusion flames, focusing on the effects of:
• local C/O atom ratio,
• local T,
• local scalar dissipation rate χ
• This numerical investigation uses detailed
chemistry to study flame structure.
4. Identification of Sooting LimitsIdentification of Sooting Limits
(a) 18% C2H4 → 27% O2 (b) 18% C2H4 → 28% O2
(c) O2 → 12% C2H4 (d) O2 → 13% C2H4
Tests performed in
NASA Glenn 2.2 s
drop tower.
Fuel – C2H4
oxidizer – O2
diluent – N2
df at 2 s = 12 - 34 mm
6. Numerical methodsNumerical methods
• Sandia’s PREMIX code was modified to model steady-state
or transient solutions of spherical laminar diffusion flames.
• Detailed chemistry (GRI Mech. 3.0, 53 species, 325
reactions) and transport properties were used.
• Discrete ordinates radiation model.
• Ignition was via a steady state solution for a small domain
(~1.2 cm) with adiabatic boundaries (Tse et al., 2001).
• At time zero, the transient computation commenced over an
extended domain (100 cm) with radiation.
7. Transient evolution of flameTransient evolution of flame
Flame 10
Inverse flame
Radiative heat losses
@ 2 s ≈ 20 W
All flames present
same transient
behavior after ignition
Time (s)
Flameradius(cm)
Flametemperature(K)0 1 2 3
0
0.25
0.5
0.75
1
1.25
1.5
1.75
2
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Flame Position
Temperature
Frame 001 29 Aug 2007 Frame 001 29 Aug 2007
8. Scalar dissipation rateScalar dissipation rate
• Scalar dissipation rate χ = 2 DN2 ( dZ / dr )2
• By definition :
• Simple definition for pure fuel : ZCH = YC + YH
• Following Bilger, we can obtain a mixture fraction for
ethylene: ( ) ( ) ( )
( ) ( ) ( )
O
OO
C
CC
H
HH
O
OO
C
CC
H
HH
CHO
MW
YY
MW
YY
MW
YY
MW
YY
MW
YY
MW
YY
Z
1,2,2,1,2,1,
2,2,2,
2
2
2
2
−
+
−
+
−
−
+
−
+
−
=
mixtureofmass
streamfuelfromgoriginatinmaterialofmass
Z =
9. Mixture FractionMixture Fraction
Mixture fraction
T(K)
0 0.025 0.05 0.075 0.1
400
600
800
1000
1200
1400
1600
ZCH
ZCHO
Zst = 0.041
Flame 10
Fuel stream : pure C2H4
ZCH does not preserve Zst
ZCHO preserves Zst,
temperature peaks at Zst
10. Structure of sooting limit flamesStructure of sooting limit flames
Structure of flame 10 at
2 seconds.
Peak χ is about 0.2 s-1
.
High temperature
gradients at flame inner
side.
Large high temperature
field at flame outer
side.
11. Critical local C/O ratioCritical local C/O ratio
C/O Ratio
Standarddeviation(K)
0.4 0.45 0.5 0.55 0.6
0
10
20
30
40
50
60
70
80
ame 001 28 Aug 2007 ame 001 28 Aug 2007
For a given C/O ratio
consider temperature of
low scalar dissipation rate
flames.
Compute the
temperature standard
deviation for this C/O.
C/OCRIT ratio minimizes
standard deviation
C/OCRIT = 0.51
12. Results : TResults : Tc/o=0.51c/o=0.51 vs. 1/vs. 1/χχc/o=0.51c/o=0.51
We consider the local T
and scalar dissipation
rate at the location where
C/O=0.51
Local T ≈ 1400 K for
1/χ >0.5 s
For shorter local mixing
time, higher local T is
required
1/X(C/O=0.51)
(s)
T(C/O=0.51)
(K)
0 5 10 15 20
0
250
500
750
1000
1250
1500
1750
2000
Normal
Inverse
Tavg = 1400 K
Frame 001 28 Aug 2007 |Frame 001 28 Aug 2007 |
13. ConclusionsConclusions
An improved mixture fraction definition suitable for C2H4 flame has
been defined.
Identified a critical C/O = 0.51
Flames with scalar dissipation rate lower than 2 s-1
at this location
present same temperature averaged at 1400 K, regardless Zst.
Flames with scalar dissipation rate greater than 2 s-1
need higher
temperature at this location to form soot.
Editor's Notes
Thank you for attending my presentation. My name is Vivien Lecoustre, mechanical engineer PhD student at UMD. My topic presentation is Effects of C/O ratio and scalar dissipation rate on sooting limits of spherical non-premixed flames
/I would like to present my co-authors who are professor Beei Huan Chao, from university of Hawaii, Professor Peter Sunderland (who is my advisor) from UMD, David Urban and Denis Stocker, from the NASA Glenn Research center and Professor Richard Axelbaum, from Washington University/.
This project is supported by NASA.
This work is about modeling results. We revisit an experimental paper which characterized 17 sooting limits spherical diffusion flames.
Those flame were characterized in microgravity. You may be familiar with the temperature and scalar dissipation rate effects on soot formation.
But maybe not on the C/O ratio.
Sooting limits arise from a competition between the reaction of fuel pyrolysis and the reaction of soot oxidation. The former will be likely to occur when we have a large number of carbon.
The latter, on the contrary, will be likely to occur when great number oxygen atoms are present, greater than the carbon atoms.
C/O ratio is a useful parameter to asses the importance of one or the other reactions.
The past work carried on soot formation was first established for premixed flame due to nearly constant temperature and Carbon to Oxygen atom ratio, C/O ratio, in the soot-forming regions of premixed flame, and to the decoupling effect of those two parameters.
Experiments, carried out by Haynes and Wagner and Glassman using a ethylene premixed flame, show that there is a critical C/O ratio value for soot inception. Soot did not form into ethylene flames with a global C/O ratio less than 0.6
Despite the differences between soot inception in premixed and non premixed flame, the C/O ratio has been shown to be relevant to sooting limits in diffusion flame.
Temperature plays an important role in soot formation. In diffusion flame, an increase of temperature leads to an increase of soot. Critical temperatures at the onset of soot formation for diffusion flame have been observed to range from 1250K to 1650K by Glassman.
Time is the third important parameters in soot formation. It has been shown that short residence time within the flame can prevent soot formation.
The microgravity allows the observation of buoyancy free and strain free diffusion flames, along with the observation of flame having longer residence or mixing time than buoyant flame. Moreover it allows the observation of the simplest flame possible, get rid off of all the non one dimensional effects because diffusive, convective and radiative transports are all in the radial direction.
17 sooting limits flame has been then characterized by Sunderland and al.
The objectives of this works are to investigate numerically the inner structure of the microgravity sooting limits diffusion flames, focusing on the effect of the C/O ratio, the local temperature within the flame, especially in the vicinity of the critical C/O ratio, and the local scalar dissipation rate, which is related to the mixing rate at a specific location and which can be seen as the inverse of a local characteristic mixing time.
We assume that soot formation occurs when 3 conditions are meet. C/O ratio needs to be greater than a critical value, which provides enough available carbon atoms for soot formation and overcoming soot oxidation. Temperature is needed, low temperature freezing reactions. Time, given by inverse of local scalar dissipation rate, balances temperature.
We now think that the C/O ratio scales with H/O ratio, which is a key parameter to specify soot oxidation, which is mainly caused by presence of OH (hydroxile radical).
The flame structure is study through the use a 1-D detailed chemitry code, aiming to quantify the critical parameters values.
The 17 sooting limits spherical diffusion flames, which you have a pictures of some, have been observed in microgravity conditions. This is from experiment we did several years ago using the 2.2 s Nasa Glenn drop tower.
Those flames were observed to reach their sooting limits at 2s. Soot was observed within the flame until 2 seconds. At 2 seconds and after, flames were permanently blue.
The experimental process was to vary the concentration of fuel or oxidizer leading to soot suppression at 2s.
Picture of four flames, Presence of bleu indicating the location of the main reaction. On some picture we see the presence of a light yellow part, presence of soot. The one with the yellow sooting limit flame.
Those flames are fueled with ethylene, diluted in diverse proportion with Nitrogen, but all equivalent to 1.51 mg/s pure ethylene. The oxidizer used was a mixture of nitrogen and oxygen.
Role of convection is study by investigating normal flame and inverse flames. Normal flame means that fuel is flowing out from the burner toward an environment of oxidizer (top picture). Inverse flame means that oxidizer is flowing out from the burner, flow in heading toward fuel (lower pictures).
Dimension involved : the burner diameter is 6.4 mm and the flame diameters range between 12 to 34 mm.
This table shows the different characteristics of the 17 sooting limits diffusion flame considered.
I apologized for all the numbers in this slkide. This is our test Matrix. Normal and inverse flame are tabulated, along with mole fraction of fuel and oxygen. Stoichiometric mixture fraction ZST, the residence time, define here as the mass of gas contained between the flame and the burner surface divided by mass the burner flow rate, The adiabatic flame temperature computed using Chemical Equilibrium with Application. (CEA) an dthe flame temperature at 2 seconds given by the code.
From this table, one can appreciate the wide range of conditions covered. We consider flame with pure fuel flame (flame 1 and 10) to flame with a fuel concentration as low as 11% (Flame 8 and 7). The oxygen concentration varies from 13 % (flames 10,11 and 12) to pure oxygen. Therefore, we cover a broad range of mixture fraction, from 0.041 (flame 10) to almost 0.7 (Flame 17).
Wide range of residence time is covered. The minimum is 29 ms for the flame 9 to 2.72s for the flame 1. Residence time represents the time for a fluid particle at the burner to reach the location of maximum temperature. However think scalar dissipation rate is the key.
Adiabatic flame temperature ranges from 1814 K (flame 12) to 2740 K (flame 9).
At 2 seconds the flame temperatures have dropped in more less extend. Max T is 2262 K and the lowest T is 1479 K, which is not the flame having the lowest adiabatic flame temperature.
The 17 flames are numerically modeled using a 1-D code to investigate their inner structure. Get accurate temperature field, species concentration at the desire time.
We used a modified Sandia’s PREMIX code, with the adequate modifications to model 1-D spherical non-buoyant flames, either at steady state or time accurate transient solutions.
The code uses a detailed chemistry model (GRI Mech. 3.0- 53 species, 325 reactions) and detailed transport properties.
No soot models incorporated.
The optically thick radiative heat losses from H2O, CO2 and CO are modeled using the discrete ordinates radiation.
Ignition is modeled used the same process than Tse. The steady state solution for the flame is computed on a small domain (1.2 cm) with adiabatic boundaries condition on both sides. This solution is used as initial condition for the computation of the transient solution.
The transient solution is computed over a 100 cm radius domain, with constant boundary temperatures and enabling radiative losses.
This process gives a very good agreement with the experimental results.
The time accurate transient computation were stopped at 2s, corresponding to flame at their sooting limit point.
Following ignition, the flame will grow with the time, expending itself. The plot here represent the variation of flame location and flame temperature for the flame 10 over a 3 seconds period, with the origin taken as ignition. The growth of the flame is observable on this chart, reading the triangle.
As the flames growth, its temperature decreases, mainly due to increase of radiative heat losses, which have shown to be proportional to the flame surface area.
At the sooting limit point (2 second) the flame is still present (Tf = 1581 K), the radiative heat losses are about 20 W (out of about 70 W)-1.51 mg/s C2H4 equivalent flame.
Our approach in this work seek for a characteristic local time scaling for the mixing of species and time allowed for soot formation reaction. The scalar dissipation is inversely proportional to such a time.
The scalar dissipation used for our study is given by the above formula, and is equal to twice the diffusivity of N2 multiply by the square of the mixture fraction gradient. The diffusivity of N2 is justify since N2 is one of the dominant species at the vicinity of the flame. We compute locally the scalar dissipation using the local value of the N2 diffusivity given by the detailed transport model.
The scalar dissipation rate is very dependant on mixture fraction Z.
By definition the mixture fraction is defined locally to be the local mass of material originating from the fuel stream divided the local mixture mass.
Since we are dealing with detailed chemistry, we must considered mass fraction of atoms, since fuel pyrolysis leads fuel drop mass fraction.
A trivial way to define the mixture fraction is to consider Z=Yc+Yh since C and H only comes from the fuel stream.
However this definition is not suitable as I will show in the next slide. Another way is to define the mixture fraction as below, Bilger like mixture fraction definition,, where we account for C, H and also O, only coming from the oxidizer stream. The suffix 1 stands for the condition at the fuel stream, 2 stands for the conditions at the oxidizer stream.
Test the accuracy of our two model, using the same way than Mahalingam. Zch is based on the sum of the local mass fraction of carbon atom with the local mass fraction of hydrogen. ZCHO accounts for Oxygen, Hydrogen and Carbon. In this graph we plot the field temperature of the flame 10, at 2 seconds, in the mixture fraction space, using both model. The flame 10 is an inverse flame with an environment of pure fuel.
The temperature curve given by ZCH does not peak at the stoichiometric value of mixture fraction but is shifted on higher value of Z. Hence, this formulation of Mixture fraction is not appropriate since it does not preserve the Zst.
On the contrary, the ZCHO temperature curve peaks at Zst, meaning that this formulation preserves the value of Zst.
Hence this model is adopted for the computation of mixture fraction, which derived is used for the scalar dissipation rate computation.
We consider the predicted solution at 2 seconds for each 17 flame. This chart illustrates the structure of an spherical diffusion flame. The temperature, C/O ratio, Mixture Fraction and scalar dissipation rate are the value from flame 10. Those value are plotted against the domain radius, with the origin taken at the center of the burner. The burner radius is 0.32 cm.
From the temperature plot, we can notice : Stiff gradient close to the burner. The outer side of the flame presents a boarder high temperature area.
The inverse nature of the flame can be seen from the behavior of the C/O ratio. Close to the burner, the C/O ratio is very low, close to 0, we are on the oxidizer side. The C/O ratio grows when we increase the radius.
The area where the C/O is greater than 1/3 corresponds to the fuel side. On this side, when the C/O ratio increases, the temperature decreases. If we put aside the temporal effect on soot formation, the balance between C/O ratio and T can be understand this way:
Important C/O provide a high number of available carbon atoms, hence promoting soot formation by fuel pyolysis. However, we can notice that the temperature on this part of the flame is low, hence blocking fuel pyrolysis. To overcome this, we need to consider hotter part, which are located in area of low C/O ratio, in area where Oxidizer and fuel pyrolysis are on the same level. This area correspond to the area close to a critical value of C/O ratio. At the critical C/O ratio, the temperature is the maximum allowed temperature for soot formation. However since oxidation of soot equal soot formation, we do not create more soot.
From our numerical data, a Critical C/O ratio value has been identified. Its critical value is 0.51.
We can study the couple effects of temperature and scalar dissipation rate. For that we plot the temperature at the critical C/O ratio location against the inverse scalar dissipation rate at the same location for every 17 flames. Using the inverse of scalar dissipation rate gives use a characteristic mixing time. The plain black symbols plots the T of normal flame, will the open symbols plots the T of the inverse flame.
2 different Temperature behaviors can be observed from this plot, depending on the value of the scalar dissipation rate. The flames with a inverse scalar dissipation rate greater than 0.5 seconds present a nearly constant temperature at the critical C/O ratio. This gives us a deep insight on mechanism of soot formation. For flame with sufficient mixing time, temperature is the controlling parameters. This temperature averaged at 1400 K.
The second behavior of the flames are given by the following:
When the mixing time or inverse of scalar dissipation rate is lower than 0.5 s-1, then time is the controlling parameters. Shorter time requires increased temperature to form soot. Hence for short mixing time, scalar dissipation rate is the controlling parameter. For a fixed temperature at a same C/O ratio, increasing the scalar dissipation rate will lead to soot free flame.