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Sample records for acid combustion rate

  1. Combustion

    CERN Document Server

    Glassman, Irvin

    1987-01-01

    Combustion, Second Edition focuses on the underlying principles of combustion and covers topics ranging from chemical thermodynamics and flame temperatures to chemical kinetics, detonation, ignition, and oxidation characteristics of fuels. Diffusion flames, flame phenomena in premixed combustible gases, and combustion of nonvolatile fuels are also discussed. This book consists of nine chapters and begins by introducing the reader to heats of reaction and formation, free energy and the equilibrium constants, and flame temperature calculations. The next chapter explores the rates of reactio

  2. Spray Combustion Modeling with VOF and Finite-Rate Chemistry

    Science.gov (United States)

    Chen, Yen-Sen; Shang, Huan-Min; Liaw, Paul; Wang, Ten-See

    1996-01-01

    A spray atomization and combustion model is developed based on the volume-of-fluid (VOF) transport equation with finite-rate chemistry model. The gas-liquid interface mass, momentum and energy conservation laws are modeled by continuum surface force mechanisms. A new solution method is developed such that the present VOF model can be applied for all-speed range flows. The objectives of the present study are: (1) to develop and verify the fractional volume-of-fluid (VOF) cell partitioning approach into a predictor-corrector algorithm to deal with multiphase (gas-liquid) free surface flow problems; (2) to implement the developed unified algorithm in a general purpose computational fluid dynamics (CFD) code, Finite Difference Navier-Stokes (FDNS), with droplet dynamics and finite-rate chemistry models; and (3) to demonstrate the effectiveness of the present approach by simulating benchmark problems of jet breakup/spray atomization and combustion. Modeling multiphase fluid flows poses a significant challenge because a required boundary must be applied to a transient, irregular surface that is discontinuous, and the flow regimes considered can range from incompressible to highspeed compressible flows. The flow-process modeling is further complicated by surface tension, interfacial heat and mass transfer, spray formation and turbulence, and their interactions. The major contribution of the present method is to combine the novel feature of the Volume of Fluid (VOF) method and the Eulerian/Lagrangian method into a unified algorithm for efficient noniterative, time-accurate calculations of multiphase free surface flows valid at all speeds. The proposed method reformulated the VOF equation to strongly couple two distinct phases (liquid and gas), and tracks droplets on a Lagrangian frame when spray model is required, using a unified predictor-corrector technique to account for the non-linear linkages through the convective contributions of VOF. The discontinuities within the

  3. Effect of oxygen enrichment in air on acid gas combustion under Claus conditions

    KAUST Repository

    Ibrahim, Salisu

    2013-09-01

    Results are presented to examine the combustion of acid gas (H2S and CO2) in hydrogen-fueled flames using a mixture of oxygen and nitrogen under Claus conditions (Φ = 3). Specifically the effect of oxygen enrichment in the above flames is examined. The compositions of acid gas examined are100% H2S and 50% H2S/50% CO2 with different percentages of oxygen enrichment (0%, 19.3% and 69.3%) in the oxygen/nitrogen mixtures. The results revealed that combustion of acid gas formed SO2 wherein the mole fraction of SO2 increased to an asymptotic value at all the oxygen concentrations examined. In addition, increase in oxygen enrichment of the air resulted in increased amounts of SO2 rather than the formation of more desirable elemental sulfur. In case of 50% H2S/50% CO2 acid gas, carbon monoxide mole fraction increased with oxygen enrichment which is an indicator to the availability of additional amounts of oxygen into the reaction pool. This gas mixture resulted in the formation of other sulfurous–carbonaceous compounds (COS and CS2) due to the presence of carbon monoxide. The results showed that the rate of COS formation increased with oxygen enrichment due to the availability of higher amounts of CO while that of CS2 reduced. The global reactions responsible for this observed phenomenon are presented.

  4. Finite-rate water condensation in combustion-heated wind tunnels

    Science.gov (United States)

    Erickson, Wayne D.; Mall, Gerald H.; Prabhu, Ramadas K.

    1988-01-01

    A quasi-one-dimensional method for computing finite rate nucleation and droplet growth of water in a supersonic expansion of combustion products is presented. Sample computations are included for the Langley 8 foot High Temperature Tunnel, but the method can also be applied to other combustion heated wind tunnels. The sample results indicate that the free stream static pressure can be in the range of 25 to 60 percent greater than that computed for isentropic nozzle flow without water condensation. The method provides a tool for examining the effects of water condensation on static state properties and velocity of the supersonic stream in combustion heated wind tunnels.

  5. Application of neural network in the study of combustion rate of natural gas/diesel dual fuel engine

    Institute of Scientific and Technical Information of China (English)

    严兆大; 周重光; 苏石川; 刘震涛; 王希珍

    2003-01-01

    In order to predict and improve the performance of natural gas/diesel dual fuel engine (DFE), a combustion rate model based on forward neural network was built to study the combustion process of the DFE. The effect of the operating parameters on combustion rate was also studied by means of this model. The study showed that the predicted results were good agreement with the experimental data. It was proved that the developed combustion rate model could be used to successfully predict and optimize the combustion process of dual fuel engine.

  6. Application of neural network in the study of combustion rate of natural gas/diesel dual fuel engine

    Institute of Scientific and Technical Information of China (English)

    严兆大; 周重光; 苏石川; 刘震涛; 王希珍

    2003-01-01

    In order to predict and improve the performance of matural gas/diesel dual fuel engine(DFE),a combustion rate model based on forward meural network was built to study the combustion process of the DFE.The effect of the operating parameters on combustion rate was also studied by means of this model.The study showed that the predicted results were good agreement with the experimental data.It was proved that the de-veloped combustion rate model could be used to successfully predict and optimize the combustion process of dual fuel engine.

  7. Effect of Chamber Pressurization Rate on Combustion and Propagation of Solid Propellant Cracks

    Science.gov (United States)

    Yuan, Wei-Lan; Wei, Shen; Yuan, Shu-Shen

    2002-01-01

    area of the propellant grain satisfies the designed value. But cracks in propellant grain can be generated during manufacture, storage, handing and so on. The cracks can provide additional surface area for combustion. The additional combustion may significantly deviate the performance of the rocket motor from the designed conditions, even lead to explosive catastrophe. Therefore a thorough study on the combustion, propagation and fracture of solid propellant cracks must be conducted. This paper takes an isolated propellant crack as the object and studies the effect of chamber pressurization rate on the combustion, propagation and fracture of the crack by experiment and theoretical calculation. deformable, the burning inside a solid propellant crack is a coupling of solid mechanics and combustion dynamics. In this paper, a theoretical model describing the combustion, propagation and fracture of the crack was formulated and solved numerically. The interaction of structural deformation and combustion process was included in the theoretical model. The conservation equations for compressible fluid flow, the equation of state for perfect gas, the heat conducting equation for the solid-phase, constitutive equation for propellant, J-integral fracture criterion and so on are used in the model. The convective burning inside the crack and the propagation and fracture of the crack were numerically studied by solving the set of nonlinear, inhomogeneous gas-phase governing equations and solid-phase equations. On the other hand, the combustion experiments for propellant specimens with a precut crack were conducted by RTR system. Predicted results are in good agreement with experimental data, which validates the reasonableness of the theoretical model. Both theoretical and experimental results indicate that the chamber pressurization rate has strong effects on the convective burning in the crack, crack fracture initiation and fracture pattern.

  8. THE ASYMPTOTIC LIMIT FOR A COMBUSTION MODEL IN REGARD TO INFINITE REACTION RATE

    Institute of Scientific and Technical Information of China (English)

    Ying Longan

    2008-01-01

    The Zeldovich-von Neumann-Doring model and the Chapman-Jouguet model for a simplified combustion model-Majda's model is studied. The author proves a uniform maximum norm estimate, then proves that as the rate of chemical reaction tends to infinity the solutions to the Zeldovich-von Neumann-Doring model tend to that of the Chapman-Jouguet model. The type of combustion waves is studied. This result is compared with the result of the projection and finite difference method for the same model.

  9. Methane combustion kinetic rate constants determination: an ill-posed inverse problem analysis

    Directory of Open Access Journals (Sweden)

    Bárbara D. L. Ferreira

    2013-01-01

    Full Text Available Methane combustion was studied by the Westbrook and Dryer model. This well-established simplified mechanism is very useful in combustion science, for computational effort can be notably reduced. In the inversion procedure to be studied, rate constants are obtained from [CO] concentration data. However, when inherent experimental errors in chemical concentrations are considered, an ill-conditioned inverse problem must be solved for which appropriate mathematical algorithms are needed. A recurrent neural network was chosen due to its numerical stability and robustness. The proposed methodology was compared against Simplex and Levenberg-Marquardt, the most used methods for optimization problems.

  10. Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks

    Energy Technology Data Exchange (ETDEWEB)

    NGUYEN, D.M.

    2000-03-01

    The purpose of this data collection activity is to obtain data for a screening of combustible gases in catch tanks that are currently operated by the River Protection Project (RPP). The results will be used to support closure of the flammable gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the ''Tank Safety Screening Data Quality Objective'' (Dukelow et al. 1995). Combustible gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible gas level measurement in a tank exceeds an established threshold, vapor grab samples (i.e., Hoke and SUMMA) will be collected for laboratory analysis. In addition, ventilation rates of some catch tanks will be determine using the tracer gas injection method to evaluate removal of flammable gas by air flowing through the tanks. This test plan identifies the field tests, sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides step-by-step direction for field measurement of combustible gas concentrations and determination of ventilation rates.

  11. Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks

    International Nuclear Information System (INIS)

    The purpose of this data collection activity is to obtain data for a screening of combustible gases in catch tanks that are currently operated by the River Protection Project (RPP). The results will be used to support closure of the flammable gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the ''Tank Safety Screening Data Quality Objective'' (Dukelow et al. 1995). Combustible gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible gas level measurement in a tank exceeds an established threshold, vapor grab samples (i.e., Hoke and SUMMA) will be collected for laboratory analysis. In addition, ventilation rates of some catch tanks will be determine using the tracer gas injection method to evaluate removal of flammable gas by air flowing through the tanks. This test plan identifies the field tests, sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides step-by-step direction for field measurement of combustible gas concentrations and determination of ventilation rates

  12. Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in TWRS Active Catch Tanks

    International Nuclear Information System (INIS)

    The purpose of this data collection activity is to obtain data for a screening of combustible gases in catch tanks that are currently operated by the River Protection Project (RPP). The results will be used to support closure of the flammable gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the ''Tank Safety Screening Data Quality Objective'' (Dukelow et a1 1995). Combustible gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible gas level measurement in a tank exceeds an established threshold, vapor grab samples will be collected for laboratory analysis. In addition, ventilation rates of some catch tanks will be determined using the tracer gas injection method to evaluate removal of flammable gas by air flowing through the tanks. This test plan identifies the field tests, sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides step by-step direction for field measurement of combustible gas concentrations and determination of ventilation rates

  13. Test Plan for Measuring Ventilation Rates and Combustible Gas Levels in RPP Active Catch Tanks

    International Nuclear Information System (INIS)

    The purpose of this sampling activity is to obtain data to support an initial evaluation of potential hazards due to the presence of combustible gas in catch tanks that are currently operated by the River Protection Project (RPP). Results of the hazard analysis will be used to support closure of the flammable gas unreviewed safety question for these facilities. The data collection will be conducted in accordance with the Tank Safety Screening Data Quality Objective (Dukelow et al. 1995). Combustible gas, ammonia, and organic vapor levels in the headspace of the catch tanks will be field-measured using hand-held instruments. If a combustible gas level measurement in a tank exceeds an established threshold, gas samples will he collected in SUMMA' canisters for more extensive laboratory analysis. In addition, ventilation rates of some catch tanks will be measured to evaluate removal of flammable gas by air flowing through the tanks. This test plan identifies the sample collection, laboratory analysis, quality assurance, and reporting objectives for this data collection effort. The plan also provides the procedures for field measurement of combustible gas concentrations and ventilation rates

  14. Factors affecting the corrosion rates of ceramics in coal combustion systems

    Energy Technology Data Exchange (ETDEWEB)

    Hurley, J.P. [Univ. of North Dakota, Grand Forks, ND (United States)

    1995-08-01

    The concentrations of approximately a dozen elements in the products of coal combustion affect the corrosion rates of ceramics used to construct the combustion system. The elements, including H, O, Na, Mg, Al, Si, P, S, Cl, K, Ca, and Fe, affect corrosion rates in three ways: as primary corrodants of the materials, as secondary corrodants that affect the activities of the primary corrodants, and by affecting the mass transport rate of the primary corrodants. A full factorial study of corrosion rates performed by varying the concentrations of these elements would involve X{sup n} tests, where X is the number of variations of each element and n is the number of different elements. For three variations (low, medium, and high concentrations) of each of 12 elements, the number of tests is 531,441 for a single temperature and pressure condition. The numbers can be reduced with the use of a fractional factorial test matrix, but the most effective way to perform corrosion tests is to base them on realistic system conditions. In this paper, the effects of the composition and physical state of the products of coal combustion on ceramic corrosion rates are given along with suggestions of appropriate test conditions for specific system components.

  15. Electroremediation of straw and co-combustion ash under acidic conditions

    DEFF Research Database (Denmark)

    Lima, Ana T.; Ottosen, Lisbeth M.; Ribeiro, Alexandra B.

    2009-01-01

    Biomass, such as wood and straw, is currently used in EU as a renewable energy source for energy production and this application is expected to rise in coming years. Combined heat and power installations produce fly ash, which is considered hazardous waste. The fly ash management issue should...... be addressed before biomass combustion is considered a truly sustainable technology. The electrodialytic process is a remediation technique able to assist the management of fly ash. For this work, straw and co-combustion of wood ash are briefly characterized and their electrodialytic treatment is carried out...... similarities with wood ash alone. However, further characterization should be carried out before any comparison regarding applicable legislation. Under acidic conditions, the electrodialytic treatment was not effective for the co-combustion wood ash. The heavy metals appeared in the least soluble fraction...

  16. Calculation of the Rate of Combustion of a Metallized Composite Solid Propellant with Allowance for the Size Distribution of Agglomerates

    Science.gov (United States)

    Poryazov, V. A.; Krainov, A. Yu.

    2016-05-01

    A physicomathematical model of combustion of a metallized composite solid propellant based on ammonium perchlorate has been presented. The model takes account of the thermal effect of decomposition of a condensed phase (c phase), convection, diffusion, the exothermal chemical reaction in a gas phase, the heating and combustion of aluminum particles in the gas flow, and the velocity lag of the particles behind the gas. The influence of the granulometric composition of aluminum particles escaping from the combustion surface on the linear rate of combustion has been investigated. It has been shown that information not only on the kinetics of chemical reactions in the gas phase, but also on the granulometric composition of aluminum particles escaping from the surface of the c phase into the gas, is of importance for determination of the linear rate of combustion.

  17. Influence of lead Inorganic Compounds on Combustion Rate of Double Base Rocket Propellants

    Directory of Open Access Journals (Sweden)

    V. B. Pillai

    1982-04-01

    Full Text Available The influence of lead nitrate, red lead, lead chromate, lead floride and lead carbonate on the combustion behaviour of double base propellants in the pressure range-35-140kg/cm /sup 2/ was studied. While all these compounds increased burning rates in lower pressure range (35-60 kg/cm/sup 2/ and higher pressure range (120-140 kg/cm/sup 2/, only lead chromate and lead fluoride were effective in the intermediate pressure range of 60-105 kg/cm/sup 2/. None of these compounds were effective as platonizer, except lead fluoride, which lowered n value to 0.34 in the lower pressure range. Addition of carbon black along with lead compounds raised burning rates further and reduced n values significantly in the higher pressure regins. A probable mechanism on the role of lead compounds studied has been suggested based on burning rate and DTA results.

  18. Emission control for precursors causing acid rain(V):Improvement of acid soil with the bio-briquette combustion ash

    Institute of Scientific and Technical Information of China (English)

    DONG Xu-hui; SAKAMOTO Kazuhiko; WANG Wei; GAO Shi-dong; ISOBE Yugo

    2004-01-01

    The bio-briquette technique which mixes coal, biomass and sulfur fixation agent and bio-briquettes under 3-5 t/cm2 line pressure has aroused people's attention in view of controlling the air pollution and the acid rain. In this paper, the physicochemical properties of bio-briquette and its ash were investigated. And the acid soil was improved by the bio-briquette combustion ash, which contained nutritive substances such as P, N, K and had the acid-neutralizing capacity(ANC). The pH, EC, effective nutrient elements(Ca, Mg, K, P and N), heavy metal elements(Al, Cu, Cd, Cr, Zn and Mn) and acid-neutralizing capacity change of ash-added soils within the range of 0%-10%, were also studied. Specially, when 5% bio-briquette combustion ash was added to the tested soil, the content of the effective elements such as Ca, Mg and K rose by 100 times, 7 times and twice, respectively. The total nitrogen also increased by about twice. The results showed the oxyanions such as that of Al, Cu, Cd, Cr, Zn and Mn were not potentially dangerous, because they were about the same as the averages of them in Chinese soil. It is shown that the ANC became stronger, though the ANC hardly increases in the ash-added soil. On the basis of the evaluation indices, it is concluded that the best mixture ratio is to add 2.5%-8% of the bio-briquette combustion ash to the tested soil.

  19. Circulating fluidized bed combustion product addition to acid soil: alfalfa (Medicago sativa L.) composition and environmental quality.

    Science.gov (United States)

    Chen, Liming; Dick, Warren A; Kost, David

    2006-06-28

    To reduce S emissions, petroleum coke with a high concentration of S was combusted with limestone in a circulating fluidized bed (CFB) boiler. The combustion process creates a bed product that has potential for agricultural uses. This CFB product is often alkaline and enriched in S and other essential plant nutrients, but also contains high concentrations of Ni and V. Agricultural land application of CFB product is encouraged, but little information is available related to plant responses and environmental impacts. CFB product and agricultural lime (ag-lime) were applied at rates of 0, 0.5, 1.0, and 2.0 times the soil's lime requirement (LR) to an acidic soil (Wooster silt loam). The 2.0x LR application rate of CFB product was equivalent to 67.2 Mg ha(-1). Alfalfa yield was increased 4.6 times by CFB product and 3.8 times by ag-lime compared to untreated control. Application of CFB product increased the concentration of V in soil and alfalfa tissue, but not in soil water, and increased the concentration of Ni in soil and soil water, but not in alfalfa tissue. However, these concentrations did not reach levels that might cause environmental problems.

  20. Study on drying and combustion process in 8rate-CFB incinerator

    Institute of Scientific and Technical Information of China (English)

    LI QingHai; ZHANG YanGuo; CHEN MeiQian; MENG AiHong; CHEN ChangHe

    2009-01-01

    The drying and combustion process in the combined grate and circulating fiuidized bed (grate-CFB)municipal solid waste (MSW) incinerator was investigated experimentally and mathematically. The drying grate bed was simulated by a muffle furnace, which could be controlled at a constant tempera-ture level. The kind of wastes, thickness of waste layer fed and temperature were chosen as the ad-justable parameters to study their effect on the drying process. The experimental results indicated that the hydrophilic wastes were more difficult to be dried than the hydrophobic wastes. The higher the temperature is the easier the waste is to be dried. The thinner waste layer is favorable to drying the waste. The pyrolysis experiment in the furnace showed that the higher temperature level could reduce the conversion rate of carbon to carbon monoxide. The semi-empirical mathematical model that in-cluded the bed material distribution subrnodel, volatile matter release submodel, carbon particle combustion submodel and so on was proposed. A 260 t/d grate-CFB incinerator was modeled and the model predicted bulk density agreed with the measured value from industrial field test. The predicted flue gas (e.g. CO2, CO) concentration deviated slightly from the industrial test data. The parameters and variables used in the model were determined by the experiments or practical field test. This model can be used to design the grate-CFB incinerator and guide its operation.

  1. The effect of CO{sub 2} on the corrosion rate in simulated combustion atmospheres

    Energy Technology Data Exchange (ETDEWEB)

    Maekipaeae, Martti [VTT Processes, P.O. Box 1601, FIN-02044 VTT, Espoo (Finland); Sroda, Szymon [European Commission, Joint Research Centre, Institute for Energy, P.O. Box 2, NL-1755 ZG Petten (Netherlands)

    2004-07-01

    The aim of the study is to improve the understanding of the corrosion mechanism in biomass and waste combustion processes. Laboratory, pilot and full scale testing of materials are performed. The obtained results are discussed, e.g., with reference to thermodynamic modelling calculations. The laboratory experiments in JRC Plant Simulation Test Laboratory are focused mainly on common ferritic and austenitic steels (X10, X20, 2.25Cr1Mo, AC66, Sanicro28, Esshette 1250 etc), which are used as superheater steel tube materials in such applications. The main aim of this part of the project is to understand the effect of deposition as well as the CO{sub 2} or/and CO/CO{sub 2} content in combustion atmospheres on corrosion rate and mechanism of studied materials. Laboratory tests include the thermogravimetric studies using Cahn thermo-balances and long exposure tests in horizontal/autoclave multi-sample furnaces. Post experimental analyses are made using SEM/EDS + XRD techniques and optical microscopy. The experiments are carried out at isothermal temperature - 535 deg. C in various simulated combustion atmospheres (22%H{sub 2}O + 5%O{sub 2} + xCO{sub 2} + N{sub 2}) with different CO{sub 2} content vary from 0 to 25 vol. % for the samples without deposit and with filter/cyclone ash deposition (long exposure tests). In this stage, following conclusions can be made: - Corrosion rate, for the alloys with and without the deposit, increase with increasing CO{sub 2} content, especially for the ferritic steels; - Corrosion rate for samples with the deposit increase significantly and in this case the internal oxidation of the studied samples was observed; - Thermodynamic model calculations performed resulted, a.o., to the following propositions still of preliminary nature; - Various carbides of metallic alloying elements become less stable at oxide scale-metallic alloy phase boundary with increasing partial pressure of carbon dioxide; - Carbides and oxides of various alloying

  2. Influence of specimen size, tray inclination and air flow rate on the emission of gases from biomass combustion

    Science.gov (United States)

    Amorim, E. B.; Carvalho, J. A.; Soares Neto, T. G.; Anselmo, E.; Saito, V. O.; Dias, F. F.; Santos, J. C.

    2013-08-01

    Experiments of biomass combustion were performed to determine whether specimen size, tray inclination, or combustion air flow rate was the factor that most affects the emission of carbon dioxide, carbon monoxide, and methane. The chosen biomass was Eucalyptus citriodora, a very abundant species in Brazil, utilized in many industrial applications, including combustion for energy generation. Analyses by gas chromatograph and specific online instruments were used to determine the concentrations of the main emitted gases, and the following figures were found for the emission factors: 1400 ± 101 g kg-1 of CO2, 50 ± 13 g kg-1 of CO, and 3.2 ± 0.5 g kg-1 of CH4, which agree with values published in the literature for biomass from the Amazon rainforest. Statistical analysis of the experiments determined that specimen size most significantly affected the emission of gases, especially CO2 and CO.

  3. A numerical study of the effects of injection rate shape on combustion and emission of diesel engines

    Directory of Open Access Journals (Sweden)

    He Zhixia

    2014-01-01

    Full Text Available The spray characteristics including spray droplet sizes, droplet distribution, spray tip penetration length and spray diffusion angle directly affects the mixture process of fuel and oxygen and then plays an important role for the improvement of combustion and emission performance of diesel engines. Different injection rate shapes may induce different spray characteristics and then further affect the subsequent combustion and emission performance of diesel engines. In this paper, the spray and combustion processes based on four different injection rate shapes with constant injection duration and injected fuel mass were simulated in the software of AVL FIRE. The numerical models were validated through comparing the results from the simulation with those from experiment. It was found that the dynamic of diesel engines with the new proposed hump shape of injection rate and the original saddle shape is better than that with the injection rate of rectangle and triangle shape, but the emission of NOX is higher. And the soot emission is lowest during the late injection period for the new hump-shape injection rate because of a higher oxidation rate with a better mixture between fuel and air under the high injection pressure.

  4. The Effects of Fuel Stratification and Heat Release Rate Shaping in Reactivity Controlled Compression Ignition (RCCI) Combustion

    Science.gov (United States)

    DelVescovo, Dan A.

    Low temperature combustion strategies have demonstrated high thermal efficiency with low emissions of pollutants, including oxides of nitrogen and particulate matter. One such combustion strategy, called Reactivity Controlled Compression Ignition (RCCI), which involves the port injection of a low reactivity fuel such as gasoline, ethanol, or natural gas, and a direct injection of a high reactivity fuel, such as diesel, has demonstrated excellent control over the heat release event due to the introduction of in-cylinder stratification of equivalence ratio and reactivity. The RCCI strategy is inherently fuel flexible, however the direct injection strategy needs to be tailored to the combination of premixed and direct injected fuels. Experimental results demonstrate that, when comparing different premixed fuels, matching combustion phasing with premixed mass percentage or SOI timing is not sufficient to retain baseline efficiency and emissions results. If the bulk characteristics of the heat release event can be matched, however, then the efficiency and emissions can be maintained. A 0-D methodology for predicting the required fuel stratification for a desired heat release for kinetically-controlled stratified-charge combustion strategies is proposed and validated with 3-D reacting and non-reacting CFD simulations performed with KIVA3Vr2 in this work. Various heat release rate shapes, phasing, duration, and premixed and DI fuel chemistries are explored using this analysis. This methodology provides a means by which the combustion process of a stratified-charge, kinetically-controlled combustion strategy could be optimized for any fuel combination, assuming that the fuel chemistry is well characterized.

  5. Rate-Controlled Constrained-Equilibrium Theory Applied to the Expansion of Combustion Products in the Power Stroke of an Internal Combustion Engine

    Directory of Open Access Journals (Sweden)

    Hameed Metghalchi

    2009-03-01

    Full Text Available Rate-controlled constrained-equilibrium method, firmly based on the second law of thermodynamics, is applied to the expansion of combustion products of methane during the power stroke of an internal combustion engine. The constraints used in this study are the elemental oxygen, hydrogen, carbon and nitrogen together with other four dynamic constraints of total number of moles, moles of DCO (CO+HCO, moles of free valence and moles of free oxygen. Since at chemical equilibrium, the mixture composition is dominated by H/O, CO/CO2, and a few other carbon-containing species, almost independent of the fuel molecule, the set results in accurate predictions of the kinetic effects observed in all H/O and CO/CO2 compounds and temperature history. It is shown that the constrained-equilibrium predictions of all the species composed of the specified atomic elements can be obtained independent of a kinetic path, provided their Gibbs free energies are known.

  6. Nanostructured aluminium oxide powders obtained by aspartic acid-nitrate gel-combustion routes

    Energy Technology Data Exchange (ETDEWEB)

    Gardey Merino, Maria Celeste, E-mail: mcgardey@frm.utn.edu.a [Laboratorio de Investigaciones y Servicios Ambientales Mendoza (LISAMEN) - CCT - CONICET, Avda. Ruiz Leal s/n, Parque Gral. San Martin, (M5502IRA) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Grupo CLIOPE, Universidad Tecnologica Nacional - Facultad Regional Mendoza, Rodriguez 273, (M5502AJE) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Lascalea, Gustavo E. [Laboratorio de Investigaciones y Servicios Ambientales Mendoza (LISAMEN) - CCT - CONICET, Avda. Ruiz Leal s/n, Parque Gral. San Martin, (M5502IRA) Ciudad de Mendoza, Prov. de Mendoza (Argentina); Sanchez, Laura M. [CINSO (Centro de Investigaciones en Solidos), CITEFA - CONICET, J.B. de La Salle 4397, (B1603ALO) Villa Martelli, Prov. de Buenos Aires (Argentina); Vazquez, Patricia G. [Centro de Investigacion y Desarrollo en Ciencias Aplicadas ' Dr. Jorge J. Ronco' (CINDECA), CONICET, Universidad Nacional de La Plata, Calle 47 nro. 257, (B1900AJK) La Plata, Prov. de Buenos Aires (Argentina); Cabanillas, Edgardo D. [CONICET and Centro Atomico Constituyentes, Comision Nacional de Energia Atomica, Gral. Paz 1499, (1650) San Martin, Prov. de Buenos Aires (Argentina); Lamas, Diego G. [CINSO (Centro de Investigaciones en Solidos), CITEFA - CONICET, J.B. de La Salle 4397, (B1603ALO) Villa Martelli, Prov. de Buenos Aires (Argentina)

    2010-04-16

    In this work, two new gel-combustion routes for the synthesis of Al{sub 2}O{sub 3} nanopowders with aspartic acid as fuel are presented. The first route is a conventional stoichiometric process, while the second one is a non-stoichiometric, pH-controlled process. These routes were compared with similar synthesis procedures using glycine as fuel, which are well-known in the literature. The samples were calcined in air at different temperatures, in a range of 600-1200 {sup o}C. They were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy and BET specific surface area. Different phases were obtained depending on the calcination temperature: amorphous, {gamma} (metastable) or {alpha} (stable). The amorphous-to-{gamma} transition was found for calcination temperatures in the range of 700-900 {sup o}C, while the {gamma}-to-{alpha} one was observed for calcination temperatures of 1100-1200 {sup o}C. The retention of the metastable {gamma} phase is probably due to a crystallite size effect. It transforms to the {alpha} phase after the crystallite size increases over a critical size during the calcination process at 1200 {sup o}C. The highest BET specific surface areas were obtained for both nitrate-aspartic acid routes proposed in this work, reaching values of about 50 m{sup 2}/g.

  7. Ice nucleating particles from biomass combustion: emission rates and the role of refractory black carbon

    Science.gov (United States)

    Levin, E. J.; McMeeking, G. R.; McCluskey, C. S.; Carrico, C. M.; Nakao, S.; Stockwell, C.; Yokelson, R. J.; Sullivan, R. C.; DeMott, P. J.; Kreidenweis, S. M.

    2015-12-01

    Ice nucleating particles (INPs) allow initial ice crystal formation in clouds at temperatures warmer than about -36 °C and are thus important for cloud and precipitation development. One potential source of INPs to the atmosphere is biomass combustion, such as wildfires, prescribed burning and agricultural burning, which emits large quantities of particulate matter into the atmosphere and is a major source of black carbon (BC) aerosol. To better understand and constrain INP emissions from biomass combustion, globally relevant fuels were used in a series of burns during a study called FLAME 4 at the USFS Fire Sciences Laboratory in Missoula, MT. Concentrations of immersion mode INPs were measured using a Colorado State University Continuous Flow Diffusion Chamber (CFDC). During the first part of the study, emissions were measured in real time as fires progressed from ignition to flaming and smoldering phases. INP emissions were observed predominately during periods of intensely flaming combustion. Roughly 75% of measured burns produced detectable INP concentrations and these had, on average, higher combustion efficiencies and higher BC emissions. During the second half of FLAME 4, we directly measured the contribution of refractory black carbon (rBC) to INP concentrations by selectively removing these particles via laser-induced incandescence (LII) using a Single Particle Soot Photometer (SP2; Droplet Measurement Technologies). The SP2 uses a 1064 nm Na:YAG laser to heat rBC aerosol to their vaporization temperatures, thus removing them from the sampled aerosol. By passing combustion aerosol through the SP2 with the laser on and off while measuring the remaining aerosol with the CFDC, we were able to determine the contribution of rBC to the INP population. Reductions in INPs of 0 - 70% were observed when removing rBC from the combustion aerosol, indicating the importance of rBC particles to INP concentrations for some burn scenarios.

  8. Investigation of Biomass Combustion Rate of Fire Radiative Energy Using Multiple-Satellite-observed Active Fires and Landsat TM Burn Severities across the Continental United States

    Science.gov (United States)

    Li, F.; Zhang, X.; Kondragunta, S.

    2015-12-01

    Biomass burning is a major source of atmospheric aerosol and greenhouse gases that substantially influence climate and regional air quality. However, the accuracy of biomass burning emissions estimated using traditional method is limited by large uncertainties in burned area and fuel loading. Alternatively, fire radiative energy (FRE) has recently been demonstrated to be linearly related to biomass combustion, which potentially improves the estimation of biomass burning emissions. The FRE-based combustion rate is 0.368-0.453 kg/MJ according to field controlled experiments while it varies from 1.37-4.5 kg/MJ derived from satellite-based bottom-up and top-down aerosol optical thickness estimates. Here we investigate the FRE combustion rate in over 1000 burn scars from 2011 to 2012 across the Continental United States (CONUS). Specifically, FRE was calculated by combining the high spatial observations from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the high temporal observations from the Geostationary Operational Environmental Satellite (GOES). Biomass consumption in burn scars was modeled using Landsat TM 30m burn severities, 30m fuel loading from Fuel Characteristic Classification System, and combustion completeness compiled from recent literatures. The combustion rate was then investigated by correlating FRE to biomass consumption across CONUS and Bailey's ecoregions. Our results show that the combustion rate can be extracted from the linear relationship between biomass consumption and FRE. The combustion rate is 0.415±10% kg/MJ across CONUS, which is similar to the rate derived from field experiments. However, it varies from 0.18-1.9 kg/MJ among ecoregions. This implies that a single combustion rate could produce large uncertainty in the estimation of biomass consumption at large scales. We suggest that ecoregion specified combustion rates should help to improve the accuracy of quantifying biomass burning emissions regionally and globally.

  9. Feasibility demonstration of a variable frequency driver-microwave transient regression rate measurement system. [for solid propellant combustion response

    Science.gov (United States)

    Strand, L. D.; Mcnamara, R. P.

    1976-01-01

    The feasibility of a system capable of rapidly and directly measuring the low-frequency (motor characteristics length bulk mode) combustion response characteristics of solid propellants has been investigated. The system consists of a variable frequency oscillatory driver device coupled with an improved version of the JPL microwave propellant regression rate measurement system. The ratio of the normalized regression rate and pressure amplitudes and their relative phase are measured as a function of varying pressure level and frequency. Test results with a well-characterized PBAN-AP propellant formulation were found to compare favorably with the results of more conventional stability measurement techniques.

  10. Combustion characteristics of fatty acid methyl esters derived from recycled cooking oil

    Energy Technology Data Exchange (ETDEWEB)

    Yo-ping Greg Wu; Ya-fen Lin; Chang-Tang Chang [National Ilan University, Ilan (Taiwan). Department of Chemical and Materials Engineering

    2007-12-15

    The goal of this study is to find out the exhaust emissions differences produced by different kinds of fatty acid methyl esters (FAME) derived from used cooking oils and animal fats, as well as the importance of the purification step in exhaust emissions production. A total of 120 L of waste vegetable oil and 30 L of waste frying oil were collected and converted into three batches of FAME. There were two batches of FAME produced from waste vegetable oil (B01 and B02), and one batch of FAME produced by mixing 2% of waste frying oil with waste vegetable oil (B03). The FAMEs used in this study had higher density, kinematic viscosity, and flash point, but a lower gross heating value, when compared to the premium diesel. The B01 engine produced higher CO formation and the diesel-fuelled engine produced higher CO than the B02 and B03 did for engine speeds higher than 1400 rpm. Most of the FAME fuels produced higher CO{sub 2} than the diesel fuel did. The FAME fuels emitted higher NOx and PM, but lower SO{sub 2}, than the diesel fuel. C{sub n}H{sub 2n+2}, diphenyl sulfone (C{sub 12}H{sub 10}O{sub 2}S), and diethyl phthalate (C{sub 12}H{sub 14}O{sub 4}) can be selected as the character index for the combustion of FAME. 26 refs., 8 figs., 1 tab.

  11. Acid mine drainage abatement using fluidized bed combustion ash grout after geophysical site characterization

    International Nuclear Information System (INIS)

    Pyritic coal refuse and pit cleanings buried in a 15-ha (37-acre) surface mine produce severe acid mine drainage (AMD). The pyritic material had been buried in discrete piles or pods in the backfill. The pods and the resulting contaminant plumes were initially defined using geophysical techniques and were confirmed by drilling. Fluidized bed combustion (FBC) ash, mixed with water to form a grout, was used in different ways to isolate the pyritic material from water and oxygen. In the first approach, grout was pressure injected directly into the buried pods to fill the void spaces within the pods and to coat the pyritic materials with a cementitious layer. A second approach used the grout to divert water from specific areas. Pods which did not accept grout because of a clay matrix were isolated from percolating water with a cap and trench seal of the grout. The grout was also used in certain areas to blanket the clay pit floor since clays are believed to be a primary source of aluminum at this site. In certain areas, the AMD migrates downward though fractures in the pit floor to the groundwater table. Grout was injected along the fractures in some of these areas to seal them. This would inhibit further AMD migration toward one of the receiving streams. The initial postgrouting water quality data have been encouraging

  12. Effect of combustion rate and annealing temperature on structural and magnetic properties of manganese substituted nickel and zinc ferrites

    International Nuclear Information System (INIS)

    An auto-combustion method was used to prepare manganese substituted nickel and zinc ferrites under three different fuel ratios (50%, 75% and 100%). The powders were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray spectrum (EDX). The combustion reaction time of 50% fuel ratio is longer than the other ratios (75% and 100%). The smallest range of particles of about 12 to 33 nm for Mn–Zn ferrites and 20–60 nm for Mn–Ni ferrites were achieved only at 50% fuel ratio. The external morphology of the samples is visualized through SEM. The microstructure and particle size of the annealed sample were analyzed by TEM. The composition of the elements presence in the samples was determined by EDX spectrum. Also, the magnetic behavior of the samples annealed at 600 °C and 900 °C was investigated by using a vibrating sample magnetometer (VSM). - Highlights: • An auto-combustion method support to prepare less size of particles. • Nature of the ferrites was affected with increasing annealing temperature. • Reaction rate influences in particle size

  13. THE USE OF COAL COMBUSTION BY-PRODUCTS FOR IN SITU TREATMENT OF ACID MINE DRAINAGE

    Energy Technology Data Exchange (ETDEWEB)

    Geoffrey A. Canty; Jess W. Everett

    2004-09-30

    In 1994 a demonstration project was undertaken to investigate the effectiveness of using CCBs for the in situ treatment of acidic mine water. Actual injection of alkaline material was performed in 1997 with initial positive results; however, the amount of alkalinity added to the system was limited and resulted in short duration treatment. In 1999, a CBRC grant was awarded to further investigate the effectiveness of alkaline injection technology (AIT). Funds were released in fall 2001. In December 2001, 2500 tons of fluidized bed combustion (FBC) ash were injected into the wells used in the 1997 injection project. Post injection monitoring continued for 24 months. During this period the mine chemistry had gone through a series of chemical changes that manifested as stages or ''treatment phases.'' The mine system appeared to be in the midst of reestablishing equilibrium with the partial pressure of mine headspace. Alkalinity and pH appeared to be gradually increasing during this transition. As of December 2003, the pH and alkalinity were roughly 7.3 and 65 ppm, respectively. Metal concentrations were significantly lower than pre-injection levels, but iron and manganese concentrations appeared to be gradually increasing (roughly 30 ppm and 1.25 ppm, respectively). Aluminum, nickel, and zinc were less than pre-injection concentrations and did not appear to be increasing (roughly

  14. Structure properties and sintering densification of Gd2Zr2O7 nanoparticles prepared via different acid combustion methods

    Institute of Scientific and Technical Information of China (English)

    马雷; 马伟民; 孙旭东; 刘佳男; 纪连永; 宋晗

    2015-01-01

    Gadolinium zirconate (Gd2Zr2O7) nanocrystals were prepared via two different combustion methods:citric acid combus-tion (CAC) and stearic acid combustion (SAC). The effects of the different preparation methods on the phase composition, micro-topography, and sintering densification of the resulting Gd2Zr2O7 nanopowders were investigated by thermal-gravimetric and differ-ential thermal analysis (TG-DTA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and transmission elec-tron microscopy (TEM) techniques. The results indicated that both methods could produce Gd2Zr2O7 nanopowders with an excellent defective fluorite structure. The reaction time was reduced by the SAC method, compared with the CAC method. The nanopowders synthesized by the two methods were different in grain size distribution. The resulting nanoparticle diameter was about 50 nm for CAC and 10 nm for SAC. After vacuum sintering, the sintered bodies also had a different relative density of about 93%and 98%, respectively. Thus the preparation of Gd2Zr2O7 nanopowders by SAC was the first choice to achieve the desired sintering densifi-cation.

  15. Inhibiting influence of traces of hydrogenated compounds on the combustion rate of artificial graphites

    International Nuclear Information System (INIS)

    After having outlined that studies related to graphite oxidation by oxygen or by carbon dioxide in different experimental conditions (graphite type, temperature range, pressure range) gave results which revealed to be non reproducible, or not consistent, and that these discrepancies could be attributed to the graphite chemical purity, to the graphite structure or to the purity of the combustion agent, this research thesis notably focused on this last aspect. As no graphite is rigorously pure and perfectly crystallised, a chemically pure but imperfectly crystallised one has been chosen (the Acheson graphite) as well as a well crystallised but unclean graphite (graphite obtained by silicon carbide dissociation). After a presentation of these materials, the author reports the study of the texture of the Acheson graphites. Then, he highlights and studies inhibition phenomena, and discusses and interprets experimental results

  16. Biofuels combustion.

    Science.gov (United States)

    Westbrook, Charles K

    2013-01-01

    This review describes major features of current research in renewable fuels derived from plants and from fatty acids. Recent and ongoing fundamental studies of biofuel molecular structure, oxidation reactions, and biofuel chemical properties are reviewed, in addition to combustion applications of biofuels in the major types of engines in which biofuels are used. Biofuels and their combustion are compared with combustion features of conventional petroleum-based fuels. Two main classes of biofuels are described, those consisting of small, primarily alcohol, fuels (particularly ethanol, n-butanol, and iso-pentanol) that are used primarily to replace or supplement gasoline and those derived from fatty acids and used primarily to replace or supplement conventional diesel fuels. Research efforts on so-called second- and third-generation biofuels are discussed briefly.

  17. Research on the Behavior and Mechanism of Citric Acid and Malic Acid of Combustion under the State Cigarette Smoking%柠檬酸和苹果酸在卷烟阴燃状态下的燃烧行为和机制研究

    Institute of Scientific and Technical Information of China (English)

    王程辉; 周顺; 徐迎波; 田振峰

    2012-01-01

    [Objective] The comparative study on the behavior and mechanism of citric acid and malic acid in the smoldering combustion of cigarette was conducted.[Method] The effect of the rate of temperature-raising in combustion on the burning behavior of citric acid and malic acid in cigarette was tested with micro-combustion calorimeter ( MCC). The combustion process of the cigarette, especially for the formation rule of the gas products of major pyrolysis, was comparatively analyzed with TG-FTIR in order to explore the combustion mechanism.[Result] It was found through MCC testing that in the same combustion condition, the flammability of citric acid was better than that of malic acid, but its combustion was slightly worse than that of citric acid. The rate of temperature-raising in combustion greatly affected the burning behavior of malic acid and citric acid in cigarette. The TG-FTIR testing results showed that the burning behavior of citric acid and malic acid in cigarette mainly depended on the formation of pyrolysis products. The citric acid was relatively more susceptible to thermal decomposition than malic acid and much more H2O, CO2, CO and carbonyl compounds would be generated in the pyrolysis process.[Conclusion] The burning behavior , in which the flammability of citric acid was better than that of malic acid and its combustion was slightly worse than that of citric acid, was determined because of the relatively weak stability of pyrolysis and the relative composition of un-flammable gas and flammable gas in initial period.%[目的]比较研究柠檬酸和苹果酸在卷烟阴燃状态下的燃烧行为和机制.[方法]利用微燃烧量热仪(MCC)考察升温速率对柠檬酸和苹果酸燃烧行为的影响;利用热重-红外联用仪(TG-FTIR)比较研究其燃烧过程,特别是主要热解气相产物的形成规律,探讨其燃烧机理.[结果] MCC测试结果发现,在相同的燃烧条件下,柠檬酸的易燃性优于苹果酸,但燃烧性稍差

  18. Analysis of potential combustion source impacts on acid deposition using an independently derived inventory. Volume II, appendices

    Energy Technology Data Exchange (ETDEWEB)

    1983-12-01

    This document contains 2 appendices. The first documents the methodologies used to calculate production, unit energy consumption, fuel type and emission estimates for 16 industries and 35 types of facilities utilizing direct-fired industrial combustion processes, located in 26 states (and the District of Columbia) east of the Mississippi River. As discussed in the text of this report, a U.S. total of 16 industries and 45 types of facilities utilizing direct-fired combustion processes were identified by an elimination type method that was developed based on evaluation of fuel use in industrial SIC codes 20-39 to identify pollutant sources contributing to acid rain. The final population included only plants that have direct-fired fuel consumption greater than or equal to 100 x 10/sup 9/ Btu/yr of equivalent energy consumption. The goal for this analysis was to provide at least a 1980 base year for the data. This was achieved for all of the industries and in fact, 1981 data were used for a number of the industries evaluated. The second contains an analysis of all consumption of major fossil fuels to: (1) identify all fuel usage categories, and (2) identify the kinds of combustion equipment used within each category. This analysis provides a frame of reference for the balance of the study and permits using an energy accounting methodology to quantify the degree to which the inventoried sources in individual consuming sectors are complete and representative of the total population for the sector.

  19. New concept of combustion technology in small DI diesel engines. 4th Report. Effects of fuel injection rates on MK combustion; Kogata chokufun diesel kikan no shinnensho concept. 4. Funsharitsu no MK nensho eno eikyo

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, S.; Matsui, Y.; Kamihara, T. [Nissan Motor Co. Ltd., Tokyo (Japan)

    1997-10-01

    A previous paper showed that EGR cooling and a low compression ratio which prolongs the ignition delay can expand the area of the new combustion concept. Experimental investigations were conducted in this research to examine the effects of the fuel injection rates, the injection pressure and the injection duration, on the exhaust emissions of an engine incorporating the MK concept The results showed that a higher injection pressure was effective in reducing NOx and particulate matter (PM) under MK combustion conditions. 10 refs., 9 figs., 1 tab.

  20. Reduction Rates for Higher Americium Oxidation States in Nitric Acid

    Energy Technology Data Exchange (ETDEWEB)

    Grimes, Travis Shane [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mincher, Bruce Jay [Idaho National Lab. (INL), Idaho Falls, ID (United States); Schmitt, Nicholas C [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2015-09-30

    The stability of hexavalent americium was measured using multiple americium concentrations and nitric acid concentrations after contact with the strong oxidant sodium bismuthate. Contrary to our hypotheses Am(VI) was not reduced faster at higher americium concentrations, and the reduction was only zero-order at short time scales. Attempts to model the reduction kinetics using zero order kinetic models showed Am(VI) reduction in nitric acid is more complex than the autoreduction processes reported by others in perchloric acid. The classical zero-order reduction of Am(VI) was found here only for short times on the order of a few hours. We did show that the rate of Am(V) production was less than the rate of Am(VI) reduction, indicating that some Am(VI) undergoes two electron-reduction to Am(IV). We also monitored the Am(VI) reduction in contact with the organic diluent dodecane. A direct comparison of these results with those in the absence of the organic diluent showed the reduction rates for Am(VI) were not statistically different for both systems. Additional americium oxidations conducted in the presence of Ce(IV)/Ce(III) ions showed that Am(VI) is reduced without the typical growth of Am(V) observed in the systems sans Ce ion. This was an interesting result which suggests a potential new reduction/oxidation pathway for Am in the presence of Ce; however, these results were very preliminary, and will require additional experiments to understand the mechanism by which this occurs. Overall, these studies have shown that hexavalent americium is fundamentally stable enough in nitric acid to run a separations process. However, the complicated nature of the reduction pathways based on the system components is far from being rigorously understood.

  1. Sulfur Recovery from Acid Gas Using the Claus Process and High Temperature Air Combustion (HiTAC Technology

    Directory of Open Access Journals (Sweden)

    Mohamed Sassi

    2008-01-01

    Full Text Available Sulfur-bearing compounds are very detrimental to the environment and to industrial process equipment. They are often obtained or formed as a by-product of separation and thermal processing of fuels containing sulfur, such as coal, crude oil and natural gas. The two sulfur compounds, which need special attention, are: hydrogen sulfide (H2S and sulfur dioxide (SO2. H2S is a highly corrosive gas with a foul smell. SO2 is a toxic gas responsible for acid rain formation and equipment corrosion. Various methods of reducing pollutants containing sulfur are described in this paper, with a focus on the modified Claus process, enhanced by the use of High Temperature Air Combustion (HiTAC technology in the Claus furnace. The Claus process has been known and used in the industry for over 100 years. It involves thermal oxidation of hydrogen sulfide and its reaction with sulfur dioxide to form sulfur and water vapor. This process is equilibrium-limited and usually achieves efficiencies in the range of 94-97%, which have been regarded as acceptable in the past years. Nowadays strict air pollution regulations regarding hydrogen sulfide and sulfur dioxide emissions call for nearly 100% efficiency, which can only be achieved with process modifications. High temperature air combustion technology or otherwise called flameless (or colorless combustion is proposed here for application in Claus furnaces, especially those employing lean acid gas streams, which cannot be burned without the use of auxiliary fuel or oxygen enrichment under standard conditions. With the use of HiTAC it has been shown, however, that fuel-lean, Low Calorific Value (LCV fuels can be burned with very uniform thermal fields without the need for fuel enrichment or oxygen addition. The uniform temperature distribution favors clean and efficient burning with an additional advantage of significant reduction of NOx, CO and hydrocarbon emission.

  2. Plan for injection of coal combustion byproducts into the Omega Mine for the reduction of acid mine drainage

    International Nuclear Information System (INIS)

    The Omega Mine Complex is located outside of Morgantown, West Virginia. The mine is in the Upper Freeport Coal, an acid-producing coal seam. The coal was mined in a manner that has resulted in acid mine drainage (AMD) discharges at multiple points. During the 1990's, the West Virginia Division of Environmental Protection (WVDEP) assumed responsibility for operating a collection and treatment system for the AMD. Collection and treatment costs are approximately $300,000 per year. Injecting grout into the mine workings to reduce AMD (and thus reducing treatment costs) is proposed. The procedure involves injecting grout mixes composed primarily of coal combustion byproducts (CCB's) and water, with a small quantity of cement. The intention of the injection program is to fill the mine voids in the north lobe of the Omega Mine (an area where most of the acidity is believed to be generated) with the grout, thus reducing the contact of air and water with potentially acidic material. The grout mix design consists of an approximate 1:1 ratio of fly ash to byproducts from fluidized bed combustion. Approximately 100 gallons of water per cubic yard of grout is used to achieve flowability. Observation of the mine workings via subsurface borings and downhole video camera confirmed that first-mined areas were generally open while second-mined areas were generally partially collapsed. The injection program was developed to account for this by utilizing closer injection hole spacing in second-mined areas. Construction began in January 1998, with grout injection expected to commence in mid-April 1998

  3. COMBUSTION HEAT RELEASE RATE ANALYSIS OF C.I. ENGINE WITH SECONDARY CO-INJECTION OF DEE-H2O SOLUTION - A VIBRATIONAL APPROACH

    Directory of Open Access Journals (Sweden)

    Y. V. V. SATYANARAYANA MURTHY

    2015-08-01

    Full Text Available This paper discusses the combustion propensity of single cylinder direct injection engine fueled with palm kernel methyl ester (PKME, which is non- edible oil and a secondary co-injection of saturated Diethyl ether (DEE with water. DEE along with water is fumigated through a high pressure nozzle fitted to the inlet manifold of the engine and the flow rate of the secondary injection was electronically controlled. DEE is known to improve the cold starting problem in engines when used in straight diesel fuel. However, its application in emulsion form is little known. Experimental results show that for 5% DEE- H2O solution injection, occurrence of maximum net heat release rate is delayed due to controlled premixed combustion, which normally helped in better torque conversion when the piston is in accelerated mode. Vibration measurements in the frequency range of 900Hz to 1300Hz revealed that a new mode of combustion has taken place with different excitation frequencies.

  4. Fire simulation in large compartments with a fire model 'FDS'. Part 3. Accuracy evaluation of pyrolysis rate of liquid combustible and wall heat transfer

    International Nuclear Information System (INIS)

    The accuracy of a fire model, FDS, were evaluated for a fire plume developed from combustible liquid and a natural convection from a high-temperature vertical wall, focusing on pyrolysis rate of combustibles and heat transfer coefficient of walls, both of which greatly affect the accuracy of air temperature in compartment fires. For a fire plume, numerical results with the submodel 'Liquid' predicting pyrolysis of combustible liquid largely depend on grid spacing and have a margin of error of approximately twenty percent at minimum in heat release rate (HRR). Thus, the submodel 'Specified HRR' prescribing the pyrolysis should be more effective when HRR is known in postulated fires. Concerning grid spacing for accurately predicting a fire plume, the condition of Δ < D*/20 (D*: characteristic fire size, Δ: grid spacing) for a combustible-gas fire plume could be applied to a combustible-liquid fire plume. For a natural convection from a wall, an empirical submodel of heat transfer coefficient was nearly independent of grid spacing, and gave the good predictions for turbulent heat transfer. Unsteady flows near walls were also predicted on the grid-spacing condition of Δη < approximately 0.6 (η: similarity variable for laminar boundary layer), although their accuracy was much lower than that of the heat transfer coefficient. (author)

  5. Utilizing maleic acid as a novel fuel for synthesis of PbFe12O19 nanoceramics via sol–gel auto-combustion route

    International Nuclear Information System (INIS)

    PbFe12O19 nanostructures were prepared in an aqueous solution by the sol–gel auto-combustion method using Pb(NO3)2 and Fe(NO3)3 as starting materials and various carboxylic acids, including oxalic acid, malonic acid, succinic acid and maleic acid as fuel and reducing and capping agents. The as-synthesized products were characterized by X- ray diffraction, scanning electron microscopy, and X-ray energy dispersive spectroscopy. The effect of carboxylic acid type, Pb+ 2 to carboxylic acid molar ratio, and calcination temperature was investigated on the morphology of the products and several experiments were carried out to obtain the optimal reaction conditions. It was found that the phase and the morphology of the products are influenced by the investigated parameters. Furthermore, vibrating sample magnetometer (VSM) was used to study the magnetic properties of PbFe12O19 samples. - Graphical abstract: Display Omitted - Highlights: • PbFe12O19 nanoceramics were synthesized from Fe(NO3)3 and Pb(NO3)2 via the sol–gel auto combustion method. • The maleic acid can be instead of common capping agent and fuel in auto-combustion sol–gel. • The synthesized PbFe12O19 is a hard magnetic material. • The specific saturation magnetization and coercivity are 27 emu/g and 1900 Oe, respectively

  6. Stearic acid coating on circulating fluidized bed combustion fly ashes and its effect on the mechanical performance of polymer composites

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Nina [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); Zhang, Ping, E-mail: pingzhang@swust.edu.cn [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Song, Lixian; Kang, Ming; Lu, Zhongyuan [State Key Laboratory Cultivation Base for Nonmetal Composites and Functional Materials, Southwest University of Science and Technology, Mianyang 621010 (China); School of Material Science and Engineering, Southwest University of Science and Technology, Mianyang, Sichuan 621010 (China); Zheng, Rong [Sichuan Jinhe Group Co., Ltd., Mianyang 621010 (China)

    2013-08-15

    The aim of this work was to test circulating fluidized bed combustion fly ashes (CFAs) for its potential to be utilized in polymer composites manufacturing to improve its toughness. CFAs was coated by stearic acid and used in the composite of polypropylene/ethylene vinyl acetate/high density polyethylene (PP/EVA/HDPE) by molding process method. The resulting coated and uncoated CFAs were fully characterized by particle size analyzer, contact angles, powder X-ray diffraction (XRD), thermogravimetric analysis/differential thermal analysis (TGA/DTA), Brunauer–Emmett–Teller (BET), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The stearic acid coated onto the surface of CFAs particles in the physical and chemical ways, and the total clad ratio reached 2.05% by measuring TGA/DTA curve. The percentage of CFAs particles focused to a narrow range 2–4 μm and the median mean size was 3.2 μm more than uncoated CFAs. The properties of hydrophobic and dispersive of CFAs particles improved and original activity was reserved after stearic acid coating. The stearic acid was verified as a coupling agent by how much effect it had on the mechanical properties. It showed the elongation at break of PP/EVA/HDPE reinforced with 15 wt% coated CFAs (c-CFAs) was 80.20% and higher than that of the uncoated. The stearic acid treatment of CFAs is a very promising approach to improve the mechanical strength due to the incorporation of stearic acid on the CFAs surface, and hence, further enhances the potential for recycling CFAs as a suitable filler material in polymer composites.

  7. Effect of CO Combustion Promoters on Combustion Air Partition in FCC under Nearly Complete Combustion

    Institute of Scientific and Technical Information of China (English)

    王锐; 罗雄麟; 许锋

    2014-01-01

    With CO combustion promoters, the role of combustion air flow rate for concerns of economics and control is important. The combustion air is conceptually divided to three parts:the air consumed by coke burning, the air consumed by CO combustion and the air unreacted. A mathematical model of a fluid catalytic cracking (FCC) unit, which includes a quantitative correlation of CO heterogeneous combustion and the amount of CO combustion promoters, is introduced to investigate the effects of promoters on the three parts of combustion air. The results show that the air consumed by coke burning is almost linear to combustion air flow rate, while the air consumed by CO combustion promoters tends to saturate as combustion air flow rate increases, indicating that higher air flow rate can only be used as a manipulated variable to control the oxygen content for an economic concern.

  8. Turbulent combustion

    Energy Technology Data Exchange (ETDEWEB)

    Talbot, L.; Cheng, R.K. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    Turbulent combustion is the dominant process in heat and power generating systems. Its most significant aspect is to enhance the burning rate and volumetric power density. Turbulent mixing, however, also influences the chemical rates and has a direct effect on the formation of pollutants, flame ignition and extinction. Therefore, research and development of modern combustion systems for power generation, waste incineration and material synthesis must rely on a fundamental understanding of the physical effect of turbulence on combustion to develop theoretical models that can be used as design tools. The overall objective of this program is to investigate, primarily experimentally, the interaction and coupling between turbulence and combustion. These processes are complex and are characterized by scalar and velocity fluctuations with time and length scales spanning several orders of magnitude. They are also influenced by the so-called {open_quotes}field{close_quotes} effects associated with the characteristics of the flow and burner geometries. The authors` approach is to gain a fundamental understanding by investigating idealized laboratory flames. Laboratory flames are amenable to detailed interrogation by laser diagnostics and their flow geometries are chosen to simplify numerical modeling and simulations and to facilitate comparison between experiments and theory.

  9. Engineering strategies aimed at control of acidification rate of lactic acid bacteria

    DEFF Research Database (Denmark)

    Martinussen, Jan; Solem, Christian; Holm, Anders Koefoed;

    2013-01-01

    The ability of lactic acid bacteria to produce lactic acid from various sugars plays an important role in food fermentations. Lactic acid is derived from pyruvate, the end product of glycolysis and thus a fast lactic acid production rate requires a high glycolytic flux. In addition to lactic acid...... glycolytic flux remains unanswered. © 2012 Elsevier Ltd....

  10. Modeling gallic acid production rate by empirical and statistical analysis

    Directory of Open Access Journals (Sweden)

    Bratati Kar

    2000-01-01

    Full Text Available For predicting the rate of enzymatic reaction empirical correlation based on the experimental results obtained under various operating conditions have been developed. Models represent both the activation as well as deactivation conditions of enzymatic hydrolysis and the results have been analyzed by analysis of variance (ANOVA. The tannase activity was found maximum at incubation time 5 min, reaction temperature 40ºC, pH 4.0, initial enzyme concentration 0.12 v/v, initial substrate concentration 0.42 mg/ml, ionic strength 0.2 M and under these optimal conditions, the maximum rate of gallic acid production was 33.49 mumoles/ml/min.Para predizer a taxa das reações enzimaticas uma correlação empírica baseada nos resultados experimentais foi desenvolvida. Os modelos representam a ativação e a desativativação da hydrolise enzimatica. Os resultados foram avaliados pela análise de variança (ANOVA. A atividade máxima da tannase foi obtida após 5 minutos de incubação, temperatura 40ºC, pH 4,0, concentração inicial da enzima de 0,12 v/v, concentração inicial do substrato 0,42 mg/ml, força iônica 0,2 M. Sob essas condições a taxa máxima de produção ácido galico foi de 33,49 µmoles/ml/min.

  11. Omega-3 Polyunsaturated Fatty Acids and Heart Rate Variability

    Directory of Open Access Journals (Sweden)

    Jeppe Hagstrup Christensen

    2011-11-01

    Full Text Available Omega-3 polyunsaturated fatty acids (PUFA may modulate autonomic control of the heart because omega-3 PUFA is abundant in the brain and other nervous tissue as well as in cardiac tissue. This might partly explain why omega-3 PUFA offer some protection against sudden cardiac death (SCD. The autonomic nervous system is involved in the pathogenesis of SCD. Heart rate variability (HRV can be used as a non-invasive marker of cardiac autonomic control and a low HRV is a predictor for SCD and arrhythmic events. Studies on HRV and omega-3 PUFA have been performed in several populations such as patients with ischemic heart disease, patients with diabetes mellitus, patients with chronic renal failure, and in healthy subjects as well as in children.. The studies have demonstrated a positive association between cellular content of omega-3 PUFA and HRV and supplementation with omega-3 PUFA seems to increase HRV which could be a possible explanation for decreased risk of arrhythmic events and SCD sometimes observed after omega-3 PUFA supplementation. However, the results are not consistent and further research is needed

  12. CORROSION RESISTANCE OF PEARLITIC AND BAINITIC CAST IRON IN A SYNTHETIC SOLUTION OF CONDENSED GAS FROM COMBUSTION

    OpenAIRE

    Sandra Matos Cordeiro Costa; Emerson Igor Reginaldo; Isolda Costa

    2015-01-01

    The corrosion of engine components of the combustion chamber is usually related to the formation of acids such as sulfuric and nitric. These acids are generated by the condensation of combustion gases that usually occur in vehicle exhaust systems. However, with the development of new technologies to reduce emissions, condensation is also being promoted in vehicle combustion chambers. This fact is associated with high exhaust gas recirculation rates, known as EGR (English term for ...

  13. Stretch rate effects and flame surface densities in premixed turbulent combustion up to 1.25 MPa

    KAUST Repository

    Bagdanavicius, Audrius

    2015-11-01

    Independent research at two centres using a burner and an explosion bomb has revealed important aspects of turbulent premixed flame structure. Measurements at pressures and temperatures up to 1.25MPa and 673K in the two rigs were aimed at quantifying the influences of flame stretch rate and strain rate Markstein number, Masr , on both turbulent burning velocity and flame surface density. That on burning velocity is expressed through the stretch rate factor, Io , or probability of burning, Pb 0.5. These depend on Masr , but they grow in importance as the Karlovitz stretch factor, K, increases, and are evaluated from the associated burning velocity data. Planar laser tomography was employed to identify contours of reaction progress variable in both rigs. These enabled both an appropriate flame front for the measurement of the turbulent burning velocity to be identified, and flame surface densities, with the associated factors, to be evaluated. In the explosion measurements, these parameters were derived also from the flame surface area, the derived Pb 0.5 factor and the measured turbulent burning velocities. In the burner measurement they were calculated directly from the flame surface density, which was derived from the flame contours.A new overall correlation is derived for the Pb 0.5 factor, in terms of Masr at different K and this is discussed in the light of previous theoretical studies. The wrinkled flame surface area normalised by the area associated with the turbulent burning velocity measurement, and the ratio of turbulent to laminar burning velocity, ut /ul , are also evaluated. The higher the value of Pb0.5, the more effective is an increased flame wrinkling in increasing ut /ul A correlation of the product of k and the laminar flame thickness with Karlovitz stretch factor and Markstein number is explored using the present data and those

  14. A practical approach to estimate emission rates of indoor air pollutants due to the use of personal combustible products based on small-chamber studies.

    Science.gov (United States)

    Szulejko, Jan E; Kim, Ki-Hyun

    2016-02-01

    As emission rates of airborne pollutants are commonly measured from combusting substances placed inside small chambers, those values need to be re-evaluated for the possible significance under practical conditions. Here, a simple numerical procedure is investigated to extrapolate the chamber-based emission rates of formaldehyde that can be released from various combustible sources including e-cigarettes, conventional cigarettes, or scented candles to their concentration levels in a small room with relatively poor ventilation. This simple procedure relies on a mass balance approach by considering the masses of pollutants emitted from source and lost through ventilation under the assumption that mixing occurs instantaneously in the room without chemical reactions or surface sorption. The results of our study provide valuable insights into re-evaluation procedure of chamber data to allow comparison between extrapolated and recommended values to judge the safe use of various combustible products in confined spaces. If two scented candles with a formaldehyde emission rate of 310 µg h(-1) each were lit for 4 h in a small 20 m(3) room with an air change rate of 0.5 h(-1), then the 4-h (candle lit) and 8-h (up to 8 h after candle lighting) TWA [FA] were determined to be 28.5 and 23.5 ppb, respectively. This is clearly above the 8-h NIOSH recommended exposure limit (REL) time weighted average of 16 ppb.

  15. A practical approach to estimate emission rates of indoor air pollutants due to the use of personal combustible products based on small-chamber studies.

    Science.gov (United States)

    Szulejko, Jan E; Kim, Ki-Hyun

    2016-02-01

    As emission rates of airborne pollutants are commonly measured from combusting substances placed inside small chambers, those values need to be re-evaluated for the possible significance under practical conditions. Here, a simple numerical procedure is investigated to extrapolate the chamber-based emission rates of formaldehyde that can be released from various combustible sources including e-cigarettes, conventional cigarettes, or scented candles to their concentration levels in a small room with relatively poor ventilation. This simple procedure relies on a mass balance approach by considering the masses of pollutants emitted from source and lost through ventilation under the assumption that mixing occurs instantaneously in the room without chemical reactions or surface sorption. The results of our study provide valuable insights into re-evaluation procedure of chamber data to allow comparison between extrapolated and recommended values to judge the safe use of various combustible products in confined spaces. If two scented candles with a formaldehyde emission rate of 310 µg h(-1) each were lit for 4 h in a small 20 m(3) room with an air change rate of 0.5 h(-1), then the 4-h (candle lit) and 8-h (up to 8 h after candle lighting) TWA [FA] were determined to be 28.5 and 23.5 ppb, respectively. This is clearly above the 8-h NIOSH recommended exposure limit (REL) time weighted average of 16 ppb. PMID:26495830

  16. Treatment of Pu-containing waste by acid digestion (wet combustion)

    International Nuclear Information System (INIS)

    Acid digestion as a process of treatment of plutonium-containing solid waste was developed and demonstrated under conditions of an active operation with respect to the recovery of plutonium. The process composes the following main steps: waste shredding, waste carbonisation, waste oxidation and conversion of plutonium oxide to plutonium sulphate, off-gas treatment, acid recovery and plutonium separation. The technical, safety and operational details of the plant will be presented. Furthermore, methods of the purification of separate plutonium and solidification of secondary waste for final disposal will be described. (orig./RW)

  17. Claus recycle with double combustion process

    Energy Technology Data Exchange (ETDEWEB)

    El-Bishtawi, Ribhi; Haimour, No' man [University of Jordan, Amman 11942 (Jordan)

    2004-12-15

    A new modification is developed on conventional Claus process to increase the overall sulfur recovery as well as to decrease the costs. The modification combines both oxygen enrichment and recycling. The process is simulated and studied for various N{sub 2}/O{sub 2} ratios with and without using SURE double combustion technique. The predictions show that using pure oxygen in combustion, condensing water vapor in a condenser following the first sulfur condenser and recycling the effluent gas to combine it with fresh acid gas feed leads to large savings in the production cost and to a clean environment. However, it leads to a high adiabatic flame temperature which exceeds the maximum allowable temperature of the furnace material of construction as well as its refractory. To avoid these effects, it is necessary to use SURE double combustion technique. The oxygen flow rate to the first combustion stage should not exceed 78% O{sub 2}.

  18. Modeling the impact of in-cylinder combustion parameters of DI engines on soot and NOx emissions at rated EGR levels using ANN approach

    International Nuclear Information System (INIS)

    Highlights: • Effect of in-cylinder combustion parameters on soot and NOx emissions at rated EGR levels was studied. • ANN model was adopted to predict the emissions under the effect of combustion parameters. • A trainlm ANN with 5-19-17-2 structure denoted MSE equal to 0.0004627 as outperforming model. • Increment of EGR reduced the emissions where the equivalence ratio had contradictory effect. - Abstract: This study examines the effect of in-cylinder combustion parameters on soot and NOx emissions at rated EGR levels by using the data obtained from the CFD implemented code. The obtained data were subsequently used to construct an artificial neural network (ANN) model to predict the soot and NOx productions. To this aim, at three different engine speeds of 2000, 3000 and 4000 rpm, heat release rate, equivalence ratio, turbulence kinetic energy and temperature varied to obtain the relevant soot and NOx data at three EGR levels of 0.2, 0.3 and 0.4. It was discovered that wherein the application of higher EGR rates reduced the NOx as a result of mixture dilution, equivalence ratio increment makes soot production to be increased as well as NOx emission. It was also found that the application of higher EGR from 20% to 40% decreased soot mass fraction in the combustion chamber. Increment of EGR reduced the emissions where the equivalence ratio had contradictory effect on the produced emissions. Various ANN topological configurations and training algorithms were incorporated to yield the optimal solution to the modeling problem applying statistical criteria. Among the four adopted training algorithms of trainlm, trainscg, trainrp, and traingdx, the training function of Levenberg–Marquardt (trainlm) with topological structure of 5-19-17-2 denoted MSE equal to 0.0004627

  19. U.S. experience with acid digestion of combustible transuranic waste

    International Nuclear Information System (INIS)

    Contaminated transuranic waste from a plutonium finishing plant has been processed in a waste treatment demonstration plant, the Radioactive Acid Digestion Test Unit (RADTU) located at Hanford, Washington, U.S.A. Waste treatment experience, including process and equipment performance, the behavior of plutonium in the system, and chemical and nuclear safety are all discussed. The complementary relationship of this research and development to that at the ALONA pilot plant in Mol, Belgium is noted

  20. Plasma igniter for internal-combustion engines

    Science.gov (United States)

    Breshears, R. R.; Fitzgerald, D. J.

    1978-01-01

    Hot ionized gas (plasma) ignites air/fuel mixture in internal combustion engines more effectively than spark. Electromagnetic forces propel plasma into combustion zone. Combustion rate is not limited by flame-front speed.

  1. Evaluation of tubular ceramic heat exchanger materials in acidic coal ash from coal-oil-mixture combustion. [Sialon; alumina; CVD, sintered, and siliconized SiC

    Energy Technology Data Exchange (ETDEWEB)

    Ferber, M.K.; Tennery, V.J.

    1981-12-01

    Tubes of five ceramic materials were exposed to the hot combustion gases from a coal-oil-mixture (COM) fuel in the Ceramic Recuperator Analysis Facility (CRAF) at about 1200/sup 0/C for about 500 h. Siliconized SiC, sintered ..cap alpha..-SiC, and chemically vapor deposited (CVD) SiC survived the long-term exposure with no major visible degradation. The alumina and sialon tubes were cracked extensively. Acidic coal slag deposited extensively on the upstream surface of all tubes. During cooldown, the slag did not strongly bond to any of the silicon carbide tubes, but a strong bond was developed with the alumina and sialon tubes. The silicon carbides corroded by a micropitting oxidation at the carbide-slag interface. The SiC and Si phases of siliconized SiC corroded at essentially the same rate. Exposure to hot coal slag increased the room-temperature helium permeability of all the SiC-based tubes. For KT and CVD SiC, both upstream and downstream sides exhibited expansion increases up to about 17% at 1000/sup 0/C. Sintered ..cap alpha..-SiC had much smaller increases. Al/sub 2/O/sub 3/ had an expansion increase of about 14% on the upstream side at 1000/sup 0/C but the downstream side was unchanged. 65 figures, 22 tables.

  2. Utilizing maleic acid as a novel fuel for synthesis of PbFe{sub 12}O{sub 19} nanoceramics via sol–gel auto-combustion route

    Energy Technology Data Exchange (ETDEWEB)

    Ansari, Fatemeh; Soofivand, Faezeh; Salavati-Niasari, Masoud, E-mail: salavati@kashanu.ac.ir

    2015-05-15

    PbFe{sub 12}O{sub 19} nanostructures were prepared in an aqueous solution by the sol–gel auto-combustion method using Pb(NO{sub 3}){sub 2} and Fe(NO{sub 3}){sub 3} as starting materials and various carboxylic acids, including oxalic acid, malonic acid, succinic acid and maleic acid as fuel and reducing and capping agents. The as-synthesized products were characterized by X- ray diffraction, scanning electron microscopy, and X-ray energy dispersive spectroscopy. The effect of carboxylic acid type, Pb{sup +} {sup 2} to carboxylic acid molar ratio, and calcination temperature was investigated on the morphology of the products and several experiments were carried out to obtain the optimal reaction conditions. It was found that the phase and the morphology of the products are influenced by the investigated parameters. Furthermore, vibrating sample magnetometer (VSM) was used to study the magnetic properties of PbFe{sub 12}O{sub 19} samples. - Graphical abstract: Display Omitted - Highlights: • PbFe{sub 12}O{sub 19} nanoceramics were synthesized from Fe(NO{sub 3}){sub 3} and Pb(NO{sub 3}){sub 2} via the sol–gel auto combustion method. • The maleic acid can be instead of common capping agent and fuel in auto-combustion sol–gel. • The synthesized PbFe{sub 12}O{sub 19} is a hard magnetic material. • The specific saturation magnetization and coercivity are 27 emu/g and 1900 Oe, respectively.

  3. Morphology and luminescence characteristics of combustion synthesized Y{sub 2}O{sub 3}: (Eu, Dy, Tb) nanoparticles with various amino-acid fuels

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, S.; Sudarsan, V. [Chemistry Division Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Sastry, P.U.; Patra, A.K. [Solid State Physics Division, Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India); Tyagi, A.K., E-mail: aktyagi@barc.gov.in [Chemistry Division Bhabha Atomic Research Centre, Trombay, Mumbai 400085 (India)

    2014-01-15

    Y{sub 2}O{sub 3} nanoparticles doped with Dy{sup 3+}, Eu{sup 3+} and Tb{sup 3+} together were prepared by the gel combustion method using a variety of amino acids namely, glycine, phenyl alanine, arginine, glutamic and aspartic acids. Number of carboxylate groups present in the amino acids used for combustion reaction was found to have strong influence on powder characteristics as well as luminescence from the samples. Based on small angle X-ray scattering studies, it is inferred that the nanoparticles prepared by using glycine and arginine as the fuels have smooth surface compared to those prepared using other amino acids. For the nanoparticles prepared using glutamic and aspartic acids, there exist a diffused pore-grain interface due to the lesser extent of heat generated in the reaction which leads to smaller particle size, poor crystallinity and improper burning of the organic materials. Lower surface area and smooth surface of the nanoparticles prepared using glycine leads to their improved luminescence properties. -- Highlights: • Surface smoothness of Y{sub 2}O{sub 3} (Dy, Eu, Tb) nanoparticles vary with amino acids. • Optimum luminescence intensity is observed when glycine is used as the fuel. • Diffused pore grain interface when glutamic and aspartic acids are used as fuels.

  4. Design and Testing of Lab-scale Red Fuming Nitric Acid/Hydroxyl-terminated Polybutadiene Hybrid Rocket Motor for Studying Regression Rate

    Directory of Open Access Journals (Sweden)

    Sankaran Venugopal

    2011-10-01

    Full Text Available This paper presents the design of a hybrid rocket motor and the experiments carried out for investigation of hybrid combustion and regression rates for a combination of liquid oxidiser red fuming nitric acid with solid fuel hydroxyl-terminated Polybutadiene. The regression rate is enhanced with the addition of small quantity of solid oxidiser ammonium perchlorate in the fuel. The characteristics of the combustion products were calculated using the NASA CEA Code and were used in a ballistic code developed for predicting the performance of the hybrid rocket motor. A lab-scale motor was designed and the oxidiser mass flow requirements of the hybrid motor for the above combination of fuel and oxidiser have been calculated using the developed ballistic code. A static rocket motor testing facility has been realised for conducting the hybrid experiments. A series of tests were conducted and proper ignition with stable combustion in the hybrid mode has been established. The regression rate correlations were obtained as a function of the oxidiser mass flux and chamber pressure from the experiments for the various combinations.Defence Science Journal, 2011, 61(6, pp.515-522, DOI:http://dx.doi.org/10.14429/dsj.61.873

  5. Opportunities in pulse combustion

    Science.gov (United States)

    Brenchley, D. L.; Bomelburg, H. J.

    1985-10-01

    In most pulse combustors, the combustion occurs near the closed end of a tube where inlet valves operate in phase with the pressure amplitude variations. Thus, within the combustion zone, both the temperature and the pressure oscillate around a mean value. However, the development of practical applications of pulse combustion has been hampered because effective design requires the right combination of the combustor's dimensions, valve characteristics, fuel/oxidizer combination, and flow pattern. Pulse combustion has several additional advantages for energy conversion efficiency, including high combustion and thermal efficiency, high combustion intensity, and high convective heat transfer rates. Also, pulse combustion can be self-aspirating, generating a pressure boost without using a blower. This allows the use of a compact heat exchanger that may include a condensing section and may obviate the need for a chimney. In the last decade, these features have revived interest in pulse combustion research and development, which has resulted in the development of a pulse combustion air heater by Lennox, and a pulse combustion hydronic unit by Hydrotherm, Inc. To appraise this potential for energy savings, a systematic study was conducted of the many past and present attempts to use pulse combustion for practical purposes. The authors recommended areas where pulse combustion technology could possibly be applied in the future and identified areas in which additional R and D would be necessary. Many of the results of the study project derived from a special workshop on pulse combustion. This document highlights the main points of the study report, with particular emphasis on pulse combustion application in chemical engineering.

  6. Combusting vegetable oils in diesel engines: the impact of unsaturated fatty acids on particle emissions and mutagenic effects of the exhaust.

    Science.gov (United States)

    Bünger, Jürgen; Bünger, Jörn F; Krahl, Jürgen; Munack, Axel; Schröder, Olaf; Brüning, Thomas; Hallier, Ernst; Westphal, Götz A

    2016-06-01

    High particle emissions and strong mutagenic effects were observed after combustion of vegetable oil in diesel engines. This study tested the hypothesis that these results are affected by the amount of unsaturated or polyunsaturated fatty acids of vegetable oils. Four different vegetable oils (coconut oil, CO; linseed oil, LO; palm tree oil, PO; and rapeseed oil, RO) and common diesel fuel (DF) were combusted in a heavy-duty diesel engine. The exhausts were investigated for particle emissions and mutagenic effects in direct comparison with emissions of DF. The engine was operated using the European Stationary Cycle. Particle masses were measured gravimetrically while mutagenicity was determined using the bacterial reverse mutation assay with tester strains TA98 and TA100. Combustion of LO caused the largest amount of total particulate matter (TPM). In comparison with DF, it particularly raised the soluble organic fraction (SOF). RO presented second highest TPM and SOF, followed by CO and PO, which were scarcely above DF. RO revealed the highest number of mutations of the vegetable oils closely followed by LO. PO was less mutagenic, but still induced stronger effects than DF. While TPM and SOF were strongly correlated with the content of polyunsaturated fatty acids in the vegetable oils, mutagenicity had a significant correlation with the amount of total unsaturated fatty acids. This study supports the hypothesis that numbers of double bounds in unsaturated fatty acids of vegetable oils combusted in diesel engines influence the amount of emitted particles and the mutagenicity of the exhaust. Further investigations have to elucidate the causal relationship. PMID:26126632

  7. Combusting vegetable oils in diesel engines: the impact of unsaturated fatty acids on particle emissions and mutagenic effects of the exhaust.

    Science.gov (United States)

    Bünger, Jürgen; Bünger, Jörn F; Krahl, Jürgen; Munack, Axel; Schröder, Olaf; Brüning, Thomas; Hallier, Ernst; Westphal, Götz A

    2016-06-01

    High particle emissions and strong mutagenic effects were observed after combustion of vegetable oil in diesel engines. This study tested the hypothesis that these results are affected by the amount of unsaturated or polyunsaturated fatty acids of vegetable oils. Four different vegetable oils (coconut oil, CO; linseed oil, LO; palm tree oil, PO; and rapeseed oil, RO) and common diesel fuel (DF) were combusted in a heavy-duty diesel engine. The exhausts were investigated for particle emissions and mutagenic effects in direct comparison with emissions of DF. The engine was operated using the European Stationary Cycle. Particle masses were measured gravimetrically while mutagenicity was determined using the bacterial reverse mutation assay with tester strains TA98 and TA100. Combustion of LO caused the largest amount of total particulate matter (TPM). In comparison with DF, it particularly raised the soluble organic fraction (SOF). RO presented second highest TPM and SOF, followed by CO and PO, which were scarcely above DF. RO revealed the highest number of mutations of the vegetable oils closely followed by LO. PO was less mutagenic, but still induced stronger effects than DF. While TPM and SOF were strongly correlated with the content of polyunsaturated fatty acids in the vegetable oils, mutagenicity had a significant correlation with the amount of total unsaturated fatty acids. This study supports the hypothesis that numbers of double bounds in unsaturated fatty acids of vegetable oils combusted in diesel engines influence the amount of emitted particles and the mutagenicity of the exhaust. Further investigations have to elucidate the causal relationship.

  8. Factorial design for the evaluation of the interaction effect between particle size and heating rate in the kinetic energy of coal combustion

    Energy Technology Data Exchange (ETDEWEB)

    Avila, Ivonete; Silva, Eugenio A.G.; Mortari, Daniela A.; Crnkovic, Paula M.; Milioli, Fernando E. [University of Sao Paulo (EESC/USP), Sao Carlos, SP (Brazil). Engineering School. Group of Thermal and Fluids Engineering], Emails: iavila@sc.usp.br, eugenio.silva@usp.br, paulam@sc.usp.br, milioli@sc.usp.br

    2010-07-01

    This paper evaluates the behavior of kinetic energy for different heating rates ({alpha}) and particle sizes of the material in the study of the coal combustion process. It aims to obtain a response surface in a large range of particle size, using heating rates between the minimum and maximum values allowed by the equipment. Therefore it searches for a model to evaluate the interaction effect between particle size and the heating rate and to predict the activation energy of the process studied. The activation energy of the process was determined using the isoconversional model Model Free Kinetics. In this model, the activation energy (E{sub {alpha}}) is obtained as a function of the reaction extent ({alpha}). The subscript in E{sub {alpha}} designates the values related to a given value of conversion ({alpha}). All experiments were conducted in thermogravimetric balance using samples of a Brazilian coal (EC4500) witch average particle size between 163 to 650 {mu}m and heating rates between 10 and 40 deg C min{sup -1} in dynamic atmosphere of air. A central rotatable composite design was applied for the 2{sup 2} factorial design including 4 tests under the axial conditions and 3 repetitions in the central point. As expected, the results show that both the particle size and the heating rate affected significantly the values of activation energy of the coal combustion process obtained by the model used. (author)

  9. Lectures on combustion theory

    Energy Technology Data Exchange (ETDEWEB)

    Burstein, S.Z.; Lax, P.D.; Sod, G.A. (eds.)

    1978-09-01

    Eleven lectures are presented on mathematical aspects of combustion: fluid dynamics, deflagrations and detonations, chemical kinetics, gas flows, combustion instability, flame spread above solids, spark ignition engines, burning rate of coal particles and hydrocarbon oxidation. Separate abstracts were prepared for three of the lectures. (DLC)

  10. Influence of fuel moisture, charge size, feeding rate and air ventilation conditions on the emissions of PM, OC, EC, parent PAHs, and their derivatives from residential wood combustion

    Institute of Scientific and Technical Information of China (English)

    Guofeng Shen; Miao Xue; Siye Wei; Yuanchen Chen; Qiuyue Zhao; Bing Li; Haisuo Wu

    2013-01-01

    Controlled combustion experiments were conducted to investigate the influence of fuel charge size,moisture,air ventilation and feeding rate on the emission factors (EFs) of carbonaceous particulate matter,parent polycyclic aromatic hydrocarbons (pPAHs) and their derivatives from residential wood combustion in a typical brick cooking stove.Measured EFs were found to be independent of fuel charge size,but increased with increasing fuel moisture.Pollution emissions from the normal burning under an adequate air supply condition were the lowest for most pollutants,while more pollutants were emitted when an oxygen deficient atmosphere was formed in the stove chamber during fast burning.The impacts of these factors on the size distribution of emitted particles was also studied.Modified combustion efficiency and the four investigated factors explained 68%,72%,and 64% of total variations in EFs of PM,organic carbon,and oxygenated PAHs,respectively,but only 36%,38% and 42% of the total variations in EFs of elemental carbon,pPAHs and nitro-PAHs,respectively.

  11. A Simulation of the Effects of Varying Repetition Rate and Pulse Width of Nanosecond Discharges on Premixed Lean Methane-Air Combustion

    Directory of Open Access Journals (Sweden)

    Moon Soo Bak

    2012-01-01

    Full Text Available Two-dimensional kinetic simulation has been carried out to investigate the effects of repetition rate and pulse width of nanosecond repetitively pulsed discharges on stabilizing premixed lean methane-air combustion. The repetition rate and pulse width are varied from 10 kHz to 50 kHz and from 9 ns to 2 ns while the total power is kept constant. The lower repetition rates provide larger amounts of radicals such as O, H, and OH. However, the effect on stabilization is found to be the same for all of the tested repetition rates. The shorter pulse width is found to favor the production of species in higher electronic states, but the varying effects on stabilization are also found to be small. Our results indicate that the total deposited power is the critical element that determines the extent of stabilization over this range of discharge properties studied.

  12. delta 13C analyses of vegetable oil fatty acid components, determined by gas chromatography--combustion--isotope ratio mass spectrometry, after saponification or regiospecific hydrolysis.

    Science.gov (United States)

    Woodbury, S E; Evershed, R P; Rossell, J B

    1998-05-01

    The delta 13C values of the major fatty acids of several different commercially important vegetable oils were measured by gas chromatography--combustion--isotope ratio mass spectrometry. The delta 13C values obtained were found to fall into two distinct groups, representing the C3 and C4 plants classes from which the oils were derived. The delta 13C values of the oils were measured by continuous flow elemental isotope ratio mass spectrometry and were found to be similar to their fatty acids, with slight differences between individual fatty acids. Investigations were then made into the influence on the delta 13C values of fatty acids of the position occupied on the glycerol backbone. Pancreatic lipase was employed to selectively hydrolyse fatty acids from the 1- and 3-positions with the progress of the reaction being followed by high-temperature gas chromatography in order to determine the optimum incubation time. The 2-monoacylglycerols were then isolated by thin-layer chromatography and fatty acid methyl esters prepared. The delta 13C values obtained indicate that fatty acids from any position on the glycerol backbone are isotopically identical. Thus, whilst quantification of fatty acid composition at the 2-position and measurement of delta 13C values of oils and their major fatty acids are useful criteria in edible oil purity assessment, measurement of delta 13C values of fatty acids from the 2-position does not assist with oil purity assignments.

  13. Measurement of the rates of oxindole-3-acetic acid turnover, and indole-3-acetic acid oxidation in Zea mays seedlings

    Science.gov (United States)

    Nonhebel, H. M.; Bandurski, R. S. (Principal Investigator)

    1986-01-01

    Oxindole-3-acetic acid is the principal catabolite of indole-3-acetic acid in Zea mays seedlings. In this paper measurements of the turnover of oxindole-3-acetic acid are presented and used to calculate the rate of indole-3-acetic acid oxidation. [3H]Oxindole-3-acetic acid was applied to the endosperm of Zea mays seedlings and allowed to equilibrate for 24 h before the start of the experiment. The subsequent decrease in its specific activity was used to calculate the turnover rate. The average half-life of oxindole-3-acetic acid in the shoots was found to be 30 h while that in the kernels had an average half-life of 35h. Using previously published values of the pool sizes of oxindole-3-acetic acid in shoots and kernels from seedlings of the same age and variety, and grown under the same conditions, the rate of indole-3-acetic acid oxidation was calculated to be 1.1 pmol plant-1 h-1 in the shoots and 7.1 pmol plant-1 h-1 in the kernels.

  14. Acidic ribosomal proteins and histone H3 from Leishmania present a high rate of divergence

    Directory of Open Access Journals (Sweden)

    Ysabel Montoya

    2000-08-01

    Full Text Available Another additional peculiarity in Leishmania will be discussed about of the amino acid divergence rate of three structural proteins: acidic ribosomal P1 and P2b proteins, and histone H3 by using multiple sequence alignment and dendrograms. These structural proteins present a high rate of divergence regarding to their homologous protein in Trypanosoma cruzi. At this regard, L. (V. peruviana P1 and T. cruzi P1 showed 57.4% of divergence rate. Likewise, L. (V. braziliensis histone H3 and acidic ribosomal P2 protein exhibited 31.8% and 41.7% respectively of rate of divergence in comparison with their homologous in T. cruzi.

  15. Modeling gallic acid production rate by empirical and statistical analysis

    OpenAIRE

    Kar Bratati; Banerjee Rintu; Bhattacharyya Bimal Chandra

    2000-01-01

    For predicting the rate of enzymatic reaction empirical correlation based on the experimental results obtained under various operating conditions have been developed. Models represent both the activation as well as deactivation conditions of enzymatic hydrolysis and the results have been analyzed by analysis of variance (ANOVA). The tannase activity was found maximum at incubation time 5 min, reaction temperature 40ºC, pH 4.0, initial enzyme concentration 0.12 v/v, initial substrate concentra...

  16. Coal Combustion Science

    Energy Technology Data Exchange (ETDEWEB)

    Hardesty, D.R. (ed.); Fletcher, T.H.; Hurt, R.H.; Baxter, L.L. (Sandia National Labs., Livermore, CA (United States))

    1991-08-01

    The objective of this activity is to support the Office of Fossil Energy in executing research on coal combustion science. This activity consists of basic research on coal combustion that supports both the Pittsburgh Energy Technology Center Direct Utilization Advanced Research and Technology Development Program, and the International Energy Agency Coal Combustion Science Project. Specific tasks for this activity include: (1) coal devolatilization - the objective of this risk is to characterize the physical and chemical processes that constitute the early devolatilization phase of coal combustion as a function of coal type, heating rate, particle size and temperature, and gas phase temperature and oxidizer concentration; (2) coal char combustion -the objective of this task is to characterize the physical and chemical processes involved during coal char combustion as a function of coal type, particle size and temperature, and gas phase temperature and oxygen concentration; (3) fate of mineral matter during coal combustion - the objective of this task is to establish a quantitative understanding of the mechanisms and rates of transformation, fragmentation, and deposition of mineral matter in coal combustion environments as a function of coal type, particle size and temperature, the initial forms and distribution of mineral species in the unreacted coal, and the local gas temperature and composition.

  17. Examining flow-flame interaction and the characteristic stretch rate in vortex-driven combustion dynamics using PIV and numerical simulation

    KAUST Repository

    Hong, Seunghyuck

    2013-08-01

    In this paper, we experimentally investigate the combustion dynamics in lean premixed flames in a laboratory scale backward-facing step combustor in which flame-vortex driven dynamics are observed. A series of tests was conducted using propane/hydrogen/air mixtures for various mixture compositions at the inlet temperature ranging from 300K to 500K and at atmospheric pressure. Pressure measurements and high speed particle image velocimetry (PIV) are used to generate pressure response curves and phase-averaged vorticity and streamlines as well as the instantaneous flame front, respectively, which describe unsteady flame and flow dynamics in each operating regime. This work was motivated in part by our earlier study where we showed that the strained flame consumption speed Sc can be used to collapse the pressure response curves over a wide range of operating conditions. In previous studies, the stretch rate at which Sc was computed was determined by trial and error. In this study, flame stretch is estimated using the instantaneous flame front and velocity field from the PIV measurement. Independently, we also use computed strained flame speed and the experimental data to determine the characteristic values of stretch rate near the mode transition points at which the flame configuration changes. We show that a common value of the characteristic stretch rate exists across all the flame configurations. The consumption speed computed at the characteristic stretch rate captures the impact of different operating parameters on the combustor dynamics. These results suggest that the unsteady interactions between the turbulent flow and the flame dynamics can be encapsulated in the characteristic stretch rate, which governs the critical flame speed at the mode transitions and thereby plays an important role in determining the stability characteristics of the combustor. © 2013 The Combustion Institute.

  18. Combustion chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Brown, N.J. [Lawrence Berkeley Laboratory, CA (United States)

    1993-12-01

    This research is concerned with the development and use of sensitivity analysis tools to probe the response of dependent variables to model input variables. Sensitivity analysis is important at all levels of combustion modeling. This group`s research continues to be focused on elucidating the interrelationship between features in the underlying potential energy surface (obtained from ab initio quantum chemistry calculations) and their responses in the quantum dynamics, e.g., reactive transition probabilities, cross sections, and thermal rate coefficients. The goals of this research are: (i) to provide feedback information to quantum chemists in their potential surface refinement efforts, and (ii) to gain a better understanding of how various regions in the potential influence the dynamics. These investigations are carried out with the methodology of quantum functional sensitivity analysis (QFSA).

  19. Effects of varying media, temperature, and growth rates on the intracellular concentrations of yeast amino acids.

    Science.gov (United States)

    Martínez-Force, E; Benítez, T

    1995-01-01

    Variations of the yeast free amino acid pool under different culture conditions were studied in two Saccharomyces strains, the laboratory haploid strain S288C and the industrial fermentative yeast IFI256. The internal amino acid pool of both strains was measured when grown in laboratory (minimal and complete) versus semiindustrial (molasses with or without added biotin and/or diammonium phosphate) media, in fermentable (glucose, fructose, sucrose) versus respirable (glycerol) carbon sources, in different temperatures (22, 30, and 37 degrees C), pHs (2.0-4.75), and growth rates (0.018-0.24 h-1) in continuous culture, and at different phases of the growth curve in batch culture (lag, exponential, early and late stationary). Results indicated that environmental conditions, particularly the presence of amino acids in the media, enormously influenced the intracellular amino acid concentration. Higher values were detected in molasses than in laboratory media and in fermentable carbon sources (glucose, fructose, sucrose) than in glycerol. Variations in the amino acid pool along the growth curve were greater at 37 degrees C than at other temperatures; in all cases, the highest values were measured at the beginning of the exponential phase. In continuous culture and at different growth rates, intracellular free amino acid concentrations increased by 3-10-fold when the growth rate was lower than 0.05 h-1, representing 20-35% of the total (free plus protein) amino acid content and indicating that amino acid yield was a partly growth-linked parameter. PMID:7654310

  20. Synthesis of magnetic ZnO/ZnFe2O4 by a microwave combustion method, and its high rate of adsorption of methylene blue.

    Science.gov (United States)

    Feng, Jing; Wang, Yuting; Zou, Linyi; Li, Bowen; He, Xiaofeng; Ren, Yueming; Lv, Yanzhuo; Fan, Zhuangjun

    2015-01-15

    The magnetic ZnO/ZnFe2O4 particles have been synthesized by a microwave combustion method using NaAc as fuel. The as-obtained ZnO/ZnFe2O4 was characterized and applied for the removal of methylene blue (MB) from aqueous solution in the batch system. The ZnO/ZnFe2O4 particles display larger S(BET) and smaller size with increase of NaAc dosage. Because a certain amount of gas is generated during NaAc decomposing and the gas prevent the particles from growing larger. More interestingly, even at neutral pH value, the ZnO/ZnFe2O4 obtained with 24 mL NaAc shows high-rate adsorption properties with the MB removal efficiency up to 90% in 0.5 min and a maximum adsorption capacity of 37.27 mg/g.

  1. Laminar Burning Velocities of Fuels for Advanced Combustion Engines (FACE) Gasoline and Gasoline Surrogates with and without Ethanol Blending Associated with Octane Rating

    KAUST Repository

    Mannaa, Ossama A.

    2016-05-04

    Laminar burning velocities of fuels for advanced combustion engines (FACE) C gasoline and of several blends of surrogate toluene reference fuels (TRFs) (n-heptane, iso-octane, and toluene mixtures) of the same research octane number are presented. Effects of ethanol addition on laminar flame speed of FACE-C and its surrogate are addressed. Measurements were conducted using a constant volume spherical combustion vessel in the constant pressure, stable flame regime at an initial temperature of 358 K and initial pressures up to 0.6 MPa with the equivalence ratios ranging from 0.8 to 1.6. Comparable values in the laminar burning velocities were measured for the FACE-C gasoline and the proposed surrogate fuel (17.60% n-heptane + 77.40% iso-octane + 5% toluene) over the range of experimental conditions. Sensitivity of flame propagation to total stretch rate effects and thermo-diffusive instability was quantified by determining Markstein length. Two percentages of an oxygenated fuel of ethanol as an additive, namely, 60 vol% and 85 vol% were investigated. The addition of ethanol to FACE-C and its surrogate TRF-1 (17.60% n-heptane + 77.40% iso-octane + 5% toluene) resulted in a relatively similar increase in the laminar burning velocities. The high-pressure measured values of Markstein length for the studied fuels blended with ethanol showed minimal influence of ethanol addition on the flame’s response to stretch rate and thermo-diffusive instability. © 2016 Taylor & Francis.

  2. Computational Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Westbrook, C K; Mizobuchi, Y; Poinsot, T J; Smith, P J; Warnatz, J

    2004-08-26

    Progress in the field of computational combustion over the past 50 years is reviewed. Particular attention is given to those classes of models that are common to most system modeling efforts, including fluid dynamics, chemical kinetics, liquid sprays, and turbulent flame models. The developments in combustion modeling are placed into the time-dependent context of the accompanying exponential growth in computer capabilities and Moore's Law. Superimposed on this steady growth, the occasional sudden advances in modeling capabilities are identified and their impacts are discussed. Integration of submodels into system models for spark ignition, diesel and homogeneous charge, compression ignition engines, surface and catalytic combustion, pulse combustion, and detonations are described. Finally, the current state of combustion modeling is illustrated by descriptions of a very large jet lifted 3D turbulent hydrogen flame with direct numerical simulation and 3D large eddy simulations of practical gas burner combustion devices.

  3. The temperature dependence of the rate constant for the reaction of hydroxyl radicals with nitric acid

    Science.gov (United States)

    Kurylo, M. J.; Cornett, K. D.; Murphy, J. L.

    1982-01-01

    The rate constant for the reaction of hydroxyl radicals with nitric acid in the 225-443 K temperature range has been measured by means of the flash photolysis resonance fluorescence technique. Above 300 K, the rate constant levels off in a way that can only be explained by the occurrence of two reaction channels, of which one, operative at low temperatures, proceeds through the formation of an adduct intermediate. The implications of these rate constant values for stratospheric reaction constants is discussed.

  4. Simulating Combustion

    Science.gov (United States)

    Merker, G.; Schwarz, C.; Stiesch, G.; Otto, F.

    The content spans from simple thermodynamics of the combustion engine to complex models for the description of the air/fuel mixture, ignition, combustion and pollutant formation considering the engine periphery of petrol and diesel engines. Thus the emphasis of the book is on the simulation models and how they are applicable for the development of modern combustion engines. Computers can be used as the engineers testbench following the rules and recommendations described here.

  5. Interactions of acetylcholinesterase with salvianolic acid B and rosmarinic acid from Salvia miltiorhiza water extract investigated by NMR relaxation rate

    Institute of Scientific and Technical Information of China (English)

    Guo Wei Yin; Yi Ming Li; Wei Wei; Shan Hao Jiang; Da Yuan Zhu; Wei Hong Du

    2008-01-01

    In order to understand whether the ameliorating effect on old ages memory disorder by the root of Salvia miltiorhiza is related to the acetylcholinesterase (AChE) inhibition, two main ingredients, salvianolic acid B (1) and rosmarinic acid (2), which were isolated from S. Miltiorhiza water extract, were investigated in vitro by NMR relaxation rate in this work. The results showed that the proton selective relaxation rates and the molecular rotational correlation time of proton pairs for compounds 1 and 2 increased significantly by adding of AChE in mixing solution. The study reveals that the two compounds might bind to the enzyme and have AChE inhibitory effect, which could contribute to the ameliorating effect at some extent on old ages memory disorder.

  6. Rates of fuel discharge as affected by the design of fuel-injection systems for internal-combustion engines

    Science.gov (United States)

    Gelalles, A G; Marsh, E T

    1933-01-01

    Using the method of weighing fuel collected in a receiver during a definite interval of the injection period, rates of discharge were determined, and the effects noted, when various changes were made in a fuel-injection system. The injection system consisted primarily of a by-pass controlled fuel pump and an automatic injection valve. The variables of the system studied were the pump speed, pump-throttle setting, discharge-orifice diameter, injection-valve opening and closing pressures, and injection-tube length and diameter.

  7. Hybrid rocket combustion study

    Science.gov (United States)

    Strand, L. D.; Ray, R. L.; Cohen, N. S.

    1993-01-01

    The objectives of this study of 'pure' or 'classic' hybrids are to (1) extend our understanding of the boundary layer combustion process and the critical engineering parameters that define this process, (2) develop an up-to-date hybrid fuel combustion model, and (3) apply the model to correlate the regression rate and scaling properties of potential fuel candidates. Tests were carried out with a hybrid slab window motor, using several diagnostic techniques, over a range of motor pressure and oxidizer mass flux conditions. The results basically confirmed turbulent boundary layer heat and mass transfer as the rate limiting process for hybrid fuel decomposition and combustion. The measured fuel regression rates showed good agreement with the analytical model predictions. The results of model scaling calculations to Shuttle SRM size conditions are presented.

  8. Determination of Constant-volume Combustion Energy for the Complexes of Zinc Nitrate with Three Amino Acids

    Institute of Scientific and Technical Information of China (English)

    高胜利; 陈三平; 杨旭武; 胡荣祖; 史启祯

    2001-01-01

    Five solid complexes of zinc with L-α- methionine, L-α-pheny-lalanine and L-α- histidine were prepared. The constant-volume combustion energies of the complexes, AEc (coordination), were determined by a precise rotating bomb calorimeter at 298.15 K. They were -2969.03+0.34, -2929.46±1.59, - 9597.13 ± 6.12, - 4378.98 ± 3.27 and - 14047 ±6.75 k J/mol, respectively. Their standard enthalpies of combustion, AHθm,c(coordination, s, 298.15 K), and standard enthalpies of formation, AHθm,f(coordination, s, 298.15 K),were calculated. They were - 2959.73 ± 0.34, - 2923.88 ±1.59, - 9649.18 ± 6.12, - 4373.40 ± 3.27, - 14048.53 ±6.75 kJ/mol and - 1180.94 ± 0.92, - 1401.26 ± 1.77,- 2501.69± 6.50, - 1381.47 ± 3.49, - 1950.19 ± 7.65 kJ/mol, respectively.

  9. Determination of low isotopic enrichment of L-[1-C-13]valine by gas chromatography combustion isotope ratio mass spectrometry : a robust method for measuring protein fractional synthetic rates in vivo

    NARCIS (Netherlands)

    Reijngoud, DJ; Hellstern, G; Elzinga, H; de Sain-van der Velden, MG; Okken, A; Stellaard, F

    1998-01-01

    A method was developed for measuring protein fractional synthetic rates using the N-methoxycarbonylmethyl ester (MCM) derivative of L-[1-C-13]valine and on-line gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). The derivatization procedure can be performed rapidly and GC sep

  10. Some Factors Affecting Combustion in an Internal-Combustion Engine

    Science.gov (United States)

    Rothrock, A M; Cohn, Mildred

    1936-01-01

    An investigation of the combustion of gasoline, safety, and diesel fuels was made in the NACA combustion apparatus under conditions of temperature that permitted ignition by spark with direct fuel injection, in spite of the compression ratio of 12.7 employed. The influence of such variables as injection advance angle, jacket temperature, engine speed, and spark position was studied. The most pronounced effect was that an increase in the injection advance angle (beyond a certain minimum value) caused a decrease in the extent and rate of combustion. In almost all cases combustion improved with increased temperature. The results show that at low air temperatures the rates of combustion vary with the volatility of the fuel, but that at high temperatures this relationship does not exist and the rates depend to a greater extent on the chemical nature of the fuel.

  11. Reduction of birth prevalence rates of neural tube defects after folic acid fortification in Chile.

    Science.gov (United States)

    López-Camelo, Jorge S; Orioli, Iêda M; da Graça Dutra, Maria; Nazer-Herrera, Julio; Rivera, Nelson; Ojeda, María Elena; Canessa, Aurora; Wettig, Elisabeth; Fontannaz, Ana María; Mellado, Cecília; Castilla, Eduardo E

    2005-06-01

    To verify whether the decreasing neural tube defects birth prevalence rates in Chile are due to folic acid fortification or to pre-existing decreasing trends, we performed a population survey using a network of Estudio Colaborativo Latino Americano de Malformaciones Congenitas (ECLAMC, Latin American Collaborative Study of Congenital Malformations) maternity hospitals in Chile, between the years 1982 and 2002. Within each maternity hospital, birth prevalence rates of spina bifida and anencephaly were calculated from two pre-fortification periods (1982-1989 and 1990-2000), and from one fortified period (2001-2002). There was no historical trend for spina bifida birth prevalence rates before folic acid fortification, and there was a 51% (minimum 27%, maximum 66%) decrease in the birth prevalence rates of this anomaly in the fortified period. The relative risks of spina bifida were homogeneous among hospitals in the two period comparisons. There was no historical trend for the birth prevalence of anencephaly comparing the two pre-fortified periods, but the relative risks were heterogeneous among hospitals in this comparison. There was a 42% (minimum 10%, maximum 63%) decrease in the birth prevalence rate of anencephaly in the fortified period as compared with the immediately pre-fortified period, with homogeneous relative risks among hospitals. Within the methodological constraints of this study we conclude that the birth prevalence rates for both spina bifida and anencephaly decreased as a result of folic acid fortification, without interference of decreasing secular trends.

  12. Rate constant and mechanism for the reaction of hydroxyl radical with formic acid

    Energy Technology Data Exchange (ETDEWEB)

    Jolly, G.S.; McKenney, D.J.; Singleton, D.L.; Paraskevopoulos, G.; Bossard, A.R.

    1986-11-20

    The rate constants for the reaction of OH with the monomer and dimer of formic acid have been determined at 296 K by a laser photolysis-resonance absorption technique. The OH radicals were generated by photolysis of formic acid at 222 nm with a KrCl excimer laser and were monitored by time-resolved absorption at several resonance lines of the (0,0) band of the A/sup 2/..sigma../sup +/-X/sup 2/II transition. The rate constant for the monomer was found to be 2.95 x 10/sup 11/ cm/sup 3/ mol/sup -1/ s/sup -1/. The dimer is much less reactive. Experiments with small amounts of oxygen added indicate that H atoms are formed during the reaction. The results can be interpreted as indicating significantly more abstraction of hydrogen by OH from the -OH bond than from the -CH bond of formic acid.

  13. Factors influencing the rate of non-enzymatic activation of carboxylic and amino acids by ATP

    Science.gov (United States)

    Mullins, D. W., Jr.; Lacey, J. C., Jr.

    1981-01-01

    The nonenzymatic formation of adenylate anhydrides of carboxylic and amino acids is discussed as a necessary step in the origin of the genetic code and protein biosynthesis. Results of studies are presented which have shown the rate of activation to depend on the pKa of the carboxyl group, the pH of the medium, temperature, the divalent metal ion catalyst, salt concentration, and the nature of the amino acid. In particular, it was found that of the various amino acids investigated, phenylalanine had the greatest affinity for the adenine derivatives adenosine and ATP. Results thus indicate that selective affinities between amino acids and nucleotides were important during prebiotic chemical evolution, and may have played a major role in the origin of protein synthesis and genetic coding.

  14. Effect of defatting on acid hydrolysis rate of maize starch with different amylose contents.

    Science.gov (United States)

    Wei, Benxi; Hu, Xiuting; Zhang, Bao; Li, Hongyan; Xu, Xueming; Jin, Zhengyu; Tian, Yaoqi

    2013-11-01

    The effect of defatting on the physiochemical properties and the acid hydrolysis rate of maize starch with different amylose contents was evaluated in this study. The increase in the number of pores and the stripping of starch surface layers were observed after defatting by scanning electron microscopy. X-ray diffraction spectrum showed that the peaks attributing to the amylose-lipid complex disappeared. The relative crystallinity increased by 19% for high-amylose maize starch (HMS) on defatting, while the other tested starches virtually unchanged. Differential scanning calorimetry study indicated an increase in the thermal stability for the defatted starches. Compared with native waxy maize starch, the acid hydrolysis rate of the defatted one increased by 6% after 10 days. For normal maize starch (NMS) and HMS, the higher rate of hydrolysis was observed during the first 5 days. Thereafter, the hydrolysis rate was lower than that of their native counterpart. The increase in susceptibility to acid hydrolysis (in the first 5 days) was mainly attributed to the defective and porous structures formed during defatting process, while the decrease of hydrolysis rate for NMS and HMS samples (after the first 5 days) probably resulted from the increase in the relative crystallinity.

  15. Combustion detector

    Science.gov (United States)

    Trimpi, R. L.; Nealy, J. E.; Grose, W. L. (Inventor)

    1973-01-01

    A device has been developed for generating a rapid response signal upon the radiation-emitting combustion reaction of certain gases in order to provide a means for the detection and identification of such reaction and concurrently discriminate against spurious signals. This combustion might be the first stage of a coal mine explosion process, and thereby this device could provide a warning of the impending explosion in time to initiate quenching action. This device has the capability of distinguishing between the light emitted from a combustion reaction and the light emitted by miners' lamps, electric lamps, welding sparks or other spurious events so that the quenching mechanism is triggered only when an explosion-initiating combustion occurs.

  16. Residual learning rates in lead-acid batteries: Effects on emerging technologies

    International Nuclear Information System (INIS)

    The low price of lead-acid, the most popular battery, is often used in setting cost targets for emerging energy storage technologies. Future cost reductions in lead acid batteries could increase investment and time scales needed for emerging storage technologies to reach cost-parity. In this paper the first documented model of cost reductions for lead-acid batteries is developed. Regression to a standard experience curve using 1989–2012 data yield a poor fit, with R2 values of 0.17 for small batteries and 0.05 for larger systems. To address this problem, battery costs are separated into material and residual costs, and experience curves developed for residual costs. Depending on the year, residual costs account for 41–86% of total battery cost. Using running-time averages to address volatility in material costs, a 4-year time average experience curve for residual costs yield much higher R2, 0.78 for small and 0.74 for large lead-acid batteries. The learning rate for residual costs in lead-acid batteries is 20%, a discovery with policy implications. Neglecting to consider cost reductions in lead-acid batteries could result in failure of energy storage start-ups and public policy programs. Generalizing this result, learning in incumbent technologies must be understood to assess the potential of emerging ones. -- Highlights: •We analyze potential cost reductions in lead-acid batteries. •Modified experience curve for non-material costs gives good empirical fit. •Historical learning rate for non-material costs from 1985–2012 is 19–24%. •Progress in incumbent technology raises barrier to new entrants

  17. Disposal of fluidized bed combustion ash in an underground mine to control acid mine drainage and subsidence. Quarterly report, December 1, 1996--February 28, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This project will evaluate the technical, economic and environmental feasibility of filling abandoned underground mine voids with alkaline, advanced coal combustion wastes (Fluidized Bed Combustion-FBC ash). Success will be measured in terms of technical feasibility of the approach (i.e. % void filling), cost, environmental benefits (acid mine drainage and subsidence control) and environmental impacts (noxious ion release). During Phase 3 the majority of the activity involves completing two full scale demonstration projects. The eleven acre Longridge mine in Preston County will be filled with 53,000 cubic yards of grout during the summer of 1997 and monitored for the following year. The second demonstration involves stowing 2,000 tons of ash into an abandoned mine to demonstrate the newly redesigned Burnett Ejector. This demonstration is anticipated to take place during Summer 1997, as well. This document will report on progress made during Phase 3. The report will be divided into four major sections. The first will be the Hydraulic Injection component. This section of the report will report on progress and milestones associated with the grouting activities of the project. The Phase 3 tasks of Economic Analysis and Regulatory Analysis is covered under this section. The second component is Pneumatic Injection. This section reports on progress made towards completing the demonstration project. The Water Quality component involves background monitoring of water quality and precipitation at the Phase 3 (Longridge) mine site. The last component involves evaluating the migration of contaminants through the grouted mine. A computer model has been developed in earlier phases and will model the flow of water in and around the grouted Longridge mine. The Gantt Chart on the following page details progress by task.

  18. Disposal of fluidized bed combustion ash in an underground mine to control acid mine drainage and subsidence. Quarterly report, December 1, 1996--February 28, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This project will evaluate the technical, economic and environmental feasibility of filling abandoned underground mine voids with alkaline, advanced coal combustion wastes (Fluidized Bed Combustion -- FBC ash). Success will be measured in terms of technical feasibility of the approach (i.e. % void filling), cost, environmental benefits (acid mine drainage and subsidence control) and environmental impacts (noxious ion release). During Phase 3 the majority of the activity involves completing two full scale demonstration projects. The eleven acre Longridge mine in Preston County will be filled with 53,000 cubic yards of grout during the summer of 1997 and monitored for the following year. The second demonstration involves stowing 2,000 tons of ash into an abandoned mine to demonstrate the newly redesigned Burnett Ejector. This demonstration is anticipated to take place during Summer 1997, as well. This document will report on progress made during Phase 3. The report will be divided into four major sections. The first will be the Hydraulic Injection component. This section of the report will report on progress and milestones associated with the grouting activities of the project. The Phase 3 tasks of Economic Analysis and Regulatory Analysis will be covered under this section. The second component is Pneumatic Injection. This section reports on progress made towards completing the demonstration project. The Water Quality component involves background monitoring of water quality and precipitation at the Phase 3 (Longridge) mine site. The last component involves evaluating the migration of contaminants through the grouted mine. A computer model has been developed in earlier phases and will model the flow of water in and around the grouted Longridge mine.

  19. Lactic acid removal and heart rate frequencies during recovery after strenuous rowing exercise.

    OpenAIRE

    Koutedakis, Y; Sharp, N C

    1985-01-01

    Three tests were conducted to assess the effectiveness of three different intensities of exercise both in reducing blood lactic acid (LA) levels and in influencing subjects' heart rate (HR), following a 2000 m race in a rowing boat. In the first and second tests these variables were investigated during a 13 min recovery exercise at 60% and 40% of the preceding maximum rowing speed respectively. In the third test the subjects had a resting recovery. The results include a significant increase (...

  20. Effect of dietary fatty acids on metabolic rate and nonshivering thermogenesis in golden hamsters.

    Science.gov (United States)

    Jefimow, Małgorzata; Wojciechowski, Michał S

    2014-02-01

    Hibernating rodents prior to winter tend to select food rich in polyunsaturated fatty acids (PUFA). Several studies found that such diet may positively affect their winter energy budget by enhancing torpor episodes. However, the effect of composition of dietary fatty acids (FA) on metabolism of normothermic heterotherms is poorly understood. Thus we tested whether diets different in FA composition affect metabolic rate (MR) and the capacity for nonshivering thermogenesis (NST) in normothermic golden hamsters (Mesocricetus auratus). Animals were housed in outdoor enclosures from May 2010 to April 2011 and fed a diet enriched with PUFA (i.e., standard food supplemented weekly with sunflower and flax seeds) or with saturated and monounsaturated fatty acids (SFA/MUFA, standard food supplemented with mealworms). Since diet rich in PUFA results in lower MR in hibernating animals, we predicted that PUFA-rich diet would have similar effect on MR of normothermic hamsters, that is, normothermic hamsters on the PUFA diet would have lower metabolic rate in cold and higher NST capacity than hamsters supplemented with SFA/MUFA. Indeed, in winter resting metabolic rate (RMR) below the lower critical temperature was higher and NST capacity was lower in SFA/MUFA-supplemented animals than in PUFA-supplemented ones. These results suggest that the increased capacity for NST in PUFA-supplemented hamsters enables them lower RMR below the lower critical temperature of the thermoneural zone.

  1. SK&F 97426-A: a novel bile acid sequestrant with higher affinities and slower dissociation rates for bile acids in vitro than cholestyramine.

    Science.gov (United States)

    Benson, G M; Alston, D R; Hickey, D M; Jaxa-Chamiec, A A; Whittaker, C M; Haynes, C; Glen, A; Blanchard, S; Cresswell, S R; Suckling, K E

    1997-01-01

    SK&F 97426-A is a novel bile acid sequestrant that is threefold more potent than cholestyramine at increasing bile acid excretion in the hamster. SK&F 97426-A is a quaternary alkylammonium polymethacrylate that was selected for comparison with cholestyramine in vivo because of its superior in vitro bile acid binding properties. Association, dissociation, affinity, and capacity experiments were performed under physiologically relevant conditions with the most abundant bile acids found in human bile. The bile acids came to equilibrium with SK&F 97426-A and cholestyramine within approximately 30 min and 6 min, respectively. SK&F 97426-A and cholestyramine had similar capacities for all the bile acids (between 2.5 and 4 mmol/g) and both had similar, very high affinities and slow dissociation rates for the dihydroxy bile acids. However, SK&F 97426-A had much higher affinities for the trihydroxy bile acids glycocholic acid and taurocholic acid than did cholestyramine. Dissociation of glycocholic acid and taurocholic acid from SK&F 97426-A was also much slower (27 and 25%, respectively, dissociated after 60 min) than from cholestyramine (89 and 84%, respectively, dissociated after 60 min). The higher affinities and slower dissociation rates of the trihydroxy bile acids for and from SK&F 97426-A probably account for the increased potency of SK&F 97426-A over cholestyramine in vivo.

  2. SAVANNAH RIVER SITE TANK CLEANING: CORROSION RATE FOR ONE VERSUS EIGHT PERCENT OXALIC ACID SOLUTION

    Energy Technology Data Exchange (ETDEWEB)

    Ketusky, E.; Subramanian, K.

    2011-01-20

    Until recently, the use of oxalic acid for chemically cleaning the Savannah River Site (SRS) radioactive waste tanks focused on using concentrated 4 and 8-wt% solutions. Recent testing and research on applicable dissolution mechanisms have concluded that under appropriate conditions, dilute solutions of oxalic acid (i.e., 1-wt%) may be more effective. Based on the need to maximize cleaning effectiveness, coupled with the need to minimize downstream impacts, SRS is now developing plans for using a 1-wt% oxalic acid solution. A technology gap associated with using a 1-wt% oxalic acid solution was a dearth of suitable corrosion data. Assuming oxalic acid's passivation of carbon steel was proportional to the free oxalate concentration, the general corrosion rate (CR) from a 1-wt% solution may not be bound by those from 8-wt%. Therefore, after developing the test strategy and plan, the corrosion testing was performed. Starting with the envisioned process specific baseline solvent, a 1-wt% oxalic acid solution, with sludge (limited to Purex type sludge-simulant for this initial effort) at 75 C and agitated, the corrosion rate (CR) was determined from the measured weight loss of the exposed coupon. Environmental variations tested were: (a) Inclusion of sludge in the test vessel or assuming a pure oxalic acid solution; (b) acid solution temperature maintained at 75 or 45 C; and (c) agitation of the acid solution or stagnant. Application of select electrochemical testing (EC) explored the impact of each variation on the passivation mechanisms and confirmed the CR. The 1-wt% results were then compared to those from the 8-wt%. The immersion coupons showed that the maximum time averaged CR for a 1-wt% solution with sludge was less than 25-mils/yr for all conditions. For an agitated 8-wt% solution with sludge, the maximum time averaged CR was about 30-mils/yr at 50 C, and 86-mils/yr at 75 C. Both the 1-wt% and the 8-wt% testing demonstrated that if the sludge was removed

  3. Combustion apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Shimizu, S.; Mitsudomi, H.

    1984-04-17

    A new burner provides the high temperatures required in the manufacture of high-grade china and artificial jewels by using air enriched with oxygen through an oxygen permselective membrane. Operators can vary the combustion air quantity and oxygen content as needed. Three flow paths arranged coaxially from a radially inner position to outside the burner supply it with the fuel, oxygen-enriched air, and combustion air. Each line is equipped with a control valve to allow variation in the furnace's heating power.

  4. Disposal of transuranic solid waste using Atomics International's molten salt combustion process. II

    International Nuclear Information System (INIS)

    The Atomics International Molten Salt Combustion Process reduces the weight and volume of combustible transuranic waste by utilizing a molten salt medium to combust organic materials, to trap particulates and fissile material, and to react chemically with any acidic gases produced during combustion. The ''ash'' is retained by the molten salt. To control the amount of noncombustible substances in the melt, a portion of the molten salt is periodically drained from the combustor. There are two options following the combustion step: the salt-ash mixture can be cast into a metal canister for direct storage, which is preferred, or the salt-ash mixture can be processed to separate ash for disposal, to recover the salt for recycle and to recover fissile materials. Either option results in the rapid, complete, and nonpolluting destruction of the combustible waste. Bench-scale (0.2 kg/hr) combustion tests with plutonium-contaminated waste showed that >99.9 percent of the plutonium is retained in the melt during combustion. A similar test with uranium indicated that uranium and plutonium behave identically during combustion. Bench-scale plutonium recovery tests have shown that approx. 98 percent of the plutonium can be recovered from the ash-melt mixture with a single acid leach. Pilot plant combustion tests were conducted with uncontaminated shredded waste consisting of paper, Kimwipes, cardboard, rubber, polyvinyl chloride, and polyethylene at feed rates up to 70 kg/hr. Hydrogen chloride (3 at approx. 7900C to 0.6 g/m3 at 10200C before the venturi scrubber, and 0.01 to 0.04 g/m3, respectively, after the scrubber. Downstream of the HEPA filters, no particulates could be detected

  5. Acid suppression increases rates of Barrett's esophagus and esophageal injury in the presence of duodenal reflux.

    LENUS (Irish Health Repository)

    2012-01-31

    BACKGROUND: The contribution of gastric acid to the toxicity of alkaline duodenal refluxate on the esophageal mucosa is unclear. This study compared the effect of duodenal refluxate when acid was present, decreased by proton pump inhibitors (PPI), or absent. METHODS: We randomized 136 Sprague-Dawley rats into 4 groups: group 1 (n = 33) were controls; group 2 (n = 34) underwent esophagoduodenostomy promoting "combined reflux"; group 3 (n = 34) underwent esophagoduodenostomy and PPI treatment to decrease acid reflux; and group 4, the \\'gastrectomy\\' group (n = 35) underwent esophagoduodenostomy and total gastrectomy to eliminate acid in the refluxate. Esophaguses were examined for inflammatory, Barrett\\'s, and other histologic changes, and expression of proliferative markers Ki-67, proliferating cell nuclear antigen (PCNA), and epidermal growth factor receptor (EGFR). RESULTS: In all reflux groups, the incidence of Barrett\\'s mucosa was greater when acid was suppressed (group C, 62%; group D, 71%) than when not suppressed (group B, 27%; P = 0.004 and P < .001). Erosions were more frequent in the PPI and gastrectomy groups than in the combined reflux group. Edema (wet weight) and ulceration was more frequent in the gastrectomy than in the combined reflux group. Acute inflammatory changes were infrequent in the PPI group (8%) compared with the combined reflux (94%) or gastrectomy (100%) groups, but chronic inflammation persisted in 100% of the PPI group. EGFR levels were greater in the PPI compared with the combined reflux group (P = .04). Ki-67, PCNA, and combined marker scores were greater in the gastrectomy compared with the combined reflux group (P = .006, P = .14, and P < .001). CONCLUSION: Gastric acid suppression in the presence of duodenal refluxate caused increased rates of inflammatory changes, intestinal metaplasia, and molecular proliferative activity. PPIs suppressed acute inflammatory changes only, whereas chronic inflammatory changes persisted.

  6. Improving arachidonic acid fermentation by Mortierella alpina through multistage temperature and aeration rate control in bioreactor.

    Science.gov (United States)

    Gao, Min-Jie; Wang, Cheng; Zheng, Zhi-Yong; Zhu, Li; Zhan, Xiao-Bei; Lin, Chi-Chung

    2016-05-18

    Effective production of arachidonic acid (ARA) using Mortierella alpina was conducted in a 30-L airlift bioreactor. Varying the aeration rate and temperature significantly influenced cell morphology, cell growth, and ARA production, while the optimal aeration rate and temperature for cell growth and product formation were quite different. As a result, a two-stage aeration rate control strategy was constructed based on monitoring of cell morphology and ARA production under various aeration rate control levels (0.6-1.8 vvm). Using this strategy, ARA yield reached 4.7 g/L, an increase of 38.2% compared with the control (constant aeration rate control at 1.0 vvm). Dynamic temperature-control strategy was implemented based on the fermentation performance at various temperatures (13-28°C), with ARA level in total cellular lipid increased by 37.1% comparing to a constant-temperature control (25°C). On that basis, the combinatorial fermentation strategy of two-stage aeration rate control and dynamic temperature control was applied and ARA production achieved the highest level of 5.8 g/L.

  7. Dietary medium chain fatty acid supplementation leads to reduced VLDL lipolysis and uptake rates in comparison to linoleic acid supplementation

    NARCIS (Netherlands)

    Schalkwijk, D.B. van; Pasman, W.J.; Hendriks, H.F.J.; Verheij, E.R.; Rubingh, C.M.; Bochove, K. van; Vaes, W.H.J.; Adiels, M.; Freidig, A.P.; Graaf, A.A. de

    2014-01-01

    Dietary medium chain fatty acids (MCFA) and linoleic acid follow different metabolic routes, and linoleic acid activates PPAR receptors. Both these mechanisms may modify lipoprotein and fatty acid metabolism after dietary intervention. Our objective was to investigate how dietary MCFA and linoleic a

  8. Homogeneous nucleation rates of nitric acid dihydrate (NAD at simulated stratospheric conditions – Part II: Modelling

    Directory of Open Access Journals (Sweden)

    O. Möhler

    2006-01-01

    Full Text Available Activation energies ΔGact for the nucleation of nitric acid dihydrate (NAD in supercooled binary HNO3/H2O solution droplets were calculated from volume-based nucleation rate measurements using the AIDA (Aerosol, Interactions, and Dynamics in the Atmosphere aerosol chamber of Forschungszentrum Karlsruhe. The experimental conditions covered temperatures T between 192 and 197 K, NAD saturation ratios SNAD between 7 and 10, and nitric acid molar fractions of the nucleating sub-micron sized droplets between 0.26 and 0.28. Based on classical nucleation theory, a new parameterisation for ΔGact=A×(T ln SNAD−2+B is fitted to the experimental data with A=2.5×106 kcal K2 mol−1 and B=11.2−0.1(T−192 kcal mol−1. A and B were chosen to also achieve good agreement with literature data of ΔGact. The parameter A implies, for the temperature and composition range of our analysis, a mean interface tension σsl=51 cal mol−1 cm−2 between the growing NAD germ and the supercooled solution. A slight temperature dependence of the diffusion activation energy is represented by the parameter B. Investigations with a detailed microphysical process model showed that literature formulations of volume-based (Salcedo et al., 2001 and surface-based (Tabazadeh et al., 2002 nucleation rates significantly overestimate NAD formation rates when applied to the conditions of our experiments.

  9. Field rates for natural attenuation of arsenic in Tinto Santa Rosa acid mine drainage (SW Spain).

    Science.gov (United States)

    Asta, Maria P; Ayora, Carlos; Acero, Patricia; Cama, Jordi

    2010-05-15

    Reactive transport modelling of the main processes related to the arsenic natural attenuation observed in the acid mine drainage (AMD) impacted stream of Tinto Santa Rosa (SW Spain) was performed. Despite the simplicity of the kinetic expressions used to deal with arsenic attenuation processes, the model reproduced successfully the major chemical trends observed along the acid discharge. Results indicated that the rate of ferrous iron oxidation was similar to the one obtained in earlier field studies in which microbial catalysis is reported to occur. With regard to the scaled arsenic oxidation rate, it is one order of magnitude faster than the values obtained under laboratory conditions suggesting the existence of a catalytic agent in the natural system. Schwertmannite precipitation rate, which was represented by a simple kinetic expression relying on Fe(III) and pH, was in the range calculated for other AMD impacted sites. Finally, the obtained distribution coefficients used for representing arsenic sorption onto Fe(III) precipitates were lower than those deduced from reported laboratory data. This discrepancy is attributed to a decrease in the schwertmannite arsenate sorption capacity as sulphate increases in the solution.

  10. Study of radio-protective effects of ascorbic acid in rates

    International Nuclear Information System (INIS)

    The aim of this study was to evaluate the potential radio-protective effects of different ascorbic acid concentrations (vitamin C) in rats before whole body irradiation with total dose of 7 Gy (60Co source) using two different dose rates of 1 and 0.55 Gy.min-1 by increasing percent of surviving. In the first group (1 Gy/m); rats were administered four different concentrations of ascorbic acid (7.5, 12.5, 100, 200 mg/kg b wt ) in drinking water for 30 days before irradiation starting from the ablactation which considered as day 0. Whereas, in the second group (0.55 Gy/m); rats were administered six different concentrations of ascorbic acid (1, 5, 7.5, 12.5, 100, 200 mg/kg b wt) before irradiation with total dose 7 Gy (60Co source). The results have showed that the ascorbic acid enhance the 30-day survival of irradiated rats in 1 and 0.55 Gy/m groups, compared to the control group. The mean cumulated probability of survival of rats (1 Gy/m group) was 66%± 6 (Mean± S.E), 69%± 5, 52%± 9 and 51%± 9 in groups of rats which administered 7.5, 12.5, 100, 200 mg/kg, respectively, versus 41%± 9 in control group for 14 days. While, it was 90%± 2, 90%± 2, 88%± 2, 94%± 1, 84%± 3 and 78%± 3 in groups of rats which administered 1, 5, 7.5, 12.5, 100, 200 mg/kg respectively, versus 52%± 6 in control group for 30 days. Our data, also, indicated that all ascorbic acid concentrations in both groups had significant reduction in mortality and increasing percent of surviving compared to the control groups. We conclude that all ascorbic acid concentrations which used in both groups (1 and 0.55 Gy/m), had radioprotective effects in rats when administrated before irradiations, and this role was more effective against lower dose rate of radiation exposure. (author)

  11. TRP0033 - PCI Coal Combustion Behavior and Residual Coal Char Carryover in the Blast Furnace of 3 American Steel Companies during Pulverized Coal Injection (PCI) at High Rates

    Energy Technology Data Exchange (ETDEWEB)

    Veena Sahajwalla; Sushil Gupta

    2005-04-15

    Combustion behavior of pulverized coals (PC), gasification and thermal annealing of cokes were investigated under controlled environments. Physical and chemical properties of PCI, coke and carbon residues of blast furnace dust/sludge samples were characterized. The strong influence of carbon structure and minerals on PCI reactivity was demonstrated. A technique to characterize char carryover in off gas emissions was established.

  12. Calcite growth-rate inhibition by fulvic acids isolated from Big Soda Lake, Nevada, USA, The Suwannee River, Georgia, USA and by polycarboxylic acids

    Science.gov (United States)

    Reddy, Michael M.; Leenheer, Jerry

    2011-01-01

    Calcite crystallization rates are characterized using a constant solution composition at 25°C, pH=8.5, and calcite supersaturation (Ω) of 4.5 in the absence and presence of fulvic acids isolated from Big Soda Lake, Nevada (BSLFA), and a fulvic acid from the Suwannee River, Georgia (SRFA). Rates are also measured in the presence and absence of low-molar mass, aliphatic-alicyclic polycarboxylic acids (PCA). BSLFA inhibits calcite crystal-growth rates with increasing BSLFA concentration, suggesting that BSLFA adsorbs at growth sites on the calcite crystal surface. Calcite growth morphology in the presence of BSLFA differed from growth in its absence, supporting an adsorption mechanism of calcite-growth inhibition by BSLFA. Calcite growth-rate inhibition by BSLFA is consistent with a model indicating that polycarboxylic acid molecules present in BSLFA adsorb at growth sites on the calcite crystal surface. In contrast to published results for an unfractionated SRFA, there is dramatic calcite growth inhibition (at a concentration of 1 mg/L) by a SRFA fraction eluted by pH 5 solution from XAD-8 resin, indicating that calcite growth-rate inhibition is related to specific SRFA component fractions. A cyclic PCA, 1, 2, 3, 4, 5, 6-cyclohexane hexacarboxylic acid (CHXHCA) is a strong calcite growth-rate inhibitor at concentrations less than 0.1 mg/L. Two other cyclic PCAs, 1, 1 cyclopentanedicarboxylic acid (CPDCA) and 1, 1 cyclobutanedicarboxylic acid (CBDCA) with the carboxylic acid groups attached to the same ring carbon atom, have no effect on calcite growth rates up to concentrations of 10 mg/L. Organic matter ad-sorbed from the air onto the seed crystals has no effect on the measured calcite crystal-growth rates.

  13. Modelling the growth rate of Escherichia coli as a function of pH and lactic acid concentration.

    OpenAIRE

    Presser, K A; Ratkowsky, D A; Ross, T.

    1997-01-01

    The growth rate responses of Escherichia coli M23 (a nonpathogenic strain) to suboptimal pH and lactic acid concentration were determined. Growth rates were measured turbidimetrically at 20 degrees C in the range of pH 2.71 to 8.45. The total concentration of lactic acid was fixed at specific values, and the pH was varied by the addition of a strong acid (hydrochloric) or base (sodium hydroxide) to enable the determination of undissociated and dissociated lactic acid concentrations under each...

  14. Growth Rate of Bumblebee Larvae is Related to Pollen Amino Acids.

    Science.gov (United States)

    Moerman, Romain; Vanderplanck, Maryse; Roger, Nathalie; Declèves, Sylvain; Wathelet, Bernard; Rasmont, Pierre; Fournier, Denis; Michez, Denis

    2016-02-01

    The use of Bombus terrestris L. commercial colonies for outdoor and greenhouse crop pollination is currently widespread. Colony breeding includes bumblebee feeding, mostly by using the honeybee pollen loads of diverse palynological composition. Because the chemical content of pollen is highly variable, the choice of commercial blend should not be random but has to be carefully selected to ensure the optimal development of workers and then pollination efficacy. In this work, we compared the impact of three common commercial blends on the development of bumblebee microcolonies, namely, Actinidia deliciosa L., Cistus sp., and Salix sp. We focus on amino acids (i.e., composition and amount), as they are currently used as an indicator of diet performance. Five parameters were used to determine microcolonies growth rate: 1) number of eggs, 2) number of alive larvae, 3) number of ejected larvae, 4) number of pupae, and 5) total number of offspring. Syrup collection was also monitored to estimate energetic requirement for colony growth. Results revealed that the three commercial blends chemically differed in their amino acid contents, with those displaying higher concentrations (i.e., Salix sp. and A. deliciosa) accelerating microcolony development along with an increase of syrup collection. The advantages of rearing bumblebee commercial colonies using a pollen diet with an optimal amino acid content are discussed. PMID:26385047

  15. Advanced Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, Gordon R. [NETL

    2013-03-11

    The activity reported in this presentation is to provide the mechanical and physical property information needed to allow rational design, development and/or choice of alloys, manufacturing approaches, and environmental exposure and component life models to enable oxy-fuel combustion boilers to operate at Ultra-Supercritical (up to 650{degrees}C & between 22-30 MPa) and/or Advanced Ultra-Supercritical conditions (760{degrees}C & 35 MPa).

  16. Influence of liquid and gas flow rates on sulfuric acid mist removal from air by packed bed tower

    Directory of Open Access Journals (Sweden)

    Jafari Mohammad Javad

    2012-12-01

    Full Text Available Abstract The possible emission of sulfuric acid mists from a laboratory scale, counter-current packed bed tower operated with a caustic scrubbing solution was studied. Acid mists were applied through a local exhaust hood. The emissions from the packed bed tower were monitored in three different categories of gas flow rate as well as three liquid flow rates, while other influencing parameters were kept almost constant. Air sampling and sulfuric acid measurement were carried out iso-kinetically using USEPA method 8. The acid mists were measured by the barium-thorin titration method. According to the results when the gas flow rate increased from 10 L/s to 30 L/s, the average removal efficiency increased significantly (p 3, respectively. L/G of 2–3 was recommended for designing purposes of a packed tower for sulfuric acid mists and vapors removal from contaminated air stream.

  17. Relationship of lipogenic enzyme activities to the rate of rat liver fatty acid synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Nelson, G.; Kelley, D.; Schmidt, P.; Virk, S.; Serrato, C.

    1986-05-01

    The mechanism by which diet regulates liver lipogenesis is unclear. Here the authors report how dietary alterations effect the activities of key enzymes of fatty acid (FA) synthesis. Male Sprague-Dawley rats, 400-500 g, were fasted for 48h and then refed a fat-free, high carbohydrate (HC) diet (75% cal. from sucrose) for 0,3,9,24 and 48h, or refed a HC diet for 48h, then fed a high-fat (HF) diet (44% cal. from corn oil) for 3,9,24 and 48h. The FA synthesis rate and the activities of acetyl CoA carboxylase (AC), fatty acid synthase (FAS), ATP citrate lyase (CL), and glucose 6-phosphate dehydrogenase (G6PDH) were determined in the livers. FA synthesis was assayed with /sup 3/H/sub 2/O, enzyme activities were measured spectrophotometrically except for AC which was assayed with /sup 14/C-bicarbonate. There was no change in the activity of AC during fasting or on the HC diet. Fasting decreased the rate of FA synthesis by 25% and the activities of FAS and CL by 50%; refeeding the HC diet induced parallel changes in FA synthesis and the activities of FAS, CL, and G6PDH. After 9h on the HF diet, FA synthesis had decreased sharply, AC activity increased significantly while no changes were detected in the other activities. Subsequently FA synthesis did not change while the activities of the enzymes decreased slowly. These enzymes did not appear to regulate FA synthesis during inhibition of lipogenesis, but FAS, CL or G6PDH may be rate limiting in the induction phase. Other key factors may regulate FA synthesis during dietary alterations.

  18. Quantifying Rates of Complete Microbial Iron Redox Cycling in Acidic Hot Springs

    Science.gov (United States)

    St Clair, B.; Pottenger, J. W.; Shock, E.

    2013-12-01

    Large accumulations of iron oxide commonly occur in shallow outflows of acidic hot springs, and culturing, molecular techniques, and microscopy by others indicate that this iron oxide (often ferrihydrite) is largely biogenic in Yellowstone National Park. The hot springs that support iron mats have several consistent geochemical features including combinations of pH, temperature, sulfide, dissolved oxygen, depth and ferrous iron concentration appropriate to support iron oxidation. These springs nearly always have a point source leading to a large shallow outflow apron. Microbial zones often, but not always, include a small clear zone near the source, followed by a sulfide oxidation zone, iron mat, and finally photosynthesis. The yellow sulfide oxidation zone is separated from the red iron mat by a sharp transition resulting from increasing dissolved oxygen from atmospheric contact and microbial depletion of sulfide. The iron mat is typically the largest microbial zone in the feature by area. Further down the outflow, iron oxidation appears to be outcompeted by phototrophs as the temperature cools. Occasionally there is overlap in these zones, but one metabolism always appears dominant. Our experiments at diverse hot springs indicate that microbial reduction is less geochemically restricted than oxidation, requiring only organic carbon, ferric minerals and an anoxic environment. With iron oxidizers fixing carbon and producing layers of ferric minerals that become rapidly anoxic with depth, iron reduction is invariably proximal to where biogenic iron oxides are forming. To characterize the interplay of oxidation and reduction rates that permit oxide accumulation, we conducted rate experiments at geochemically diverse Yellowstone hot springs featuring visible iron oxides in thermal areas throughout the park. These experiments were performed during two summer field seasons to determine in situ and maximum rates of iron oxidation and reduction by measuring changing

  19. Bile acid metabolism in hereditary forms of hypertriglyceridemia: evidence for an increased synthesis rate in monogenic familial hypertriglyceridemia.

    OpenAIRE

    Angelin, B; Hershon, K S; Brunzell, J D

    1987-01-01

    This study was undertaken to characterize bile acid metabolism in hereditary forms of hypertriglyceridemia. Ten hypertriglyceridemic patients (type IV phenotype) with familial combined hyperlipidemia and 7 patients with monogenic familial hypertriglyceridemia (FHTG) were compared with 18 healthy controls; all subjects were males. Pool size, synthesis rate, and fractional catabolic rate of cholic and chenodeoxycholic acids were determined with an isotope dilution technique. Patients with FHTG ...

  20. Effect of dietary omega-3 fatty acids on the heart rate and the heart rate variability responses to myocardial ischemia or submaximal exercise

    OpenAIRE

    George E Billman; William S. Harris

    2011-01-01

    The consumption of omega-3 polyunsaturated fatty acids (n-3 PUFAs) has been reported to decrease resting heart rate (HR) and increase heart rate variability (HRV). However, the effects of n-3 PUFAs on these variables in response to a physiological stress (e.g., exercise or acute myocardial ischemia), particularly in postmyocardial infarction (MI) patients, are unknown. Therefore, HR and HRV (high frequency and total R-R interval variability) were evaluated at rest, during submaximal exercise,...

  1. Effect of Dietary Omega-3 Polyunsaturated Fatty Acids on Heart Rate and Heart Rate Variability in Animals Susceptible or Resistant to Ventricular Fibrillation

    OpenAIRE

    George E Billman

    2012-01-01

    The consumption of omega-3 polyunsaturated fatty acids (n-3 PUFAs) has been reported to reduce cardiac mortality following myocardial infarction as well as to decrease resting heart rate (HR) and increase heart rate variability (HRV). However, it has not been established whether n-3 PUFAs exhibit the same actions on HR and HRV in individuals known to be either susceptible or resistant to ventricular fibrillation (VF). Therefore, HR and HRV (high frequency and total R-R interval variability)...

  2. Effect of Strip Velocity on Pickling Rate of Hot-Rolled Steel in Hydrochloric Acid

    Science.gov (United States)

    Hudson, R. M.; Warning, C. J.

    1982-02-01

    The combined effect of strip velocity with other parameters on pickling rate of hot-rolled low-carbon steel in hydrochloric acid (HCl) solutions was determined. At temperatures from 150 to200°F(66 to 93°), the time required for pickling decreased substantially as strip velocity was increased from 0 to about 250 fpm (76 mpm); no further decrease in time resulted when velocities were increased to 800 fpm (244 mpm). Other pickling variables were studied with a velocity of 400 fpm (122 mpm). Pickling times decrease with increases in HCl concentrations, CHCl, and temperature, TF, according to prediction equations of the form log t = A + B log CHCl + D(459 + TF)-1. At 200°F, temper-mill scalebreaking decreased pickling times by about 5 sec; at lower temperatures, a larger magnitude effect was noted for one steel in the group tested.

  3. Changes in ruminal volatile fatty acid production and absorption rate during the dry period and early lactation as affected by rate of increase of concentrate allowance

    NARCIS (Netherlands)

    Dieho, K.; Dijkstra, Jan; Schonewille, J.T.; Bannink, A.

    2016-01-01

    The aim of the present experiment was to study changes in volatile fatty acid (VFA) production using an isotope dilution technique, and changes in VFA fractional absorption rate (k aVFA) using a buffer incubation technique (BIT) during the dry period and early lactation, as affected by

  4. Sandia Combustion Research Program: Annual report, 1986

    Energy Technology Data Exchange (ETDEWEB)

    1986-01-01

    This report presents research results of the past year, divided thematically into some ten categories. Publications and presentations arising from this work are included in the appendix. Our highlighted accomplishment of the year is the announcement of the discovery and demonstration of the RAPRENOx process. This new mechanism for the elimination of nitrogen oxides from essentially all kinds of combustion exhausts shows promise for commercialization, and may eventually make a significant contribution to our nation's ability to control smog and acid rain. The sections of this volume describe the facility's laser and computer system, laser diagnostics of flames, combustion chemistry, reacting flows, liquid and solid propellant combustion, mathematical models of combustion, high-temperature material interfaces, studies of engine/furnace combustion, coal combustion, and the means of encouraging technology transfer. 182 refs., 170 figs., 12 tabs.

  5. Combustion modeling in waste tanks

    International Nuclear Information System (INIS)

    This paper has two objectives. The first one is to repeat previous simulations of release and combustion of flammable gases in tank SY-101 at the Hanford reservation with the recently developed code GASFLOW-II. The GASFLOW-II results are compared with the results obtained with the HMS/TRAC code and show good agreement, especially for non-combustion cases. For combustion GASFLOW-II predicts a steeper pressure rise than HMS/TRAC. The second objective is to describe a so-called induction parameter model which was developed and implemented into GASFLOW-II and reassess previous calculations of Bureau of Mines experiments for hydrogen-air combustion. The pressure time history improves compared with the one-step model, and the time rate of pressure change is much closer to the experimental data

  6. CFD simulation of pulse combustion's performance

    Science.gov (United States)

    Rahmatika, Annie Mufyda; Widiyastuti, W.; Winardi, Sugeng; Nurtono, Tantular; Machmudah, Siti; Kusdianto, Joni, I. Made

    2016-02-01

    This study aims to show changes in the performance of combustion using pulse combustion at specified intervals using simulation. Simulations is performed using Computational Fluid Dynamics analysis (CFD) software Ansys Fluent 15.0. Analysis used 2D illustration axisymmetric with k-ɛ turbulence models. Propane was selected as fuel at a flow rate of 15 L/min. Air with flow rate of 375 L/min is used as oxidizer. To investigate the advantages of using pulse combustion, the simulated pulse combustion is compared to normal combustion without a pulse. This is done by displaying descriptions of the phenomenon, mechanisms and results output gas combustor. From the analysis of simulation results showed that in 1 minute burning time, burning fuel without requiring pulse as much as 15 L while the pulse combustion requires half of the fuel which is 12.5 L. However, the higher average of temperature was generated by pulse combustion and the amounts of unburned fuel that comes out of the combustor less than without the use of pulse combustion. So, it can be concluded that the pulse combustion is more efficient than combustion without a pulse.

  7. Aspartic acid racemization rate in narwhal (Monodon monoceros) eye lens nuclei estimated by counting of growth layers in tusks

    DEFF Research Database (Denmark)

    Garde, Eva; Heide-Jørgensen, Mads Peter; Ditlevsen, Susanne;

    2012-01-01

    ) technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid D/L ratios in eye lens nuclei against growth layer groups in tusks (n=9). Two racemization rates were...

  8. Influence of solution volume on the dissolution rate of silicon dioxide in hydrofluoric acid.

    Science.gov (United States)

    Shvartsev, Boris; Gelman, Danny; Komissarov, Ilia; Epshtein, Alon; Starosvetsky, David; Ein-Eli, Yair

    2015-02-01

    Experimental data and modeling of the dissolution of various Si/SiO2 thermal coatings in different volumes of hydrofluoric acid (HF) are reported. The rates of SiO2 -film dissolution, measured by means of various electrochemical techniques, and alteration in HF activity depend on the thickness of the film coating. Despite the small volumes (0.6-1.2 mL) of the HF solution, an effect of SiO2 -coating thickness on the dissolution rate was detected. To explain alterations detected in HF activity after SiO2 dissolution, spectroscopic analyses (NMR and FTIR) of the chemical composition of the solutions were conducted. This is associated with a modification in the chemical composition of the HF solution, which results in either the formation of an oxidized species in solution or the precipitation of dissolution products. HF2 (-) accumulation in the HF solution, owing to SiO2 dissolution was identified as the source of the chemical alteration.

  9. High Combustion Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — At NETL's High-Pressure Combustion Research Facility in Morgantown, WV, researchers can investigate new high-pressure, high-temperature hydrogen turbine combustion...

  10. Dissolution rate of bunsenite (NiO) in acid solution to 130 deg. C

    International Nuclear Information System (INIS)

    Nickel oxide is present on surfaces of the components of the primary circuit and can get activated into 58Co. A complete understanding of the behaviour of nickel in the primary circuit must include the dissolution kinetics, but no relevant data was available until now. Rates of proton-promoted dissolution of bunsenite (NiO) were measured from 50 deg. C to 130 deg. C in hydrochloric acid solutions (pH 3, 4.5 and 5) in a titanium mixed flow reactor. Measurements were also realized at 25 deg. C with the stationary pH method [1] to confirm data from literature [2,3]. Pure bunsenite powder (Alfa Aesar Puratronic, Lot No. 23430) was used for dissolution rate measurements, after being calcinated for 2*20 h at 1000 deg. C in air. To avoid plug up of the outlet filter by fine particles, the powder was not directly introduced in the titanium reactor but in a specific designed cell with walls made of a porous membrane. Bunsenite dissolution rates far from equilibrium at 25 deg. C are equal to 1.0 ± 0.3.10-10, 2.4 ± 0.6.10-11 and 2.0 ± 0.7.10-11 mol.m2.s-1 at pH 3, 4.5 and 5, respectively. Apparent activation energies for the dissolution reaction (25-130 deg. C) are equal to 56.1 ± 3.7 kJ/mol, 32.9 ± 1.7 and 27.6 ± 1.1 kJ/mol at pH 3, 4.5 and 5, respectively. [1] Westrich H. et al (1992) Am. J. Sci. 293, 869-893. [2] Ludwig C. and Casey W. (1996) J. Colloid Interface Sci. 178, 176-185. [3] Pichugina et al. (2002) Theoretical Foundations of Chem. Eng. 36, 485-494 (authors)

  11. Comparison of gas chromatography-combustion-mass spectrometry and gas chromatography-flame ionization detector for the determination of fatty acid methyl esters in biodiesel without specific standards.

    Science.gov (United States)

    Sobrado, Laura Alonso; Freije-Carrelo, Laura; Moldovan, Mariella; Encinar, Jorge Ruiz; Alonso, J Ignacio García

    2016-07-29

    GC-FID has been effectively used as a universal quantification technique for volatile organic compounds for a long time. In most cases, the use of the ECN allows for quantification by GC-FID without external calibration using only the response of a single internal standard. In this paper we compare the performance characteristics of GC-FID with those of post-column (13)C Isotope Dilution GC-Combustion-MS for the absolute quantification of organic compounds without the need for individual standards. For this comparison we have selected the quantification of FAMEs in biodiesel. The selection of the right internal standard was critical for GC-FID even when ECN were considered. On the other hand, the nature of the internal standard was not relevant when GC-Combustion-MS was employed. The proposed method was validated with the analysis of the certified reference material SRM 2772 and comparative data was obtained on real biodiesel samples. The analysis of the SRM 2772 biodiesel provided recoveries in the range 100.6-103.5% and 96.4-103.6% for GC-combustion-MS and GC-FID, respectively. The detection limit for GC-combustion-MS was found to be 4.2ng compound/g of injected sample. In conclusion, the quantitative performance of GC-Combustion-MS compared satisfactorily with that of GC-FID constituting a viable alternative for the quantification of organic compounds without the need for individual standards. PMID:27371016

  12. Calcite growth-rate inhibition by fulvic acid and magnesium ion—Possible influence on biogenic calcite formation

    Science.gov (United States)

    Reddy, Michael M.

    2012-01-01

    Increases in ocean surface water dissolved carbon dioxide (CO2) concentrations retard biocalcification by reducing calcite supersaturation (Ωc). Reduced calcification rates may influence growth-rate dependent magnesium ion (Mg) incorporation into biogenic calcite modifying the use of calcifying organisms as paleoclimate proxies. Fulvic acid (FA) at biocalcification sites may further reduce calcification rates. Calcite growth-rate inhibition by FA and Mg, two common constituents of seawater and soil water involved in the formation of biogenic calcite, was measured separately and in combination under identical, highly reproducible experimental conditions. Calcite growth rates (pH=8.5 and Ωc=4.5) are reduced by FA (0.5 mg/L) to 47% and by Mg (10−4 M) to 38%, compared to control experiments containing no added growth-rate inhibitor. Humic acid (HA) is twice as effective a calcite growth-rate inhibitor as FA. Calcite growth rate in the presence of both FA (0.5 mg/L) and Mg (10−4 M) is reduced to 5% of the control rate. Mg inhibits calcite growth rates by substitution for calcium ion at the growth site. In contrast, FA inhibits calcite growth rates by binding multiple carboxylate groups on the calcite surface. FA and Mg together have an increased affinity for the calcite growth sites reducing calcite growth rates.

  13. Investigation of the effects of renewable diesel fuels on engine performance, combustion, and emissions

    KAUST Repository

    Ogunkoya, Dolanimi

    2015-01-01

    A study was undertaken to investigate renewable fuels in a compression-ignition internal combustion engine. The focus of this study was the effect of newly developed renewable fuels on engine performance, combustion, and emissions. Eight fuels were investigated, and they include diesel, jet fuel, a traditional biodiesel (fatty acid methyl ester: FAME), and five next generation biofuels. These five fuels were derived using a two-step process: hydrolysis of the oil into fatty acids (if necessary) and then a thermo-catalytic process to remove the oxygen via a decarboxylation reaction. The fuels included a fed batch deoxygenation of canola derived fatty acids (DCFA), a fed batch deoxygenation of canola derived fatty acids with varying amounts of H2 used during the deoxygenation process (DCFAH), a continuous deoxygenation of canola derived fatty acids (CDCFA), fed batch deoxygenation of lauric acid (DLA), and a third reaction to isomerize the products of the deoxygenated canola derived fatty acid alkanes (IPCF). Diesel, jet fuel, and biodiesel (FAME) have been used as benchmarks for comparing with the newer renewable fuels. The results of the experiments show slightly lower mechanical efficiency but better brake specific fuel consumption for the new renewable fuels. Results from combustion show shorter ignition delays for most of the renewable (deoxygenated) fuels with the exception of fed batch deoxygenation of lauric acid. Combustion results also show lower peak in-cylinder pressures, reduced rate of increase in cylinder pressure, and lower heat release rates for the renewable fuels. Emission results show an increase in hydrocarbon emissions for renewable deoxygenated fuels, but a general decrease in all other emissions including NOx, greenhouse gases, and soot. Results also demonstrate that isomers of the alkanes resulting from the deoxygenation of the canola derived fatty acids could be a potential replacement to conventional fossil diesel and biodiesel based on the

  14. The Effect of Fuel Grain Size on the Combustion Characteristics in the Primary Combustion Chamber of Staged Combustion Hybrid Rocket

    Science.gov (United States)

    Nagata, Harunori; Hashiba, Kenta; Sakai, Hiroya; Totani, Tsuyoshi; Wakita, Masashi

    To clarify the fuel gasification characteristics in a primary combustion chamber of a staged combustion hybrid rocket, the effect of fuel grain size on the regression rate of a grain was investigated experimentally. The grain size distribution in the combustion region achieved a steady state in 30 seconds burning duration. Examining fuel size distributions and fuel consumption rate at steady states, we obtained a history of fuel size and the regression rate of a grain in the combustion region. Regression rate increases with decreasing grain size. With a constant oxidizer flow rate, the regression rate is a function of grain size and independent to the initial grain size. After an initial transient the grain size decreases following the classical d-square law in droplet combustion: The square of the grain size decreases linearly with time. Although why the regression history of a grain in the combustion region follows the d-square law is not clear, this result is useful to estimate the fuel gasification rate of a staged combustion hybrid rocket.

  15. Salinity and Salicylic Acid Interactions in Affecting Nitrogen Assimilation, Enzyme Activity, Ions Content and Translocation Rate of Maize Plants

    International Nuclear Information System (INIS)

    This study was carried out to establish the relationship between nitrogen metabolism, enzyme activity, ions concentration as well as the translocation rate (TR) of carbohydrates and salicylic acid (SA) in salt-stressed maize (Zea mays L). Salicylic acid plus salinity treatment highly significantly increased: nucleic acids (DNA and RNA), protein content, phosphoenolpyruvate carboxylase (PEPCase) and nitrate reductase (NR) and inhibited nucleases (DNase and RNase) activities compared with Na CI-treated plants. In addition, the ionic levels of potassium (K), phosphorus (P), nitrate (NO3) and the translocation rate of the labelled photo assimilates have also been stimulated while sodium (Na) ions content was decreased. It is concluded that, salinazid maize plants might show an enhancement in their growth pattern upon salicylic acid application

  16. How and why electrostatic charge of combustible nanoparticles can radically change the mechanism and rate of their oxidation in humid atmosphere

    CERN Document Server

    Meshcheryakov, Oleg

    2010-01-01

    Electrostatically charged aerosol nanoparticles strongly attract surrounding polar gas molecules due to a charge-dipole interaction. In humid air, the substantial electrostatic attraction and acceleration of surrounding water vapour molecules towards charged combustible nanoparticles cause intense electrostatic hydration and preferential oxidation of these nanoparticles by accelerated water vapor molecules rather than non-polar oxygen molecules. In particular, electrostatic acceleration, acquired by surrounding water vapour molecules at a distance of their mean free path from the minimally charged iron metal nanoparticle can increase an oxidative activity of these polar molecules with respect to the nanoparticle by a factor of one million. Intense electrostatic hydration of charged metal nanoparticles converts the nanoparticle's oxide based shells into the hydroxide based electrolyte shells, transforming these nanoparticles into metal/air core-shell nanobatteries, periodically short-circuited by intra-particl...

  17. Development of a carbonate absorption-based process for post-combustion CO2 capture: The role of biocatalyst to promote CO2 absorption rate

    Science.gov (United States)

    Lu, Y.; Ye, X.; Zhang, Z.; Khodayari, A.; Djukadi, T.

    2011-01-01

    An Integrated Vacuum Carbonate Absorption Process (IVCAP) for post-combustion carbon dioxide (CO2) capture is described. IVCAP employs potassium carbonate (PC) as a solvent, uses waste or low quality steam from the power plant for CO2 stripping, and employs a biocatalyst, carbonic anhydrase (CA) enzyme, for promoting the CO2 absorption into PC solution. A series of experiments were performed to evaluate the activity of CA enzyme mixed in PC solutions in a stirred tank reactor system under various temperatures, CA dosages, CO2 loadings, CO2 partial pressures, and the presence of major flue gas contaminants. It was demonstrated that CA enzyme is an effective biocatalyst for CO2 absorption under IVCAP conditions. ?? 2011 Published by Elsevier Ltd.

  18. Interaction of hydrated electron with dietary flavonoids and phenolic acids. Rate constants and transient spectra studied by pulse radiolysis

    International Nuclear Information System (INIS)

    The reaction rate constants and transient spectra of 11 flavonoids and 4 phenolic acids reacting with eaq- at neutral pH were measured. The results suggest that C4 keto group is the active site for eaq- to attack on flavonoids and phenolic acids, while the o-dihydroxy structure in B-ring, the C2,3 double bond, the C3-OH group and glycosylation have little effects on the eaq- scavenging activities. (author)

  19. Smoldering Combustion Experiments in Microgravity

    Science.gov (United States)

    Walther, David C.; Fernandez-Pello, A. Carlos; Urban, David L.

    1997-01-01

    The Microgravity Smoldering Combustion (MSC) experiment is part of a study of the smolder characteristics of porous combustible materials in a microgravity environment. Smoldering is a non-flaming form of combustion that takes place in the interior of porous materials and takes place in a number of processes ranging from smoldering of porous insulation materials to high temperature synthesis of metals. The objective of the study is to provide a better understanding of the controlling mechanisms of smolder, both in microgravity and normal-gravity. As with many forms of combustion, gravity affects the availability of oxidizer and transport of heat, and therefore the rate of combustion. Microgravity smolder experiments, in both a quiescent oxidizing environment, and in a forced oxidizing flow have been conducted aboard the NASA Space Shuttle (STS-69 and STS-77 missions) to determine the effect of the ambient oxygen concentration and oxidizer forced flow velocity on smolder combustion in microgravity. The experimental apparatus is contained within the NASA Get Away Special Canister (GAS-CAN) Payload. These two sets of experiments investigate the propagation of smolder along the polyurethane foam sample under both diffusion driven and forced flow driven smoldering. The results of the microgravity experiments are compared with identical ones carried out in normal gravity, and are used to verify present theories of smolder combustion. The results of this study will provide new insights into the smoldering combustion process. Thermocouple histories show that the microgravity smolder reaction temperatures (Ts) and propagation velocities (Us) lie between those of identical normal-gravity upward and downward tests. These observations indicate the effect of buoyancy on the transport of oxidizer to the reaction front.

  20. Effect of flaxseed supplementation rate and processing on the production, fatty acid profile, and texture of milk, butter, and cheese.

    Science.gov (United States)

    Oeffner, S P; Qu, Y; Just, J; Quezada, N; Ramsing, E; Keller, M; Cherian, G; Goddick, L; Bobe, G

    2013-02-01

    Health and nutrition professionals advise consumers to limit consumption of saturated fatty acids and increase the consumption of foods rich in n-3 fatty acids. Researchers have previously reported that feeding extruded flaxseed, which is high in C18:3n-3, improves the fatty acid profile of milk and dairy products to less saturated fatty acids and to more C18:3n-3. Fat concentrations in milk and butter decreased when cows were fed higher concentrations of extruded flaxseed. The objective of this study was to determine the optimal rate of flaxseed supplementation for improving the fatty acid profile without decreasing production characteristics of milk and dairy products. By using a double 5 × 5 Latin square design, 10 mid- to late-lactation Holstein cows were fed extruded (0, 0.91, 1.81, and 2.72 kg/d) and ground (1.81 kg/d) flaxseed as a top dressing for 2-wk periods each. At the end of each 2-wk treatment period, milk and serum samples were taken. Milk was subsequently manufactured into butter and fresh Mozzarella cheese. Increasing supplementation rates of extruded flaxseed improved the fatty acid profile of milk, butter, and cheese gradually to less saturated and atherogenic fatty acids and to more C18:3n-3 by increasing concentrations of C18:3n-3 in serum. The less saturated fatty acid profile was associated with decreased hardness and adhesiveness of refrigerated butter, which likely cause improved spreadability. Supplementation rates of extruded flaxseed did not affect dry matter intake of the total mixed ration, milk composition, and production of milk, butter, or cheese. Flaxseed processing did not affect production, fatty acid profile of milk, or texture of butter and cheese. Feeding up to 2.72 kg/d of extruded flaxseed to mid- to late-lactation Holstein cows may improve nutritional and functional properties of milk fat without compromising production parameters.

  1. Solid waste combustion for alpha waste incineration

    International Nuclear Information System (INIS)

    Radioactive waste incinerator development at the Savannah River Laboratory has been augmented by fundamental combustion studies at the University of South Carolina. The objective was to measure and model pyrolysis and combustion rates of typical Savannah River Plant waste materials as a function of incinerator operating conditions. The analytical models developed in this work have been incorporated into a waste burning transient code. The code predicts maximum air requirement and heat energy release as a function of waste type, package size, combustion chamber size, and temperature. Historically, relationships have been determined by direct experiments that did not allow an engineering basis for predicting combustion rates in untested incinerators. The computed combustion rates and burning times agree with measured values in the Savannah River Laboratory pilot (1 lb/hr) and full-scale (12 lb/hr) alpha incinerators for a wide variety of typical waste materials

  2. Combustion of Pure, Hydrolyzed and Methyl Ester Formed of Jatropha Curcas Lin oil

    Directory of Open Access Journals (Sweden)

    Muhaji Muhaji

    2015-10-01

    Full Text Available The density and viscosity of vegetable oil are higher than that of diesel oil. Thus its direct combustion in the diesel engine results many problems. This research was conducted to investigate the flame characteristics of combustion of jatropha curcas lin in pure, hydrolyzed and methyl ester form. The results indicated that the combustion of pure jatropha curcas lin occurs in three stages, hydrolyzed in two stages    and methyl ester in one stage. For pure jatropha curcas lin, in the first stage, unsaturated fatty acid burned for  0.265 s.  It is followed by saturated fatty acid, burned for 0.389 s in the second stage. And, in the last stage is the burned of glycerol for 0.560 s. Meanwhile for hydrolyzed one, in the first stage, unsaturated fatty acid burned for 0.736 s, followed by saturated fatty acid, burned  for 0.326 s in the second stage. And the last, for methyl ester is the burned for 0.712 s. The highest burning rate was for methyl ester which was 0.003931cc/s. The energy releasing rate of methyl ester, which was for 13,628.67 kcal/(kg.s resembled that of diesel oil the most, while the lowest rate was for pure jatropha curcas lin which was 8,200.94 kcal/(kg.s. In addition, massive explosion occurred in the fuel containing unsaturated fatty acid and glycerol

  3. Association between serum uric acid and different states of glucose metabolism and glomerular filtration rate

    Institute of Scientific and Technical Information of China (English)

    CAI Xiao-ling; HAN Xue-yao; JI Li-nong

    2010-01-01

    Background Recently, it has been suggested that the serum uric acid (SUA) level decreased in diabetic patients. The aim of this study was to explore the association between SUA level and different state of glucose metabolism and glomerular filtration rate (GFR) reflected by the simplified Modification of Diet in Renal Disease (MDRD) equation and to test the hypothesis that high MDRD is one of the determinants of SUA level.Methods This cross-sectional study included 2373 subjects in Beijing who underwent a 75 g oral glucose tolerance test (OGTT) for screening of diabetes. According to the states of glucose metabolism, they were divided into normal glucose tolerance, impaired glucose regulation and diabetes.Results Multiple stepwise linear regression analysis showed that adjusted by gender, SUA was positively correlated with body mass index (BMI), waist/hippo ratio, systolic blood pressure (SBP) and triglyceride, meanwhile negatively correlated with age, hemoglobin A1c, fasting insulin and MDRD. There was an increasing trend in SUA concentration and a decreasing trend in MDRD when the levels of fasting plasma glucose (FPG) increased from low to high up to the FPG level of 8.0 mmol/L; thereafter, the SUA concentration started to decrease with further increases in FPG levels, and the MDRD started to increase with further increases in FPG levels.Conclusion This study confirmed the previous finding that SUA decreased in diabetes and provided the supporting evidence that the increased MDRD might contribute to the fall of SUA.

  4. Effect of Dietary Omega-3 Polyunsaturated Fatty Acids on Heart Rate and Heart Rate Variability in Animals Susceptible or Resistant to Ventricular Fibrillation

    OpenAIRE

    George E Billman

    2012-01-01

    The consumption of omega-3 polyunsaturated fatty acids (n−3 PUFAs) has been reported to reduce cardiac mortality following myocardial infarction as well as to decrease resting heart rate (HR) and increase HR variability (HRV). However, it has not been established whether n−3 PUFAs exhibit the same actions on HR and HRV in individuals known to be either susceptible or resistant to ventricular fibrillation (VF). Therefore, HR and HRV (high frequency and total R–R interval variability) were eval...

  5. Structural calibration of the rates of amino acid evolution in a search for Darwin in drifting biological systems.

    Science.gov (United States)

    Toft, Christina; Fares, Mario A

    2010-10-01

    In the last two decades, many reports of proteins under positive selection have brought the neutral theory into question. However, the methods used to detect selection have ignored the evolvability of amino acids within proteins, which is fundamental to distinguishing positive selection from the relaxed constraints caused by genetic drift. Disentangling these two counterbalancing forces is essential to test the neutral theory. Here, we calibrate rates of amino acid divergence by using structural information from the full set of crystallized proteins in bacteria. In agreement with previous reports, we show that rates of amino acid evolution correlate negatively with the number of per-amino acid atomic interactions. Calibration of the rates of evolution allows identifying signatures of selection in biological systems that evolve under strong genetic drift, such as endosymbiotic bacteria. Application of this method identifies different rates and dynamics of evolution for highly connected amino acids in the structure compared with sparsely connected ones. We also unearth patterns of Darwinian selection in fundamental cellular proteins in endosymbiotic bacteria including the cochaperonin GroES, ribosomal proteins, proteins involved in cell cycle control, DNA-binding proteins, and proteins involved in DNA replication and repair. This is, to our knowledge, the first attempt to distinguish adaptive evolution from relaxed constraints in biological systems under genetic drift.

  6. Correlating multidimensional fetal heart rate variability analysis with acid-base balance at birth

    International Nuclear Information System (INIS)

    Fetal monitoring during labour currently fails to accurately detect acidemia. We developed a method to assess the multidimensional properties of fetal heart rate variability (fHRV) from trans-abdominal fetal electrocardiogram (fECG) during labour. We aimed to assess this novel bioinformatics approach for correlation between fHRV and neonatal pH or base excess (BE) at birth. We enrolled a prospective pilot cohort of uncomplicated singleton pregnancies at 38–42 weeks’ gestation in Milan, Italy, and Liverpool, UK. Fetal monitoring was performed by standard cardiotocography. Simultaneously, with fECG (high sampling frequency) was recorded. To ensure clinician blinding, fECG information was not displayed. Data from the last 60 min preceding onset of second-stage labour were analyzed using clinically validated continuous individualized multiorgan variability analysis (CIMVA) software in 5 min overlapping windows. CIMVA allows simultaneous calculation of 101 fHRV measures across five fHRV signal analysis domains. We validated our mathematical prediction model internally with 80:20 cross-validation split, comparing results to cord pH and BE at birth. The cohort consisted of 60 women with neonatal pH values at birth ranging from 7.44 to 6.99 and BE from −0.3 to −18.7 mmol L−1. Our model predicted pH from 30 fHRV measures (R2 = 0.90, P < 0.001) and BE from 21 fHRV measures (R2 = 0.77, P < 0.001). Novel bioinformatics approach (CIMVA) applied to fHRV derived from trans-abdominal fECG during labor correlated well with acid-base balance at birth. Further refinement and validation in larger cohorts are needed. These new measurements of fHRV might offer a new opportunity to predict fetal acid-base balance at birth. (fast track communication)

  7. Oxygen-enhanced combustion

    CERN Document Server

    Baukal, Charles E

    2013-01-01

    Combustion technology has traditionally been dominated by air/fuel combustion. However, two developments have increased the significance of oxygen-enhanced combustion-new technologies that produce oxygen less expensively and the increased importance of environmental regulations. Advantages of oxygen-enhanced combustion include less pollutant emissions as well as increased energy efficiency and productivity. Oxygen-Enhanced Combustion, Second Edition compiles information about using oxygen to enhance industrial heating and melting processes. It integrates fundamental principles, applications, a

  8. Docosahexaenoic acid-rich fish oil improves heart rate variability and heart rate responses to exercise in overweight adults.

    Science.gov (United States)

    Ninio, Daniel M; Hill, Alison M; Howe, Peter R; Buckley, Jonathan D; Saint, David A

    2008-11-01

    Dietary fish oil supplementation and regular physical activity can improve outcomes in patients with established CVD. Exercise has been shown to improve heart rate variability (HRV), a predictor of cardiac death, but whether fish oil benefits HRV is controversial. Obese adults at risk of future coronary disease have impaired HRV and may benefit from these interventions. We evaluated the effect of DHA-rich tuna fish oil supplementation with and without regular exercise on HRV in sedentary, overweight adults with risk factors for coronary disease. In a randomised, double-blind, parallel comparison, sixty-five volunteers consumed 6 g fish oil/d (DHA 1.56 g/d, EPA 0.36 g/d) or sunflower-seed oil (placebo) for 12 weeks. Half of each oil group also undertook regular moderate physical activity (3 d/week for 45 min, at 75 % of age-predicted maximal heart rate (HR)). Resting HR and the HR response to submaximal exercise were measured at weeks 0, 6 and 12. In forty-six subjects, HRV was also assessed by power spectrum analysis of 20 min electrocardiogram recordings taken supine at baseline and 12 weeks. Fish oil supplementation improved HRV by increasing high-frequency power, representing parasympathetic activity, compared with placebo (P = 0.01; oil x time interaction). It also reduced HR at rest and during submaximal exercise (P = 0.008; oil x time interaction). There were no significant fish oil x exercise interactions. Dietary supplementation with DHA-rich fish oil reduced HR and modulated HRV in keeping with an improved parasympathetic-sympathetic balance in overweight adults with risk factors for future coronary disease. PMID:18339222

  9. Correlating multidimensional fetal heart rate variability analysis with acid-base balance at birth.

    Science.gov (United States)

    Frasch, Martin G; Xu, Yawen; Stampalija, Tamara; Durosier, Lucien D; Herry, Christophe; Wang, Xiaogang; Casati, Daniela; Seely, Andrew Je; Alfirevic, Zarko; Gao, Xin; Ferrazzi, Enrico

    2014-12-01

    Fetal monitoring during labour currently fails to accurately detect acidemia. We developed a method to assess the multidimensional properties of fetal heart rate variability (fHRV) from trans-abdominal fetal electrocardiogram (fECG) during labour. We aimed to assess this novel bioinformatics approach for correlation between fHRV and neonatal pH or base excess (BE) at birth.We enrolled a prospective pilot cohort of uncomplicated singleton pregnancies at 38-42 weeks' gestation in Milan, Italy, and Liverpool, UK. Fetal monitoring was performed by standard cardiotocography. Simultaneously, with fECG (high sampling frequency) was recorded. To ensure clinician blinding, fECG information was not displayed. Data from the last 60 min preceding onset of second-stage labour were analyzed using clinically validated continuous individualized multiorgan variability analysis (CIMVA) software in 5 min overlapping windows. CIMVA allows simultaneous calculation of 101 fHRV measures across five fHRV signal analysis domains. We validated our mathematical prediction model internally with 80:20 cross-validation split, comparing results to cord pH and BE at birth.The cohort consisted of 60 women with neonatal pH values at birth ranging from 7.44 to 6.99 and BE from -0.3 to -18.7 mmol L(-1). Our model predicted pH from 30 fHRV measures (R(2) = 0.90, P base balance at birth. Further refinement and validation in larger cohorts are needed. These new measurements of fHRV might offer a new opportunity to predict fetal acid-base balance at birth. PMID:25407948

  10. Domain-confined catalytic soot combustion over Co3O4 anchored on a TiO2 nanotube array catalyst prepared by mercaptoacetic acid induced surface-grafting

    Science.gov (United States)

    Ren, Jiale; Yu, Yifu; Dai, Fangfang; Meng, Ming; Zhang, Jing; Zheng, Lirong; Hu, Tiandou

    2013-11-01

    Herein, we introduce a specially designed domain-confined macroporous catalyst, namely, the Co3O4 nanocrystals anchored on a TiO2 nanotube array catalyst, which was synthesized by using the mercaptoacetic acid induced surface-grafting method. This catalyst exhibits much better performance for catalytic soot combustion than the conventional TiO2 powder supported one in gravitational contact mode (GMC).Herein, we introduce a specially designed domain-confined macroporous catalyst, namely, the Co3O4 nanocrystals anchored on a TiO2 nanotube array catalyst, which was synthesized by using the mercaptoacetic acid induced surface-grafting method. This catalyst exhibits much better performance for catalytic soot combustion than the conventional TiO2 powder supported one in gravitational contact mode (GMC). Electronic supplementary information (ESI) available: The images of XRD, UV-vis, EDX and soot-TPR. The table providing information on Co/Ti-NA catalysts. See DOI: 10.1039/c3nr03757f

  11. Combustion 2000

    Energy Technology Data Exchange (ETDEWEB)

    A. Levasseur; S. Goodstine; J. Ruby; M. Nawaz; C. Senior; F. Robson; S. Lehman; W. Blecher; W. Fugard; A. Rao; A. Sarofim; P. Smith; D. Pershing; E. Eddings; M. Cremer; J. Hurley; G. Weber; M. Jones; M. Collings; D. Hajicek; A. Henderson; P. Klevan; D. Seery; B. Knight; R. Lessard; J. Sangiovanni; A. Dennis; C. Bird; W. Sutton; N. Bornstein; F. Cogswell; C. Randino; S. Gale; Mike Heap

    2001-06-30

    . To achieve these objectives requires a change from complete reliance of coal-fired systems on steam turbines (Rankine cycles) and moving forward to a combined cycle utilizing gas turbines (Brayton cycles) which offer the possibility of significantly greater efficiency. This is because gas turbine cycles operate at temperatures well beyond current steam cycles, allowing the working fluid (air) temperature to more closely approach that of the major energy source, the combustion of coal. In fact, a good figure of merit for a HIPPS design is just how much of the enthalpy from coal combustion is used by the gas turbine. The efficiency of a power cycle varies directly with the temperature of the working fluid and for contemporary gas turbines the optimal turbine inlet temperature is in the range of 2300-2500 F (1260-1371 C). These temperatures are beyond the working range of currently available alloys and are also in the range of the ash fusion temperature of most coals. These two sets of physical properties combine to produce the major engineering challenges for a HIPPS design. The UTRC team developed a design hierarchy to impose more rigor in our approach. Once the size of the plant had been determined by the choice of gas turbine and the matching steam turbine, the design process of the High Temperature Advanced Furnace (HITAF) moved ineluctably to a down-fired, slagging configuration. This design was based on two air heaters: one a high temperature slagging Radiative Air Heater (RAH) and a lower temperature, dry ash Convective Air Heater (CAH). The specific details of the air heaters are arrived at by an iterative sequence in the following order:-Starting from the overall Cycle requirements which set the limits for the combustion and heat transfer analysis-The available enthalpy determined the range of materials, ceramics or alloys, which could tolerate the temperatures-Structural Analysis of the designs proved to be the major limitation-Finally the commercialization

  12. Combustion 2000

    Energy Technology Data Exchange (ETDEWEB)

    A. Levasseur; S. Goodstine; J. Ruby; M. Nawaz; C. Senior; F. Robson; S. Lehman; W. Blecher; W. Fugard; A. Rao; A. Sarofim; P. Smith; D. Pershing; E. Eddings; M. Cremer; J. Hurley; G. Weber; M. Jones; M. Collings; D. Hajicek; A. Henderson; P. Klevan; D. Seery; B. Knight; R. Lessard; J. Sangiovanni; A. Dennis; C. Bird; W. Sutton; N. Bornstein; F. Cogswell; C. Randino; S. Gale; Mike Heap

    2001-06-30

    . To achieve these objectives requires a change from complete reliance of coal-fired systems on steam turbines (Rankine cycles) and moving forward to a combined cycle utilizing gas turbines (Brayton cycles) which offer the possibility of significantly greater efficiency. This is because gas turbine cycles operate at temperatures well beyond current steam cycles, allowing the working fluid (air) temperature to more closely approach that of the major energy source, the combustion of coal. In fact, a good figure of merit for a HIPPS design is just how much of the enthalpy from coal combustion is used by the gas turbine. The efficiency of a power cycle varies directly with the temperature of the working fluid and for contemporary gas turbines the optimal turbine inlet temperature is in the range of 2300-2500 F (1260-1371 C). These temperatures are beyond the working range of currently available alloys and are also in the range of the ash fusion temperature of most coals. These two sets of physical properties combine to produce the major engineering challenges for a HIPPS design. The UTRC team developed a design hierarchy to impose more rigor in our approach. Once the size of the plant had been determined by the choice of gas turbine and the matching steam turbine, the design process of the High Temperature Advanced Furnace (HITAF) moved ineluctably to a down-fired, slagging configuration. This design was based on two air heaters: one a high temperature slagging Radiative Air Heater (RAH) and a lower temperature, dry ash Convective Air Heater (CAH). The specific details of the air heaters are arrived at by an iterative sequence in the following order:-Starting from the overall Cycle requirements which set the limits for the combustion and heat transfer analysis-The available enthalpy determined the range of materials, ceramics or alloys, which could tolerate the temperatures-Structural Analysis of the designs proved to be the major limitation-Finally the commercialization

  13. Protein and lipid deposition rates in male broiler chickens : separate responses to amino acids and protein-free energy

    NARCIS (Netherlands)

    Eits, R.M.; Kwakkel, R.P.; Verstegen, M.W.A.; Stoutjesdijk, P.; Greef, de K.H.

    2002-01-01

    Two experiments of similar design were conducted with male broiler chickens over two body weight ranges, 200 to 800 g in Experiment 1 and 800 to 1,600 g in Experiment 2. The data were used to test the hypothesis that protein deposition rate increases (linearly) with increasing amino acid intake, unt

  14. Effect of substrate and cation requirement on anaerobic volatile fatty acid conversion rates at elevated biogas pressure

    NARCIS (Netherlands)

    Lindeboom, R.E.F.; Ferrer, I.; Weijma, J.; Lier, van J.B.

    2013-01-01

    This work studied the anaerobic conversion of neutralized volatile fatty acids (VFA) into biogas under Autogenerative High Pressure Digestion (AHPD) conditions. The effects of the operating conditions on the biogas quality, and the substrate utilisation rates were evaluated using 3 AHPD reactors (0.

  15. Study on Influence of Fuel Properties on Premixed Diesel Combustion

    OpenAIRE

    熊, 仟

    2014-01-01

    Premixed diesel combustion, as a promising combustion concept to achieve low NOx and smoke emissions as well as high thermal efficiency, is paid much attention. Sufficiently long ignition delay is required for pre-mixture preparation to avoid over-rich mixture taking part in the combustion while the maximum pressure rise rate is suppressed to a tolerance level. Therefore, the operational load range of premixed diesel combustion with diesel fuel is limited at low and medium loads by the high p...

  16. Chemical kinetics and combustion modeling

    Energy Technology Data Exchange (ETDEWEB)

    Miller, J.A. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this program is to gain qualitative insight into how pollutants are formed in combustion systems and to develop quantitative mathematical models to predict their formation rates. The approach is an integrated one, combining low-pressure flame experiments, chemical kinetics modeling, theory, and kinetics experiments to gain as clear a picture as possible of the process in question. These efforts are focused on problems involved with the nitrogen chemistry of combustion systems and on the formation of soot and PAH in flames.

  17. Fuel gas combustion research at METC

    Energy Technology Data Exchange (ETDEWEB)

    Norton, T.S.

    1995-06-01

    The in-house combustion research program at METC is an integral part of many METC activities, providing support to METC product teams, project managers, and external industrial and university partners. While the majority of in-house combustion research in recent years has been focussed on the lean premixed combustion of natural gas fuel for Advanced Turbine Systems (ATS) applications, increasing emphasis is being placed on issues of syngas combustion, as the time approaches when the ATS and coal-fired power systems programs will reach convergence. When the METC syngas generator is built in 1996, METC will have the unique combination of mid-scale pressurized experimental facilities, a continuous syngas supply with variable ammonia loading, and a team of people with expertise in low-emissions combustion, chemical kinetics, combustion modeling, combustion diagnostics, and the control of combustion instabilities. These will enable us to investigate such issues as the effects of pressure, temperature, and fuel gas composition on the rate of conversion of fuel nitrogen to NOx, and on combustion instabilities in a variety of combustor designs.

  18. Combustion 2000

    Energy Technology Data Exchange (ETDEWEB)

    None

    2000-06-30

    This report presents work carried out under contract DE-AC22-95PC95144 ''Combustion 2000 - Phase II.'' The goals of the program are to develop a coal-fired high performance power generation system (HIPPS) that is capable of: {lg_bullet} thermal efficiency (HHV) {ge} 47% {lg_bullet} NOx, SOx, and particulates {le} 10% NSPS (New Source Performance Standard) {lg_bullet} coal providing {ge} 65% of heat input {lg_bullet} all solid wastes benign {lg_bullet} cost of electricity {le} 90% of present plants Phase I, which began in 1992, focused on the analysis of various configurations of indirectly fired cycles and on technical assessments of alternative plant subsystems and components, including performance requirements, developmental status, design options, complexity and reliability, and capital and operating costs. Phase I also included preliminary R&D and the preparation of designs for HIPPS commercial plants approximately 300 MWe in size. Phase II, had as its initial objective the development of a complete design base for the construction and operation of a HIPPS prototype plant to be constructed in Phase III. As part of a descoping initiative, the Phase III program has been eliminated and work related to the commercial plant design has been ended. The rescoped program retained a program of engineering research and development focusing on high temperature heat exchangers, e.g. HITAF development (Task 2); a rescoped Task 6 that is pertinent to Vision 21 objectives and focuses on advanced cycle analysis and optimization, integration of gas turbines into complex cycles, and repowering designs; and preparation of the Phase II Technical Report (Task 8). This rescoped program deleted all subsystem testing (Tasks 3, 4, and 5) and the development of a site specific engineering design and test plan for the HIPPS prototype plant (Task 7). Work reported herein is from: {lg_bullet} Task 2.2.4 Pilot Scale Testing {lg_bullet} Task 2.2.5.2 Laboratory and Bench

  19. Effect of feeding diet containing protected protein on volatile fatty acids production rate and passage rate of digesta in crossbred cattle

    International Nuclear Information System (INIS)

    Twelve crossbred rumen fistulated male cattle were divided into 3 groups (A,B and C). All the animals were fed concentrate mixture according to their requirement and wheat straw ad lib. However, ground nut cake (GNC) of concentrate mixture in group A (0 per cent), B (50 per cent) and C (100 per cent) were treated with formaldehyde. Dry matter intake and digestibility of proximate principles and fibre were similar in 3 groups. TVFA (total volatile fatty acids) content in rumen fluid was 8.92 ± 0.31, 8.87 ± 0.06 and 9.40 ± 0.48 m mol/100 SRL (P > 0.05) in groups A, B and C, respectively. Molar percentage of acetate and propionate were not affected by treatment. On the other hand, molar percentage of butyrate was significantly lower in group C. Production rate of volatile fatty acids was 10.48 ± 0.57, 9.70 ± 0.51 and 9.19 ± 0.35 mol/day (P > 0.05) in groups A, B and C, respectively. While flow rate of liquid digesta was significantly lower in group B and C than in group A, passage rate of solid digesta was not affected due to protected protein in diet. However, passage rate of solid digesta as per cent of total DM in rumen at zero hour was significantly higher in animals fed protected protein. Thus, the incorporation of formaldehyde treated protein in diet decreased the VFA production and outflow of liquid digesta but did not affect (P > 0.05) the passage rate of solid digesta and digestibility coefficients of various nutrients. (author). 28 refs., 2 tabs., 2 figs

  20. HCCI Combustion: Analysis and Experiments

    International Nuclear Information System (INIS)

    Homogeneous charge compression ignition (HCCI) is a new combustion technology that may develop as an alternative to diesel engines with high efficiency and low NOx and particulate matter emissions. This paper describes the HCCI research activities being currently pursued at Lawrence Livermore National Laboratory and at the University of California Berkeley. Current activities include analysis as well as experimental work. On analysis, we have developed two powerful tools: a single zone model and a multi-zone model. The single zone model has proven very successful in predicting start of combustion and providing reasonable estimates for peak cylinder pressure, indicated efficiency and NOX emissions. This model is being applied to develop detailed engine performance maps and control strategies, and to analyze the problem of engine startability. The multi-zone model is capable of very accurate predictions of the combustion process, including HC and CO emissions. The multi-zone model h as applicability to the optimization of combustion chamber geometry and operating conditions to achieve controlled combustion at high efficiency and low emissions. On experimental work, we have done a thorough evaluation of operating conditions in a 4-cylinder Volkswagen TDI engine. The engine has been operated over a wide range of conditions by adjusting the intake temperature and the fuel flow rate. Satisfactory operation has been obtained over a wide range of operating conditions. Cylinder-to-cylinder variations play an important role in limiting maximum power, and should be controlled to achieve satisfactory performance

  1. Interaction of hydrated electron with dietary flavonoids and phenolic acids. Rate constants and transient spectra studied by pulse radiolysis

    Energy Technology Data Exchange (ETDEWEB)

    Cai, Zhongli; Li, Xifeng; Katsumura, Yosuke [Tokyo Univ., Tokai, Ibaraki (Japan). Nuclear Engineering Research Lab

    2000-03-01

    The reaction rate constants and transient spectra of 11 flavonoids and 4 phenolic acids reacting with e{sub aq}{sup -} at neutral pH were measured. The results suggest that C{sub 4} keto group is the active site for e{sub aq}{sup -} to attack on flavonoids and phenolic acids, while the o-dihydroxy structure in B-ring, the C{sub 2,3} double bond, the C{sub 3}-OH group and glycosylation have little effects on the e{sub aq}{sup -} scavenging activities. (author)

  2. Fatty Acid Composition and Hedonic Ratings of Meat from Light Lambs of Leccese Breed in Relation to Slaughter Age

    Directory of Open Access Journals (Sweden)

    Angela Gabriella D’Alessandro

    2016-01-01

    Full Text Available Twenty lambs from Leccese local breed were used to investigate the effect of two slaughter ages (45 vs 60 d on fatty acid composition and hedonic ratings of meat. The lambs, born as singles in spring, were subdivided into two groups (n. 10 corresponding to the slaughter ages of 45 and 60 d. The animals received their mother’s milk and a supplementation of hay and concentrate from 30 d to slaughter. The increase to 60 d of slaughter age resulted in higher proportion of lauric acid (C12:0; P<0.05, pentadecanoic acid (C15:0; P<0.01 and conjugated linoleic acid (CLA; P<0.05, and lower proportion of stearic acid (C18:0; P<0.05 and linoleic acid (C20:3 n-6; P<0.05. Using a none-point hedonic scale, consumer test showed that meat from lambs slaughtered at 60 d received a higher hedonic scores (P < 0.01 as well as higher scores for tenderness (P < 0.05, flavour (P < 0.05, and juiciness (P < 0.001 than meat from lambs slaughtered at 45 d. These findings might be useful to characterise lamb meat of local origin in relation to its nutritional traits and market perspectives connected to consumer acceptability.

  3. Combustion Research Facility

    Data.gov (United States)

    Federal Laboratory Consortium — For more than 30 years The Combustion Research Facility (CRF) has served as a national and international leader in combustion science and technology. The need for a...

  4. On supersonic combustion

    Institute of Scientific and Technical Information of China (English)

    袁生学

    1999-01-01

    Some basic concepts and features of supersonic combustion are explained from the view point of macroscopic aerodynamics. Two kinds of interpretations of supersonic combustion are proposed. The difference between supersonic combustion and subsonic combustion is discussed, and the mechanism of supersonic combustion propagation and the limitation of heat addition in supersonic flow are pointed out. The results of the calculation of deflagration in supersonic flow show that the entropy increment and the total pressure loss of the combustion products may decrease with the increase of combustion velocity. It is also demonstrated that the oblique detonation wave angle may not be controlled by the wedge angle under weak underdriven solution conditions and be determined only by combustion velocity. Therefore, the weak underdriven solution may become self-sustaining oblique detonation waves with a constant wave angle.

  5. Combustion of Fractal Distributions

    OpenAIRE

    Sotolongo, Oscar; Lopez, Enrique

    1994-01-01

    The advantages of introducing a fractal viewpoint in the field of combustion is emphasized. It is shown that the condition for perfect combustion of a collection of drops is the self-similarity of the distribution.

  6. Ignition and combustion behaviour of vegetable oils after injection in a constant volume combustion chamber

    International Nuclear Information System (INIS)

    The ignition and combustion behaviour of vegetable oils to be used as fuel in combustion engines was researched using a constant volume combustion chamber. The chosen vegetable oils were characterised using the two structure indices average number of carbon atoms AC and average number of double bonds ADB. The structure indices were derived from the composition of the analysed fatty acids. The performance of these two structure indices in estimating differences in fuel properties, such as density, net calorific value, elementary composition and surface tension, was shown. The structure indices were also used to explain ignition and combustion behaviour. Differences in ignition and combustion behaviour were primarily recognised in the ignition delay and the first phase of combustion (premixed combustion). No differences were observed between the vegetable oils in subsequent phases of combustion. The longer the ignition delay, the higher the share was of premixed combustion. Models for the prediction of the ignition delay were developed using ADB. The ignition delay rises with increasing ADB. Differences in AC had no significant impact on the ignition delay. Hence, vegetable oils with a high ignition quality are characterised by a low amount of double bonds. The developed models can be used for estimation of the ignition quality and combustion behaviour of unknown vegetable oils. - Highlights: • Ten vegetable oils and two vegetable oil mixtures were tested. • Two suitable structure indices were developed from the fatty acid composition to predict fuel properties. • Differences were detected in the ignition behaviour and in the first combustion phase. • Vegetable oils with short ignition delay are characterised by a low number of double bonds

  7. 气相色谱-燃烧-同位素比值质谱法测定单体氨基酸的碳稳定同位素组成%Analysis of Stable Carbon Isotope Composition of Individual N-Trifluoroacetyl-Isopropyl Amino Acid Esters by Gas Chromatography-Combustion-Isotope Ratio Mass Spectrometry

    Institute of Scientific and Technical Information of China (English)

    蔡德陵; 刘金钟; 刘海珍

    2004-01-01

    A combined gas chromatography combustion-isotope ratio mass spectrometry method(GC-C IRMS) for stable carbon isotope analysis of amino acids is presented. Unlike hydrocarbons, amino acids require derivatization prior to GC-C-IRMS analysis. Replicate carbon isotope analyses of trifluoroacetyl isopropyl ester derivatives of 17 amino acids by IRMS revealed that the derivatization process is reproducible. Due to a reproducible isotopic fractionation an empirical correction factor for each individual amino acid is derived separately for derivatives and the original δ13C value of the underivatized amino acid is calculated.

  8. AN ANALYSIS OF PETROL - COMPRESSED AIR POWERED INTERNAL COMBUSTION ENGINE: A HYBRID ENGINE CONCEPT

    OpenAIRE

    Lalit Kumar*, Dharmendra Patel, Vinod Sehrawat, Tarun Gupta

    2016-01-01

    Nowadays environment pollution becomes a much serious issue in the world. Vehicles’ exhaust product is one of the major source of environmental pollution. The engine combustion products are causing the greenhouse effect, acid rains, ozone layer depletion and some other pollution. On the other hand, many study research on fossil fuel in the previous years, observed that if the oil is consumed at this rates, 81% of the entire available resource will be consumed very soon. So now we begin ...

  9. Continuous High Rate Anaerobic Treatment of Oleic Acid Based Wastewater is Possible after a Step Feeding Start-Up

    OpenAIRE

    Cavaleiro, A. J.; Salvador, A. F.; Alves, J.I.; Alves, M. M.

    2009-01-01

    Mineralization of a synthetic effluent containing 50% COD as oleic acid was achieved in a continuous anaerobic reactor at organic loading rates up to 21 kg COD m−3 day−1, HRT of 9 h, attaining 99% of COD removal efficiency and a methane yield higher than 70%. A maximum specific methane production rate of 1170 ± 170 mg COD-CH4 g VS−1 day−1 was measured during the reactor’s operation. A start-up strategy combining feeding phases and batch degradation phases was applied to promote the developmen...

  10. Vitamin E supplementation in elderly lowers the oxidation rate of linoleic acid in LDL.

    NARCIS (Netherlands)

    Waart, de F.; Moser, U.; Kok, F.J.

    1997-01-01

    .Oxidation of LDL–linoleic acid (LDL–LA), a major substrate for lipid peroxidation, may be counteracted by the antioxidant vitamin E. In a 3-month randomized double-blind placebo-controlled trial in 83 apparently healthy Dutch elderly, aged 67–85 years, the direct protective effect of 100 IU vitamin

  11. High rate treatment of terephthalic acid production wastewater in a two-stage anaerobic bioreactor

    NARCIS (Netherlands)

    Kleerebezem, R.; Beckers, J.; Pol, L.W.H.; Lettinga, G.

    2005-01-01

    The feasibility was studied of anaerobic treatment of wastewater generated during purified terephthalic acid (PTA) production in two-stage upflow anaerobic sludge blanket (UASB) reactor system. The artificial influent of the system contained the main organic substrates of PTA-wastewater: acetate, be

  12. 3D Polyaniline Architecture by Concurrent Inorganic and Organic Acid Doping for Superior and Robust High Rate Supercapacitor Performance

    Science.gov (United States)

    Gawli, Yogesh; Banerjee, Abhik; Dhakras, Dipti; Deo, Meenal; Bulani, Dinesh; Wadgaonkar, Prakash; Shelke, Manjusha; Ogale, Satishchandra

    2016-02-01

    A good high rate supercapacitor performance requires a fine control of morphological (surface area and pore size distribution) and electrical properties of the electrode materials. Polyaniline (PANI) is an interesting material in supercapacitor context because it stores energy Faradaically. However in conventional inorganic (e.g. HCl) acid doping, the conductivity is high but the morphological features are undesirable. On the other hand, in weak organic acid (e.g. phytic acid) doping, interesting and desirable 3D connected morphological features are attained but the conductivity is poorer. Here the synergy of the positive quality factors of these two acid doping approaches is realized by concurrent and optimized strong-inorganic (HCl) and weak-organic (phytic) acid doping, resulting in a molecular composite material that renders impressive and robust supercapacitor performance. Thus, a nearly constant high specific capacitance of 350 F g-1 is realized for the optimised case of binary doping over the entire range of 1 A g-1 to 40 A g-1 with stability of 500 cycles at 40 A g-1. Frequency dependant conductivity measurements show that the optimized co-doped case is more metallic than separately doped materials. This transport property emanates from the unique 3D single molecular character of such system.

  13. Humic acids-based hierarchical porous carbons as high-rate performance electrodes for symmetric supercapacitors.

    Science.gov (United States)

    Qiao, Zhi-jun; Chen, Ming-ming; Wang, Cheng-yang; Yuan, Yun-cai

    2014-07-01

    Two kinds of hierarchical porous carbons (HPCs) with specific surface areas of 2000 m(2)g(-1) were synthesized using leonardite humic acids (LHA) or biotechnology humic acids (BHA) precursors via a KOH activation process. Humic acids have a high content of oxygen-containing groups which enabled them to dissolve in aqueous KOH and facilitated the homogeneous KOH activation. The LHA-based HPC is made up of abundant micro-, meso-, and macropores and in 6M KOH it has a specific capacitance of 178 F g(-1) at 100 Ag(-1) and its capacitance retention on going from 0.05 to 100 A g(-1) is 64%. In contrast, the BHA-based HPC exhibits a lower capacitance retention of 54% and a specific capacitance of 157 F g(-1) at 100 A g(-1) which is due to the excessive micropores in the BHA-HPC. Moreover, LHA-HPC is produced in a higher yield than BHA-HPC (51 vs. 17 wt%). PMID:24851713

  14. Dynamic Combustion Stability Rating of LOX/LH2 Rocket Engine%氢氧火箭发动机动态燃烧稳定性评定技术研究

    Institute of Scientific and Technical Information of China (English)

    丁兆波; 许晓勇; 乔桂玉; 陶瑞峰

    2013-01-01

      为了实现氢氧发动机的动态燃烧稳定性试验评定,基于国内外液体火箭发动机动态稳定性评定的相关经验,并结合 CPIA655关于稳定性评定的准则,进行了氢氧发动机动态稳定性评定的方案探讨。分析表明,氢氧发动机有必要在全系统热试车状态下进行动态稳定性评定试验。所选定的扰动装置和传感器在喷注器面安装的方案可实现性最好,结构变动最小,可保持试验在原型燃烧室状态下进行,同时扰动效果较好,传感器敏感性较好。%In order to carry out dynamic combustion stability rating of a LOX/LH2 rocket engine, the schemes of stability rating for the LOX/LH2 rocket engine are investigated based on the stability rating datum of some rocket engines and the basic criteria of CPIA655, including the evaluation standard, testing method, disturbance method, dynamic pressure testing and structure design. Compared to other schemes, the selected scheme that disturbance device and high frequency pressure sensors install on injector surface has better feasibility and less structural changes, which could ensure the rating test to be carried in a prototype engine, thereby leading to better disturbance efficiency and measure sensitivity.

  15. Combustive management of oil spills

    International Nuclear Information System (INIS)

    Extensive experiments with in situ incineration were performed on a desert site at the University of Arizona with very striking results. The largest incinerator, 6 feet in diameter with a 30 foot chimney, developed combustion temperatures of 3000, F, and attendant soot production approximately 1000 times less than that produced by conventional in situ burning. This soot production, in fact, is approximately 30 times less than current allowable EPA standards for incinerators and internal combustion engines. Furthermore, as a consequence of the high temperature combustion, the bum rate was established at a very high 3400 gallons per hour for this particular 6 foot diameter structure. The rudimentary design studies we have carried out relative to a seagoing 8 foot diameter incinerator have predicted that a continuous burn rate of 7000 gallons per hour is realistic. This structure was taken as a basis for operational design because it is compatible with C130 flyability, and will be inexpensive enough ($120,000 per copy) to be stored at those seaside depots throughout the US coast line in which the requisite ancillary equipments (booms, service tugs, etc.) are already deployed. The LOX experiments verified our expectations with respect to combustion of debris and various highly weathered or emulsified oils. We have concluded, however, that the use of liquid oxygen in actual beach clean up is not promising because the very high temperatures associated with this combustion are almost certain to produce environmentally deleterious effects on the beach surface and its immediately sublying structures. However, the use of liquid oxygen augmentation for shore based and flyable incinerators may still play an important role in handing the problem of accumulated debris

  16. Combustion modeling in internal combustion engines

    Science.gov (United States)

    Zeleznik, F. J.

    1976-01-01

    The fundamental assumptions of the Blizard and Keck combustion model for internal combustion engines are examined and a generalization of that model is derived. The most significant feature of the model is that it permits the occurrence of unburned hydrocarbons in the thermodynamic-kinetic modeling of exhaust gases. The general formulas are evaluated in two specific cases that are likely to be significant in the applications of the model.

  17. Combustion characteristics of aluminium-iron oxidein SHS-gravitational process

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    In order to get high quality of products, the combustion of aluminium-iron oxide thermite in SHS-gravitational process must be under control. The effects of thermite filling density, hole in thermite and inclined angle of pipe on combustion rate were studied. It shows that the combustion rate decreases with the decrease of filling density. The thermite combusts downwards the pipe much more quickly if there are holes in the thermite. And the combustion rate increases with the increase of the inclined angle of pipe. The experiment results show that the combustion of thermite is predominantly controlled by gas phasereaction, which is attributed to the high temperature of the thermitecombustion.

  18. Measuring Combustion Advance in Solid Propellants

    Science.gov (United States)

    Yang, L. C.

    1986-01-01

    Set of gauges on solid-propellant rocket motor with electrically insulating case measures advance of combustion front and local erosion rates of propellant and insulation. Data furnished by gauges aid in motor design, failure analysis, and performance prediction. Technique useful in determining propellant uniformity and electrical properties of exhaust plum. Gauges used both in flight and on ground. Foilgauge technique also useful in basic research on pulsed plasmas or combustion of solids.

  19. Saliva secretion rate and acidity in a group of physically disabled older care home residents

    NARCIS (Netherlands)

    Putten, G.J. van der; Brand, H.S.; De Visschere, L.M.; Schols, J.M.; Baat, C. de

    2013-01-01

    A growing number of older people have teeth, which are vulnerable to oral diseases. To maintain good oral health, an adequate amount of saliva should be secreted and the saliva should possess adequate buffer capacity. The study aim was to investigate the associations of saliva secretion rate and aci

  20. Corrosion rate of construction materials in hot phosphoric acid with the contribution of anodic polarization

    DEFF Research Database (Denmark)

    Kouril, M.; Christensen, Erik; Eriksen, S.;

    2011-01-01

    ). Several grades of stainless steels were tested as well as tantalum, niobium, titanium, nickel alloys and silicon carbide. The corrosion rate was evaluated by means of mass loss at free corrosion potential as well as under various levels of polarization. The only corrosion resistant material in 85...

  1. Experimental validation of calculated capture rate for nucleus involved in fuel cycle; Validation experimentale du calcul du taux de capture des noyaux intervenant dans le cycle du combustible

    Energy Technology Data Exchange (ETDEWEB)

    Benslimane-Bouland, A

    1997-09-01

    The framework of this study was the evaluation of the nuclear data requirements for Actinides and Fission Products applied to current nuclear reactors as well as future applications. This last item includes extended irradiation campaigns, 100 % Mixed Oxide fuel, transmutation or even incineration. The first part of this study presents different types of integral measurements which are available for capture rate measurements, as well as the methods used for reactor core calculation route design and nuclear data library validation. The second section concerns the analysis of three specific irradiation experiments. The results have shown the extent of the current knowledge on nuclear data as well as the associated uncertainties. The third and last section shows both the coherency between all the results, and the statistical method applied for nuclear data library adjustment. A relevant application of this method has demonstrated that only specifically chosen integral experiments can be of use for the validation of nuclear data libraries. The conclusion is reached that even if co-ordinated efforts between reactor and nuclear physicists have made possible a huge improvement in the knowledge of capture cross sections of the main nuclei such as uranium and plutonium, some improvements are currently necessary for the minor actinides (Np, Am and Cm). Both integral and differential measurements are recommended to improve the knowledge of minor actinide cross sections. As far as integral experiments are concerned, a set of criteria to be followed during the experimental conception have been defined in order to both reduce the number of required calculation approximations, and to increase as much as possible the maximum amount of extracted information. (author)

  2. Absolute rate constants for the reaction of hypochlorous acid with protein side chains and peptide bonds

    DEFF Research Database (Denmark)

    Pattison, D I; Davies, Michael Jonathan

    2001-01-01

    , absolute second-order rate constants for the reactions of HOCl with protein side chains, model compounds, and backbone amide (peptide) bonds have been determined at physiological pH values. The reactivity of HOCl with potential reactive sites in proteins is summarized by the series: Met (3.8 x 10(7) M(-1......) x s(-1)) > backbone amides (10-10(-3) M(-1) x s(-1)) > Gln(0.03 M(-1) x s(-1)) approximately Asn (0.03 M(-1) x s(-1)). The rate constants for reaction of HOCl with backbone amides (peptide bonds) vary by 4 orders of magnitude with uncharged peptide bonds reacting more readily with HOCl than those...

  3. Glycyrrhizic Acid Reduces Heart Rate and Blood Pressure by a Dual Mechanism

    OpenAIRE

    Kailash Singh; Aung Moe Zaw; Revathi Sekar; Ahuja Palak; Allam, Ahmed A.; Jamaan Ajarem; Chow, Billy K. C.

    2016-01-01

    Beta adrenergic receptors are crucial for their role in rhythmic contraction of heart along with their role in the pathological conditions such as tachycardia and high risk of heart failure. Studies report that the levels of beta-1 adrenergic receptor tend to decrease by 50%, whereas, the levels of beta-2 adrenergic receptor remains constant during the risk of heart failure. Beta blockers—the antagonistic molecules for beta-adrenergic receptors, function by slowing the heart rate, which there...

  4. Oxidative desulfurization of askale coal by nitric acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Guru, M. [Gazi University, Ankara (Turkey). Dept. of Chemical Engineering

    2007-07-01

    Efficient use of fossil fuels is of utmost importance in a world that depends on these for the greatest part of its energy needs. Although lignite is a widely used fossil fuel, its sulfur content limits its consumption. This study aims to capture combustible sulfur in the ash by oxidizing it with solution of nitric acid solution. Thus, the combustible sulfur in the coal was converted to sulfate form in the ash. Parameters affecting the conversion of sulfur were determined to be nitric acid concentration, reaction time and mean particle size at constant (near room) temperature and shaking rate. The maximum desulfurization efficiency reached was 38.7% of the original combustible sulfur with 0.3 M nitric acid solution, 16 h of reaction time and 0.1 mm mean particle size.

  5. Application of spectral analysis to renal uptake rate measurement with {sup 99m}Tc-dimercaptosuccinic acid

    Energy Technology Data Exchange (ETDEWEB)

    Murase, Kenya; Tanada, Shuji; Ikezoe, Junpei [Ehime University, Shigenobu (Japan). School of Medicine

    1997-06-01

    In our previous paper, we demonstrated a new method for renal uptake rate measurement with {sup 99m}Tc-dimercaptosuccinic acid (DMSA) which required no background and kidney depth corrections and only 20 min for examination. In this study, we applied spectral analysis to renal uptake rate measurement with DMSA. The net uptake rate of DMSA by tubular cells (K) calculated using spectral analysis correlated well with the renal uptake rates measured two hours after DMSA administration (r=0.918 for the 3-parameter model and r=0.924 for the 4-parameter model), and agreed well with the K values obtained using the nonlinear least-squares method (r=0.997 for the 3-parameter model and r=0.998 for the 4-parameter model). These results indicate that spectral analysis is applicable and useful for quantification of renal uptake rate of DMSA and it can be an alternative approach to our previous method. We believe that this method will facilitate even more widespread utilization of the quantitative assessment of DMSA uptake by planar scintigraphy, because it is much simpler for practical use as compared to the previous method. (author)

  6. Combustion Byproducts Recycling Consortium

    Energy Technology Data Exchange (ETDEWEB)

    Paul Ziemkiewicz; Tamara Vandivort; Debra Pflughoeft-Hassett; Y. Paul Chugh; James Hower

    2008-08-31

    Ashlines: To promote and support the commercially viable and environmentally sound recycling of coal combustion byproducts for productive uses through scientific research, development, and field testing.

  7. 以有机酸钾盐为可燃剂的气溶胶灭火剂试验%Experimental study on aerosol fire extinguishing agent with organic acid potassium as combustible material

    Institute of Scientific and Technical Information of China (English)

    王鹏; 李玉

    2011-01-01

    用1 m密闭试验葙进行灭火性能试验,采用半分法得出两种以有机酸钾盐为主要可燃剂的气溶胶灭火剂的配方,并对比其灭火时间.在热气溶胶灭火剂中添加碳酸钾作为热耗散剂,以降低反应速度,减小火焰外喷.用兰利法进行试验,得出了两种灭火剂的99%概率灭火效能,在70~75 g/m之间.经测量,气溶胶灭火剂的燃烧产物是低毒的.气溶胶灭火剂在灭火时的不确定度很大,应以概率论的方法研究其灭火能力.%An airtight box with 1 m3 was used to test fire extinguishing performance; two kinds of aerosol fire extinguishing agents with organic acid potassium as combustible material were got by split- half method, and the fire- extinguishing time was compared. Potassium carbonate was added into aerosol fire extinguishing agents as heat dissipative agents to slow down the reaction and reduce the flame. Langlie method was used in experiments, the 99% application density of these twa extinguishing agents were got, between 70~75 g/m3. At last, the toxicity of combustion product of these two aerosol fire extinguishing agents was tested to be low. The application of probability theory in the study of fire extinguishing performance of aerosol fire extinguishing agent is necessary because of the uncertainty of putting out fire by aerosol fire extinguishing agents.

  8. Nitrate, ascorbic acid, mineral and antioxidant activities of Cosmos caudatus in response to organic and mineral-based fertilizer rates.

    Science.gov (United States)

    Hassan, Siti Aishah; Mijin, Salumiah; Yusoff, Umi Kalsom; Ding, Phebe; Wahab, Puteri Edaroyati Megat

    2012-06-28

    The source and quantity of nutrients available to plants can affect the quality of leafy herbs. A study was conducted to compare quality of Cosmos caudatus in response to rates of organic and mineral-based fertilizers. Organic based fertilizer GOBI (8% N:8% P₂O₅:8% K₂O) and inorganic fertilizer (15% N, 15% P₂O₅, 15% K₂O) were evaluated based on N element rates at 0, 30, 60, 90, 120 kg h⁻¹. Application of organic based fertilizer reduced nitrate, improved vitamin C, antioxidant activity as well as nitrogen and calcium nutrients content. Antioxidant activity and chlorophyll content were significantly higher with increased fertilizer application. Fertilization appeared to enhance vitamin C content, however for the maximum ascorbic acid content, regardless of fertilizer sources, plants did not require high amounts of fertilizer.

  9. Reaction rates of hydroxyl radical with nitric acid and with hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Marinelli, W.J.; Johnston, H.S.

    1982-08-01

    The rates of the reactions HO+HNO/sub 3/ ..-->.. H/sub 2/O+NO/sub 3/, (1), HO+H/sub 2/O/sub 2/ ..-->.. H/sub 2/O+HOO (2) have been studied by laser flash photolysis of reactants and resonance fluorescence of hydroxyl radicals. The recently reported high rate constants at room temperature for both reactions and the negative activation energy for Reaction (1) at low temperature have been confirmed. Results obtained here are: k/sub 1/ = 1.52 x 10/sup -14/ exp(644/T) cm/sup 3/ molecule/sup -1/ s/sup -1/ from 218--363 K and k/sub 2/ = 1.81 x 10/sup -12/ cm/sup 3/ molecule/sup -1/ s/sup -1/ at 298 K. These two reactions have been examined by transition-state theory; (1) is assigned a cyclic and (2) a chainlike transition state. Even with no potential energy barrier, the reaction coordinate of (1) involves a quantum-mechanical, temperature independent frequency; and with this model the low pre-exponential factor and negative activation energy of Reaction (1) can be explained.

  10. Aspartic acid racemization rate in narwhal (Monodon monoceros eye lens nuclei estimated by counting of growth layers in tusks

    Directory of Open Access Journals (Sweden)

    Eva Garde

    2012-11-01

    Full Text Available Ages of marine mammals have traditionally been estimated by counting dentinal growth layers in teeth. However, this method is difficult to use on narwhals (Monodon monoceros because of their special tooth structures. Alternative methods are therefore needed. The aspartic acid racemization (AAR technique has been used in age estimation studies of cetaceans, including narwhals. The purpose of this study was to estimate a species-specific racemization rate for narwhals by regressing aspartic acid d/l ratios in eye lens nuclei against growth layer groups in tusks (n=9. Two racemization rates were estimated: one by linear regression (r2=0.98 based on the assumption that age was known without error, and one based on a bootstrap study, taking into account the uncertainty in the age estimation (r2 between 0.88 and 0.98. The two estimated 2kAsp values were identical up to two significant figures. The 2k Asp value from the bootstrap study was found to be 0.00229±0.000089 SE, which corresponds to a racemization rate of 0.00114−yr±0.000044 SE. The intercept of 0.0580±0.00185 SE corresponds to twice the (d/l0 value, which is then 0.0290±0.00093 SE. We propose that this species-specific racemization rate and (d/l0 value be used in future AAR age estimation studies of narwhals, but also recommend the collection of tusks and eyes of narwhals for further improving the (d/l0 and 2kAsp estimates obtained in this study.

  11. COMBUSTION PROPERTIES OF EUCALYPTUS WOOD

    Directory of Open Access Journals (Sweden)

    Yalçın ÖRS

    1999-03-01

    Full Text Available In this study, the combustion properties of some impregnation materials (abiotic and biotic factors used for eucalyptus wood in interior or exterior environments were investigated. The experimental samples were prepared from Eucalyptus wood based on ASTM-D-1413-76 Tanalith-CBC, boric acid, borax, vacsol-WR, immersol-WR, polyethylen glycole-400 and ammonium sulphate were used as an impregnation material. The results indicated that, vacuum treatment on Eucalyptus gave the lowest retention value of salts. Compounds containing boron+salt increased fire resistance however water repellents decreased the wood flammability.

  12. Changes in ruminal volatile fatty acid production and absorption rate during the dry period and early lactation as affected by rate of increase of concentrate allowance.

    Science.gov (United States)

    Dieho, K; Dijkstra, J; Schonewille, J T; Bannink, A

    2016-07-01

    The aim of the present experiment was to study changes in volatile fatty acid (VFA) production using an isotope dilution technique, and changes in VFA fractional absorption rate (kaVFA) using a buffer incubation technique (BIT) during the dry period and early lactation, as affected by the postpartum (pp) rate of increase of concentrate allowance. The current results are complementary to previously reported changes on rumen papillae morphology from the same experiment. From 50 d antepartum to 80 d pp, VFA production rate was measured 5 times and kaVFA was measured 10 times in 12 rumen-cannulated Holstein Friesian cows. Cows had free access to a mixed ration, consisting of grass and corn silage, soybean meal, and (dry period only) chopped straw. Treatment consisted of either a rapid (RAP; 1.0 kg of DM/d; n=6) or gradual (GRAD; 0.25 kg of DM/d; n=6) increase of concentrate allowance (up to 10.9 kg of DM/d), starting at 4 d pp, aimed at creating a contrast in rumen-fermentable organic matter intake. For the BIT, rumen contents were evacuated, the rumen washed, and a standardized buffer fluid introduced [120 mM VFA, 60% acetic (Ac), 25% propionic (Pr), and 15% butyric (Bu) acid; pH 5.9 and Co-EDTA as fluid passage marker]. For the isotope dilution technique, a pulse-dose of (13)C-labeled Ac, Pr, and Bu and Co-EDTA as fluid passage marker was infused. The rate of total VFA production was similar between treatments and was 2 times higher during the lactation (114 mol/d) than the dry period (53 mol/d). Although papillae surface area at 16, 30, and 44 d pp was greater in RAP than GRAD, Bu and Ac production at these days did not differ between RAP and GRAD, whereas at 16 d pp RAP produced more Pr than GRAD. These results provide little support for the particular proliferative effects of Bu on papillae surface area. Similar to developments in papillae surface area in the dry period and early lactation, the kaVFA (per hour), measured using the BIT, decreased from 0.45 (Ac), 0

  13. Assessing glomerular filtration rate in healthy adult potential kidney donors in Bangladesh: a comparison of various prediction equations with measured glomerular filtration rate by diethylentriamine pentaacetic acid renogram.

    Science.gov (United States)

    Jahan, F; Chowdhury, M N U; Mahbub, T; Arafat, S M; Jahan, S; Hossain, M; Khan, M F

    2013-08-01

    To ensure that potential kidney donors in Bangladesh have no renal impairment, it is extremely important to have accurate methods for evaluating the glomerular filtration rate (GFR). We evaluated the performance of serum creatinine based GFR in healthy adult potential kidney donors in Bangladesh to compare GFR determined by DTPA with that determined by various prediction equations. In this study GFR in 61 healthy adult potential kidney donors were measured with 99mTc-diethylenetriamine penta-acetic acid (DTPA) renogram. We also estimated GFR using a four variable equation modification of diet in renal disease (MDRD), Cockcroft-Gault creatinine clearance (CGCrCl), Cockcroft-Gault glomerular filtration rate (CG-GFR). The mean age of study population was 34.31 +/- 9.46 years and out of them 65.6% was male. In this study mean mGFR was 85.4 +/- 14.8. Correlation of estimated GFR calculated by CG-CrCl, CG-GFR and MDRD were done with measured GFR DTPA using quartile. Kappa values were also estimated which was found to be 0.104 for (p = 0.151), 0.336 for (p = 0.001) and 0.125 for (p = 0.091) respectively. This indicates there is no association between estimated GFR calculated by CG-CrCl, CG-GFR, MDRD with measured GFR DTPA. These results show poor performance of these equations in evaluation of renal function among healthy population and also raise question regarding validity of these equations for assessment of renal function in chronic kidney disease in our population.

  14. A comparative study of sound generation by laminar, combusting and non-combusting jet flows

    Science.gov (United States)

    Talei, Mohsen; Brear, Michael J.; Hawkes, Evatt R.

    2014-08-01

    Sound production by two-dimensional, laminar jet flows with and without combustion is studied numerically and theoretically. The compressible Navier-Stokes, energy and progress variable equations are solved by resolving both the near field and the acoustics. The combusting jet flows are compared to non-combusting jets of the same jet Mach number, with the non-combusting, non-isothermal jets having the same steady temperature difference as the combusting jets. This infers that the magnitude of entropic and density disturbances is similar in some of the combusting and non-combusting cases. The flows are perturbed by a sinusoidal inlet velocity fluctuation at different Strouhal numbers. The computational domain is resolved to the far field in all cases, allowing direct examination of the sound radiated and its sources. Lighthill's acoustic analogy is then solved numerically using Green's functions. The radiated sound calculated using Lighthill's equation is in good agreement with that from the simulations for all cases, validating the numerical solution of Lighthill's equation. The contribution of the source terms in Dowling's reformulation of Lighthill's equation is then investigated. It is shown that the source term relating to changes in the momentum of density inhomogeneities is the dominant source term for all non-reacting, non-isothermal cases. Further, this source term has similar magnitude in the combusting cases and is one of the several source terms that have similar magnitude to the source term involving fluctuations in the heat release rate.

  15. Effect of hydrion evolution by polylactic-co-glycolic acid coating on degradation rate of pure iron.

    Science.gov (United States)

    Wu, Jingyao; Lu, Xi; Tan, Lili; Zhang, Bingchun; Yang, Ke

    2013-10-01

    For biodegradable iron coronary stents, the major problem is the low degradation rate in body environment. In this study, a new strategy was proposed to increase the degradation rate of iron in vitro. The hydrion evolution was intended to be introduced into the degradation system to increase the degradation rate. To realize this strategy, polylactic-co-glycolic acid (PLGA) was coated onto the surface of pure iron. The degradation process and mechanism of pure iron coated with PLGA were investigated. The results showed that iron coated with PLGA exhibited higher degradation rate in the static immersion test all along. With the degradation of PLGA, the oligomers of PLGA could release abundant H(+) which could dissolve the ferrous oxide to make the electrolyte and oxygen to reach the surface of iron again and simultaneity trigger the hydrion evolution at the middle stage of the degradation. The study also revealed that the solution ions failed to permeate the PLGA coating and the deposition of calcium and phosphorus in the degradation layer was inhibited which further enhanced the degradation.

  16. Trends in modeling of porous media combustion

    Energy Technology Data Exchange (ETDEWEB)

    Mujeebu, M. Abdul; Abdullah, M. Zulkifly [Porous Media Combustion Laboratory, School of Mechanical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia); Mohamad, A.A. [College of Engineering, Alfaisal University, Riyadh 11533, P.O. Box 50927 (Saudi Arabia); Bakar, M.Z. Abu [School of Chemical Engineering, Universiti Sains Malaysia, Engineering Campus, 14300 Nibong Tebal, Penang (Malaysia)

    2010-12-15

    Porous media combustion (PMC) has interesting advantages compared with free flame combustion due to higher burning rates, increased power dynamic range, extension of the lean flammability limits, and low emissions of pollutants. Extensive experimental and numerical works were carried out and are still underway, to explore the feasibility of this interesting technology for practical applications. For this purpose, numerical modeling plays a crucial role in the design and development of promising PMC systems. This article provides an exhaustive review of the fundamental aspects and emerging trends in numerical modeling of gas combustion in porous media. The modeling works published to date are reviewed, classified according to their objectives and presented with general conclusions. Numerical modeling of liquid fuel combustion in porous media is excluded. (author)

  17. Buoyancy effects on smoldering combustion

    Science.gov (United States)

    Dosanjh, S.; Peterson, J.; Fernandez-Pello, A. C.; Pagni, P. J.

    1985-01-01

    The effect of buoyancy on the rate of spread of a concurrent smolder reaction through a porous combustible material is investigated theoretically and experimentally. In the experiments, buoyant forces are controlled by varying the density difference, and the smolder rate spread through porous alpha cellulose (0.83 void fraction) is measured as a function of the ambient air pressure. The smolder velocity is found to increase with the ambient pressure; extinction occurs when the buoyancy forces cannot overcome the drag forces, indicating that diffusion by itself cannot support the spread of a smolder reaction. Theoretical predictions are found to be in good qualitative agreement with the experimental results.

  18. Steady state HNG combustion modeling

    Energy Technology Data Exchange (ETDEWEB)

    Louwers, J.; Gadiot, G.M.H.J.L. [TNO Prins Maurits Lab., Rijswijk (Netherlands); Brewster, M.Q. [Univ. of Illinois, Urbana, IL (United States); Son, S.F. [Los Alamos National Lab., NM (United States); Parr, T.; Hanson-Parr, D. [Naval Air Warfare Center, China Lake, CA (United States)

    1998-04-01

    Two simplified modeling approaches are used to model the combustion of Hydrazinium Nitroformate (HNF, N{sub 2}H{sub 5}-C(NO{sub 2}){sub 3}). The condensed phase is treated by high activation energy asymptotics. The gas phase is treated by two limit cases: the classical high activation energy, and the recently introduced low activation energy approach. This results in simplification of the gas phase energy equation, making an (approximate) analytical solution possible. The results of both models are compared with experimental results of HNF combustion. It is shown that the low activation energy approach yields better agreement with experimental observations (e.g. regression rate and temperature sensitivity), than the high activation energy approach.

  19. Combustion of coffee husks

    Energy Technology Data Exchange (ETDEWEB)

    Saenger, M.; Hartge, E.-U.; Werther, J. [Technical Univ. Hamburg-Harburg, Chemical Engineering 1, Hamburg (Germany); Ogada, T.; Siagi, Z. [Moi Univ., Dept. of Production Engineering, Eldoret (Kenya)

    2001-05-01

    Combustion mechanisms of two types of coffee husks have been studied using single particle combustion techniques as well as combustion in a pilot-scale fluidized bed facility (FBC), 150 mm in diameter and 9 m high. Through measurements of weight-loss and particle temperatures, the processes of drying, devolatilization and combustion of coffee husks were studied. Axial temperature profiles in the FBC were also measured during stationary combustion conditions to analyse the location of volatile release and combustion as a function of fuel feeding mode. Finally the problems of ash sintering were analysed. The results showed that devolatilization of coffee husks (65-72% volatile matter, raw mass) starts at a low temperature range of 170-200degC and takes place rapidly. During fuel feeding using a non water-cooled system, pyrolysis of the husks took place in the feeder tube leading to blockage and non-uniform fuel flow. Measurements of axial temperature profiles showed that during under-bed feeding, the bed and freeboard temperatures were more or less the same, whereas for over-bed feeding, freeboard temperatures were much higher, indicating significant combustion of the volatiles in the freeboard. A major problem observed during the combustion of coffee husks was ash sintering and bed agglomeration. This is due to the low melting temperature of the ash, which is attributed to the high contents of K{sub 2}O (36-38%) of the coffee husks. (Author)

  20. Fifteenth combustion research conference

    International Nuclear Information System (INIS)

    The BES research efforts cover chemical reaction theory, experimental dynamics and spectroscopy, thermodynamics of combustion intermediates, chemical kinetics, reaction mechanisms, combustion diagnostics, and fluid dynamics and chemically reacting flows. 98 papers and abstracts are included. Separate abstracts were prepared for the papers

  1. Municipal waste combustion

    International Nuclear Information System (INIS)

    This book covers the proceedings of the second annual International Specialty Conference on Municipal Waste Combustion. Topics covered include: combustion; refuse derived fuel plants; ash characterization; flue gas cleaning; ash disposal; environmental effects; risk and quality assurance; mercury control; sampling; regulations

  2. Coal combustion by wet oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Bettinger, J.A.; Lamparter, R.A.; McDowell, D.C.

    1980-11-15

    The combustion of coal by wet oxidation was studied by the Center for Waste Management Programs, of Michigan Technological University. In wet oxidation a combustible material, such as coal, is reacted with oxygen in the presence of liquid water. The reaction is typically carried out in the range of 204/sup 0/C (400/sup 0/F) to 353/sup 0/C (650/sup 0/F) with sufficient pressure to maintain the water present in the liquid state, and provide the partial pressure of oxygen in the gas phase necessary to carry out the reaction. Experimental studies to explore the key reaction parameters of temperature, time, oxidant, catalyst, coal type, and mesh size were conducted by running batch tests in a one-gallon stirred autoclave. The factors exhibiting the greatest effect on the extent of reaction were temperature and residence time. The effect of temperature was studied from 204/sup 0/C (400/sup 0/F) to 260/sup 0/C (500/sup 0/F) with a residence time from 600 to 3600 seconds. From this data, the reaction activation energy of 2.7 x 10/sup 4/ calories per mole was determined for a high-volatile-A-Bituminous type coal. The reaction rate constant may be determined at any temperature from the activation energy using the Arrhenius equation. Additional data were generated on the effect of mesh size and different coal types. A sample of peat was also tested. Two catalysts were evaluated, and their effects on reaction rate presented in the report. In addition to the high temperature combustion, low temperature desulfurization is discussed. Desulfurization can improve low grade coal to be used in conventional combustion methods. It was found that 90% of the sulfur can be removed from the coal by wet oxidation with the carbon untouched. Further desulfurization studies are indicated.

  3. Heart rate is associated with markers of fatty acid desaturation: the GOCADAN study

    Directory of Open Access Journals (Sweden)

    Sven O.E. Ebbesson

    2012-03-01

    Full Text Available Objectives: To determine if heart rate (HR is associated with desaturation indexes as HR is associated with arrhythmia and sudden death. Study design: A community based cross-sectional study of 1214 Alaskan Inuit. Methods: Data of FA concentrations from plasma and red blood cell membranes from those ≥35 years of age (n = 819 were compared to basal HR at the time of examination. Multiple linear regression with backward stepwise selection was employed to analyze the effect of the desaturase indexes on HR, after adjustment for relevant covariates. Results: The Δ5 desaturase index (Δ5-DI measured in serum has recently been associated with a protective role for cardiovascular disease. This index measured here in plasma and red blood cells showed a negative correlation with HR. The plasma stearoyl-CoA-desaturase (SCD index, previously determined to be related to cardiovascular disease (CVD mortality, on the other hand, was positively associated with HR, while the Δ6 desaturase index (Δ6-DI had no significant effect on HR. Conclusion: Endogenous FA desaturation is associated with HR and thereby, in the case of SCD, possibly with arrhythmia and sudden death, which would at least partially explain the previously observed association between cardiovascular mortality and desaturase activity.

  4. Turnover rates of fatty acid and amino acid in the coelomic fluid of the sea star Asterias rubens: Implications for the route of nutrient translocation during vitellogenesis

    NARCIS (Netherlands)

    Voogt, P.A.; Beijnink, F.B.; Sluis, I. van der

    1984-01-01

    1. 1. The turnover of fatty acid and amino acid in the coelomic fluid of the sea star Asterias rubens was quantified by intra-coelomic injection of radiolabelled oleic acid and L-leucine which had half times of 2 and 10 min, respectively. 2. 2. The molar composition of the amino acids of the cell-f

  5. Kinetic investigation for slow combustion of biomass

    Energy Technology Data Exchange (ETDEWEB)

    Haykiri-Acma, H.; Yaman, S. [Istanbul Technical Univ., Istanbul (Turkey). Dept. of Chemical Engineering, Faculty of Chemical and Metallurgical Engineering

    2006-07-01

    The renewed interest in biomass as a renewable, clean, and inexpensive fuel was discussed. Many different mechanisms take place simultaneously during biomass combustion and also during other thermal processes such as gasification, pyrolysis or carbonization. These mechanisms have a pronounced influence on the design and operation of thermal conversion processes. In addition, product yields and product distributions from the thermal processes are sensitive to the kinetic properties of biomass. In order to evaluate the combustion mechanisms and the combustion kinetics of biomass, the behavior of these constituents under combustion conditions were properly evaluated. In this study, combustion of biomass samples was carried out in a thermogravimetric analyzer by heating them from ambient to 1173 K with heating rates of 5 K/min and 10 K/min under dynamic dry air atmosphere of 40 mL/min. The biomass samples included olive refuse, sunflower seed shell, rapeseed, grape seed, and hybrid poplar. The purpose of the study was to examine the kinetic properties of biomass during slow combustion for the overall combustion process as well as for some definite temperature intervals at which different combustion mechanisms are present according to the type and complexity of biomass used. Derivative thermogravimetric analysis (DTG) curves were derived, and data obtained from these curves were used to compute the kinetic parameters such as activation energy, pre-exponential factor, and governing mechanisms for the combustion processes. The governing mechanisms for individual temperature intervals were examined along with the overall combustion process. The study showed that at lower temperature intervals, the combustion process was controlled primarily by the chemical reaction. At least 3 sequential mechanisms may occur at different temperature intervals during combustion of biomass. Activation energy and pre-exponential factors were determined for each temperature interval

  6. Oil content and saturated fatty acids in sunflower (Helianthus annuus L.) as a function of planting date, N rate, and hybrid

    Science.gov (United States)

    The fatty acids (FA) composition of sunflower determines its uses and health effects on humans, while oil content determines the price paid to producers. The hypothesis of this study was that agronomic factors (genotype, planting date, and N rate) will affect total saturated fatty acid (TSFA) concen...

  7. Seasonal Changes in Mycosporine-Like Amino Acid Production Rate with Respect to Natural Phytoplankton Species Composition

    Directory of Open Access Journals (Sweden)

    Sun-Yong Ha

    2015-11-01

    Full Text Available After in situ incubation at the site for a year, phytoplanktons in surface water were exposed to natural light in temperate lakes (every month; thereafter, the net production rate of photoprotective compounds (mycosporine-like amino acids, MAAs was calculated using 13C labeled tracer. This is the first report describing seasonal variation in the net production rate of individual MAAs in temperate lakes using a compound-specific stable isotope method. In the mid-latitude region of the Korean Peninsula, UV radiation (UVR usually peaks from July to August. In Lake Paldang and Lake Cheongpyeong, diatoms dominated among the phytoplankton throughout the year. The relative abundance of Cyanophyceae (Anabaena spiroides reached over 80% during July in Lake Cheongpyeong. Changes in phytoplankton abundance indicate that the phytoplankton community structure is influenced by seasonal changes in the net production rate and concentration of MAAs. Notably, particulate organic matter (POM showed a remarkable change based on the UV intensity occurring during that period; this was because of the fact that cyanobacteria that are highly sensitive to UV irradiance dominated the community. POM cultured in Lake Paldang had the greatest shinorine (SH production rate during October, i.e., 83.83 ± 10.47 fgC·L−1·h−1. The dominance of diatoms indicated that they had a long-term response to UVR. Evaluation of POM cultured in Lake Cheongpyeong revealed that there was an increase in the net MAA production in July (when UVR reached the maximum; a substantial amount of SH, i.e., 17.62 ± 18.34 fgC·L−1·h−1, was recorded during this period. Our results demonstrate that both the net production rate as well as the concentration of MAAs related to photoinduction depended on the phytoplankton community structure. In addition, seasonal changes in UVR also influenced the quantity and production of MAAs in phytoplanktons (especially Cyanophyceae.

  8. Relation between relative growth rate, endogenous gibberellins, and the response to applied gibberellic acid for Plantago major.

    Science.gov (United States)

    Dijkstra, P; Reegen, H; Kuiper, P J

    1990-08-01

    Relationships between relative growth rate (RGR), endogenous gibberellin (GA) concentration and the response to application of gibberellic acid (GA(3) ) were studied for two inbred lines of Plantago major L., which differed in RGR. A4, the fast-growing inbred line, had a higher free GA concentration than the slow-growing W9, as analyzed by enzyme immunoassay. GA(3) application increased total plant weight and RGR(3) particularly for the slow-growing line. Chlorophyll a content and photosynthetic activity per unit leaf area were decreased, while transpiration rate was unaffected by GA(3) application. The increase in RGR by GA(3) application was associated with an increased leaf weight ratio; specific leaf area and percentage of dry matter in the leaves were only temporarily affected. Root respiration rate per unit dry weight was unaffected. The correlation between low RGR, low GA concentration and high responsiveness to applied GA(3) supports the contention that gibberellins are involved in the regulation of RGR. However, the transient influence of GA(3) application on some growth components suggests the involvement of other regulatory factors in addition to GA.

  9. Progressive combustion in SI-Engines—Experimental investigation on influence of combustion related parameters

    Indian Academy of Sciences (India)

    R Harish Kumar; A J Antony

    2008-12-01

    The fuel heat release rate which virtually controls the combustion process is dependent on the ‘Mass-Fraction-Burnt (MFB)’. In the present research work, a ‘logistic model with conditional variability in MFB’, has been developed for precise simulation of combustion in SI engines as the model has built in routines to take into account such factors as location of spark plug, single/dual spark plugs, intake generated swirl, combustion chamber geometry (associated with Bore/Stroke ratio), etc. A major contribution of this paper is that new and improved models for the ‘overall combustion duration’, and ‘ignition delay/flame development angle’, taking into account primarily the influence of compression ratio on the overall combustion process in SI engine have been developed. Taylor’s original equation for estimating the overall combustion duration has been modified by including a logistic equation for the error term and incorporating it in the original equation. Ignition delay as proposed by Keck et al has been modified by incorporating a polynomial of 3rd order into the original equation. The empirical correlations that have been proposed in this paper may serve to be the starting point for simulation of ‘photodetonation concept’ to simulate HCCI combustion which is presently the hot research work in the area of pre-mixed combustion. A program in Turbo-C++ has been developed for the complete simulation of SI engine combustion, taking into account the conditional variability effect, variable specific heats of burnt gases, dissociation of gases at high temperatures, progressive combustion phenomena, heat transfer (based on Woschni‘s equation), gas exchange process based on 1D-steady gas flow equation employing Taylor’s mach index of 0·6 for valve design.

  10. Mechanisms of Docosahexaenoic and Eicosapentaenoic Acid Loss from Pacific Saury and Comparison of Their Retention Rates after Various Cooking Methods.

    Science.gov (United States)

    Cheung, Lennie K Y; Tomita, Haruo; Takemori, Toshikazu

    2016-08-01

    The docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contents of Pacific saury (Cololabis saira), a fatty fish and staple of the Japanese diet, have been reported to decrease after cooking. This study compared the DHA and EPA contents remaining in saury after grilling, pan-frying or deep-frying to center temperatures of 75, 85, or 95 °C, and examined physical loss, lipid oxidation, and thermal degradation as mechanisms of DHA and EPA loss. Temperature changes inside the saury were monitored using thermocouples, while DHA and EPA contents, oxygen radical absorbance capacity, and measurements of lipid oxidation (that is, carbonyl value and thiobarbituric acid value) were determined chemically. Visualization of temperature distribution inside fish samples during cooking revealed large differences in heat transfer among cooking methods. True retention rates in grilled (DHA: 84 ± 15%; EPA: 87 ± 14%) and pan-fried samples (DHA: 85 ± 16%; EPA: 77 ± 17%) were significantly higher than deep-fried samples (DHA: 58 ± 17%; EPA: 51 ± 18%), but were not affected by final center temperatures despite differences in cooking times. Physical loss via cooking losses (grilling and pan-frying) or migration into frying oil (deep-frying) accounted for large quantities of DHA and EPA loss, while lipid oxidation and thermal degradation did not appear to be major mechanisms of loss. The antioxidant capacity of saury was not significantly affected by cooking treatments. The results of this study suggest that minimization of physical losses during cooking may increase DHA and EPA contents retained in cooked Pacific saury. PMID:27305642

  11. Modeling the internal combustion engine

    Science.gov (United States)

    Zeleznik, F. J.; Mcbride, B. J.

    1985-01-01

    A flexible and computationally economical model of the internal combustion engine was developed for use on large digital computer systems. It is based on a system of ordinary differential equations for cylinder-averaged properties. The computer program is capable of multicycle calculations, with some parameters varying from cycle to cycle, and has restart capabilities. It can accommodate a broad spectrum of reactants, permits changes in physical properties, and offers a wide selection of alternative modeling functions without any reprogramming. It readily adapts to the amount of information available in a particular case because the model is in fact a hierarchy of five models. The models range from a simple model requiring only thermodynamic properties to a complex model demanding full combustion kinetics, transport properties, and poppet valve flow characteristics. Among its many features the model includes heat transfer, valve timing, supercharging, motoring, finite burning rates, cycle-to-cycle variations in air-fuel ratio, humid air, residual and recirculated exhaust gas, and full combustion kinetics.

  12. Renal uptake of dimercaptosuccinic acid and glomerular filtration rate in chronic nephropathy at angiotensin converting enzyme inhibition

    DEFF Research Database (Denmark)

    Kamper, A L; Thomsen, H S; Nielsen, S L;

    1990-01-01

    Glomerular filtration rate (GFR) and renal uptake of dimercaptosuccinic acid (DMSA) were measured in 31 patients with progressive chronic nephropathy before and immediately after the start of treatment with angiotensin converting enzyme (ACE) inhibitor in order to control adverse effects on kidney...... function. Scintigrams of the kidneys showed an unaltered distribution of DMSA during treatment. GFR estimated by 51Cr-EDTA plasma clearance fell by 14% (P less than 0.01), but renal uptake of 99mTc-DMSA increased by 10% (P less than 0.01). It is concluded that DMSA in chronic renal failure is mainly taken...... up by the tubular cells from the peritubular capillaries since the uptake was unaffected by the acute decrease in GFR....

  13. Calculated Third Order Rate Constants for Interpreting the Mechanisms of Hydrolyses of Chloroformates, Carboxylic Acid Halides, Sulfonyl Chlorides and Phosphorochloridates

    Directory of Open Access Journals (Sweden)

    T. William Bentley

    2015-05-01

    Full Text Available Hydrolyses of acid derivatives (e.g., carboxylic acid chlorides and fluorides, fluoro- and chloroformates, sulfonyl chlorides, phosphorochloridates, anhydrides exhibit pseudo-first order kinetics. Reaction mechanisms vary from those involving a cationic intermediate (SN1 to concerted SN2 processes, and further to third order reactions, in which one solvent molecule acts as the attacking nucleophile and a second molecule acts as a general base catalyst. A unified framework is discussed, in which there are two reaction channels—an SN1-SN2 spectrum and an SN2-SN3 spectrum. Third order rate constants (k3 are calculated for solvolytic reactions in a wide range of compositions of acetone-water mixtures, and are shown to be either approximately constant or correlated with the Grunwald-Winstein Y parameter. These data and kinetic solvent isotope effects, provide the experimental evidence for the SN2-SN3 spectrum (e.g., for chloro- and fluoroformates, chloroacetyl chloride, p-nitrobenzoyl p-toluenesulfonate, sulfonyl chlorides. Deviations from linearity lead to U- or V-shaped plots, which assist in the identification of the point at which the reaction channel changes from SN2-SN3 to SN1-SN2 (e.g., for benzoyl chloride.

  14. Residue Geometry Networks: A Rigidity-Based Approach to the Amino Acid Network and Evolutionary Rate Analysis.

    Science.gov (United States)

    Fokas, Alexander S; Cole, Daniel J; Ahnert, Sebastian E; Chin, Alex W

    2016-01-01

    Amino acid networks (AANs) abstract the protein structure by recording the amino acid contacts and can provide insight into protein function. Herein, we describe a novel AAN construction technique that employs the rigidity analysis tool, FIRST, to build the AAN, which we refer to as the residue geometry network (RGN). We show that this new construction can be combined with network theory methods to include the effects of allowed conformal motions and local chemical environments. Importantly, this is done without costly molecular dynamics simulations required by other AAN-related methods, which allows us to analyse large proteins and/or data sets. We have calculated the centrality of the residues belonging to 795 proteins. The results display a strong, negative correlation between residue centrality and the evolutionary rate. Furthermore, among residues with high closeness, those with low degree were particularly strongly conserved. Random walk simulations using the RGN were also successful in identifying allosteric residues in proteins involved in GPCR signalling. The dynamic function of these residues largely remain hidden in the traditional distance-cutoff construction technique. Despite being constructed from only the crystal structure, the results in this paper suggests that the RGN can identify residues that fulfil a dynamical function. PMID:27623708

  15. Compound specific radiocarbon analyses to apportion sources of combustion products in sedimentary pyrogenic carbon deposits

    Science.gov (United States)

    Hanke, Ulrich M.; Schmidt, Michael W. I.; McIntyre, Cameron P.; Reddy, Christopher M.; Wacker, Lukas; Eglinton, Timothy I.

    2016-04-01

    Pyrogenic carbon (PyC) is a collective term for carbon-rich residues comprised of a continuum of products generated during biomass burning and fossil fuel combustion. PyC is a key component of the global carbon cycle due to its slow intrinsic decomposition rate and its ubiquity in the environment. It can originate from natural or anthropogenic vegetation fires, coal mining, energy production, industry and transport. Subsequently, PyC can be transported over long distances by wind and water and can eventually be buried in sediments. Information about the origin of PyC (biomass burning vs. fossil fuel combustion) deposited in estuarine sediments is scarce. We studied the highly anoxic estuarine sediments of the Pettaquamscutt River (Rhode Island, U.S.) in high temporal resolution over 250 years and found different combustion proxies reflect local and regional sources of PyC (Hanke et al. in review; Lima et al. 2003). The polycyclic aromatic hydrocarbons (PAH) originate from long-range atmospheric transport, whereas bulk PyC, detected as benzene polycarboxylic acids (BPCA), mainly stems from local catchment run-off. However, to unambiguously apportion PyC sources, we need additional information, such as compound specific radiocarbon (14C) measurements. We report 14C data for individual BPCA including error analysis and for combustion-related PAH. First results indicate that biomass burning is the main source of PyC deposits, with additional minor contributions from fossil fuel combustion. References Hanke U.M., T.I. Eglinton, A.L.L. Braun, C. Reddy, D.B. Wiedemeier, M.W.I. Schmidt. Decoupled sedimentary records of combustion: causes and implications. In review. Lima, A. L.; Eglinton, T. I.; Reddy, C. M., High-resolution record of pyrogenic polycyclic aromatic hydrocarbon deposition during the 20th century. ES&T, 2003, 37 (1), 53-61.

  16. Bile acid sequestration reduces plasma glucose levels in db/db mice by increasing its metabolic clearance rate.

    Directory of Open Access Journals (Sweden)

    Maxi Meissner

    Full Text Available AIMS/HYPOTHESIS: Bile acid sequestrants (BAS reduce plasma glucose levels in type II diabetics and in murine models of diabetes but the mechanism herein is unknown. We hypothesized that sequestrant-induced changes in hepatic glucose metabolism would underlie reduced plasma glucose levels. Therefore, in vivo glucose metabolism was assessed in db/db mice on and off BAS using tracer methodology. METHODS: Lean and diabetic db/db mice were treated with 2% (wt/wt in diet Colesevelam HCl (BAS for 2 weeks. Parameters of in vivo glucose metabolism were assessed by infusing [U-(13C]-glucose, [2-(13C]-glycerol, [1-(2H]-galactose and paracetamol for 6 hours, followed by mass isotopologue distribution analysis, and related to metabolic parameters as well as gene expression patterns. RESULTS: Compared to lean mice, db/db mice displayed an almost 3-fold lower metabolic clearance rate of glucose (p = 0.0001, a ∼300% increased glucokinase flux (p = 0.001 and a ∼200% increased total hepatic glucose production rate (p = 0.0002. BAS treatment increased glucose metabolic clearance rate by ∼37% but had no effects on glucokinase flux nor total hepatic or endogenous glucose production. Strikingly, BAS-treated db/db mice displayed reduced long-chain acylcarnitine content in skeletal muscle (p = 0.0317 but not in liver (p = 0.189. Unexpectedly, BAS treatment increased hepatic FGF21 mRNA expression 2-fold in lean mice (p = 0.030 and 3-fold in db/db mice (p = 0.002. CONCLUSIONS/INTERPRETATION: BAS induced plasma glucose lowering in db/db mice by increasing metabolic clearance rate of glucose in peripheral tissues, which coincided with decreased skeletal muscle long-chain acylcarnitine content.

  17. Real-Time Combustion Controls and Diagnostics Sensors (CCADS)

    Energy Technology Data Exchange (ETDEWEB)

    Thornton, J.D.; Richard, G.A.; Dodrill, K.A.; Nutter, R.S. Jr; Straub, D.

    2005-05-03

    The present invention is directed to an apparatus for the monitoring of the combustion process within a combustion system. The apparatus comprises; a combustion system, a means for supplying fuel and an oxidizer, a device for igniting the fuel and oxidizer in order to initiate combustion, and a sensor for determining the current conducted by the combustion process. The combustion system comprises a fuel nozzle and an outer shell attached to the combustion nozzle. The outer shell defines a combustion chamber. Preferably the nozzle is a lean premix fuel nozzle (LPN). Fuel and an oxidizer are provided to the fuel nozzle at separate rates. The fuel and oxidizer are ignited. A sensor positioned within the combustion system comprising at least two electrodes in spaced-apart relationship from one another. At least a portion of the combustion process or flame is between the first and second electrodes. A voltage is applied between the first and second electrodes and the magnitude of resulting current between the first and second electrodes is determined.

  18. Disposal of fluidized bed combustion ash in an underground mine to control acid mine drainage and subsidence - phase II - small scale field demonstration. Topical report, December 1, 1996--February 28, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Ziemkiewicz, P.F.; Head, W.J.; Gray, D.D.; Siriwardane, H.J.; Sack, W.A.

    1998-01-01

    It has been proposed that a mix made from fly and bottom ash from atmospheric pressure fluidized bed coal combusters (FBC ash), water, and stabilizers be injected from the surface into abandoned room and pillar coal mines through boreholes. Besides ash disposal, this process would prevent subsidence and acid mine drainage. Such a mix (called `grout`) needs to be an adequately stable and flowable suspension for it to spread and cover large areas in the mine. This is necessary as the drilling of the boreholes will be an expensive operation and the number such holes should be minimized. Addition of bentonite was found to be needed for this purpose. A suitable grout mix was tested rheologically to determine its fluid flow properties. Finding little published information on such materials, tests were performed using a commercial rotational viscometer with a T-bar rotor and a stand which produced a helical rotor path. Existing mixer viscometer test methods were modified and adapted to convert the measurements of torque vs. angular speed to the material properties appearing in several non-Newtonian constitutive equations. Yield stress was measured by an independent test called the vane method. The rheological behavior was a close fit to the Bingham fluid model. Bleed tests were conducted to ascertain the stability of the mixtures. Spread tests were conducted to compare the flowability of various mixes. Using the flow parameters determined in the laboratory, numerical simulations of grout flow were performed and compared with the results of scale model and field tests. A field injection of this grout was performed at the Fairfax mines in Preston county, W.V.. The observations there proved that this FBC ash grout flows as desired, is a very economical way of disposing the environmentally menacing ash, while also preventing the subsidence and acid mine drainage of the mines.

  19. Comparative sinterability of combustion synthesized and commercial titanium carbides

    International Nuclear Information System (INIS)

    The influence of various parameters on the sinterability of combustion synthesized titanium carbide was investigaged. Titanium carbide powders, prepared by the combustion synthesis process, were sintered in the temperature range 1150 to 16000C. Incomplete combustion and high oxygen contents were found to be the cause of reduced shrinkage during sintering of the combustion syntheized powders when compared to the shrinkage of commercial TiC. Free carbon was shown to inhibit shrinkage. The activation energy for sintering was found to depend on stoichiometry (C/Ti). With decreasing C/Ti, the rate of sintering increased. 29 references, 16 figures, 13 tables

  20. Effect of oxydesulphurization on the combustion characteristics of coal

    Energy Technology Data Exchange (ETDEWEB)

    Yaman, S.; Kucukbayrak, S. [Technical University of Istanbul, Istanbul (Turkey). Dept. of Chemical Engineering

    1997-06-01

    Desulphurization of a Turkish lignite by oxydesulphurization using dilute alkaline solutions, obtained by the extraction of fly ash with water, was carried out under 0-1.5 MPa partial pressure of oxygen at temperatures between 403 and 498 K for 30-90 min time intervals. The combustion characteristics of original and desulphurized lignite samples are compared using TGA. DTG curves were derived and the effects of desulphurization conditions such as temperature, partial pressure of oxygen and time on coal reactivity were studied. Ignition temperature, maximum combustion rate, combustion period, and the end temperature of combustion were considered. Relations between coal reactivity and removals of sulphur and ash contents were also studied.

  1. Chemical Kinetic Modeling of Biofuel Combustion

    Science.gov (United States)

    Sarathy, Subram Maniam

    Bioalcohols, such as bioethanol and biobutanol, are suitable replacements for gasoline, while biodiesel can replace petroleum diesel. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This study's contribution is experimentally validated chemical kinetic combustion mechanisms for biobutanol and biodiesel. Fundamental combustion data and chemical kinetic mechanisms are presented and discussed to improve our understanding of biofuel combustion. The net environmental impact of biobutanol (i.e., n-butanol) has not been studied extensively, so this study first assesses the sustainability of n-butanol derived from corn. The results indicate that technical advances in fuel production are required before commercializing biobutanol. The primary contribution of this research is new experimental data and a novel chemical kinetic mechanism for n-butanol combustion. The results indicate that under the given experimental conditions, n-butanol is consumed primarily via abstraction of hydrogen atoms to produce fuel radical molecules, which subsequently decompose to smaller hydrocarbon and oxygenated species. The hydroxyl moiety in n-butanol results in the direct production of the oxygenated species such as butanal, acetaldehyde, and formaldehyde. The formation of these compounds sequesters carbon from forming soot precursors, but they may introduce other adverse environmental and health effects. Biodiesel is a mixture of long chain fatty acid methyl esters derived from fats and oils. This research study presents high quality experimental data for one large fatty acid methyl ester, methyl decanoate, and models its combustion using an improved skeletal mechanism. The results indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which ultimately lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular

  2. Sandia Combustion Research: Technical review

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1995-07-01

    This report contains reports from research programs conducted at the Sandia Combustion Research Facility. Research is presented under the following topics: laser based diagnostics; combustion chemistry; reacting flow; combustion in engines and commercial burners; coal combustion; and industrial processing. Individual projects were processed separately for entry onto the DOE databases.

  3. The effects of dietary omega fatty acids on pregnancy rate, plasma prostaglandin metabolite levels, serum progesterone levels, and milk fatty-acid profile in beef cows.

    Science.gov (United States)

    Richardson, Gavin F; McNiven, Mary A; Petit, Hélène V; Duynisveld, John L

    2013-10-01

    The objectives were to determine the effects of feeding supplements rich in omega-6 or omega-3 fatty acids (FA) during the late gestation to the early postpartum and breeding periods on reproduction and milk FA profile in beef cows. For each of two years, at the beginning of period 1 (mid-December), 72 beef cows, calving in January or February, were assigned to diets supplemented with roasted flaxseed (Flax) or roasted soybean (Soybean). For each of two years, after 11 wk (end of period 1), 18 cows of 36 in the Flax group were switched to the soybean supplement and 18 cows of 36 in the Soybean group were switched to the flax supplement (start of Period 2). Cows were bred by timed artificial insemination (TAI) in week 5 of period 2. The FA composition of the milk reflected the FA profile of the oilseed supplements. There were no differences in pregnancy rates among the 4 groups. The treatments had no effect on plasma prostaglandin metabolite levels or ratios at 4 to 11 d postpartum. At 5 to 6 d post- TAI, pregnant cows fed Flax in period 1 had lower (P Flax in period 2 had higher (P < 0.05) serum progesterone levels at 5 to 6 d post-TAI than cows fed Soybean, but there was no difference at 19 to 20 d post-TAI. The dietary treatments had no effect on pregnancy rates, but there were some effects on plasma PGFM levels, PGFM to PGEM ratios, and serum progesterone levels. The FA supplements influenced the FA composition of milk. PMID:24124276

  4. Numerical models for the phenomenological study of flameless combustion

    Directory of Open Access Journals (Sweden)

    Bernardo Argemiro Herrera Múnera

    2010-07-01

    Full Text Available Flameless combustion is a technique which offers environmental advantages such as lower than 100 ppm NOx and CO emis- sions due to below 200 K temperature gradients. Flameless combustion also supplies higher than 70% energy efficiency. Knowledge of the phenomena in this combustion regime has been facilitated by using numerical simulation. This paper reviewed the specialised literature about the most commonly used turbulence, combustion, heat transfer and NOx formation models in modelling flameless combustion with CFD codes. The review concluded that the k-ε standard model is the most used for turbu- lence. Finite rate/eddy dissipation with modified constants and eddy dissipation concept models are suitable for combustion reac- tions, discrete ordinates and weighted sum gray gas (WSGG models are used for radiation and thermal, prompt and N2O inter- mediate models are used for NOx.

  5. Combustion of Jordanian oil shale using circulating fluidized bed

    International Nuclear Information System (INIS)

    this study re[resents design and manufacturing of a lab-scale circulating fluidized bed (C.F.B) to burn low grade fuel such as Jordanian oil shale. Hydrodynamic properties of C.F.B. were studied like minimum fluidization velocity, circulation flux and carryover rate. a hot run was firstly conducted by the combustion of L.P.G. to start up the combustion process. It proceeds until reaching the minimum burning temperature of oil shale particles, at which time the LPG supply was gradually reduced and oil shale feeding started. soon after reaching a self sustainable condition of oil shale particles, the LPG supply was cut off. The main combustion variables were investigated such as air to fuel ratios, temperature profiles across the bed, exhaust gas analysis and combustion efficiency. a combustion intensity of 859 kg/hr.m2 and combustion efficiency of 96% were achieved. (authors). 19 refs., 9 tab., 18 fig

  6. Free-radicals aided combustion with scramjet applications

    Science.gov (United States)

    Yang, Yongsheng; Kumar, Ramohalli

    1992-01-01

    Theoretical and experimental investigations aimed at altering 'nature-prescribed' combustion rates in hydrogen/hydrocarbon reactions with (enriched) air are presented. The intent is to anchor flame zones in supersonic streams, and to ensure proper and controllable complete combustion in scramjets. The diagnostics are nonintrusive through IR thermograms and acoustic emissions in the control and free-radicals altered flame zones.

  7. Fine particle emissions from residential wood combustion

    Energy Technology Data Exchange (ETDEWEB)

    Tissari, J.

    2008-07-01

    Residential wood combustion (RWC) appliances have the high probability of incomplete combustion, producing e.g. fine particles and hazardous organic compounds. In this thesis, the fine particle number and mass emissions, particle composition and morphology, and gas emissions were investigated from the modern (MMH) and conventional masonry heaters (CMH), sauna stoves (SS) and pellet burner. The investigation was based on laboratory and field experiments applying extensive and unique particle sampling methods. The appliance type, fuel and operational practices were found to affect clearly the fine particle emissions. In good combustion conditions (e.g. in pellet combustion), the fine particle mass (PM{sub 1}) emission factors were low, typically below 0.3 g kg-1, and over 90% of the PM{sub 1} consisted of inorganic compounds (i.e fine ash). From the CMH the typical PM{sub 1} values were 1.6-1.8 g kg-1, and from the SS 2.7-5.0 g kg-1, but were strongly dependent on operational practices. The smouldering combustion in CMH increased PM{sub 1} emission up to 10 g kg-1. The good secondary combustion in the MMH reduced the particle organic matter (POM) and gaseous emissions, but not substantially the elemental carbon (EC, i.e. soot) emission, and the typical PM{sub 1} values were 0.7-0.8 g kg-1. The particle number emissions were high, and did not correspond with the completition of combustion. The particle number distributions were mainly dominated by ultrafine (<100 nm) particles, but varied dependent on combustion conditions. The electronmicroscopy analyses showed that ultrafine particles were composed mainly of K, S and Zn. From the smouldering combustion, particles were composed mainly of carbon compounds and they had a closed sinteredlike structure, due to organic matter on the particles. Controlling the gasification rate via the primary air supply, log and batch size, as well as fuel moisture content, is important for the reduction of emissions in batch combustion

  8. Technical Report: Rayleigh Scattering Combustion Diagnostic

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Wyatt [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States); Hecht, Ethan [Sandia National Laboratories (SNL-NM), Albuquerque, NM (United States)

    2015-07-29

    A laser Rayleigh scattering (LRS) temperature diagnostic was developed over 8 weeks with the goal of studying oxy-combustion of pulverized coal char in high temperature reaction environments with high concentrations of carbon dioxide. Algorithms were developed to analyze data collected from the optical diagnostic system and convert the information to temperature measurements. When completed, the diagnostic will allow for the kinetic gasification rates of the oxy-combustion reaction to be obtained, which was previously not possible since the high concentrations of high temperature CO2 consumed thermocouples that were used to measure flame temperatures inside the flow reactor where the combustion and gasification reactions occur. These kinetic rates are important for studying oxycombustion processes suitable for application as sustainable energy solutions.

  9. Combustion Behaviour of Advanced Solid Propellants.

    Directory of Open Access Journals (Sweden)

    S. N. Asthana

    1993-07-01

    Full Text Available The study reports the effect of incorporation of Al and ammonium perchlorate (AP individually and in combination with each other on combustion pattern and specific impulse (Isp of minimum signature propellants. Incorporation of Al obviates the combustion instability problems; however, it has marginal effect on burning rates. The composition containing AP and zirconium silicate combination gives superior performance; however, its Isp is considerably lower than the composition incorporating 9 per cent AP. A combination of 6 per cent Al gave 20 per cent enhancement in burning rate and 12 s increase in Isp as compared to purely nitramine-based composition, cal-val results also reveal increase in energy output on incorporating AP and Al. Hot stage microscopic and propellant combustion studies indicate occurrence of intense decomposition reaction in case of AP-based compositions.

  10. SCR at bio fuel combustion

    International Nuclear Information System (INIS)

    In this project the cause for and the extent of catalyst deactivation has been investigated when using 100 % wood as fuel. The trend of deactivation has been studied as a function of the flue gas temperature, the type of catalyst and the type of combustion technique used. The field tests have been performed in the CFB boiler in Norrkoeping, firing forest residues, and in the boiler in Jordbro, firing pulverized wood (PC). Samples of four different commercial catalyst types have been exposed to flue gas in a test rig connected to the convection section of the boiler. The samples have been analysed at even time intervals. The results after 2 100 hours show a large difference in deactivation trend between the two plants; when using a conventional honeycomb catalyst 80 % of the original activity remains in the CFB boiler but only 20 % remains in the PC boiler. The deactivation in the CFB boiler is about 3 - 4 times faster than what is expected for a conservative design for a coal fired boiler. The results show that the general deactivation trend is similar for the plate and the honeycomb catalyst types. With a catalyst optimised for bio fuels the deactivation rate was about 2/3 compared with a conventional catalyst. At an operating temperature of 315 deg C the deactivation was not as rapid as at 370 deg C. The amount of easily dissolved potassium increases on the surface of the catalyst, especially in the PC boiler, and this is probably the reason for the deactivation. The total amount of potassium in the flue gas is about 5 times higher in the CFB boiler compared with the PC boiler. This indicates that only a certain form of potassium attacks the catalyst and that the total alkali content of the fuel is not a good indicator of the deactivation tendency. The potassium on the catalyst dissolves easily in both water and sulphuric acid. A wash of deactivated catalyst samples with water resulted in higher activity than for the fresh samples if the washing was supplemented

  11. Organic compounds in PM 2.5 emitted from fireplace and woodstove combustion of typical Portuguese wood species

    Science.gov (United States)

    Gonçalves, Cátia; Alves, Célia; Fernandes, Ana Patrícia; Monteiro, Cristina; Tarelho, Luís; Evtyugina, Margarita; Pio, Casimiro

    2011-09-01

    The aim of this study is the further characterisation of PM 2.5 emissions from the residential wood combustion of common woods grown in Portugal. This new research extends to eight the number of biomass fuels studied and tries to understand the differences that the burning appliance (fireplace versus woodstove) and the combustion temperature (cold and hot start) have on emissions. Pinus pinaster (Maritime pine), Eucalyptus globulus (eucalypt), Quercus suber (cork oak), Acacia longifolia (Golden wattle), Quercus faginea (Portuguese oak), Olea europea (Olive), Quercus ilex rotundifolia (Holm oak) and briquettes produced from forest biomass waste were used in the combustion tests. Determinations included fine particle emission factors, carbonaceous content (OC and EC) by a thermal-optical transmission technique and detailed identification and quantification of organic compounds by gas chromatography-mass spectrometry. Fine particle emission factors from the woodstove were lower than those from the fireplace. For both combustion appliances, the OC/EC ratio was higher in "cold start" tests (1.56 ± 0.95 for woodstove and 2.03 ± 1.34 for fireplace). These "cold start" OC/EC values were, respectively, for the woodstove and the fireplace, 51% and 69% higher than those obtained in "hot start" experiments. The chromatographically resolved organics included n-alkanes, n-alkenes, PAHs, n-alkanals, ketones, n-alkanols, terpenoids, triterpenoids, phenolic compounds, phytosterols, alcohols, n-alkanoic acids, n-di-acids, unsaturated acids and alkyl esters of acids. The smoke emission rate and composition varied widely depending on fuel type, burning appliance and combustion temperature.

  12. Effects of Docosahexaenoic Acid Supplementation on Blood Pressure, Heart Rate, and Serum Lipids in Scottish Men with Hypertension and Hypercholesterolemia

    Directory of Open Access Journals (Sweden)

    Miki Sagara

    2011-01-01

    Full Text Available To investigate the effects of daily supplementation with docosahexaenoic acid (DHA on coronary heart disease risks in 38 middle-aged men with hypertension and/or hypercholesterolemia in Scotland, a five-week double-blind placebo-controlled dietary supplementation with either 2 g of DHA or active placebo (1 g of olive oil was conducted. Percent composition of DHA in plasma phospholipids increased significantly in DHA group. Systolic and diastolic blood pressure and heart rate decreased significantly in DHA group, but not in placebo group. High-density lipoprotein cholesterol (HDL-C increased significantly, and total cholesterol (TC/HDL-C and non-HDL-C/HDL-C ratios decreased significantly in both groups. There was no change in TC and non-HDL-C. We conclude that 2 g/day of DHA supplementation reduced coronary heart disease risk factor level improving blood pressure, heart rate, and lipid profiles in hypertensive, hypercholesterolemic Scottish men who do not eat fish on a regular basis.

  13. Establishment of Combustion Model for Isooctane HCCI Marine Diesel Engine and Research on the Combustion Characteristic

    Directory of Open Access Journals (Sweden)

    Li Biao

    2016-01-01

    Full Text Available The homogeneous charge compression ignition (HCCI combustion mode applied in marine diesel engine is expected to be one of alternative technologies to decrease nitrogen oxide (NOX emission and improve energy utilization rate. Applying the chemical-looping combustion (CLC mechanism inside the cylinder, a numerical study on the HCCI combustion process is performed taking a marine diesel engine as application object. The characteristic feature of combustion process is displayed. On this basis, the formation and emission of NOX are analyzed and discussed. The results indicate that the HCCI combustion mode always exhibit two combustion releasing heats: low-temperature reaction and high-temperature reaction. The combustion phase is divided into low-temperature reaction zone, high-temperature reaction zone and negative temperature coefficient (NTC zone. The operating conditions of the high compression ratio, high intake air temperature, low inlet pressure and small excess air coefficient would cause the high in-cylinder pressure which often leads engine detonation. The low compression ratio, low intake air temperature and big excess air coefficient would cause the low combustor temperature which is conducive to reduce NOX emissions. These technological means and operating conditions are expected to meet the NOX emissions limits in MARPOL73/78 Convention-Annex VI Amendment.

  14. Shale oil combustion

    International Nuclear Information System (INIS)

    A 'coutant' carbon steel combustion chamber cooled by water jacket was conslructed to burn diesel fuel and mixlure of shale oil and diesel fuels. During experimental work nir fuel ratio was determined, temperaturces were measured using Chromel/ Almel thermocouple, finally the gasous combustion product analysis was carricd out using gas chromatograph technique. The constructed combustion chamber was operating salisfactory for several hours of continous work. According to the measurements it was found that: the flame temperature of a mixture of diesel and shale oil fuels was greater than the flame temperature of diesel fuel. and the sulfer emissious of a mixture of diesel and shale oil fuels was higher than that of diesel fuel. Calculation indicated that the dry gas energy loss was very high and the incomplete combustion energy loss very small. (author). 23 refs., 35 figs

  15. Improving combustion efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Bulsari, A.; Wemberg, A.; Multas, A. [Nonlinear Solutions Oy (Finland)

    2009-06-15

    The paper describes how nonlinear models are used to improve the efficiency of coal combustion while keeping NOx and other emissions under desired limits in the Naantali 2 boiler of Fortum Power and Heat Oy. 16 refs., 6 figs.

  16. Combustion within Porous Waste

    OpenAIRE

    Pfahl, Ulrich; Shepherd, Joseph E.; Unal, Cetin

    1998-01-01

    Flammable gases (primarily hydrogen and nitrous oxide but also ammonia and methane) are continuously being generated within the waste contained in the tank farms at Hanford Site. Some portions of the waste are porous and conceivably, a combustion event could occur within the waste due to accidental ignition. This has been postulated as a potential hazard since deflagrations and detonations are observed in laboratory experiments to propagate through combustible gases in porous materials, or ...

  17. Combustion gas scrubbing system

    Energy Technology Data Exchange (ETDEWEB)

    Dahlstrom, D.A.; Ellison, W.; Wilhelm, J.H.

    1979-04-03

    In a cooperative combination of two scrubbing systems, the first scrubbing system operates upon combustion gases with an aqueous solution to remove hydrogen chloride gas and other chlorine components. The second scrubbing system subsequently operates upon the combustion gases with a sodium-base solution to absorb sulfur oxides. The products of the two scrubbing systems are treated in combination to form a material for disposal and to generate the aqueous scrubbing solution for the chloride scrubbing system.

  18. Sandia Combustion Research Program

    Energy Technology Data Exchange (ETDEWEB)

    Johnston, S.C.; Palmer, R.E.; Montana, C.A. (eds.)

    1988-01-01

    During the late 1970s, in response to a national energy crisis, Sandia proposed to the US Department of Energy (DOE) a new, ambitious program in combustion research. Shortly thereafter, the Combustion Research Facility (CRF) was established at Sandia's Livermore location. Designated a ''user facility,'' the charter of the CRF was to develop and maintain special-purpose resources to support a nationwide initiative-involving US inventories, industry, and national laboratories--to improve our understanding and control of combustion. This report includes descriptions several research projects which have been simulated by working groups and involve the on-site participation of industry scientists. DOE's Industry Technology Fellowship program, supported through the Office of Energy Research, has been instrumental in the success of some of these joint efforts. The remainder of this report presents results of calendar year 1988, separated thematically into eleven categories. Referred journal articles appearing in print during 1988 and selected other publications are included at the end of Section 11. Our traditional'' research activities--combustion chemistry, reacting flows, diagnostics, engine and coal combustion--have been supplemented by a new effort aimed at understanding combustion-related issues in the management of toxic and hazardous materials.

  19. Caffeic Acid Reduces the Viability and Migration Rate of Oral Carcinoma Cells (SCC-25 Exposed to Low Concentrations of Ethanol

    Directory of Open Access Journals (Sweden)

    Arkadiusz Dziedzic

    2014-10-01

    Full Text Available Alcohol increases the risk of carcinoma originated from oral epithelium, but the biological effects of ultra-low doses of ethanol on existing carcinoma cells in combination with natural substances are still unclear. A role for ethanol (EtOH, taken in small amounts as an ingredient of some beverages or mouthwashes to change the growth behavior of established squamous cell carcinoma, has still not been examined sufficiently. We designed an in vitro study to determine the effect of caffeic acid (CFA on viability and migration ability of malignant oral epithelial keratinocytes, exposed to ultra-low concentrations (maximum 100 mmol/L EtOH. MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-dimethyltetrazolium bromide and LDH (lactate dehydrogenase assays were used to assess the cytotoxic effect of EtOH/CFA and the viability of squamous carcinoma SCC-25 cells (ATCC CRL-1628, mobile part of the tongue. Tested EtOH concentrations were: 2.5, 5, 10, 25, 50, and 100 mmol/L, along with an equal CFA concentration of 50 μmol/L. Carcinoma cells’ migration was investigated by monolayer “wound” healing assay. We demonstrated that very low concentrations of EtOH ranging between 2.5 and 10 mmol/L may induce the viability of oral squamous cell carcinoma cells, while the results following addition of CFA reveal an antagonistic effect, attenuating pro-proliferative EtOH activity. The migration rate of oral squamous carcinoma cells can be significantly inhibited by the biological activity of caffeic acid.

  20. Combustion Velocity of Benzine-Benzol-Air Mixtures in High-Speed Internal-Combustion Engines

    Science.gov (United States)

    Schnauffer, Kurt

    1932-01-01

    The present paper describes a device whereby rapid flame movement within an internal-combustion engine cylinder may be recorded and determined. By the aid of a simple cylindrical contact and an oscillograph the rate of combustion within the cylinder of an airplane engine during its normal operation may be measured for gas intake velocities of from 30 to 35 m/s and for velocities within the cylinder of from 20 to 25 m/s. With it the influence of mixture ratios, of turbulence, of compression ratio and kind of fuel on combustion velocity may be determined. Besides the determination of the influence of the above factors on combustion velocity, the degree of turbulence may also be determined. As a unit of reference in estimating the degree of turbulence, the intake velocity of the charge is chosen.

  1. Experimental and CFD investigation of gas phase freeboard combustion

    DEFF Research Database (Denmark)

    Andersen, Jimmy

    , but under well-defined conditions. Comprehensive experimental data for velocity field, temperatures, and gas composition are obtained from a 50 kW axisymmetric non-swirling natural gas fired combustion setup under two different settings. Ammonia is added to the combustion setup in order to simulate fuel......Reliable and accurate modeling capabilities for combustion systems are valuable tools for optimization of the combustion process. This work concerns primary precautions for reducing NO emissions, thereby abating the detrimental effects known as “acid rain”, and minimizing cost for flue gas...... treatment. The aim of this project is to provide validation data for Computational Fluid Dynamic (CFD) models relevant for grate firing combustion conditions. CFD modeling is a mathematical tool capable of predicting fluid flow, mixing and chemical reaction with thermal conversion and transport. Prediction...

  2. Numerical analysis of combustion characteristics of hybrid rocket motor with multi-section swirl injection

    Science.gov (United States)

    Li, Chengen; Cai, Guobiao; Tian, Hui

    2016-06-01

    This paper is aimed to analyse the combustion characteristics of hybrid rocket motor with multi-section swirl injection by simulating the combustion flow field. Numerical combustion flow field and combustion performance parameters are obtained through three-dimensional numerical simulations based on a steady numerical model proposed in this paper. The hybrid rocket motor adopts 98% hydrogen peroxide and polyethylene as the propellants. Multiple injection sections are set along the axis of the solid fuel grain, and the oxidizer enters the combustion chamber by means of tangential injection via the injector ports in the injection sections. Simulation results indicate that the combustion flow field structure of the hybrid rocket motor could be improved by multi-section swirl injection method. The transformation of the combustion flow field can greatly increase the fuel regression rate and the combustion efficiency. The average fuel regression rate of the motor with multi-section swirl injection is improved by 8.37 times compared with that of the motor with conventional head-end irrotational injection. The combustion efficiency is increased to 95.73%. Besides, the simulation results also indicate that (1) the additional injection sections can increase the fuel regression rate and the combustion efficiency; (2) the upstream offset of the injection sections reduces the combustion efficiency; and (3) the fuel regression rate and the combustion efficiency decrease with the reduction of the number of injector ports in each injection section.

  3. Continuous dissolution of irradiated nuclear fuels; Dissolution continue des combustibles nucleaires irradies

    Energy Technology Data Exchange (ETDEWEB)

    Michel, P.; Talmont, X.; Tarnerq, M. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1967-07-01

    In the case of the continuous dissolution of nuclear fuels, the equations for the calculation of the fuel concentration of the solution flowing out of a pot dissolver have been written. Nitric acid feed flow rates have been calculated in order to obtain an adjusted solution when starting or stopping a dissolution, or when changing the number of rods introduced per hour. Then some transient states brought on by perturbations, have been studied: a) sudden change in nitric acid flow rate; b) continuous drift of the latter; c) sudden change in nitric acid feed concentration; d) transition from a fuel concentration to another by changing the flow rate of nitric acid feed. It has been shown that some transient states cannot be solved with general equations. Computer calculation programs would be probably more useful. (authors) [French] L'etude se rapporte a la dissolution dans l'acide nitrique des combustibles nucleaires irradies, en vue de la recuperation de la matiere fissile qu'ils contiennent. On a etabli, dans le cas de la dissolution continue, les differentes equations permettant le calcul de la concentration en combustible a la sortie d'un dissolveur du type 'marmite'. On a etudie les regimes du debit d'alimentation en acide nitrique a imposer lors du demarrage, de l'arret d'une dissolution, ou lors d'un changement de cadence d'introduction des barreaux, de facon a obtenir une solution ajustee. On a etudie ensuite differents regimes transitoires consecutifs a des perturbations: changement brusque du debit d'acide d'alimentation, derive continue de ce debit, changement brusque de la concentration de l'acide d'alimentation, passage d'une concentration en combustible a une autre par changement du debit d'acide d'alimentation. On a pu montrer que certains regimes transitoires ne peuvent se traiter par des equations generales, et necessiteraient plustot l'etablissement d

  4. The PDF method for turbulent combustion

    Science.gov (United States)

    Pope, S. B.

    1991-01-01

    Probability Density Function (PDF) methods provide a means of calculating the properties of turbulent reacting flows. They have been successfully applied to many turbulent flames, including some with finite rate kinetic effects. Here the methods are reviewed with an emphasis on computational issues and their application to turbulent combustion.

  5. Effect of Arachidonic Acid on the Rate of Oxygen Consumption in Isolated Cardiomyocytes from Intact Rats and Animals with Ischemic or Diabetic Injury to the Heart.

    Science.gov (United States)

    Egorova, M V; Kutsykova, T V; Afanas'ev, S A; Popov, S V

    2015-12-01

    We studied the rate of oxygen consumption by isolated cardiomyocytes from intact rats and animals with experimental myocardial infarction or streptozotocin-induced diabetes mellitus. The measurements were performed in standard incubation medium under various conditions of oxygenation and after addition of arachidonic acid (20 μmol/liter). Under normoxic conditions, arachidonic acid improves respiration of cardiomyocytes from intact animals, but reduces this parameter in cells isolated from animals with pathologies. The intensity of O2 consumption by cardiomyocytes from intact rats and animals with pathologies was shown to decrease during hypoxia. Addition of arachidonic acid aggravated inhibition of respiration for cardiomyocytes from intact rats and specimens with myocardial infarction, but had no effect in diabetes mellitus. The effect of arachidonic acid on oxygen consumption rate is probably mediated by a nonspecific mechanism realized at the mitochondrial level.

  6. Chemical Kinetic Modeling of 2-Methylhexane Combustion

    KAUST Repository

    Mohamed, Samah Y.

    2015-03-30

    Accurate chemical kinetic combustion models of lightly branched alkanes (e.g., 2-methylalkanes) are important for investigating the combustion behavior of diesel, gasoline, and aviation fuels. Improving the fidelity of existing kinetic models is a necessity, as new experiments and advanced theories show inaccuracy in certain portions of the models. This study focuses on updating thermodynamic data and kinetic model for a gasoline surrogate fuel, 2-methylhexane, with recently published group values and rate rules. These update provides a better agreement with rapid compression machine measurements of ignition delay time, while also strengthening the fundamental basis of the model.

  7. Kinetic data base for combustion modeling

    Energy Technology Data Exchange (ETDEWEB)

    Tsang, W.; Herron, J.T. [National Institute of Standards and Technology, Gaithersburg, MD (United States)

    1993-12-01

    The aim of this work is to develop a set of evaluated rate constants for use in the simulation of hydrocarbon combustion. The approach has been to begin with the small molecules and then introduce larger species with the various structural elements that can be found in all hydrocarbon fuels and decomposition products. Currently, the data base contains most of the species present in combustion systems with up to four carbon atoms. Thus, practically all the structural grouping found in aliphatic compounds have now been captured. The direction of future work is the addition of aromatic compounds to the data base.

  8. THE COMBUSTION CHARACTERISTICS OF LIGNITE BLENDS

    Institute of Scientific and Technical Information of China (English)

    Cheng Jun; Zhou Junhu; Cao Xinyu; Cen Kefa

    2000-01-01

    The combustion characteristics of lignite blends were studied with a thermogravimetric analyzer (t.g.a.), at constant heating rate.The characteristic temperatures were determined from the burning profiles.It was found that the characteristic times of combustion reaction moved forward, the ignition temperature dropped and the burnout efficiency slightly changed when blending lignites.The characteristic parameters of blends could not be predicted as a linear function of the average values of the individual lignites.when blending with less reactive coal, the ignition and burnout characteristics of lignite turned worse.

  9. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Science.gov (United States)

    Provine, J.; Schindler, Peter; Kim, Yongmin; Walch, Steve P.; Kim, Hyo Jin; Kim, Ki-Hyun; Prinz, Fritz B.

    2016-06-01

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD) of silicon nitride (SiNx), particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER) in hydrofluoric (HF) acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD) of SiNx and evaluate the film's WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  10. Modeling the impact of paste additives and pellet geometry on paste utilization within lead acid batteries during low rate discharges

    Science.gov (United States)

    Vargonen, Muhammed M.

    2015-01-01

    When designing a lead acid battery, there are many factors to consider in order to obtain the best compromise of cost, performance, and ease of manufacturability. We use a modeling approach to study some of the key factors which affect the amount of active material which can be utilized during a low rate discharge. We investigate the effects of pellet size, pellet geometry, disconnected grid mesh borders, and inert paste additives. Furthermore, we look at how the internal path length resistance within a pellet is dependent on those features. Our findings correlate well with earlier works, and help to explain some of the previously observed phenomenon. It is observed that utilization is indeed affected by pellet size, but small grid mesh sizes on the order of ∼4 mm edge lengths are necessary in order to realize a significant benefit. Utilization is presented as a function of pellet size, aspect ratio of the pellets, and the loading level of the inert additives in the pellets up to ten percent by volume.

  11. Correlation of film density and wet etch rate in hydrofluoric acid of plasma enhanced atomic layer deposited silicon nitride

    Directory of Open Access Journals (Sweden)

    J. Provine

    2016-06-01

    Full Text Available The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposition (ALD of silicon nitride (SiNx, particularly for use a low k dielectric spacer. One of the key material properties needed for SiNx films is a low wet etch rate (WER in hydrofluoric (HF acid. In this work, we report on the evaluation of multiple precursors for plasma enhanced atomic layer deposition (PEALD of SiNx and evaluate the film’s WER in 100:1 dilutions of HF in H2O. The remote plasma capability available in PEALD, enabled controlling the density of the SiNx film. Namely, prolonged plasma exposure made films denser which corresponded to lower WER in a systematic fashion. We determined that there is a strong correlation between WER and the density of the film that extends across multiple precursors, PEALD reactors, and a variety of process conditions. Limiting all steps in the deposition to a maximum temperature of 350 °C, it was shown to be possible to achieve a WER in PEALD SiNx of 6.1 Å/min, which is similar to WER of SiNx from LPCVD reactions at 850 °C.

  12. Combustion and regulation; Combustion et reglementation

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    This conference was organized after the publication of the French by-law no 2010 relative to combustion installations and to the abatement of atmospheric pollution. Five topics were discussed during the conference: the new regulations, their content, innovations and modalities of application; the means of energy suppliers to face the new provisions and their schedule; the manufacturers proposals for existing installations and the new equipments; the administration control; and the impact of the new measures on exploitation and engineering. Twenty papers and 2 journal articles are reported in these proceedings. (J.S.)

  13. Co-combustion of waste materials using fluidized bed technology

    Energy Technology Data Exchange (ETDEWEB)

    M. Lopes; I. Gulyurtlu; P. Abelha; T. Crujeira; D. Boavida; I. Cabrita [INETI-DEECA, Lisbon (Portugal)

    2004-07-01

    There is growing interest in using renewable fuels in order to sustain the CO{sub 2} accumulation. Several waste materials can be used as coal substitutes as long as they contain significant combustible matter, as for example MSW and sewage sludge. Besides the outcome of the energetic valorization of such materials, combustion must be regarded as a pre-treatment process, contributing to the safe management of wastes. Landfilling is an expensive management option and requires a previous destruction of the organic matter present in residues, since its degradation generates greenhouse gases and produces acidic organic leachates. Fluidized bed combustion is a promising technology for the use of mixtures of coal and combustible wastes. This paper presents INETI's experience in the co-combustion of coal with this kind of residues performed in a pilot fluidized bed. Both the RDF (from MSW and sewage sludge) and sewage sludge combustion problems were addressed, relating the gaseous emissions, the behaviour of metals and the leachability of ashes and a comparison was made between co-combustion and mono-combustion in order to verify the influence of the utilization of coal. 9 refs., 1 fig., 3 tabs.

  14. Studies on Selection of Combustion-supporting Agent in the Combustion Heat Test of Boron Powder%硼粉燃烧热测试中助燃剂选取的研究

    Institute of Scientific and Technical Information of China (English)

    张勤林; 袁红春; 楼旭俊; 王春红; 王英红

    2012-01-01

    为了提高助燃法测试硼粉燃烧热值的准确性,探寻助燃剂选取的规律原则,分别选用含硼推进剂研制领域常见的苯甲酸、90方片药、镁粉、某火箭推进剂测试标准药四种物质作为助燃剂,采用于法和湿法两种混合方式,在GR3500氧弹量热计中测试了95级无定形硼粉的燃烧热,进行对比实验研究.结果显示:不加助燃剂,直接测试硼粉燃烧热,点火失败;采用不同的助燃剂,硼粉的燃烧效率不同.分析认为选择的助燃剂应具有易引燃、高热值、高燃温、低成气率的特点,同时燃速应和硼粉相匹配,化学性质应和硼粉具有良好的相容性.另外,混合试样中,助燃剂和硼粉结合地越紧密,混合地越均匀,越能发挥助燃作用.相比于干法混合,温法混合制作固态药条试样测试硼粉燃烧热值时,硼粉燃烧效率更高.%In order to improve the accuracy of the test of combustion heat value of boron powder using combustion-supporting agent and to explore the principles of combustion-supporting agent selection, four substances commonly used in the field of developing boron-containing propellant, such as benzoic acid, 90 square tablet, magnesium powder, and a standard drug in rocket propellant test were selected to be combustion-supporting agents respectively, two methods namely dry mixing and wet mixing were used, the combustion heat value of amorphous boron powder with 95 grade was tested in GR3500 oxygen bomb calorimeter, and comparative experimental study was then studied. The results show that the ignition failed when directly testing the combustion heat value of boron powder without combustion-supporting agent, and the combustion efficiency of the boron powder is different when using different combustion-supporting agent. The conclusions are that the selected combustion-supporting agent should be easy to ignite, having high heat value, high ignition temperature, and low gas rates, burning rate of which

  15. Combustible structural composites and methods of forming combustible structural composites

    Science.gov (United States)

    Daniels, Michael A.; Heaps, Ronald J.; Steffler, Eric D; Swank, William D.

    2011-08-30

    Combustible structural composites and methods of forming same are disclosed. In an embodiment, a combustible structural composite includes combustible material comprising a fuel metal and a metal oxide. The fuel metal is present in the combustible material at a weight ratio from 1:9 to 1:1 of the fuel metal to the metal oxide. The fuel metal and the metal oxide are capable of exothermically reacting upon application of energy at or above a threshold value to support self-sustaining combustion of the combustible material within the combustible structural composite. Structural-reinforcing fibers are present in the composite at a weight ratio from 1:20 to 10:1 of the structural-reinforcing fibers to the combustible material. Other embodiments and aspects are disclosed.

  16. Combustion modeling in a model combustor

    Institute of Scientific and Technical Information of China (English)

    L.Y.Jiang; I.Campbell; K.Su

    2007-01-01

    The flow-field of a propane-air diffusion flame combustor with interior and exterior conjugate heat transfers was numerically studied.Results obtained from four combustion models,combined with the re-normalization group (RNG) k-ε turbulence model,discrete ordinates radiation model and enhanced wall treatment are presented and discussed.The results are compared with a comprehensive database obtained from a series of experimental measurements.The flow patterns and the recirculation zone length in the combustion chamber are accurately predicted,and the mean axial velocities are in fairly good agreement with the experimental data,particularly at downstream sections for all four combustion models.The mean temperature profiles are captured fairly well by the eddy dissipation (EDS),probability density function (PDF),and laminar flamelet combustion models.However,the EDS-finite-rate combustion model fails to provide an acceptable temperature field.In general,the flamelet model illustrates little superiority over the PDF model,and to some extent the PDF model shows better performance than the EDS model.

  17. Modeling internal ballistics of gas combustion guns.

    Science.gov (United States)

    Schorge, Volker; Grossjohann, Rico; Schönekess, Holger C; Herbst, Jörg; Bockholdt, Britta; Ekkernkamp, Axel; Frank, Matthias

    2016-05-01

    Potato guns are popular homemade guns which work on the principle of gas combustion. They are usually constructed for recreational rather than criminal purposes. Yet some serious injuries and fatalities due to these guns are reported. As information on the internal ballistics of homemade gas combustion-powered guns is scarce, it is the aim of this work to provide an experimental model of the internal ballistics of these devices and to investigate their basic physical parameters. A gas combustion gun was constructed with a steel tube as the main component. Gas/air mixtures of acetylene, hydrogen, and ethylene were used as propellants for discharging a 46-mm caliber test projectile. Gas pressure in the combustion chamber was captured with a piezoelectric pressure sensor. Projectile velocity was measured with a ballistic speed measurement system. The maximum gas pressure, the maximum rate of pressure rise, the time parameters of the pressure curve, and the velocity and path of the projectile through the barrel as a function of time were determined according to the pressure-time curve. The maximum gas pressure was measured to be between 1.4 bar (ethylene) and 4.5 bar (acetylene). The highest maximum rate of pressure rise was determined for hydrogen at (dp/dt)max = 607 bar/s. The muzzle energy was calculated to be between 67 J (ethylene) and 204 J (acetylene). To conclude, this work provides basic information on the internal ballistics of homemade gas combustion guns. The risk of injury to the operator or bystanders is high, because accidental explosions of the gun due to the high-pressure rise during combustion of the gas/air mixture may occur. PMID:26239103

  18. Studies in combustion dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Koszykowski, M.L. [Sandia National Laboratories, Livermore, CA (United States)

    1993-12-01

    The goal of this program is to develop a fundamental understanding and a quantitative predictive capability in combustion modeling. A large part of the understanding of the chemistry of combustion processes comes from {open_quotes}chemical kinetic modeling.{close_quotes} However, successful modeling is not an isolated activity. It necessarily involves the integration of methods and results from several diverse disciplines and activities including theoretical chemistry, elementary reaction kinetics, fluid mechanics and computational science. Recently the authors have developed and utilized new tools for parallel processing to implement the first numerical model of a turbulent diffusion flame including a {open_quotes}full{close_quotes} chemical mechanism.

  19. Alcohol combustion chemistry

    KAUST Repository

    Sarathy, Mani

    2014-10-01

    Alternative transportation fuels, preferably from renewable sources, include alcohols with up to five or even more carbon atoms. They are considered promising because they can be derived from biological matter via established and new processes. In addition, many of their physical-chemical properties are compatible with the requirements of modern engines, which make them attractive either as replacements for fossil fuels or as fuel additives. Indeed, alcohol fuels have been used since the early years of automobile production, particularly in Brazil, where ethanol has a long history of use as an automobile fuel. Recently, increasing attention has been paid to the use of non-petroleum-based fuels made from biological sources, including alcohols (predominantly ethanol), as important liquid biofuels. Today, the ethanol fuel that is offered in the market is mainly made from sugar cane or corn. Its production as a first-generation biofuel, especially in North America, has been associated with publicly discussed drawbacks, such as reduction in the food supply, need for fertilization, extensive water usage, and other ecological concerns. More environmentally friendly processes are being considered to produce alcohols from inedible plants or plant parts on wasteland. While biofuel production and its use (especially ethanol and biodiesel) in internal combustion engines have been the focus of several recent reviews, a dedicated overview and summary of research on alcohol combustion chemistry is still lacking. Besides ethanol, many linear and branched members of the alcohol family, from methanol to hexanols, have been studied, with a particular emphasis on butanols. These fuels and their combustion properties, including their ignition, flame propagation, and extinction characteristics, their pyrolysis and oxidation reactions, and their potential to produce pollutant emissions have been intensively investigated in dedicated experiments on the laboratory and the engine scale

  20. Effect of dose-rate of gamma irradiation (60Co) on the anti nutritional compounds phytic acid and antitrypsin on soybean (glycine max L.)

    International Nuclear Information System (INIS)

    An investigation on the effect of gamma irradiation at different dose-rate on the anti-nutritional compounds (phytic acid and antitrypsin) and the color of soybean has been conducted. The purpose of the study was to analyze the influence of the dose-rate on the rate of change of anti-nutritional compounds and color. Samples were irradiated with dose-rates of 1.30; 3.17; 5.71 and 8.82 kGy/hour with irradiation time varied from 0.5 to 55 hours. Phytic acid content and antitrypsin activity, as well as their L α b color values were analyzed. Results showed that a simple first order kinetics model can be used to describe changes in the concentration of the anti-nutritional compounds and color soybeans during the radiation processing. Data indicate that irradiation process at higher dose-rate (shorter time) is more effective in destroying anti-nutritional compounds as compared to that of irradiation process at lower dose-rate (longer time). Furthermore, irradiation process at higher dose-rate (shorter time) also have less detrimental effect on color of the soybean and the resulted soybean flour as compared to that of irradiation process at lower dose-rate (longer time). These findings suggest that irradiation process at a same dose may potentially be optimized by selecting the most appropriate combination of dose-rate and time of irradiation. (author)

  1. Toxicology of Biodiesel Combustion products

    Science.gov (United States)

    1. Introduction The toxicology of combusted biodiesel is an emerging field. Much of the current knowledge about biological responses and health effects stems from studies of exposures to other fuel sources (typically petroleum diesel, gasoline, and wood) incompletely combusted. ...

  2. Evaluation and Optimization of Amino Acids Retention Rate of Japanese Scallop Powder with Different Food Additives in Spray-drying Process by Response Surface Method

    Directory of Open Access Journals (Sweden)

    Jianfeng Sun

    2014-01-01

    Full Text Available Spray-drying process for Japanese scallop powder can cause damage because of its heat-sensitive components such as amino acids. Therefore it is important for amino acids to be embedded with the appropriate food additives in spray-drying process. In this study, with Japanese scallop as the raw, Response Surface Method (RSM with three variables (the addition level of &beta-cyclodextrin, modified starch and CMC was used to investigate the effect of food additives on the amino acids retention rate in Japanese scallop powder in spray drying. The equation model to predict amino acids retention rate was reported. The results showed that the optimal addition level of &beta-cyclodextrin, modified starch and CMC were 25.55, 24.55 and 2.96%, respectively. And the amino acids retention rate was 56.75±0.64%. This model was testified to fit the actual situation preferably, therefore it can provide theoretical and practical basis for industrial production of Japanese scallop powder.

  3. Pulverized straw combustion in a low-NOx multifuel burner

    DEFF Research Database (Denmark)

    Mandø, Matthias; Rosendahl, Lasse; Yin, Chungen;

    2010-01-01

    and shape distribution is the most influential parameter for the correct prediction of straw combustion. The inlet boundary conditions and the application of a turbulence modulation model can significantly affect the predicted combustion efficiency whereas the choice of devolatilization parameters was found......A CFD simulation of pulverized coal and straw combustion using a commercial multifuel burner have been undertaken to examine the difference in combustion characteristics. Focus has also been directed to development of the modeling technique to deal with larger non-spherical straw particles...... and to determine the relative importance of different modeling choices for straw combustion. Investigated modeling choices encompass the particle size and shape distribution, the modification of particle motion and heating due to the departure from the spherical ideal, the devolatilization rate of straw...

  4. Nonlinear Combustion Instability Prediction

    Science.gov (United States)

    Flandro, Gary

    2010-01-01

    The liquid rocket engine stability prediction software (LCI) predicts combustion stability of systems using LOX-LH2 propellants. Both longitudinal and transverse mode stability characteristics are calculated. This software has the unique feature of being able to predict system limit amplitude.

  5. Coal combustion research

    Energy Technology Data Exchange (ETDEWEB)

    Daw, C.S.

    1996-06-01

    This section describes research and development related to coal combustion being performed for the Fossil Energy Program under the direction of the Morgantown Energy Technology Center. The key activity involves the application of chaos theory for the diagnosis and control of fossil energy processes.

  6. Combustion Models in Finance

    CERN Document Server

    Tannous, C

    2001-01-01

    Combustion reaction kinetics models are used for the description of a special class of bursty Financial Time Series. The small number of parameters they depend upon enable financial analysts to predict the time as well as the magnitude of the jump of the value of the portfolio. Several Financial Time Series are analysed within this framework and applications are given.

  7. Propagated fixed-bed mixed-acid fermentation: Part I: Effect of volatile solid loading rate and agitation at high pH.

    Science.gov (United States)

    Golub, Kristina W; Forrest, Andrea K; Mercy, Kevin L; Holtzapple, Mark T

    2011-11-01

    Countercurrent fermentation is a high performing process design for mixed-acid fermentation. However, there are high operating costs associated with moving solids, which is an integral component of this configuration. This study investigated the effect of volatile solid loading rate (VSLR) and agitation in propagated fixed-bed fermentation, a configuration which may be more commercially viable. To evaluate the role of agitation on fixed-bed configuration performance, continuous mixing was compared with periodic mixing. VSLR was also varied and not found to affect acid yields. However, increased VSLR and liquid retention time did result in higher conversions, productivity, acid concentrations, but lower selectivities. Agitation was demonstrated to be important for this fermentor configuration, the periodically-mixed fermentation had the lowest conversion and yields. Operating at a high pH (∼9) contributed to the high selectivity to acetic acid, which might be industrially desirable but at the cost of lower yield compared to a neutral pH.

  8. Burning characteristics of microcellular combustible objects

    Institute of Scientific and Technical Information of China (English)

    Wei-tao YANG; Yu-xiang LI; San-jiu YING

    2014-01-01

    Microcellular combustible objects for application of combustible case, caseless ammunition or combustible detonator-holding tubes are fabricated through one-step foaming process, in which supercritical CO2 is used as foaming agent. The formulations consist of inert polymer binder and ultra fine RDX. For the inner porous structures of microcellular combustible objects, the cell sizes present a unimodal or bimodal distribution by adjusting the foaming conditions. Closed bomb test is to investigate the influence of both porous structure style and RDX content on burning behavior. The sample with bimodal distribution of cell sizes burns faster than that with unimodal distribution, and the concentration of RDX can influence the burning characteristics in a positive manner. In addition, the translation of laminar burning to convective burning is determined by burning rate versus pressure curves of samples at two different loading densities, and the resulting transition pressure is 30 MPa. Moreover, the samples with bigger sample size present higher burning rate, resulting in providing deeper convective depth. Dynamic vivacity of samples is also studied. The results show that the vivacity increases with RDX content and varies with inner structure.

  9. Burning characteristics of microcellular combustible objects

    Directory of Open Access Journals (Sweden)

    Wei-tao Yang

    2014-06-01

    Full Text Available Microcellular combustible objects for application of combustible case, caseless ammunition or combustible detonator-holding tubes are fabricated through one-step foaming process, in which supercritical CO2 is used as foaming agent. The formulations consist of inert polymer binder and ultra fine RDX. For the inner porous structures of microcellular combustible objects, the cell sizes present a unimodal or bimodal distribution by adjusting the foaming conditions. Closed bomb test is to investigate the influence of both porous structure style and RDX content on burning behavior. The sample with bimodal distribution of cell sizes burns faster than that with unimodal distribution, and the concentration of RDX can influence the burning characteristics in a positive manner. In addition, the translation of laminar burning to convective burning is determined by burning rate versus pressure curves of samples at two different loading densities, and the resulting transition pressure is 30 MPa. Moreover, the samples with bigger sample size present higher burning rate, resulting in providing deeper convective depth. Dynamic vivacity of samples is also studied. The results show that the vivacity increases with RDX content and varies with inner structure.

  10. Fundamental Aspects of Droplet Combustion Modelling

    Directory of Open Access Journals (Sweden)

    Shah Shahood Alam

    2014-11-01

    Full Text Available The present paper deals with important aspects of liquid droplet evaporation and combustion. A detailed spherically symmetric, single component droplet combustion model is evolved first by solving time dependent energy and species conservation equations in the gas phase using finite difference technique. Results indicate that the flame diameter F first increases and then decreases and the square of droplet diameter decreases linearly with time. Also, the FD/ ratio increases throughout the droplet burning period unlike the quasi-steady model where it assumes a large constant value. The spherically symmetric model is then extended to include the effects of forced convection. Plots of 2 D and droplet mass burning rate mf versus time are obtained for steady state, droplet heating and heating with convection cases for a n-octane droplet of 1.3 mm diameter burning in standard atmosphere. It is observed that the mass burning rate is highest for forced convective case and lowest for droplet heating case. The corresponding values of droplet lifetime follow the inverse relationship with the mass burning rate as expected. Emission data for a spherically symmetric, 100 m n-heptane droplet burning in air are determined using the present gas phase model in conjunction with the Olikara and Borman code [1] with the aim of providing a qualitative trend rather than quantitative with a simplified approach. It is observed that the products of combustion maximise in the reaction zone and NO concentration is very sensitive to the flame temperature. This paper also discusses the general methodology and basic governing equations for analysing multicomponent and high pressure droplet vaporisation/combustion in a comprehensible manner. The results of the present study compare fairly well with the experimental/theoretical observations of other authors for the same conditions. The droplet sub models developed in the present work are accurate and yet simple for their

  11. Geochemical Rate/RNA Integration Study (GRIST): A Pilot Field Experiment for Inter-Calibration of Biogeochemistry and Nucleic Acid Measurements Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Bronk, Deborah

    2007-01-08

    The Geochemical Rate/RNA Integration Study (GRIST) project sought to correlate biogeochemical flux rates with measurements of gene expression and mRNA abundance to demonstrate the application of molecular approaches to estimate the presence and magnitude of a suite of biogeochemical processes. The study was headed by Lee Kerkhoff of Rutgers University. In this component of the GRIST study, we characterized ambient nutrient concentrations and measured uptake rates for dissolved inorganic nitrogen (DIN, ammonium, nitrate and nitrite) and dissolved organic nitrogen (urea and dissolved free amino acids) during two diel studies at the Long-Term Ecosystem Observatory (LEO-15) on the New Jersey continental shelf.

  12. Combustion calorimetry experimental chemical thermodynamics

    CERN Document Server

    Sunner, Stig

    1979-01-01

    Combustion Calorimetry deals with expertise knowledge concerning the calorimetry of combustion reactions of an element or compound. After defining the use of units and physical constants, the book discusses the basic principles of combustion calorimetry and the various instruments and calorimeters used in the experiments to measure operations concerning temperatures and its time variations. One paper discusses the theory and design criteria of combustion calorimeter calibration. Another paper discusses the results obtained from a combustion calorimeter after it has measured the energy or entha

  13. Modelling of CWS combustion process

    Science.gov (United States)

    Rybenko, I. A.; Ermakova, L. A.

    2016-10-01

    The paper considers the combustion process of coal water slurry (CWS) drops. The physico-chemical process scheme consisting of several independent parallel-sequential stages is offered. This scheme of drops combustion process is proved by the particle size distribution test and research stereomicroscopic analysis of combustion products. The results of mathematical modelling and optimization of stationary regimes of CWS combustion are provided. During modeling the problem of defining possible equilibrium composition of products, which can be obtained as a result of CWS combustion processes at different temperatures, is solved.

  14. Heat regenerative external combustion engine

    Science.gov (United States)

    Duva, Anthony W.

    1993-10-01

    A heat regenerative external combustion engine is disclosed. The engine includes fuel inlet means which extends along the exhaust passage and/or combustion chamber in order to preheat the fuel, To provide for preheating by gases in both the combustion chamber and the exhaust passage, the combustion chamber is arranged annularly around the drive shaft and between the cylinders. This configuration also is advantageous in that it reduces the noise of combustion. The engine of the invention is particularly well-suited for use in a torpedo.

  15. Effects of dietary fatty acid composition on metabolic rate and responses to hypoxia in the European eel (Anguilla anguilla)

    DEFF Research Database (Denmark)

    McKenzie, D.J.; Piraccini, G.; Piccolella, M.;

    2000-01-01

    European eels (Anguilla anguilla, L.) were fed on a commercial diet supplemented either with 15% by dry feed weight of menhaden oil (MO), an oil rich in highly unsaturated fatty acids of the n-3 series (n-3 HUFA), or with 15% by dry feed weight of coconut oil (CO), an oil composed primarily...... of saturated fatty acids (SFA). Following 90 days of feeding, the mean final masses of eels fed the two different oil supplements were similar, and higher than the mean final mass of a group fed the commercial diet alone. The diets created two distinct phenotypes of eels, distinguished by the fatty acid (FA...

  16. Update of the water chemistry effect on the flow-accelerated corrosion rate of carbon steel: influence of hydrazine, boric acid, ammonia, morpholine and ethanolamine

    International Nuclear Information System (INIS)

    The influence of the water chemistry on Flow-Accelerated Corrosion (FAC) affecting carbon steel components has been studied for many years and is relatively well known and taken into account by the models. Nonetheless, experimental studies were conducted in the last few years at EDF on the CIROCO loop in order to check the influence of the water chemistry parameters (hydrazine, boric acid, ammonia, morpholine and ethanolamine) on the FAC rate of carbon steel in one phase flow conditions. The hydrazine impact on the FAC rate was shown to be minor in EDF's chemistry recommendation range, compared to other parameters' effects such as the pH effect. The presence of boric acid in the nominal secondary circuit conditions was negligible. Finally, as expected, the nature of the chemical conditioning (ammonia, morpholine or ethanolamine) did not modify the FAC rate, the influencing chemical variable being the at-temperature pH in one-phase flow conditions. (author)

  17. Oxy-Combustion Boiler Material Development

    Energy Technology Data Exchange (ETDEWEB)

    Michael Gagliano; Andrew Seltzer; Hans Agarwal; Archie Robertson; Lun Wang

    2012-01-31

    Under U.S. Department of Energy Cooperative Agreement No. DE-NT0005262 Foster Wheeler North America Corp conducted a laboratory test program to determine the effect of oxy-combustion on boiler tube corrosion. In this program, CFD modeling was used to predict the gas compositions that will exist throughout and along the walls of air-fired and oxy-fired boilers operating with low to high sulfur coals. Test coupons of boiler tube materials were coated with deposits representative of those coals and exposed to the CFD predicted flue gases for up to 1000 hours. The tests were conducted in electric tube furnaces using oxy-combustion and air-fired flue gases synthesized from pressurized cylinders. Following exposure, the test coupons were evaluated to determine the total metal wastage experienced under air and oxy-combustions conditions and materials recommendations were made. Similar to air-fired operation, oxy-combustion corrosion rates were found to vary with the boiler material, test temperature, deposit composition, and gas composition. Despite this, comparison of air-fired and oxy-fired corrosion rates showed that oxy-firing rates were, for the most part, similar to, if not lower than those of air-firing; this finding applied to the seven furnace waterwall materials (wrought and weld overlay) and the ten superheater/reheater materials (wrought and weld overlay) that were tested. The results of the laboratory oxy-combustion tests, which are based on a maximum bulk flue gas SO{sub 2} level of 3200 ppmv (wet) / 4050 ppmv (dry), suggest that, from a corrosion standpoint, the materials used in conventional subcritical and supercritical, air-fired boilers should also be suitable for oxy-combustion retrofits. Although the laboratory test results are encouraging, they are only the first step of a material evaluation process and it is recommended that follow-on corrosion tests be conducted in coal-fired boilers operating under oxy-combustion to provide longer term (one to

  18. Oxy-Combustion Boiler Material Development

    Energy Technology Data Exchange (ETDEWEB)

    Gagliano, Michael; Seltzer, Andrew; Agarwal, Hans; Robertson, Archie; Wang, Lun

    2012-01-31

    Under U.S. Department of Energy Cooperative Agreement No. DE-NT0005262 Foster Wheeler North America Corp conducted a laboratory test program to determine the effect of oxy-combustion on boiler tube corrosion. In this program, CFD modeling was used to predict the gas compositions that will exist throughout and along the walls of air-fired and oxy-fired boilers operating with low to high sulfur coals. Test coupons of boiler tube materials were coated with deposits representative of those coals and exposed to the CFD predicted flue gases for up to 1000 hours. The tests were conducted in electric tube furnaces using oxy-combustion and air-fired flue gases synthesized from pressurized cylinders. Following exposure, the test coupons were evaluated to determine the total metal wastage experienced under air and oxy-combustions conditions and materials recommendations were made. Similar to air-fired operation, oxy-combustion corrosion rates were found to vary with the boiler material, test temperature, deposit composition, and gas composition. Despite this, comparison of air-fired and oxy-fired corrosion rates showed that oxy-firing rates were, for the most part, similar to, if not lower than those of air-firing; this finding applied to the seven furnace waterwall materials (wrought and weld overlay) and the ten superheater/reheater materials (wrought and weld overlay) that were tested. The results of the laboratory oxy-combustion tests, which are based on a maximum bulk flue gas SO2 level of 3200 ppmv (wet) / 4050 ppmv (dry), suggest that, from a corrosion standpoint, the materials used in conventional subcritical and supercritical, air-fired boilers should also be suitable for oxy-combustion retrofits. Although the laboratory test results are encouraging, they are only the first step of a material evaluation process and it is recommended that follow-on corrosion tests be conducted in coal-fired boilers operating under oxy-combustion to provide longer term (one to two year

  19. Combustion Ratio of Waste Tire Particle, PC and Mixture at Blast Temperature of BF

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jian-liang; REN Shan; SU Bu-xin; LIN Yin-he; LONG Shi-gang

    2012-01-01

    In order to study the combustion characteristics of waste tire particle (WTP), pulverized coal (PC) and their mixture, the contents of CO, CO2 and O2 of off-gas during the combustion of WTP, PC and mixture under the condition of rich oxygen by 0--4% in blast and at 1 250℃ were measured simultaneously using synthetically infrared analyzer, and then the corresponding combustion ratio was calculated and compared. The results showed that the burning rate of WTP reached approximately 57%, which is much higher than that of PC (only about 18%) in the in- itial 650 s in fresh air, and then the increase of combustion rate of PC is faster than that of WTP; the combustion rate of PC improved remarkably with the addition of WTP. Meanwhile, the combustion rates of all these materials improved with the increase of oxygen content.

  20. Continuous fermentation and in-situ reed separation of butyric acid for higher sugar consumption rate and productivity

    DEFF Research Database (Denmark)

    Baroi, George Nabin; Skiadas, Ioannis; Westermann, Peter;

    For a couple a decades, in the frame of bio-based chemicals and materials, there has been focus on biological butyric acid production due to the wide application of butyric acid in chemical, pharmaceutical and food industries. Major challenges for biological production are strain selection...... and development, and process improvement for higher yield, productivity and selectivity. Compared with other microbial strains Clostridium tyrobutyricum has been well characterised, exhibits higher yield and selectivity and can utilize glucose and xylose simultaneously. However, a prerequisite for cost effective...... production of butyric acid is the use of cheap feedstocks as carbon source as well as a process allowing for increased productivity. The present work focuses on butyric acid fermentation of pre-treated and hydrolysed wheat straw (PHWS), consisted of around 72 and 55 g/L glucose and xylose, respectively...

  1. The Influence of Combustion-derived pollutants on limestone deterioration

    DEFF Research Database (Denmark)

    Johnson, J.B.; Montgomery, Melanie; Thompson, G.E.;

    1996-01-01

    The wet deposition of combustion-derived atmospheric pollutant species, on to freshly cut or diesel-smoked Portland and Monks Park limestone and marble samples, was carried out in a laboratory 'wetting and drying' salt spray chamber for 84 days. Along with the effect of CO2-equilibrated de.......e. released from limestone to reaction ions and products, a theoretical limestone surface chemical recession rate was calculated. It was found that, at pH 5.5, water and solutions of individual anions gave similar recession rates within the range of 7.8 +/- 1.8 and 11.5 +/- 2.3 mu m yr(-1) for Portland...... and Monks Park limestones, respectively. At pH 3.8 the individual anion recession rates were increased to 11.1 +/- 0.5 and 13.9 +/- 0.5 mu m yr(-1) respectively, similar to the rates of 12.5 +/- 1.6 and 13.8 +/- 2.2 mu m yr(-1) for the mixed anion artificial acid rain solution on Portland and Monks Park...

  2. Effects of solids concentration, pH and carbon addition on the production rate and composition of volatile fatty acids in prefermenters using primary sewage sludge

    DEFF Research Database (Denmark)

    Zeng, Raymond Jianxiong; Yuan, Z.; Keller, J.

    2006-01-01

    in prefermenters. In this study, a series of controlled batch experiments were conducted with sludge from a full-scale prefermenter to determine the impact of solids concentration, pH and addition of molasses on prefermentation processes. It was found that an increase in solids concentration enhanced total VFA...... production with an increased propionic acid fraction. The optimal pH for prefermentation was in the range of 6-7 with significant productivity loss when pH was below 5.5. Molasses addition significantly increased the production of VFAs particularly the propionic acid. However, the fermentation rate...

  3. Computer simulation of combustion of mine fires

    Institute of Scientific and Technical Information of China (English)

    余明高; 张和平; 范维澄; 王清安

    2002-01-01

    According to control theories, mine fires can be considered as an unsteady process after the normal ventilation system is disturbed. Applied the principal of physical chemistry and thermal fluid mechanics, the parameters models of the unsteady state system have been given, such as fuel combustion rate, heat of combustion, concentration, temperature, heat losses, heat resistance, work of expansion and heat pressure difference. The results of the calculation agree approximately with the results of the test. By the computer simulation, it is shown that the main factor of producing the throttling effect is the fire rate, second is the heat resistance and the heat pressure difference. The rate of heat flow that passes through the airway wall is the maximum on the surface, and decrease with time. The heat transfer progresses only within the range of 0.5 m away from theairway wall during combustion for 2 hours. Its variable for the mass flux rate and the percentage concentration of the gas along the airway of the downstream. When the delayed time is very small, the variation can be neglected. Viscosity resistance is the main part of the heat resistance, second is the expansion resistance that is less than tens Pascal when Mach number is very small. Work of expansion is principally turned into heat losses, only a very small part is consumed by the work of the heat resistance and the inertia acceleration.

  4. Metabolic rate and membrane fatty acid composition in birds: a comparison between long-living parrots and short-living fowl.

    Science.gov (United States)

    Montgomery, Magdalene K; Hulbert, A J; Buttemer, William A

    2012-01-01

    Both basal metabolic rate (BMR) and maximum lifespan potential (MLSP) vary with body size in mammals and birds and it has been suggested that these are mediated through size-related variation in membrane fatty acid composition. Whereas the physical properties of membrane fatty acids affect the activity of membrane proteins and, indirectly, an animal's BMR, it is the susceptibility of those fatty acids to peroxidation which influence MLSP. Although there is a correlation between body size and MLSP, there is considerable MLSP variation independent of body size. For example, among bird families, Galliformes (fowl) are relatively short-living and Psittaciformes (parrots) are unusually long-living, with some parrot species reaching maximum lifespans of more than 100 years. We determined BMR and tissue phospholipid fatty acid composition in seven tissues from three species of parrots with an average MLSP of 27 years and from two species of quails with an average MLSP of 5.5 years. We also characterised mitochondrial phospholipids in two of these tissues. Neither BMR nor membrane susceptibility to peroxidation corresponded with differences in MLSP among the birds we measured. We did find that (1) all birds had lower n-3 polyunsaturated fatty acid content in mitochondrial membranes compared to those of the corresponding tissue, and that (2) irrespective of reliance on flight for locomotion, both pectoral and leg muscle had an almost identical membrane fatty acid composition in all birds.

  5. Aerosols from biomass combustion

    Energy Technology Data Exchange (ETDEWEB)

    Nussbaumer, T.

    2001-07-01

    This report is the proceedings of a seminar on biomass combustion and aerosol production organised jointly by the International Energy Agency's (IEA) Task 32 on bio energy and the Swiss Federal Office of Energy (SFOE). This collection of 16 papers discusses the production of aerosols and fine particles by the burning of biomass and their effects. Expert knowledge on the environmental impact of aerosols, formation mechanisms, measurement technologies, methods of analysis and measures to be taken to reduce such emissions is presented. The seminar, visited by 50 participants from 11 countries, shows, according to the authors, that the reduction of aerosol emissions resulting from biomass combustion will remain a challenge for the future.

  6. An Experimental and Kinetic Modeling Study of Methyl Decanoate Combustion

    Energy Technology Data Exchange (ETDEWEB)

    Sarathy, S M; Thomson, M J; Pitz, W J; Lu, T

    2010-02-19

    Biodiesel is typically a mixture of long chain fatty acid methyl esters for use in compression ignition engines. Improving biofuel engine performance requires understanding its fundamental combustion properties and the pathways of combustion. This research study presents new combustion data for methyl decanoate in an opposed-flow diffusion flame. An improved detailed chemical kinetic model for methyl decanoate combustion is developed, which serves as the basis for deriving a skeletal mechanism via the direct relation graph method. The novel skeletal mechanism consists of 648 species and 2998 reactions. This mechanism well predicts the methyl decanoate opposed-flow diffusion flame data. The results from the flame simulations indicate that methyl decanoate is consumed via abstraction of hydrogen atoms to produce fuel radicals, which lead to the production of alkenes. The ester moiety in methyl decanoate leads to the formation of low molecular weight oxygenated compounds such as carbon monoxide, formaldehyde, and ketene.

  7. Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: a kinetic approach.

    Science.gov (United States)

    Ghosh, Aniruddha; Saha, Rumpa; Ghosh, Sumanta K; Mukherjee, Kakali; Saha, Bidyut

    2013-05-15

    The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.

  8. Lowering GTP level increases survival of amino acid starvation but slows growth rate for Bacillus subtilis cells lacking (p)ppGpp.

    Science.gov (United States)

    Bittner, Alycia N; Kriel, Allison; Wang, Jue D

    2014-06-01

    Bacterial cells sense external nutrient availability to regulate macromolecular synthesis and consequently their growth. In the Gram-positive bacterium Bacillus subtilis, the starvation-inducible nucleotide (p)ppGpp negatively regulates GTP levels, both to resist nutritional stress and to maintain GTP homeostasis during growth. Here, we quantitatively investigated the relationship between GTP level, survival of amino acid starvation, and growth rate when GTP synthesis is uncoupled from its major homeostatic regulator, (p)ppGpp. We analyzed growth and nucleotide levels in cells that lack (p)ppGpp and found that their survival of treatment with a nonfunctional amino acid analog negatively correlates with both growth rate and GTP level. Manipulation of GTP levels modulates the exponential growth rate of these cells in a positive dose-dependent manner, such that increasing the GTP level increases growth rate. However, accumulation of GTP levels above a threshold inhibits growth, suggesting a toxic effect. Strikingly, adenine counteracts GTP stress by preventing GTP accumulation in cells lacking (p)ppGpp. Our results emphasize the importance of maintaining appropriate levels of GTP to maximize growth: cells can survive amino acid starvation by decreasing GTP level, which comes at a cost to growth, while (p)ppGpp enables rapid adjustment to nutritional stress by adjusting GTP level, thus maximizing fitness.

  9. Synthesis of functional materials in combustion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Zhuravlev, V. D., E-mail: zhvd@ihim.uran.ru; Bamburov, V. G.; Ermakova, L. V.; Lobachevskaya, N. I. [Russian Academy of Sciences, Institute of Solid State Chemistry, Ural Branch (Russian Federation)

    2015-12-15

    The conditions for obtaining oxide compounds in combustion reactions of nitrates of metals with organic chelating–reducing agents such as amino acids, urea, and polyvinyl alcohol are reviewed. Changing the nature of internal fuels and the reducing agent-to-oxidizing agent ratio makes possible to modify the thermal regime of the process, fractal dimensionality, morphology, and dispersion of synthesized functional materials. This method can be used to synthesize simple and complex oxides, composites, and metal powders, as well as ceramics and coatings. The possibilities of synthesis in combustion reactions are illustrated by examples of αand γ-Al{sub 2}O{sub 3}, YSZ composites, uranium oxides, nickel powder, NiO and NiO: YSZ composite, TiO{sub 2}, and manganites, cobaltites, and aluminates of rare earth elements.

  10. Synthesis of functional materials in combustion reactions

    Science.gov (United States)

    Zhuravlev, V. D.; Bamburov, V. G.; Ermakova, L. V.; Lobachevskaya, N. I.

    2015-12-01

    The conditions for obtaining oxide compounds in combustion reactions of nitrates of metals with organic chelating-reducing agents such as amino acids, urea, and polyvinyl alcohol are reviewed. Changing the nature of internal fuels and the reducing agent-to-oxidizing agent ratio makes possible to modify the thermal regime of the process, fractal dimensionality, morphology, and dispersion of synthesized functional materials. This method can be used to synthesize simple and complex oxides, composites, and metal powders, as well as ceramics and coatings. The possibilities of synthesis in combustion reactions are illustrated by examples of αand γ-Al2O3, YSZ composites, uranium oxides, nickel powder, NiO and NiO: YSZ composite, TiO2, and manganites, cobaltites, and aluminates of rare earth elements.

  11. Combustion powered linear actuator

    Science.gov (United States)

    Fischer, Gary J.

    2007-09-04

    The present invention provides robotic vehicles having wheeled and hopping mobilities that are capable of traversing (e.g. by hopping over) obstacles that are large in size relative to the robot and, are capable of operation in unpredictable terrain over long range. The present invention further provides combustion powered linear actuators, which can include latching mechanisms to facilitate pressurized fueling of the actuators, as can be used to provide wheeled vehicles with a hopping mobility.

  12. Combustion science and engineering

    CERN Document Server

    Annamalai, Kalyan

    2006-01-01

    Introduction and Review of Thermodynamics Introduction Combustion Terminology Matter and Its Properties Microscopic Overview of Thermodynamics Conservation of Mass and Energy and the First Law of Thermodynamics The Second Law of Thermodynamics Summary Stoichiometry and Thermochemistry of Reacting Systems Introduction Overall Reactions Gas Analyses Global Conservation Equations for Reacting Systems Thermochemistry Summary Appendix Reaction Direction and Equilibrium Introduction Reaction Direction and Chemical Equilibrium Chemical Equilibrium Relations Vant Hoff Equation Adi

  13. PEP3 overexpression shortens lag phase but does not alter growth rate in Saccharomyces cerevisiae exposed to acetic acid stress.

    Science.gov (United States)

    Ding, Jun; Holzwarth, Garrett; Bradford, C Samuel; Cooley, Ben; Yoshinaga, Allen S; Patton-Vogt, Jana; Abeliovich, Hagai; Penner, Michael H; Bakalinsky, Alan T

    2015-10-01

    In fungi, two recognized mechanisms contribute to pH homeostasis: the plasma membrane proton-pumping ATPase that exports excess protons and the vacuolar proton-pumping ATPase (V-ATPase) that mediates vacuolar proton uptake. Here, we report that overexpression of PEP3 which encodes a component of the HOPS and CORVET complexes involved in vacuolar biogenesis, shortened lag phase in Saccharomyces cerevisiae exposed to acetic acid stress. By confocal microscopy, PEP3-overexpressing cells stained with the vacuolar membrane-specific dye, FM4-64 had more fragmented vacuoles than the wild-type control. The stained overexpression mutant was also found to exhibit about 3.6-fold more FM4-64 fluorescence than the wild-type control as determined by flow cytometry. While the vacuolar pH of the wild-type strain grown in the presence of 80 mM acetic acid was significantly higher than in the absence of added acid, no significant difference was observed in vacuolar pH of the overexpression strain grown either in the presence or absence of 80 mM acetic acid. Based on an indirect growth assay, the PEP3-overexpression strain exhibited higher V-ATPase activity. We hypothesize that PEP3 overexpression provides protection from acid stress by increasing vacuolar surface area and V-ATPase activity and, hence, proton-sequestering capacity. PMID:26051671

  14. Modulation of drug release rate of diltiazem-HCl from hydrogel matrices of succinic acid-treated ispaghula husk.

    Science.gov (United States)

    Gohel, M C; Amin, A F; Chhabaria, M T; Panchal, M K; Lalwani, A N

    2000-01-01

    The feasibility of using succinic acid-treated ispaghula husk in matrix-based tablets of diltiazem-HCl was investigated. The sample prepared using 4:1 weight ratio of ispaghula husk to succinic acid showed improved swelling and gelling. A 3(2) factorial design was employed to investigate the effect of amount of succinic acid-treated ispaghula husk and dicalcium phosphate (DCP) on the percentage of the drug dissolved in 60, 300, and 480 min from the compressed tablets. The results of multiple linear regression analysis revealed that the significance of the amount of succinic acid-treated ispaghula husk was greater in magnitude than that of the amount of DCP in controlling the drug release. Acceptable batches were identified from a contour plot with constraints on the percentage drug released at the three sampling times. A mathematical model was also evolved to describe the entire dissolution profile. The results of F-test revealed that the Higuchi model fits well to the in vitro dissolution data. The tablets showed considerable radial and axial swelling in distilled water. Succinic acid-treated ispaghula husk can be used as an economical hydrophilic matrixing agent.

  15. Emissions from RDF combustion

    International Nuclear Information System (INIS)

    The paper deals with the emissions from refuse derived fuel (RDF) combustion. The disposal of refuse has during the last years been a matter of increasing concern for many municipalities. The environment options for waste disposal has not been focusing much. This means that first the waste generation must be reduced. Then recycling of a portion of the waste must be considered before a solution with combustion of waste is chosen. Two methods are currently in use for the combustion of municipal solid waste (MSW) which are the mass burning of unprocessed MSW and RDF. The RDF product consists of the burnable organic fraction of raw MSW. In contrast to mass burning systems, the RDF-system is pre-processing the raw MSW to make a more homogeneous fuel product. By processing the MSW, it is possible to recover RDF and other materials. The RDF process is a low cost approach to resource recovery. RDF is a merchant fuel, and can be used in existing boilers alone or as a supplement to conventional fuels as oil and coal. It is important that the RDF processing technology and RDF quality matches the energy user requirements. The RDF-processing-systems is of great importance to the RDF quality. The paper shows the different steps in the RDF process. 4 refs., 15 figs

  16. Issues in waste combustion

    Energy Technology Data Exchange (ETDEWEB)

    Gustavsson, Lennart; Robertson, Kerstin; Tullin, Claes [Swedish National Testing and Research Inst., Boraas (Sweden); Sundquist, Lena; Wrangensten, Lars [AaF-Energikonsult AB, Stockholm (Sweden); Blom, Elisabet [AaF-Processdesign AB, Stockholm (Sweden)

    2003-05-01

    The main purpose of this review is to provide an overview of the state-of-the-art on research and development issues related to waste combustion with relevance for Swedish conditions. The review focuses on co-combustion in grate and fluidised bed furnaces. It is primarily literature searches in relevant databases of scientific publications with to material published after 1995. As a complement, findings published in different report series, have also been included. Since the area covered by this report is very wide, we do not claim to cover the issues included completely and it has not been possitile to evaluate the referred studies in depth. Basic knowledge about combustion issues is not included since such information can be found elsewhere in the literature. Rather, this review should be viewed as an overview of research and development in the waste-to-energy area and as such we hope that it will inspire scientists and others to further work in relevant areas.

  17. Numerical modeling of straw combustion in a fixed bed

    DEFF Research Database (Denmark)

    Zhou, Haosheng; Jensen, Anker; Glarborg, Peter;

    2005-01-01

    Straw is being used as main renewable energy source in grate boilers in Denmark. For optimizing operating conditions and design parameters, a one-dimensional unsteady heterogeneous mathematical model has been developed and experiments have been carried out for straw combustion in a fixed bed....... The straw combustion processes include moisture evaporation, straw pyrolysis, gas combustion, and char combustion. The model provides detailed information of the structure of the ignition flame front. Simulated gas species concentrations at the bed surface, ignition flame front rate, and bed temperature...... are in good agreement with measurements at different operating conditions such as primary air-flow rate, pre-heating of the primary air, oxygen concentration, moisture content in straw, and bulk density of the straw in the fixed bed. A parametric study indicates that the effective heat conductivity, straw...

  18. NOx Emission Reduction by Oscillating Combustion

    Energy Technology Data Exchange (ETDEWEB)

    John C. Wagner

    2004-03-31

    High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce large quantities of NO{sub x} per ton of material processed. Regulations on emissions from industrial furnaces are becoming increasingly more stringent. In addition, competition is forcing operators to make their furnaces more productive and/or efficient. Switching from preheated air to industrial oxygen can increase efficiency and reduce NO{sub x}, but oxygen is significantly more costly than air and may not be compatible with the material being heated. What was needed, and what was developed during this project, is a technology that reduces NO{sub x} emissions while increasing furnace efficiency for both air- and oxy-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace. Heat transfer from the flame to the load increases due to the more luminous fuel-rich zones, a longer overall flame length, and the breakup of the thermal boundary layer. The increased heat transfer shortens heat up times, thereby increasing furnace productivity, and reduces the heat going up the stack, thereby increasing efficiency. The fuel-rich and fuel-lean zones also produce substantially less NO{sub x} than firing at a constant excess air level. The longer flames and higher heat transfer rate reduces overall peak flame temperature and thus reduces additional NO{sub x} formation from the eventual mixing of the zones and burnout of combustibles from the rich zones. This project involved the development of hardware to implement oscillating combustion on an industrial scale, the laboratory testing of oscillating combustion on various types of industrial burners, and the field testing of oscillating combustion on several types of industrial furnace. Before laboratory testing began, a market study was conducted, based on the

  19. NOx Emission Reduction by Oscillating combustion

    Energy Technology Data Exchange (ETDEWEB)

    Institute of Gas Technology

    2004-01-30

    High-temperature, natural gas-fired furnaces, especially those fired with preheated air, produce large quantities of NO{sub x} per ton of material processed. Regulations on emissions from industrial furnaces are becoming increasingly more stringent. In addition, competition is forcing operators to make their furnaces more productive and/or efficient. Switching from preheated air to industrial oxygen can increase efficiency and reduce NO{sub x}, but oxygen is significantly more costly than air and may not be compatible with the material being heated. What was needed, and what was developed during this project, is a technology that reduces NO{sub x} emissions while increasing furnace efficiency for both air- and oxy-fired furnaces. Oscillating combustion is a retrofit technology that involves the forced oscillation of the fuel flow rate to a furnace. These oscillations create successive, fuel-rich and fuel-lean zones within the furnace. Heat transfer from the flame to the load increases due to the more luminous fuel-rich zones, a longer overall flame length, and the breakup of the thermal boundary layer. The increased heat transfer shortens heat up times, thereby increasing furnace productivity, and reduces the heat going up the stack, thereby increasing efficiency. The fuel-rich and fuel-lean zones also produce substantially less NO{sub x} than firing at a constant excess air level. The longer flames and higher heat transfer rate reduces overall peak flame temperature and thus reduces additional NO{sub x} formation from the eventual mixing of the zones and burnout of combustibles from the rich zones. This project involved the development of hardware to implement oscillating combustion on an industrial scale, the laboratory testing of oscillating combustion on various types of industrial burners, and the field testing of oscillating combustion on several types of industrial furnace. Before laboratory testing began, a market study was conducted, based on the

  20. The Diesel Combustion Collaboratory: Combustion Researchers Collaborating over the Internet

    Energy Technology Data Exchange (ETDEWEB)

    C. M. Pancerella; L. A. Rahn; C. Yang

    2000-02-01

    The Diesel Combustion Collaborator (DCC) is a pilot project to develop and deploy collaborative technologies to combustion researchers distributed throughout the DOE national laboratories, academia, and industry. The result is a problem-solving environment for combustion research. Researchers collaborate over the Internet using DCC tools, which include: a distributed execution management system for running combustion models on widely distributed computers, including supercomputers; web-accessible data archiving capabilities for sharing graphical experimental or modeling data; electronic notebooks and shared workspaces for facilitating collaboration; visualization of combustion data; and video-conferencing and data-conferencing among researchers at remote sites. Security is a key aspect of the collaborative tools. In many cases, the authors have integrated these tools to allow data, including large combustion data sets, to flow seamlessly, for example, from modeling tools to data archives. In this paper the authors describe the work of a larger collaborative effort to design, implement and deploy the DCC.

  1. Internal combustion engine using premixed combustion of stratified charges

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, Craig D. (Rochester Hills, MI); Reitz, Rolf D. (Madison, WI

    2003-12-30

    During a combustion cycle, a first stoichiometrically lean fuel charge is injected well prior to top dead center, preferably during the intake stroke. This first fuel charge is substantially mixed with the combustion chamber air during subsequent motion of the piston towards top dead center. A subsequent fuel charge is then injected prior to top dead center to create a stratified, locally richer mixture (but still leaner than stoichiometric) within the combustion chamber. The locally rich region within the combustion chamber has sufficient fuel density to autoignite, and its self-ignition serves to activate ignition for the lean mixture existing within the remainder of the combustion chamber. Because the mixture within the combustion chamber is overall premixed and relatively lean, NO.sub.x and soot production are significantly diminished.

  2. Numerical Simulation of Combustion Characteristics in High Temperature Air Combustion Furnace

    Institute of Scientific and Technical Information of China (English)

    WANG Ai-hua; CAI Jiu-ju; XIE Guo-wei

    2009-01-01

    The influences of air preheating temperature, oxygen concentration, and fuel inlet temperature on flame properties, and NOx formation and emission in the furnace were studied with numerical simulation. The turbulence behavior was modeled using the standard k-e model with wall function, and radiation was handled using discrete ordi-nate radiation model. The PDF (probability density funetion)/mixture fraction combustion model was used to simu-late the propane combustion. Additionally, computations of NOx formation rates and NOx concentration were carried out using a post-processor on the basis of previously calculated velocities, turbulence, temperature, and chemical composition fields. The results showed that high temperature air combustion (HiTAC) is spread over a much larger volume than traditional combustion, flame volume increases with a reduction of oxygen eoncentration, and this trend is clearer if oxygen concentration in the preheated air is below 10%. The temperature profile becomes more uniform when oxygen concentration in preheated air decreases, especially at low oxygen levels. Increase in fuel inlet tempera-ture lessens the mixing of the fuel and air in primary combustion zone, ereates more uniform distribution of reactants inside the flame, decreases the maximum temperature in furnace, and reduces NOx emission greatly.

  3. Development of flameless combustion; Desarrollo de la combustion sin flama

    Energy Technology Data Exchange (ETDEWEB)

    Flores Sauceda, M. Leonardo; Cervantes de Gortari, Jaime Gonzalo [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)]. E-mail: 8344afc@prodigy.net.mx; jgonzalo@servidor.unam.mx

    2010-11-15

    The paper intends contribute to global warming mitigation joint effort that develops technologies to capture the CO{sub 2} produced by fossil fuels combustion and to reduce emission of other greenhouse gases like the NO{sub x}. After reviewing existing combustion bibliography is pointed out that (a) touches only partial aspects of the collective system composed by Combustion-Heat transfer process-Environment, whose interactions are our primary interest and (b) most specialists think there is not yet a clearly winning technology for CO{sub 2} capture and storage. In this paper the study of combustion is focused as integrated in the aforementioned collective system where application of flameless combustion, using oxidant preheated in heat regenerators and fluent gas recirculation into combustion chamber plus appropriated heat and mass balances, simultaneously results in energy saving and environmental impact reduction. [Spanish] El trabajo pretende contribuir al esfuerzo conjunto de mitigacion del calentamiento global que aporta tecnologias para capturar el CO{sub 2} producido por la combustion de combustibles fosiles y para disminuir la emision de otros gases invernadero como NOx. De revision bibliografica sobre combustion se concluye que (a) trata aspectos parciales del sistema compuesto por combustion-proceso de trasferencia de calor-ambiente, cuyas interacciones son nuestro principal interes (b) la mayoria de especialistas considera no hay todavia una tecnologia claramente superior a las demas para captura y almacenaje de CO{sub 2}. Se estudia la combustion como parte integrante del mencionado sistema conjunto, donde la aplicacion de combustion sin flama, empleando oxidante precalentado mediante regeneradores de calor y recirculacion de gases efluentes ademas de los balances de masa y energia adecuados, permite tener simultaneamente ahorros energeticos e impacto ambiental reducido.

  4. Dilute Oxygen Combustion Phase 3 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Riley, M.F.; Ryan, H.M.

    2000-05-31

    Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel?s standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion of furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.

  5. Dilute Oxygen Combustion - Phase 3 Report

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Michael F.

    2000-05-31

    Dilute Oxygen Combustion (DOC) burners have been successfully installed and operated in the reheat furnace at Auburn Steel Co., Inc., Auburn, NY, under Phase 3 of the Dilute Oxygen Combustion project. Two new preheat zones were created employing a total of eight 6.5 MMBtu/hr capacity burners. The preheat zones provide a 30 percent increase in maximum furnace production rate, from 75 tph to 100 tph. The fuel rate is essentially unchanged, with the fuel savings expected from oxy-fuel combustion being offset by higher flue gas temperatures. When allowance is made for the high nitrogen level and high gas phase temperature in the furnace, measured NOx emissions are in line with laboratory data on DOC burners developed in Phase 1 of the project. Burner performance has been good, and there have been no operating or maintenance problems. The DOC system continues to be used as part of Auburn Steel's standard reheat furnace practice. High gas phase temperature is a result of the high firing density needed to achieve high production rates, and little opportunity exists for improvement in that area. However, fuel and NOx performance can be improved by further conversion on furnace zones to DOC burners, which will lower furnace nitrogen levels. Major obstacles are cost and concern about increased formation of oxide scale on the steel. Oxide scale formation may be enhanced by exposure of the steel to higher concentrations of oxidizing gas components (primarily products of combustion) in the higher temperature zones of the furnace. Phase 4 of the DOC project will examine the rate of oxide scale formation in these higher temperature zones and develop countermeasures that will allow DOC burners to be used successfully in these furnace zones.

  6. Combustion synthesis of radioactive waste immobilization

    Institute of Scientific and Technical Information of China (English)

    ZHANG Ruizhu; GUO Zhimeng; LU Xin; JIA Chengchang; LIN Tao

    2005-01-01

    Using chromium oxide (CrO3) as an oxidant, the immobilization of simulating radioactive waste in perovskite (CaTiO3) structure by a combustion synthesis (CS) method was tested. The products were characterized by Archimedes liquid displacement technique, microhardness technique, X-ray diffraction, and scanning electron microscopy. The leaching rate was measured by the method of MCC-1 or MCC-2.The primary results show that the CS method can be used to solidify the immobilizate waste effectively.

  7. The Effect of Varying Magnetic Field Gradient on Combustion Dynamic

    Science.gov (United States)

    Suzdalenko, Vera; Zake, Maija; Barmina, Inesa; Gedrovics, Martins

    2011-01-01

    The focus of the recent experimental research is to provide control of the combustion dynamics and complex measurements (flame temperature, heat production rate, and composition of polluting emissions) for pelletized wood biomass using a non-uniform magnetic field that produces magnetic force interacting with magnetic moment of paramagnetic oxygen. The experimental results have shown that a gradient magnetic field provides enhanced mixing of the flame compounds by increasing combustion efficiency and enhancing the burnout of volatiles.

  8. Consequences of sludge composition on combustion performance derived from thermogravimetry analysis

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meiyan; Xiao, Benyi; Wang, Xu; Liu, Junxin, E-mail: jxliu@rcees.ac.cn

    2015-01-15

    Highlights: • Volatiles, particularly proteins, play a key role in sludge combustion. • Sludge combustion performance varies with different sludge organic concentrations. • Carbohydrates significantly affect the combustion rate in the second stage. • Combustion performance of digested sludge is more negative compared with others. - Abstract: Wastewater treatment plants produce millions of tons of sewage sludge. Sewage sludge is recognized as a promising feedstock for power generation via combustion and can be used for energy crisis adaption. We aimed to investigate the quantitative effects of various sludge characteristics on the overall sludge combustion process performance. Different types of sewage sludge were derived from numerous wastewater treatment plants in Beijing for further thermogravimetric analysis. Thermogravimetric–differential thermogravimetric curves were used to compare the performance of the studied samples. Proximate analytical data, organic compositions, elementary composition, and calorific value of the samples were determined. The relationship between combustion performance and sludge composition was also investigated. Results showed that the performance of sludge combustion was significantly affected by the concentration of protein, which is the main component of volatiles. Carbohydrates and lipids were not correlated with combustion performance, unlike protein. Overall, combustion performance varied with different sludge organic composition. The combustion rate of carbohydrates was higher than those of protein and lipid, and carbohydrate weight loss mainly occurred during the second stage (175–300 °C). Carbohydrates have a substantial effect on the rate of system combustion during the second stage considering the specific combustion feature. Additionally, the combustion performance of digested sewage sludge is more negative than the others.

  9. Combustion, emission and engine performance characteristics of used cooking oil biodiesel - A review

    Energy Technology Data Exchange (ETDEWEB)

    Enweremadu, C.C. [Department of Mechanical Engineering, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa); Rutto, H.L. [Department of Chemical Engineering, Vaal University of Technology, Private Bag X021, Vanderbijlpark 1900 (South Africa)

    2010-12-15

    As the environment degrades at an alarming rate, there have been steady calls by most governments following international energy policies for the use of biofuels. One of the biofuels whose use is rapidly expanding is biodiesel. One of the economical sources for biodiesel production which doubles in the reduction of liquid waste and the subsequent burden of sewage treatment is used cooking oil (UCO). However, the products formed during frying, such as free fatty acid and some polymerized triglycerides, can affect the transesterification reaction and the biodiesel properties. This paper attempts to collect and analyze published works mainly in scientific journals about the engine performance, combustion and emissions characteristics of UCO biodiesel on diesel engine. Overall, the engine performance of the UCO biodiesel and its blends was only marginally poorer compared to diesel. From the standpoint of emissions, NOx emissions were slightly higher while un-burnt hydrocarbon (UBHC) emissions were lower for UCO biodiesel when compares to diesel fuel. There were no noticeable differences between UCO biodiesel and fresh oil biodiesel as their engine performances, combustion and emissions characteristics bear a close resemblance. This is probably more closely related to the oxygenated nature of biodiesel which is almost constant for every biodiesel (biodiesel has some level of oxygen bound to its chemical structure) and also to its higher viscosity and lower calorific value, which have a major bearing on spray formation and initial combustion. (author)

  10. The effects of dietary omega fatty acids on pregnancy rate, plasma prostaglandin metabolite levels, serum progesterone levels, and milk fatty-acid profile in beef cows

    OpenAIRE

    Richardson, Gavin F.; McNiven, Mary A.; Petit, Hélène V.; Duynisveld, John L.

    2013-01-01

    The objectives were to determine the effects of feeding supplements rich in omega-6 or omega-3 fatty acids (FA) during the late gestation to the early postpartum and breeding periods on reproduction and milk FA profile in beef cows. For each of two years, at the beginning of period 1 (mid-December), 72 beef cows, calving in January or February, were assigned to diets supplemented with roasted flaxseed (Flax) or roasted soybean (Soybean). For each of two years, after 11 wk (end of period 1), 1...

  11. Influence of citric acid content on magnetic properties of BaFe12O19 powder prepared by sol-gel auto-combustion method%柠檬酸含量对溶胶凝胶自燃烧法制备的钡铁氧体磁性能的影响

    Institute of Scientific and Technical Information of China (English)

    钟敏建; 徐国庆; 马洪良; 周炯; 岳中岳; 何正明

    2007-01-01

    BaFe12O19 powders with nanocrystalline sizes were produced by sol-gel auto-combustion method.The precursors were prepared under the molar ratios of citric acid to the metal nitrate of 0.5.1.0 and 1.5.Appropriate ethylene diamine C2HsN2)was added in order to adjust pH of 7.The ions distribution of citric acid at different pH explains the effect of citric acid in the starting solution.The XRD patterns of the as-burnt powders and annealing powders show different phases for different citric acid content.In addition,the lattice constants(a,c)derived from X-ray diffraction pattern were changed from 0.58881 nm to 0.58997 nm and 2.32057 nin to 2.32296 nm respectively.The data from VSM indicated that the powder with high citric acid content took on good magnetic properties.Pure single BaFe12O19 of the specific maximum magnetization M(1 T)≈49.73 Am2/kg,the specific remanent magnetization Mr≈30.77 Am2/kg and the coercive force Hc≈467 kA/m Was produced when the molar ratios of citric acid to the metal nitrate was 1.5.

  12. Novel approaches in advanced combustion characterization of fuels for advanced pressurized combustion

    Energy Technology Data Exchange (ETDEWEB)

    Aho, M.; Haemaelaeinen, J. [VTT Energy (Finland); Joutsenoja, T. [Tampere Univ. of Technology (Finland)

    1996-12-01

    This project is a part of the EU Joule 2 (extension) programme. The objective of the research of Technical Research Centre of Finland (VTT) is to produce experimental results of the effects of pressure and other important parameters on the combustion of pulverized coals and their char derivates. The results can be utilized in modelling of pressurized combustion and in planning pilot-scale reactors. The coals to be studied are Polish hvb coal, French lignite (Gardanne), German anthracite (Niederberg) and German (Goettelbom) hvb coal. The samples are combusted in an electrically heated, pressurized entrained flow reactor (PEFR), where the experimental conditions are controlled with a high precision. The particle size of the fuel can vary between 100 and 300 {mu}m. The studied things are combustion rates, temperatures and sizes of burning single coal and char particles. The latter measurements are performed with a method developed by Tampere University of Technology, Finland. In some of the experiments, mass loss and elemental composition of the char residue are studied in more details as the function of time to find out the combustion mechanism. Combustion rate of pulverized (140-180 {mu}m) Gardanne lignite and Niederberg anthracite were measured and compared with the data obtained earlier with Polish hvb coal at various pressures, gas temperatures, oxygen partial pressures and partial pressures of carbon dioxide in the second working period. In addition, particle temperatures were measured with anthracite. The experimental results were treated with multivariable partial least squares (PLS) method to find regression equation between the measured things and the experimental variables. (author)

  13. Structure-dependent photocatalytic decomposition of formic acid on the anatase TiO2(101) surface and strategies to increase its reaction rate

    Science.gov (United States)

    Ji, Yongfei; Luo, Yi

    2016-02-01

    Formic acid is a typical molecule that is involved in a lot important solar energy conversion processes. We perform first-principles calculations on the molecular mechanism of its photocatalytic decomposition reaction (PCD) on the anatase TiO2(101) surface. We find that the reaction barrier is sensitively dependent on the adsorption structure of the molecule. The one-step PCD of the monodentate formic acid has a lower barrier than that of bidentate formate. Coadsorbed water molecules can transform the formate from a bidentate to a monodentate configuration which greatly lower its decomposition barrier. Water molecule can also induce the spontaneous dissociation of the formic acid molecule. The monodentate dissociated formic acid is stabilized by the hydrogen bonds which will slightly enhance the barrier for its photodecomposition. However, the reaction rate can be further enhanced if the hydrogens are removed (for example, by oxygen molecules). Therefore, using coadsorbate and deliberately introducing and removing hydrogen bonds can be two strategies to tailor the photoreaction rate of the molecules.

  14. A chamber study of the influence of boreal BVOC emissions and sulphuric acid on nanoparticle formation rates at ambient concentrations

    OpenAIRE

    Dal Maso, M.; Liao, L.; Wildt, J.; Kiendler-Scharr, A; Kleist, E; Tillmann, R.; Sipilä, M.; Hakala, J.; Lehtipalo, K.; M. Ehn; V.-M. Kerminen; M. Kulmala; Worsnop, D.; Mentel, T.

    2014-01-01

    Aerosol formation from biogenic and anthropogenic precursor trace gases in continental background areas affects climate via altering the amount of available cloud condensation nuclei. Significant uncertainty still exists regarding the agents controlling the formation of aerosol nanoparticles. We have performed experiments in the Jülich Plant-Atmosphere Simulation Chamber with instrumentation for the detection of sulphuric acid and nanoparticles, and present ...

  15. Bile Acid Sequestration Reduces Plasma Glucose Levels in db/db Mice by Increasing Its Metabolic Clearance Rate

    NARCIS (Netherlands)

    Meissner, M.; Herrema, H.J.; Dijk, van Th.; Gerding, A.; Havinga, R.; Boer, T.; Müller, M.R.; Reijngoud, D.J.; Groen, A.K.; Kuipers, F.

    2011-01-01

    Aims/Hypothesis: Bile acid sequestrants (BAS) reduce plasma glucose levels in type II diabetics and in murine models of diabetes but the mechanism herein is unknown. We hypothesized that sequestrant-induced changes in hepatic glucose metabolism would underlie reduced plasma glucose levels. Therefore

  16. Volatile fatty acids production rate and nutrient utilization on supplementation of urea-molasses-mineral lick in adult crossbred cattle

    International Nuclear Information System (INIS)

    Twelve adult crossbred rumen fistulated animals were divided into three groups and fed with different diets containing various ingredients. Total volatile fatty acids were estimated in these diets using 14C acetate in single dose isotope dilution experiment. The nutrient uptake from different diets were assessed

  17. Post combustion in converter steelmaking

    Energy Technology Data Exchange (ETDEWEB)

    Oghbasilasie, H.; Holappa, L.

    1997-12-31

    The purpose of this work is to study the fundamentals of post combustion and the effect of different process parameters on the post combustion ratio (PCR) and heat transfer efficiency (HTE) in converter steelmaking process. The PCR and HTE have been determined under normal operating conditions. Trials assessed the effect of lance height, vessel volume, foaming slag and pellet additions on PCR and HTE. Based on enthalpy considerations, post combustion of CO gas is regarded as one of the most effective means of increasing the heat supply to the BOP. The thermodynamic study of gas-metal-slag reactions gives the limiting conditions for post combustion inside the converter reactor. Different process parameters influencing both thermodynamic equilibria and kinetic conditions can greatly affect the post combustion ratio. Different features of converter processes as well smelting reduction processes utilizing post combustion have been reviewed. (orig.) SULA 2 Research Programme; 26 refs.

  18. Temperature Shift Experiments Suggest That Metabolic Impairment and Enhanced Rates of Photorespiration Decrease Organic Acid Levels in Soybean Leaflets Exposed to Supra-Optimal Growth Temperatures

    Directory of Open Access Journals (Sweden)

    Richard C. Sicher

    2015-08-01

    Full Text Available Elevated growth temperatures are known to affect foliar organic acid concentrations in various plant species. In the current study, citrate, malate, malonate, fumarate and succinate decreased 40 to 80% in soybean leaflets when plants were grown continuously in controlled environment chambers at 36/28 compared to 28/20 °C. Temperature effects on the above mentioned organic acids were partially reversed three days after plants were transferred among optimal and supra-optimal growth temperatures. In addition, CO2 enrichment increased foliar malate, malonate and fumarate concentrations in the supra-optimal temperature treatment, thereby mitigating effects of high temperature on respiratory metabolism. Glycerate, which functions in the photorespiratory pathway, decreased in response to CO2 enrichment at both growth temperatures. The above findings suggested that diminished levels of organic acids in soybean leaflets upon exposure to high growth temperatures were attributable to metabolic impairment and to changes of photorespiratory flux. Leaf development rates differed among temperature and CO2 treatments, which affected foliar organic acid levels. Additionally, we report that large decreases of foliar organic acids in response to elevated growth temperatures were observed in legume species.

  19. Photocatalytic H2 Production Using Pt-TiO2 in the Presence of Oxalic Acid: Influence of the Noble Metal Size and the Carrier Gas Flow Rate

    Directory of Open Access Journals (Sweden)

    Ákos Kmetykó

    2014-10-01

    Full Text Available The primary objective of the experiments was to investigate the differences in the photocatalytic performance when commercially available Aeroxide P25 TiO2 photocatalyst was deposited with differently sized Pt nanoparticles with identical platinum content (1 wt%. The noble metal deposition onto the TiO2 surface was achieved by in situ chemical reduction (CRIS or by mixing chemically reduced Pt nanoparticle containing sols to the aqueous suspensions of the photocatalysts (sol-impregnated samples, CRSIM. Fine and low-scale control of the size of resulting Pt nanoparticles was obtained through variation of the trisodium citrate concentration during the syntheses. The reducing reagent was NaBH4. Photocatalytic activity of the samples and the reaction mechanism were examined during UV irradiation (λmax = 365 nm in the presence of oxalic acid (50 mM as a sacrificial hole scavenger component. The H2 evolution rates proved to be strongly dependent on the Pt particle size, as well as the irradiation time. A significant change of H2 formation rate during the oxalic acid transformation was observed which is unusual. It is probably regulated both by the decomposition rate of accumulated oxalic acid and the H+/H2 redox potential on the surface of the catalyst. The later potential is influenced by the concentration of the dissolved H2 gas in the reaction mixture.

  20. Numerical simulation of fuel sprays and combustion in a premixed lean diesel engine; Kihaku yokongo diesel kikan ni okeru nenryo funmu to nensho no suchi simulation

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, T.; Harada, A.; Sasaki, S.; Shimazaki, N.; Hashizume, T.; Akagawa, H.; Tsujimura, K.

    1997-10-01

    Fuel sprays and combustion in a direct injection Premixed lean Diesel Combustion (PREDIC) engine, which can make smokeless combustion with little NOx emission, is studied numerically. Numerical simulation was carried out by means of KIVA II based computer code with a combustion submodel. The combustion submodel describes the formation of combustible fuel vapor by turbulent mixing and four-step chemical reaction which includes low temperature oxidation. Comparison between computation and experiment shows qualitatively good agreement in terms of heat release rate and NO emission. Computational results indicate that the combustion is significantly influenced by fuel spray characteristics and injection timing to vary NO emission. 10 refs., 8 figs., 1 tab.

  1. Measurement of emissions from air pollution sources. 3. C1-C29 organic compounds from fireplace combustion of wood.

    Science.gov (United States)

    Schauer, J J; Kleeman, M J; Cass, G R; Simoneit, B R

    2001-05-01

    Organic compound emission rates for volatile organic compounds (VOC), gas-phase semivolatile organic compounds, and particle-phase organic compounds are measured from residential fireplace combustion of wood. Firewood from a conifer tree (pine) and from two deciduous trees (oak and eucalyptus) is burned to determine organic compound emissions profiles for each wood type including the distribution of the alkanes, alkenes, aromatics, polycyclic aromatic hydrocarbons (PAH), phenol and substituted phenols, guaiacol and substituted guaiacol, syringol and substituted syringols, carbonyls, alkanoic acids, resin acids, and levoglucosan. Levoglucosan is the major constituent in the fine particulate emissions from all three wood types, contributing 18-30% of the fine particulate organic compound emissions. Guaiacol (2-methoxyphenol), and guaiacols with additional substituents at position 4 on the molecule, and resin acids are emitted in significant quantities from pine wood combustion. Syringol (2,6-dimethoxyphenol) and syringols with additional substituents at position 4 on the molecule are emitted in large amounts from oak and eucalyptus firewood combustion, but these compounds are not detected in the emissions from pine wood combustion. Syringol and most of the substituted syringols are found to be semivolatile compounds that are present in both the gas and particle phases, but two substituted syringols that have not been previously quantified in wood smoke emissions, propionylsyringol and butyrylsyringol, are found exclusively in the particle phase and can be used to help trace hardwood smoke particles in the atmosphere. Benzene, ethene, and acetylene are often used as tracers for motor vehicle exhaust in the urban atmosphere. The contribution of wood smoke to the ambient concentrations of benzene, ethene, and acetylene could lead to an overestimate of the contribution of motor vehicle tailpipe exhaust to atmospheric VOC concentrations. PMID:11355184

  2. Pulsating combustion - Combustion characteristics and reduction of emissions

    Energy Technology Data Exchange (ETDEWEB)

    Lindholm, Annika

    1999-11-01

    In the search for high efficiency combustion systems pulsating combustion has been identified as one of the technologies that potentially can meet the objectives of clean combustion and good fuel economy. Pulsating combustion offers low emissions of pollutants, high heat transfer and efficient combustion. Although it is an old technology, the interest in pulsating combustion has been renewed in recent years, due to its unique features. Various applications of pulsating combustion can be found, mainly as drying and heating devices, of which the latter also have had commercial success. It is, however, in the design process of a pulse combustor, difficult to predict the operating frequency, the heat release etc., due to the lack of a well founded theory of the phenomenon. Research concerning control over the combustion process is essential for developing high efficiency pulse combustors with low emissions. Natural gas fired Helmholtz type pulse combustors have been the experimental objects of this study. In order to investigate the interaction between the fluid dynamics and the chemistry in pulse combustors, laser based measuring techniques as well as other conventional measuring techniques have been used. The experimental results shows the possibilities to control the combustion characteristics of pulsating combustion. It is shown that the time scales in the large vortices created at the inlet to the combustion chamber are very important for the operation of the pulse combustor. By increasing/decreasing the time scale for the large scale mixing the timing of the heat release is changed and the operating characteristics of the pulse combustor changes. Three different means for NO{sub x} reduction in Helmholtz type pulse combustors have been investigated. These include exhaust gas recirculation, alteration of air/fuel ratio and changed inlet geometry in the combustion chamber. All used methods achieved less than 10 ppm NO{sub x} emitted (referred to stoichiometric

  3. Reduced order modeling and analysis of combustion instabilities

    Science.gov (United States)

    Tamanampudi, Gowtham Manikanta Reddy

    The coupling between unsteady heat release and pressure fluctuations in a combustor leads to the complex phenomenon of combustion instability. Combustion instability can lead to enormous pressure fluctuations and high rates of combustor heat transfer which play a very important role in determining the life and performance of engine. Although high fidelity simulations are starting to yield detailed understanding of the underlying physics of combustion instability, the enormous computing power required restricts their application to a few runs and fairly simple geometries. To overcome this, low order models are being employed for prediction and analysis. Since low order models cannot account for the coupling between heat release and pressure fluctuations, lower-order combustion response models are required. One such attempt is made through the work presented here using a commercial software COMSOL. The linearized Euler Equations with combustion response models were solved in the frequency domain implementing Arnoldi algorithm using 3D Finite Element solver COMSOL. This work is part of a larger effort to investigate a low order, computationally inexpensive and accurate solver which accounts for mean flow effects, complex boundary conditions and combustion response. This tool was tested against a number of cases presenting longitudinal instabilities. Further, combustion instabilities in transverse instability chamber were studied and are compared with experiments. Both sets of results are in good agreement with experiment. In addition, the effect of nozzle length on the mode shapes in transverse instability chamber was studied and presented.

  4. Active Combustion Control Valve Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Over the past decade, research into active combustion control has yielded impressive results in suppressing thermoacoustic instabilities and widening the...

  5. The modes of gaseous combustion

    CERN Document Server

    Rubtsov, Nickolai M

    2016-01-01

    This book provides an analysis of contemporary problems in combustion science, namely flame propagation, detonation and heterophaseous combustion based on the works of the author. The current problems in the area of gas combustion, as well as the methods allowing to calculate and estimate limiting conditions of ignition, and flame propagation on the basis of experimental results are considered. The book focuses on the virtually inaccessible works of Russian authors and will be useful for experienced students and qualified scientists in the area of experimental studies of combustion processes.

  6. Mathematical Modeling in Combustion Science

    CERN Document Server

    Takeno, Tadao

    1988-01-01

    An important new area of current research in combustion science is reviewed in the contributions to this volume. The complicated phenomena of combustion, such as chemical reactions, heat and mass transfer, and gaseous flows, have so far been studied predominantly by experiment and by phenomenological approaches. But asymptotic analysis and other recent developments are rapidly changing this situation. The contributions in this volume are devoted to mathematical modeling in three areas: high Mach number combustion, complex chemistry and physics, and flame modeling in small scale turbulent flow combustion.

  7. Combustion Branch Website Development

    Science.gov (United States)

    Bishop, Eric

    2004-01-01

    The NASA combustion branch is a leader in developing and applying combustion science to focused aerospace propulsion systems concepts. It is widely recognized for unique facilities, analytical tools, and personnel. In order to better communicate the outstanding research being done in this Branch to the public and other research organization, a more substantial website was desired. The objective of this project was to build an up-to-date site that reflects current research in a usable and attractive manner. In order to accomplish this, information was requested from all researchers in the Combustion branch, on their professional skills and on the current projects. This information was used to fill in the Personnel and Research sections of the website. A digital camera was used to photograph all personnel and these photographs were included in the personnel section as well. The design of the site was implemented using the latest web standards: xhtml and external css stylesheets. This implementation conforms to the guidelines recommended by the w3c. It also helps to ensure that the web site is accessible by disabled users, and complies with Section 508 Federal legislation (which mandates that all Federal websites be accessible). Graphics for the new site were generated using the gimp (www.gimp.org) an open-source graphics program similar to Adobe Photoshop. Also, all graphics on the site were of a reasonable size (less than 20k, most less than 2k) so that the page would load quickly. Technologies such as Macromedia Flash and Javascript were avoided, as these only function on some clients which have the proper software installed or enabled. The website was tested on different platforms with many different browsers to ensure there were no compatibility issues. The website was tested on windows with MS IE 6, MSIE 5 , Netscape 7, Mozilla and Opera. On a Mac, the site was tested with MS IE 5 , Netscape 7 and Safari.

  8. Inferences from protein and nucleic acid sequences - Early molecular evolution, divergence of kingdoms and rates of change

    Science.gov (United States)

    Dayhoff, M. O.; Barker, W. C.; Mclaughlin, P. J.

    1974-01-01

    Description of new sensitive, objective methods for establishing the probable common ancestry of very distantly related sequences and the quantitative evolutionary change which has taken place. These methods are applied to four families of proteins and nucleic acids and evolutionary trees will be derived where possible. Of the three families containing duplications of genetic material, two are nucleic acids: transfer RNA and 5S ribosomal RNA. Both of these structures are functional in the synthesis of coded proteins, and prototypes must have been present in the cell at the inception of the fundamental coding process that all living things share. There are many types of tRNA which recognize the various nucleotide triplets and the 20 amino acids. These types are thought to have arisen as a result of many gene duplications. Relationships among these types are discussed. The 5S ribosomal RNA, presently functional in both eukaryotes and prokaryotes, is very likely descended from an early form incorporating almost a complete duplication of genetic material. The amount of evolution in the various lines can again be compared. The other two families containing duplications are proteins; ferredoxin and cytochrome c.

  9. Alternate fuels; Combustibles alternos

    Energy Technology Data Exchange (ETDEWEB)

    Romero Paredes R, Hernando; Ambriz G, Juan Jose [Universidad Autonoma Metropolitana. Iztapalapa (Mexico)

    2003-07-01

    In the definition and description of alternate fuels we must center ourselves in those technological alternatives that allow to obtain compounds that differ from the traditional ones, in their forms to be obtained. In this article it is tried to give an overview of alternate fuels to the conventional derivatives of petroleum and that allow to have a clear idea on the tendencies of modern investigation and the technological developments that can be implemented in the short term. It is not pretended to include all the tendencies and developments of the present world, but those that can hit in a relatively short term, in accordance with agreed with the average life of conventional fuels. Nevertheless, most of the conversion principles are applicable to the spectrum of carbonaceous or cellulosic materials which are in nature, are cultivated or wastes of organic origin. Thus one will approach them in a successive way, the physical, chemical and biological conversions that can take place in a production process of an alternate fuel or the same direct use of the fuel such as burning the sweepings derived from the forests. [Spanish] En la definicion y descripcion de combustibles alternos nos debemos centrar en aquellas alternativas tecnologicas que permitan obtener compuestos que difieren de los tradicionales, al menos en sus formas de ser obtenidos. En este articulo se pretende dar un panorama de los combustibles alternos a los convencionales derivados del petroleo y que permita tener una idea clara sobre las tendencias de la investigacion moderna y los desarrollos tecnologicos que puedan ser implementados en el corto plazo. No se pretende abarcar todas las tendencias y desarrollos del mundo actual, sino aquellas que pueden impactar en un plazo relativamente corto, acordes con la vida media de los combustibles convencionales. Sin embargo, la mayor parte de los principios de conversion son aplicables al espectro de materiales carbonaceos o celulosicos los cuales se

  10. N2O formation in combustion systems

    International Nuclear Information System (INIS)

    The objective of this project is to characterize N2O emissions from combustion sources emphasizing N2O emissions from post-combustion selective gas phase NOx reduction processes and reburning. The processes to be evaluated include ammonia, urea and cyanuric acid injection and reburning. The project includes pilot-scale testing at two facilities supported by chemical kinetic modeling. Testing will be performed on both a gas-fired plug flow combustor and a pulverized-coal fired combustor. Work performed to date has included the performance of the initial detailed chemical kinetics calculations. These calculations showed that both urea and cyanuric acid produce significant quantities of N2O, while NH3 injection produced negligible amounts. These kinetics data support limited test results reported for cyanuric acid and ammonia injection. Laboratory work to evaluate the selective gas phase NOx reduction processes listed above will begin in the gas-fired facility early in CY 1990. Testing to evaluate reburning at the coal-fired facility is currently planned to be performed in parallel with the testing at the gas-fired facility. Following completion of that work, additional kinetics calculations will be performed

  11. N2O formation in combustion systems

    International Nuclear Information System (INIS)

    The objective of this project is to characterize N2O emissions from combustion sources emphasizing N2O emissions from post-combustion selective gas phase NOx reduction processes and reburning. The processes to be evaluated include selective noncatalytic NOx control (ammonia, urea and cyanuric acid injection), and reburning. The project includes pilot-scale testing at two facilities supported by chemical kinetic modeling. Testing is being performed on both a gas-fired plug flow combustor and a pulverized-coal fired combustor. Work performed to date has included the performance of the initial detailed chemical kinetics calculations. These calculations showed that both urea and cyanuric acid produce significant quantities of N2O, while NH3 injection produced negligible amounts, These kinetics data support limited test results reported for cyanuric acid and ammonia injection. Laboratory work to evaluate the selective gas phase NOx reduction processes listed above has begun. Testing to evaluate reburning at the coal-fired facility is being performed in parallel with the testing at the gas-fired facility. Following completion of the test work, additional kinetics calculations will be performed

  12. Coal Combustion Products Extension Program

    Energy Technology Data Exchange (ETDEWEB)

    Tarunjit S. Butalia; William E. Wolfe

    2006-01-11

    This final project report presents the activities and accomplishments of the ''Coal Combustion Products Extension Program'' conducted at The Ohio State University from August 1, 2000 to June 30, 2005 to advance the beneficial uses of coal combustion products (CCPs) in highway and construction, mine reclamation, agricultural, and manufacturing sectors. The objective of this technology transfer/research program at The Ohio State University was to promote the increased use of Ohio CCPs (fly ash, FGD material, bottom ash, and boiler slag) in applications that are technically sound, environmentally benign, and commercially competitive. The project objective was accomplished by housing the CCP Extension Program within The Ohio State University College of Engineering with support from the university Extension Service and The Ohio State University Research Foundation. Dr. Tarunjit S. Butalia, an internationally reputed CCP expert and registered professional engineer, was the program coordinator. The program coordinator acted as liaison among CCP stakeholders in the state, produced information sheets, provided expertise in the field to those who desired it, sponsored and co-sponsored seminars, meetings, and speaking at these events, and generally worked to promote knowledge about the productive and proper application of CCPs as useful raw materials. The major accomplishments of the program were: (1) Increase in FGD material utilization rate from 8% in 1997 to more than 20% in 2005, and an increase in overall CCP utilization rate of 21% in 1997 to just under 30% in 2005 for the State of Ohio. (2) Recognition as a ''voice of trust'' among Ohio and national CCP stakeholders (particularly regulatory agencies). (3) Establishment of a national and international reputation, especially for the use of FGD materials and fly ash in construction applications. It is recommended that to increase Ohio's CCP utilization rate from 30% in 2005 to

  13. Development of High Efficiency and Low Emission Low Temperature Combustion Diesel Engine with Direct EGR Injection

    Science.gov (United States)

    Ho, R. J.; Kumaran, P.; Yusoff, M. Z.

    2016-03-01

    Focus on energy and environmental sustainability policy has put automotive research & development directed to developing high efficiency and low pollutant power train. Diffused flame controlled diesel combustion has reach its limitation and has driven R&D to explore other modes of combustions. Known effective mode of combustion to reduce emission are Low temperature combustion (LTC) and homogeneous charge combustion ignition by suppressing Nitrogen Oxide(NOx) and Particulate Matter (PM) formation. The key control to meet this requirement are chemical composition and distribution of fuel and gas during a combustion process. Most research to accomplish this goal is done by manipulating injected mass flow rate and varying indirect EGR through intake manifold. This research paper shows viable alternative direct combustion control via co-axial direct EGR injection with fuel injection process. A simulation study with OpenFOAM is conducted by varying EGR injection velocity and direct EGR injector diameter performed with under two conditions with non-combustion and combustion. n-heptane (C7H16) is used as surrogate fuel together with 57 species 290 semi-detailed chemical kinetic model developed by Chalmers University is used for combustion simulation. Simulation result indicates viability of co-axial EGR injection as a method for low temperature combustion control.

  14. Oxygen isotopic signature of CO2 from combustion processes

    Directory of Open Access Journals (Sweden)

    W. A. Brand

    2011-02-01

    Full Text Available For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires, and human induced (fossil fuel combustion, biomass burning in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects on the order of up to 26%permil; became obvious in the derived CO2 from combustion of different kinds of material, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature, sample geometries (e.g. texture and surface-volume ratios and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original total 18O signature of the material appeared to have little influence, however, a contribution of specific bio

  15. Pre-Combustion Carbondioxide Capture in Integrated Gasification Combined Cycles

    Directory of Open Access Journals (Sweden)

    M. Zeki YILMAZOĞLU

    2010-02-01

    Full Text Available Thermal power plants have a significant place big proportion in the production of electric energy. Thermal power plants are the systems which converts heat energy to mechanical energy and also mechanical energy to electrical energy. Heat energy is obtained from combustion process and as a result of this, some harmful emissions, like CO2, which are the reason for global warming, are released to atmosphere. The contribution of carbondioxide to global warming has been exposed by the previous researchs. Due to this fact, clean energy technologies are growing rapidly all around the world. Coal is generally used in power plants and when compared to other fossil energy sources unit electricity production cost is less than others. When reserve rate is taken into account, coal may be converted to energy in a more efficient and cleaner way. The aim for using the clean coal technologies are to eradicate the harmful emissions of coal and to store the carbondioxide, orginated from combustion, in different forms. In line with this aim, carbondioxide may be captured by either pre-combustion, by O2/CO2 recycling combustion systems or by post combustion. The integrated gasification combined cycles (IGCC are available in pre-combustion capture systems, whereas in O2/CO2 recycling combustion systems there are ultrasuper critical boiler technologies and finally flue gas washing systems by amines exists in post combustion systems. In this study, a pre-combustion CO2 capture process via oxygen blown gasifiers is compared with a conventional power plant in terms of CO2 emissions. Captured carbondioxide quantity has been presented as a result of the calculations made throughout the study.

  16. Oxygen isotopic signature of CO2 from combustion processes

    Science.gov (United States)

    Schumacher, M.; Werner, R. A.; Meijer, H. A. J.; Jansen, H. G.; Brand, W. A.; Geilmann, H.; Neubert, R. E. M.

    2011-02-01

    For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O) abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires), and human induced (fossil fuel combustion, biomass burning) in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects on the order of up to 26%permil; became obvious in the derived CO2 from combustion of different kinds of material, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature), sample geometries (e.g. texture and surface-volume ratios) and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive) transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original total 18O signature of the material appeared to have little influence, however, a contribution of specific bio-chemical compounds to

  17. AIR EMISSIONS FROM SCRAP TIRE COMBUSTION

    Science.gov (United States)

    The report discusses air emissions from two types of scrap tire combustion: uncontrolled and controlled. Uncontrolled sources are open tire fires, which produce many unhealthful products of incomplete combustion and release them directly into the atmosphere. Controlled combustion...

  18. Path planning during combustion mode switch

    Science.gov (United States)

    Jiang, Li; Ravi, Nikhil

    2015-12-29

    Systems and methods are provided for transitioning between a first combustion mode and a second combustion mode in an internal combustion engine. A current operating point of the engine is identified and a target operating point for the internal combustion engine in the second combustion mode is also determined. A predefined optimized transition operating point is selected from memory. While operating in the first combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion engine to approach the selected optimized transition operating point. When the engine is operating at the selected optimized transition operating point, the combustion mode is switched from the first combustion mode to the second combustion mode. While operating in the second combustion mode, one or more engine actuator settings are adjusted to cause the operating point of the internal combustion to approach the target operating point.

  19. Studying the specific features pertinent to combustion of chars obtained from coals having different degrees of metamorphism and biomass chars

    Science.gov (United States)

    Bestsennyi, I. V.; Shchudlo, T. S.; Dunaevskaya, N. I.; Topal, A. I.

    2013-12-01

    Better conditions for igniting low-reaction coal (anthracite) can be obtained, higher fuel burnout ratio can be achieved, and the problem of shortage of a certain grade of coal can be solved by firing coal mixtures and by combusting coal jointly with solid biomass in coal-fired boilers. Results from studying the synergetic effect that had been revealed previously during the combustion of coal mixtures in flames are presented. A similar effect was also obtained during joint combustion of coal and wood in a flame. The kinetics pertinent to combustion of char mixtures obtained from coals characterized by different degrees of metamorphism and the kinetics pertinent to combustion of wood chars were studied on the RSK-1D laboratory setup. It was found from the experiments that the combustion rate of char mixtures obtained from coals having close degrees of metamorphism is equal to the value determined as a weighted mean rate with respect to the content of carbon. The combustion rate of char mixtures obtained from coals having essentially different degrees of metamorphism is close to the combustion rate of more reactive coal initially in the process and to the combustion rate of less reactive coal at the end of the process. A dependence of the specific burnout rate of carbon contained in the char of two wood fractions on reciprocal temperature in the range 663—833 K is obtained. The combustion mode of an experimental sample is determined together with the reaction rate constant and activation energy.

  20. Modelling of fuel spray and combustion in diesel engines

    Energy Technology Data Exchange (ETDEWEB)

    Huttunen, M.T.; Kaario, O.T. [VTT Energy, Espoo (Finland)

    1997-12-31

    Fuel spray and air motion characteristics and combustion in direct injection (DI) diesel engines was studied using computational models of the commercial CFD-code FIRE. Physical subprocesses modelled included Lagrangian spray droplet movement and behaviour (atomisation, evaporation and interaction of spray droplets) and combustion of evaporated liquid spray in the gas phase. Fuel vapour combustion rate was described by the model of Magnussen and Hjertager. The standard k,{epsilon}-model was used for turbulence. In order to be able to predict combustion accurately, the fuel spray penetration should be predicted with reasonable accuracy. In this study, the standard drag coefficient had to be reduced in order to match the computed penetration to the measured one. In addition, the constants in the submodel describing droplet breakup also needed to be adjusted for closer agreement with the measurements. The characteristic time scale of fuel consumption rate k/C{sub R} {epsilon} strongly influenced the heat release and in-cylinder pressure. With a value around 2.0 to 5.0 for C{sub R}, the computed in-cylinder pressure during the compression stroke agreed quite well with the measurements. On the other hand, the in-cylinder pressure was underpredicted during the expansion stroke. This is partly due to the fact that hydrocarbon fuel combustion was modelled as a one-step reaction reading to CO{sub 2} and H{sub 2}O and inadequate description of the mixing of reactants and combustion products. (author) 16 refs.

  1. Model analysis for combustion characteristics of RDF pellet

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Fundamental studies of the combustion characteristics and the de-HCl behavior of a single refuse-derived fuel(RDF) pellet were carried out to explain the de-HCl phenomena of RDF during fluidized bed combustion and to provide data for the development of high efficiency power generation technology using RDF previously. For further interpreting the devolatilization and the char combustion processes of RDF quantitatively, an unsteady combustion model for single RDF pellet, involving reaction rates, heat transfer and oxygen diffusion in the RDF pellet, was developed. Comparisons of simulation results with experimental data for mass loss of the RDF samples made from municipal solid waste, wood chips and poly-propylene when they were heated at 10K/min or put into the furnace under 1073K show the verifiability of the model. Using this model, the distributions of the temperature and the reaction ratio along the radius of RDF pellet during the devolatilization process and the char combustion process were presented, and discussion about the inference of heating rate on the combustion characteristics were performed.

  2. EXPERIMENTAL STUDY ON HORIZONTAL COMBUSTION TECHNIQUE FOR BITUMINOUS COAL BRIQUET

    Institute of Scientific and Technical Information of China (English)

    路春美; 程世庆; 邵延玲; 张晔

    1997-01-01

    Through a lot of experiments, a new kind of stove using horizontal combustion technique for bituminous coal briquet has been developed. Making use of this stove, studies have been made on burning process of bituminous coal briquet, distribution of temperature field in the stove, the regularities of evolution and combustion of volatile matter, the burning rate and efficiency of bituminous coal briquet, characteristics of fire-sealing and sulfur-retention. The results show that, with the technique, some achievements can be obtained in combustion of bituminous coal briquet, such as lower pollution that the flue gas black degree is below 0.5R and dust concentration is below 90mg/m3 . The stove's combustion efficiency reaches 90%, sulfur fixing efficiency is 60%, and CO concentration is decreased by 40% compared with other traditional stoves. With so many advantages, the stove can be used extensively in civil stoves and smaller industrial boilers.

  3. Reactivity Studies of Sludge and Biomass Combustion

    Directory of Open Access Journals (Sweden)

    Mohammad T Afzal

    2009-11-01

    Full Text Available Sludge and biomass are wastes with energy value. Both can provide a renewable energy in the form of gaseous fuels through thermal conversion processes. Proper understanding of the thermal properties and reaction kinetic of sludge and biomass is important for efficient design, operation and modeling of the conversion process. This study was carried out to obtain the kinetics data of the sludge and biomass in pure oxygen atmosphere at 30 mlmin-1 with the combustion temperature ranging from 50 to 900oC. The effect of sample size and heating rate on thermal degradation were studied and kinetic parameters of sludge, bagasse and sawdust combustion were described using Arrhenius equation. Two distinct reaction zones were observed for sludge, bagasse and sawdust samples. The activation energy and pre-exponential factors, in the first zone were found to be significantly higher than that of the second zone where as the opposite way for sawdust.

  4. Combustion of bulk titanium in oxygen

    Science.gov (United States)

    Clark, A. F.; Moulder, J. C.; Runyan, C. C.

    1975-01-01

    The combustion of bulk titanium in one atmosphere oxygen is studied using laser ignition and several analytical techniques. These were high-speed color cinematography, time and space resolved spectra in the visible region, metallography (including SEM) of specimens quenched in argon gas, X-ray and chemical product analyses, and a new optical technique, the Hilbert transform method. The cinematographic application of this technique for visualizing phase objects in the combustion zone is described. The results indicate an initial vapor phase reaction immediately adjacent to the molten surface but as the oxygen uptake progresses the evaporation approaches the point of congruency and a much reduced evaporation rate. This and the accumulation of the various soluble oxides soon drive the reaction zone below the surface where gas formation causes boiling and ejection of particles. The buildup of rutile cuts off the oxygen supply and the reaction ceases.

  5. Continuous monitoring of salivary flow rate and pH at the surface of the dentition following consumption of acidic beverages.

    Science.gov (United States)

    Millward, A; Shaw, L; Harrington, E; Smith, A J

    1997-01-01

    Use of a splint-mounted flexible pH electrode has allowed reliable continuous monitoring of pH at the surface of the dentition whilst still enabling subjects to drink normally. pH was monitored at the palatal upper left central incisor and upper right first permanent molar sites after drinking 1% (w/v) citric acid. A maximal decrease in pH to values of 2-3 was observed after 1 min followed by a slower recovery which was above pH 5.5 within 2 min at the former site and in 4-5 min at the latter site. A sharp rise in parotid saliva flow rate was seen at 1 min after drinking the same concentration of citric acid by glass, straw or feeder cup, which returned to resting levels within 6 min although the fall-off of flow rate was slower with the feeder cup. Thus, after dietary acid intake the pH at the surface of the dentition is below the critical pH for enamel dissolution for shorter periods than previously suggested, which is probably a reflection of salivary neutralisation and washing. PMID:8955994

  6. Preliminary Study on the Effect of Ethylene Diamine- n, n-diacetic Acid on Methane Gas Production Rate from Cow Manure

    Directory of Open Access Journals (Sweden)

    Nwokem N Calvin

    2014-09-01

    Full Text Available In an effort to improve methane gas production rate from cattle slurry; ethylene diamine- N, N-diacetic acid chelating ligand was introduced into the digester system. Experimental analysis involving the determination of trace metals, pH and methane gas yield, were carried out with the use of the Flame Atomic Absorption Spectrophotometer and Biogas5000 analyser. The results showed that there was an increase in the pH of the system; the amount of methane gas yield equally increased by 12% and the Hydraulic Retention Time decreased from 50 days to 25 days on addition of ethylene diamine- N, N-diacetic acid chelating ligand. Also, increasing the concentration of the chelating ligand further decreased the HRT of the digester system from 25 days to 19days. Concentration of trace metals like Iron, Cobalt and Nickel within the digester system ranged from 0.001-0.050 mg/L; these metals reacted with ethylene diamine- N, N-diacetic acid chelating ligand to form metal chelates. The metal chelate formed resulted in the catalysis of the hydrolysis stage (which is the rate determining step of the anaerobic digestion process. Thus, the decrease in HRT was due to the metal chelate catalysis of the hydrolysis stage of the anaerobic digestion process were the metal chelate formation served as the driving force in the solvolysis process.

  7. Propagated fixed-bed mixed-acid fermentation: Part I: Effect of volatile solid loading rate and agitation at high pH.

    Science.gov (United States)

    Golub, Kristina W; Forrest, Andrea K; Mercy, Kevin L; Holtzapple, Mark T

    2011-11-01

    Countercurrent fermentation is a high performing process design for mixed-acid fermentation. However, there are high operating costs associated with moving solids, which is an integral component of this configuration. This study investigated the effect of volatile solid loading rate (VSLR) and agitation in propagated fixed-bed fermentation, a configuration which may be more commercially viable. To evaluate the role of agitation on fixed-bed configuration performance, continuous mixing was compared with periodic mixing. VSLR was also varied and not found to affect acid yields. However, increased VSLR and liquid retention time did result in higher conversions, productivity, acid concentrations, but lower selectivities. Agitation was demonstrated to be important for this fermentor configuration, the periodically-mixed fermentation had the lowest conversion and yields. Operating at a high pH (∼9) contributed to the high selectivity to acetic acid, which might be industrially desirable but at the cost of lower yield compared to a neutral pH. PMID:21963249

  8. Propagated fixed-bed mixed-acid fermentation: effect of volatile solid loading rate and agitation at near-neutral pH.

    Science.gov (United States)

    Golub, Kristina W; Golub, Stacey R; Meysing, Daniel M; Holtzapple, Mark T

    2012-11-01

    To increase conversion and product concentration, mixed-acid fermentation can use a countercurrent strategy where solids and liquids pass in opposite directions through a series of fermentors. To limit the requirement for moving solids, this study employed a propagated fixed-bed fermentation, where solids were stationary and only liquid was transferred. To evaluate the role of agitation, continuous mixing was compared with periodic mixing. The periodically mixed fermentation had similar conversion, but lower yield and selectivity. Increasing volatile solid loading rate from 1.5 to 5.1g non-acid volatile solids/(L(liq)·d) and increasing liquid retention time decreased yield, conversion, selectivity, but increased product concentrations. Compared to a previous study at high pH (~9), this study achieved higher performance at near neutral pH (~6.5) and optimal C-N ratios. Compared to countercurrent fermentation, propagated fixed-bed fermentations have similar selectivities and produce similar proportions of acetic acid, but have lower yields, conversion, productivities, and acid concentrations. PMID:22995159

  9. Propagated fixed-bed mixed-acid fermentation: effect of volatile solid loading rate and agitation at near-neutral pH.

    Science.gov (United States)

    Golub, Kristina W; Golub, Stacey R; Meysing, Daniel M; Holtzapple, Mark T

    2012-11-01

    To increase conversion and product concentration, mixed-acid fermentation can use a countercurrent strategy where solids and liquids pass in opposite directions through a series of fermentors. To limit the requirement for moving solids, this study employed a propagated fixed-bed fermentation, where solids were stationary and only liquid was transferred. To evaluate the role of agitation, continuous mixing was compared with periodic mixing. The periodically mixed fermentation had similar conversion, but lower yield and selectivity. Increasing volatile solid loading rate from 1.5 to 5.1g non-acid volatile solids/(L(liq)·d) and increasing liquid retention time decreased yield, conversion, selectivity, but increased product concentrations. Compared to a previous study at high pH (~9), this study achieved higher performance at near neutral pH (~6.5) and optimal C-N ratios. Compared to countercurrent fermentation, propagated fixed-bed fermentations have similar selectivities and produce similar proportions of acetic acid, but have lower yields, conversion, productivities, and acid concentrations.

  10. Combustion synthesis of porous titanium microspheres

    International Nuclear Information System (INIS)

    The synthesis of titanium porous microspheres by a combustion technique was studied under an argon atmosphere by using a TiO2 − 2.5Mg reactive mixture. The precursor, a fine TiO2 powder, was thermally treated in the range 600–1300 °C prior to the combustion experiments. TiO2 microspheres whose diameters were between 10 and 50 μm were obtained from precursor particles annealed in the range 900–1100 °C. A biphase product consisting of Ti and MgO phases was obtained when the TiO2 microspheres were reduced with Mg. The spherical morphology of the final particles was retained despite the relatively high combustion temperatures (1630–1670 °C) used in this study. Moreover, porous titanium microspheres were obtained when the MgO particles were dissolved using acid leaching. Scanning electron microscopy (SEM) images of the microspheres suggested that the spherical structure contained ∼0.5–2.0-μm-diameter porous windows. The Brunauer–Emmett–Teller (BET) surface area of the Ti microspheres was determined to be 2.8 m2 g−1. - Highlights: • TiO2 + 2.5Mg mixture was combusted under argon pressure to produce titanium microspheres. • Microspheres with a porous framework structure were obtained at 1630–1670 °C. • The microspheres exhibited 10–50 μm average diameters with porous window of ∼0.5–2.0 μm and BET surface area of 2.8 m2 g−1. - Graphical abstract: Display Omitted

  11. Manifold methods for methane combustion

    Energy Technology Data Exchange (ETDEWEB)

    Yang, B.; Pope, S.B. [Cornell Univ., Ithaca, NY (United States)

    1995-10-01

    Great progresses have been made in combustion research, especially, the computation of laminar flames and the probability density function (PDF) method in turbulent combustion. For one-dimensional laminar flames, by considering the transport mechanism, the detailed chemical kinetic mechanism and the interactions between these two basic processes, today it is a routine matter to calculate flame velocities, extinction, ignition, temperature, and species distributions from the governing equations. Results are in good agreement with those obtained for experiments. However, for turbulent combustion, because of the complexities of turbulent flow, chemical reactions, and the interaction between them, in the foreseeable future, it is impossible to calculate the combustion flow field by directly integrating the basic governing equations. So averaging and modeling are necessary in turbulent combustion studies. Averaging, on one hand, simplifies turbulent combustion calculations, on the other hand, it introduces the infamous closure problems, especially the closure problem with chemical reaction terms. Since in PDF calculations of turbulent combustion, the averages of the chemical reaction terms can be calculated, PDF methods overcome the closure problem with the reaction terms. It has been shown that the PDF method is a most promising method to calculate turbulent combustion. PDF methods have been successfully employed to calculate laboratory turbulent flames: they can predict phenomena such as super equilibrium radical levels, and local extinction. Because of these advantages, PDF methods are becoming used increasingly in industry combustor codes.

  12. Effects of ractopamine hydrochloride on performance, rate and variation in feed intake, and acid-base balance in feedlot cattle.

    Science.gov (United States)

    Abney, C S; Vasconcelos, J T; McMeniman, J P; Keyser, S A; Wilson, K R; Vogel, G J; Galyean, M L

    2007-11-01

    Two experiments evaluated effects of ractopamine hydrochloride (RAC) on performance, intake patterns, and acid-base balance of feedlot cattle. In Exp. 1, 360 crossbred steers (Brangus, British, and British x Continental breeding; initial BW = 545 kg) were used in a study with a 3 x 3 factorial design to study the effects of dose [0, 100, or 200 mg/(steer x d) of RAC] and duration (28, 35, or 42 d) of feeding of RAC in a randomized complete block design (9 treatments, 8 pens/treatment). No dose x duration interactions were detected (P > 0.10). As RAC dose increased, final BW (FBW; P = 0.01), ADG (P 0.10) in feedlot performance, urine pH, blood gas measurements, or variation in intake patterns between RAC and control cattle, but steers fed RAC had increased (P = 0.04) LM area, decreased (P = 0.03) yield grade, and increased (P < 0.10) time to consume 50 and 75% of daily intake relative to control steers. Our results suggest that feeding RAC for 35 d at 200 mg/(steer x d) provided optimal performance, and no effects on acid-base balance or variation in intake patterns of finishing steers were noted with RAC fed at 200 mg/(steer x d) over a 30-d period. PMID:17609477

  13. An experiment study of homogeneous charge compression ignition combustion and emission in a gasoline engine

    Directory of Open Access Journals (Sweden)

    Zhang Jianyong

    2014-01-01

    Full Text Available Homogenous charge compression ignition (HCCI technology has exhibited high potential to reduce fuel consumption and NOx emissions over normal spark ignition engines significantly. Optimized kinetic process (OKP technology is implemented to realize HCCI combustion in a port fuel injection gasoline engine. The combustion and emission characteristics are investigated with variation of intake air temperature, exhaust gas recirculation (EGR rate and intake air pressure. The results show that intake air temperature has great influence on HCCI combustion characteristic. Increased intake air temperature results in advance combustion phase, shorten combustion duration, and lower indicated mean effective pressure (IMEP. Increased EGR rate retards combustion start phase and prolongs combustion duration, while maximum pressure rising rate and NOx emission are reduced with increase of EGR rate. In the condition with constant fuel flow quantity, increased air pressure leads to retarded combustion phase and lower pressure rising rate, which will reduce the engine knocking tendency. In the condition with constant air fuel ratio condition, fuel injection quantity increases as intake air pressure increases, which lead to high heat release rate and high emission level. The optimal intake air temperature varies in different operating area, which can be tuned from ambient temperature to 220℃ by heat management system. The combination of EGR and air boost technology could expand operating area of HCCI engine, which improve indicated mean effective pressure from maximum 510kPa to 720kPa.

  14. Combustion Of Metals In Reduced Gravity And Extraterrestrial Environments

    Science.gov (United States)

    Abbud-Madrid, A.; Modak, A.; Branch, M. C.

    2003-01-01

    The recent focus of this research project has been to model the combustion of isolated metal droplets and, in particular, to couple the existing theories and formulations of phenomena such as condensation, reaction kinetics, radiation, and surface reactions to formulate a more complete combustion model. A fully transient, one-dimensional (spherical symmetry) numerical model that uses detailed chemical kinetics, multi-component molecular transport mechanisms, condensation kinetics, and gas phase radiation heat transfer was developed. A coagulation model was used to simulate the particulate formation of MgO. The model was used to simulate the combustion of an Mg droplet in pure O2 and CO2. Methanol droplet combustion is considered as a test case for the solution method for both quasi-steady and fully transient simulations. Although some important processes unique to methanol combustion, such as water absorption at the surface, are not included in the model, the results are in sufficient agreement with the published data. Since the major part of the heat released in combustion of Mg, and in combustion of metals in general, is due to the condensation of the metal oxide, it is very important to capture the condensation processes correctly. Using the modified nucleation theory, an Arrhenius type rate expression is derived to calculate the condensation rate of MgO. This expression can be easily included in the CHEMKIN reaction mechanism format. Although very little property data is available for MgO, the condensation rate expression derived using the existing data is able to capture the condensation of MgO. An appropriate choice of the reference temperature to calculate the rate coefficients allows the model to correctly predict the subsequent heat release and hence the flame temperature.

  15. Resting heart rate in infants and toddlers: variations associated with early infant diet and the omega 3 fatty acid DHA

    Science.gov (United States)

    Although early postnatal nutrition can have long-term effects on developmental processes, the influence of infant diet on the maturation of cardiac development has not been documented. To study this relationship we recorded resting heart-rate (HR) in awake, healthy infants and toddlers exclusively b...

  16. Sulfur Chemistry in Combustion I

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Glarborg, Peter

    2000-01-01

    Most fossil fuels contain sulphur and also biofuels and household waste have a sulphur content. As a consequence sulphur species will often be present in combustion processes. In this paper the fate and influence of fuel sulphur species in combustion will be treated. First a description...... of the sulphur compounds in fossil fuels and the possibilities to remove them will be given. Then the combustion of sulphur species and their influence on the combustion chemistry and especially on the CO oxidation and the NOx formation will be described. Finally the in-situ removal of sulphur in the combustion...... process by reaction between SO2 and calcium containing sorbents and the influence on the NOx chemistry will be treated....

  17. Evaluation of a hybrid kinetics/mixing-controlled combustion model for turbulent premixed and diffusion combustion using KIVA-II

    Science.gov (United States)

    Nguyen, H. Lee; Wey, Ming-Jyh

    1990-01-01

    Two-dimensional calculations were made of spark ignited premixed-charge combustion and direct injection stratified-charge combustion in gasoline fueled piston engines. Results are obtained using kinetic-controlled combustion submodel governed by a four-step global chemical reaction or a hybrid laminar kinetics/mixing-controlled combustion submodel that accounts for laminar kinetics and turbulent mixing effects. The numerical solutions are obtained by using KIVA-2 computer code which uses a kinetic-controlled combustion submodel governed by a four-step global chemical reaction (i.e., it assumes that the mixing time is smaller than the chemistry). A hybrid laminar/mixing-controlled combustion submodel was implemented into KIVA-2. In this model, chemical species approach their thermodynamics equilibrium with a rate that is a combination of the turbulent-mixing time and the chemical-kinetics time. The combination is formed in such a way that the longer of the two times has more influence on the conversion rate and the energy release. An additional element of the model is that the laminar-flame kinetics strongly influence the early flame development following ignition.

  18. Evaluation of a hybrid kinetics/mixing-controlled combustion model for turbulent premixed and diffusion combustion using KIVA-2

    Science.gov (United States)

    Nguyen, H. Lee; Wey, Ming-Jyh

    Two dimensional calculations were made of spark ignited premixed-charge combustion and direct injection stratified-charge combustion in gasoline fueled piston engines. Results are obtained using kinetic-controlled combustion submodel governed by a four-step global chemical reaction or a hybrid laminar kinetics/mixing-controlled combustion submodel that accounts for laminar kinetics and turbulent mixing effects. The numerical solutions are obtained by using KIVA-2 computer code which uses a kinetic-controlled combustion submodel governed by a four-step global chemical reaction (i.e., it assumes that the mixing time is smaller than the chemistry). A hybrid laminar/mixing-controlled combustion submodel was implemented into KIVA-2. In this model, chemical species approach their thermodynamics equilibrium with a rate that is a combination of the turbulent-mixing time and the chemical-kinetics time. The combination is formed in such a way that the longer of the two times has more influence on the conversion rate and the energy release. An additional element of the model is that the laminar-flame kinetics strongly influence the early flame development following ignition.

  19. Combustion & Laser Diagnostics Research Complex (CLDRC)

    Data.gov (United States)

    Federal Laboratory Consortium — Description: The Combustion and Laser Diagnostics Research Complex (CLRDC) supports the experimental and computational study of fundamental combustion phenomena to...

  20. Experimental Investigation of Oxygen Enriched air intake on Combustion Parameters of a Single Cylinder Diesel Engine

    OpenAIRE

    Rajkumar, K; Govindarajan, P

    2010-01-01

    In the present experimental work a computerized Single cylinder Diesel engine with data acquisition system was used to study the effects of oxygen enriched air intake on combustion parameters. Increasing the oxygen content with the air leads to faster burn rates and the ability to burn more fuel at the same stoichiometery. Addedoxygen in the combustion air leads to shorter ignition delays and offers more potential for burning diesel. Oxy-fuel combustion reduces the volume of flue gases and re...

  1. HCCI Heat Release Data for Combustion Simulation, based on Results from a Turbocharged Multi Cylinder Engine

    OpenAIRE

    Johansson, Thomas; Borgqvist, Patrick; Johansson, Bengt; Tunestål, Per; Aulin, Hans

    2010-01-01

    When simulating homogenous charge compression ignition or HCCI using one-dimensional models it is important to have the right combustion parameters. When operating in HCCI the heat release parameters will have a high influence on the simulation result due to the rapid combustion rate, especially if the engine is turbocharged. In this paper an extensive testing data base is used for showing the combustion data from a turbocharged engine operating in HCCI mode. The experimental data cover a wid...

  2. Effects of intake air temperature on homogenous charge compression ignition combustion and emissions with gasoline and n-heptane

    Directory of Open Access Journals (Sweden)

    Zhang Jianyong

    2015-01-01

    Full Text Available In a port fuel injection engine, Optimized kinetic process (OKP technology is implemented to realize HCCI combustion with dual-fuel injection. The effects of intake air temperature on HCCI combustion and emissions are investigated. The results show that dual-fuel control prolongs HCCI combustion duration and improves combustion stability. Dual-fuel HCCI combustion needs lower intake air temperature than gasoline HCCI combustion, which reduces the requirements on heat management system. As intake air temperature decreases, air charge increases and maximum pressure rising rate decreases. When intake air temperature is about 55ºC, HCCI combustion becomes worse and misfire happens. In fixed dual fuel content condition, HC and CO emission decreases as intake air temperature increases. The combination of dual-fuel injection and intake air temperature control can expand operation range of HCCI combustion.

  3. Effects of network dissolution changes on pore-to-core upscaled reaction rates for kaolinite and anorthite reactions under acidic conditions

    KAUST Repository

    Kim, Daesang

    2013-11-01

    We have extended reactive flow simulation in pore-network models to include geometric changes in the medium from dissolution effects. These effects include changes in pore volume and reactive surface area, as well as topological changes that open new connections. The computed changes were based upon a mineral map from an X-ray computed tomography image of a sandstone core. We studied the effect of these changes on upscaled (pore-scale to core-scale) reaction rates and compared against the predictions of a continuum model. Specifically, we modeled anorthite and kaolinite reactions under acidic flow conditions during which the anorthite reactions remain far from equilibrium (dissolution only), while the kaolinite reactions can be near-equilibrium. Under dissolution changes, core-scale reaction rates continuously and nonlinearly evolved in time. At higher injection rates, agreement with predictions of the continuum model degraded significantly. For the far-from-equilibrium reaction, our results indicate that the ability to correctly capture the heterogeneity in dissolution changes in the reactive mineral surface area is critical to accurately predict upscaled reaction rates. For the near-equilibrium reaction, the ability to correctly capture the heterogeneity in the saturation state remains critical. Inclusion of a Nernst-Planck term to ensure neutral ionic currents under differential diffusion resulted in at most a 9% correction in upscaled rates.

  4. NOx formation in combustion of gaseous fuel in ejection burner

    Science.gov (United States)

    Rimár, Miroslav; Kulikov, Andrii

    2016-06-01

    The aim of this work is to prepare model for researching of the formation in combustion of gaseous fuels. NOx formation is one of the main ecological problems nowadays as nitrogen oxides is one of main reasons of acid rains. The ANSYS model was designed according to the calculation to provide full combustion and good mixing of the fuel and air. The current model is appropriate to research NOx formation and the influence of the different principles of NOx reduction method. Applying of designed model should spare both time of calculations and research and also money as you do not need to measure the burner characteristics.

  5. Combustion Processes in Hybrid Rocket Engines

    Science.gov (United States)

    Venkateswaran,S.; Merkle, C. L.

    1996-01-01

    In recent years, there has been a resurgence of interest in the development of hybrid rocket engines for advanced launch vehicle applications. Hybrid propulsion systems use a solid fuel such as hydroxyl-terminated polybutadiene (HTPB) along with a gaseous/liquid oxidizer. The performance of hybrid combustors depends on the convective and radiative heat fluxes to the fuel surface, the rate of pyrolysis in the solid phase, and the turbulent combustion processes in the gaseous phases. These processes in combination specify the regression rates of the fuel surface and thereby the utilization efficiency of the fuel. In this paper, we employ computational fluid dynamics (CFD) techniques in order to gain a quantitative understanding of the physical trends in hybrid rocket combustors. The computational modeling is tailored to ongoing experiments at Penn State that employ a two dimensional slab burner configuration. The coordinated computational/experimental effort enables model validation while providing an understanding of the experimental observations. Computations to date have included the full length geometry with and with the aft nozzle section as well as shorter length domains for extensive parametric characterization. HTPB is sed as the fuel with 1,3 butadiene being taken as the gaseous product of the pyrolysis. Pure gaseous oxygen is taken as the oxidizer. The fuel regression rate is specified using an Arrhenius rate reaction, which the fuel surface temperature is given by an energy balance involving gas-phase convection and radiation as well as thermal conduction in the solid-phase. For the gas-phase combustion, a two step global reaction is used. The standard kappa - epsilon model is used for turbulence closure. Radiation is presently treated using a simple diffusion approximation which is valid for large optical path lengths, representative of radiation from soot particles. Computational results are obtained to determine the trends in the fuel burning or

  6. CORROSION RESISTANCE OF PEARLITIC AND BAINITIC CAST IRON IN A SYNTHETIC SOLUTION OF CONDENSED GAS FROM COMBUSTION

    Directory of Open Access Journals (Sweden)

    Sandra Matos Cordeiro Costa

    2015-03-01

    Full Text Available The corrosion of engine components of the combustion chamber is usually related to the formation of acids such as sulfuric and nitric. These acids are generated by the condensation of combustion gases that usually occur in vehicle exhaust systems. However, with the development of new technologies to reduce emissions, condensation is also being promoted in vehicle combustion chambers. This fact is associated with high exhaust gas recirculation rates, known as EGR (English term for Exhaust Gas Recirculation. Consequently, corrosion problems in the engine components are increasing, especially in cylinder liners alloy manufactured using cast iron. In this study, the corrosion resistance of two cast iron alloys, one with a pearlitic microstructure and the other with a bainite microstructure in a solution simulating the composition of the condensate obtained from the combustion gases. It was found that the microstructure of the cast iron is an important factor affecting the corrosion behavior. The results showed that none of the two materials investigated is resistant to corrosion in the test medium, and the small difference observed between the behavior of the two cast iron was related to its microstructure, which are dependent on their chemical compositions. The cast iron with a pearlitic microstructure showed less formation of corrosion products than the bainitic cast iron. This result is related to the presence of steadite phase, highly stable and resistant to corrosion in pearlitic microstructure. This phase (steadite anchors the corrosion products formed on the surface and act as a partial barrier slowing the progress of the corrosion process, that was more pronounced in the bainitic cast iron.

  7. Combustion Properties of Straw Briquettes

    Directory of Open Access Journals (Sweden)

    Zhao Qing-ling

    2013-05-01

    Full Text Available The low bulk density of straw is one of the major barriers, which blocks the collection, handling, transportation and storage. Densification of biomass into briquettes/pellets is a suitable method of increasing the bulk density of biomass. Yet in the process, a tremendous amount of air is ejected from biomass grind, which brings substantial specific variation including combustion property. Among them, combustion property is critical for proper design and operation of burning facilities. Therefore, a series of tests about combustion properties of 75mm diameter corn briquettes were done. First, the combustion process (ignition, full flaming and glowing phases., precipitation of tar were investigated by a heating stove, then, Some ash sample from the muffle burner was subjected to an ash melting characteristic test. The results show the combustion of briquettes takes more time than that of raw straw from ignition to complete combustion; in order to meet complete combustion in a short time, the raw straw needs more supply air volume than briquettes under the same α value; the temperature of furnace chamber should been controlled under 900°C, which help to reduce the dark smoke, tar and slag.

  8. [Inhibition rate of gamma-aminolevulinic acid dehydratase activity in erythrocytes as a reliable index for individual workers of low lead exposure].

    Science.gov (United States)

    Hirano, H; Omichi, M; Ohishi, H; Ishikawa, K; Hirashima, N

    1983-09-01

    As the delta-aminolevulinic acid dehydratase (ALAD) activity in erythrocytes is decreased by lead exposure, we considered that a net reduction of ALAD activity by lead in blood should be the difference between the activity fully activated with zinc (Zn2+) and dithiothreitol (DTT) and that without activation. The optimal condition of activation of ALAD was found by addition of 0.25 mM of Zn2+ and 10 mM of DTT in the reaction mixture. Judging from our previous results that the amount of inhibition of ALAD activity can be represented as the rate of inhibition and is closely correlated with the dose of lead administered to rabbits, the inhibition rate of ALAD activity and lead content in blood (Pb-B) of lead workers were measured. The scatter diagram obtained from the inhibition rate and lead content in blood has two groups being divided at 50 micrograms/ml of Pb-B. In one group less than 50 micrograms/100 ml of Pb-B, the inhibition rate has been closely related to Pb-B., the regression equation being Y = 1.82 X + 11.7, and the correlation coefficient + 0.926. In another group more than 50 micrograms/100 ml of Pb-B the inhibition rate remained constant at the 90% level. Measurement of the inhibition rate suggests to have practical validity for monitoring lead exposure in workers, and by means of a nomograph lead content in blood can be estimated from the inhibition rate.

  9. Catalytic Combustion of Gasified Waste

    Energy Technology Data Exchange (ETDEWEB)

    Kusar, Henrik

    2003-09-01

    This thesis concerns catalytic combustion for gas turbine application using a low heating-value (LHV) gas, derived from gasified waste. The main research in catalytic combustion focuses on methane as fuel, but an increasing interest is directed towards catalytic combustion of LHV fuels. This thesis shows that it is possible to catalytically combust a LHV gas and to oxidize fuel-bound nitrogen (NH{sub 3}) directly into N{sub 2} without forming NO{sub x} The first part of the thesis gives a background to the system. It defines waste, shortly describes gasification and more thoroughly catalytic combustion. The second part of the present thesis, paper I, concerns the development and testing of potential catalysts for catalytic combustion of LHV gases. The objective of this work was to investigate the possibility to use a stable metal oxide instead of noble metals as ignition catalyst and at the same time reduce the formation of NO{sub x} In paper II pilot-scale tests were carried out to prove the potential of catalytic combustion using real gasified waste and to compare with the results obtained in laboratory scale using a synthetic gas simulating gasified waste. In paper III, selective catalytic oxidation for decreasing the NO{sub x} formation from fuel-bound nitrogen was examined using two different approaches: fuel-lean and fuel-rich conditions. Finally, the last part of the thesis deals with deactivation of catalysts. The various deactivation processes which may affect high-temperature catalytic combustion are reviewed in paper IV. In paper V the poisoning effect of low amounts of sulfur was studied; various metal oxides as well as supported palladium and platinum catalysts were used as catalysts for combustion of a synthetic gas. In conclusion, with the results obtained in this thesis it would be possible to compose a working catalytic system for gas turbine application using a LHV gas.

  10. Combustion kinetics and reaction pathways

    Energy Technology Data Exchange (ETDEWEB)

    Klemm, R.B.; Sutherland, J.W. [Brookhaven National Laboratory, Upton, NY (United States)

    1993-12-01

    This project is focused on the fundamental chemistry of combustion. The overall objectives are to determine rate constants for elementary reactions and to elucidate the pathways of multichannel reactions. A multitechnique approach that features three independent experiments provides unique capabilities in performing reliable kinetic measurements over an exceptionally wide range in temperature, 300 to 2500 K. Recent kinetic work has focused on experimental studies and theoretical calculations of the methane dissociation system (CH{sub 4} + Ar {yields} CH{sub 3} + H + Ar and H + CH{sub 4} {yields} CH{sub 3} + H{sub 2}). Additionally, a discharge flow-photoionization mass spectrometer (DF-PIMS) experiment is used to determine branching fractions for multichannel reactions and to measure ionization thresholds of free radicals. Thus, these photoionization experiments generate data that are relevant to both reaction pathways studies (reaction dynamics) and fundamental thermochemical research. Two distinct advantages of performing PIMS with high intensity, tunable vacuum ultraviolet light at the National Synchrotron Light Source are high detection sensitivity and exceptional selectivity in monitoring radical species.

  11. QSAR models for removal rates of organic pollutants adsorbed by in situ formed manganese dioxide under acid condition.

    Science.gov (United States)

    Su, Pingru; Zhu, Huicen; Shen, Zhemin

    2016-02-01

    Manganese dioxide formed in oxidation process by potassium permanganate exhibits promising adsorptive capacity which can be utilized to remove organic pollutants in wastewater. However, the structure variances of organic molecules lead to wide difference of adsorption efficiency. Therefore, it is of great significance to find a general relationship between removal rate of organic compounds and their quantum parameters. This study focused on building up quantitative structure activity relationship (QSAR) models based on experimental removal rate (r(exp)) of 25 organic compounds and 17 quantum parameters of each organic compounds computed by Gaussian 09 and Material Studio 6.1. The recommended model is rpre = -0.502-7.742 f(+)x + 0.107 E HOMO + 0.959 q(H(+)) + 1.388 BOx. Both internal and external validations of the recommended model are satisfied, suggesting optimum stability and predictive ability. The definition of applicability domain and the Y-randomization test indicate all the prediction is reliable and no possibility of chance correlation. The recommended model contains four variables, which are closely related to adsorption mechanism. f(+)x reveals the degree of affinity for nucleophilic attack. E HOMO represents the difficulty of electron loss. q(H(+)) reflect the distribution of partial charge between carbon and hydrogen atom. BO x shows the stability of a molecule. PMID:26490942

  12. Numerical Analysis on Combustion Characteristic of Leaf Spring Rotary Engine

    Directory of Open Access Journals (Sweden)

    Yan Zhang

    2015-08-01

    Full Text Available The purpose of this paper is to investigate combustion characteristics for rotary engine via numerical studies. A 3D numerical model was developed to study the influence of several operative parameters on combustion characteristics. A novel rotary engine called, “Leaf Spring Rotary Engine”, was used to illustrate the structure and principle of the engine. The aims are to (1 improve the understanding of combustion process, and (2 quantify the influence of rotational speed, excess air ratio, initial pressure and temperature on combustion characteristics. The chamber space changed with crankshaft rotation. Due to the complexity of chamber volume, an equivalent modeling method was presented to simulate the chamber space variation. The numerical simulations were performed by solving the incompressible, multiphase Unsteady Reynolds-Averaged Navier–Stokes Equations via the commercial code FLUENT using a transport equation-based combustion model; a realizable  turbulence model and finite-rate/eddy-dissipation model were used to account for the effect of local factors on the combustion characteristics.

  13. Effects of Homeopathic Arsenicum Album, Nosode, and Gibberellic Acid Preparations on the Growth Rate of Arsenic-Impaired Duckweed (Lemna gibba L.

    Directory of Open Access Journals (Sweden)

    Tim Jäger

    2010-01-01

    Full Text Available This study evaluated the effects of homeopathically potentized Arsenicum album, nosode, and gibberellic acid in a bioassay with arsenic-stressed duckweed (Lemna gibba L.. The test substances were applied in nine potency levels (17x, 18x, 21x–24x, 28x, 30x, 33x and compared with controls (unsuccussed and succussed water regarding their influence on the plant’s growth rate. Duckweed was stressed with arsenic(V for 48 h. Afterwards, plants grew in either potentized substances or water controls for 6 days. Growth rates of frond (leaf area and frond number were determined with a computerized image analysis system for different time intervals (days 0–2, 2–6, 0–6. Five independent experiments were evaluated for each test substance. Additionally, five water control experiments were analyzed to investigate the stability of the experimental setup (systematic negative control experiments. All experiments were randomized and blinded. The test system exhibited a low coefficient of variation (≈1%. Unsuccussed and succussed water did not result in any significant differences in duckweed growth rate. Data from the control and treatment groups were pooled to increase statistical power. Growth rates for days 0–2 were not influenced by any homeopathic preparation. Growth rates for days 2–6 increased after application of potentized Arsenicum album regarding both frond area (p < 0.001 and frond number (p < 0.001, and by application of potentized nosode (frond area growth rate only, p < 0.01. Potencies of gibberellic acid did not influence duckweed growth rate. The systematic negative control experiments did not yield any significant effects. Thus, false-positive results can be excluded with high certainty. To conclude, the test system with L. gibba impaired by arsenic(V was stable and reliable. It yielded evidence for specific effects of homeopathic Arsenicum album preparations and it will provide a valuable tool for future experiments that aim at

  14. On Lean Turbulent Combustion Modeling

    Directory of Open Access Journals (Sweden)

    Constantin LEVENTIU

    2014-06-01

    Full Text Available This paper investigates a lean methane-air flame with different chemical reaction mechanisms, for laminar and turbulent combustion, approached as one and bi-dimensional problem. The numerical results obtained with Cantera and Ansys Fluent software are compared with experimental data obtained at CORIA Institute, France. First, for laminar combustion, the burn temperature is very well approximated for all chemical mechanisms, however major differences appear in the evaluation of the flame front thickness. Next, the analysis of turbulence-combustion interaction shows that the numerical predictions are suficiently accurate for small and moderate turbulence intensity.

  15. Positive effect of reduced aeration rate on growth and stereospecificity of DL-malic acid consumption by Azospirillum brasilense: improving the shelf life of a liquid inoculant formulation.

    Science.gov (United States)

    Carrasco-Espinosa, Karen; García-Cabrera, Ramsés I; Bedoya-López, Andrea; Trujillo-Roldán, Mauricio A; Valdez-Cruz, Norma A

    2015-02-10

    Azospirillum brasilense has significance as a growth promoter in plants of commercial interest. Two industrial native strains (Start and Calf), used as a part of an inoculant formulation in Mexico during the last 15 years, were incubated in laboratory-scale pneumatic bioreactors at different aeration rates. In both strains, the positive effect of decreased aeration was observed. At the lowest (0.1 vvm, air volume/liquid volume×minute), the highest biomass were obtained for Calf (7.8 × 10(10)CFU/ml), and Start (2.9 × 10(9)CFU/ml). These were higher in one magnitude order compared to cultures carried out at 0.5 vvm, and two compared to those at 1.0 vvm. At lower aeration, both stereoisomeric forms of malic acid were consumed, but at higher aeration, just L-malate was consumed. A reduction in aeration allows an increase of the shelf life and the microorganism saved higher concentrations of polyhydroxybutyrate. The selected fermentation conditions are closely related to those prevalent in large-scale bioreactors and offer the possibility of achieving high biomass titles with high shelf life at a reduced costs, due to the complete use of a carbon source at low aeration of a low cost raw material as DL-malic acid mixture in comparison with the L-malic acid stereoisomer.

  16. Delayed gastric emptying rate as a potential mechanism for lowered glycemia after eating sourdough bread: studies in humans and rats using test products with added organic acids or an organic salt.

    Science.gov (United States)

    Liljeberg, H G; Björck, I M

    1996-12-01

    The possible effects of organic acids or an organic salt on the rate of gastric emptying was studied to identify the cause for reduced postmeal responses of blood glucose and insulin to foods containing such components, eg, sourdough bread. Paracetamol was included in bread products with added lactic acid or sodium propionate and used as a marker for the rate of gastric emptying in healthy subjects. In parallel, postprandial glycemia, insulinemia, and satiety were evaluated. The influence of lactic acid, propionic acid, and sodium propionate was also studied in rats after they were tube-fed with glucose solutions. The bread products with lactic acid or sodium propionate both lowered blood glucose and insulin responses. The bread with sodium propionate also prolonged satiety. The reason for the lowered metabolic responses with sodium propionate was probably a lowered gastric emptying rate, as judged from reduced blood paracetamol concentrations; there was no such effect observed with bread with added lactic acid. A similar amount of lactic acid in solution tube-fed to rats did not affect the disappearance of glucose from the stomach. In contrast with the finding in humans, sodium propionate had no effect on the rate of gastric emptying in rats whereas an equimolar solution of propionic acid reduced gastric emptying rate in rats. Possibly, less of this acid was produced in the gastric contents after a bolus load of a sodium propionate solution (in rats) than in an eating situation. Also, the pH and/or the osmolarity may be important, and when provided in excessive amounts, lactic acid reduced the gastric emptying rate in rats. A hydrochloric acid solution of similar pH was much less effective in this respect.

  17. The effect of CaCl2 on growth rate, wood decay and oxalic acid accumulation in Serpula lacrymans and related brown-rot fungi

    DEFF Research Database (Denmark)

    Hastrup, Anne Christine Steenkjær; Jensen, Bo; Clausen, Carol. A.;

    2006-01-01

    The dry rot fungus, Serpula lacrymans, is one of the most destructive copper-tolerant fungi causing timber decay in buildings in temperate regions. Calcium and oxalic acid have been shown to play important roles in the mechanism of wood decay. The effect of calcium on growth and decay was evaluated...... for 12 strains of S. lacrymans and compared to five brown-rot fungi. This was done by treating copper citrate (CC)-treated Southern yellow pine (SYP) wood with a CaCl2 solution and estimating the decay rate and amount of soluble oxalic acid in an ASTM soil block test. Decay by S. lacrymans was found...... to be significantly inhibited by treatment with CaCl2 in the presence of copper. In addition, calcium showed no effect on two strains of S. lacrymans and one Serpula himantioides strain in non-copper-treated SYP wood blocks. The growth rate of S. lacrymans was not affected on malt extract agar containing CaCl2...

  18. Predicted reaction rates of H(x)N(y)O(z) intermediates in the oxidation of hydroxylamine by aqueous nitric acid.

    Science.gov (United States)

    Ashcraft, Robert W; Raman, Sumathy; Green, William H

    2008-08-21

    This work reports computed rate coefficients of 90 reactions important in the autocatalytic oxidation of hydroxylamine in aqueous nitric acid. Rate coefficients were calculated using four approaches: Smoluchowski (Stokes-Einstein) diffusion, a solution-phase incarnation of transition state theory based on quantum chemistry calculations, simple Marcus theory for electron-transfer reactions, and a variational TST approach for dissociative isomerization reactions that occur in the solvent cage. Available experimental data were used to test the accuracy of the computations. There were significant discrepancies between the computed and experimental values for some key parameters, indicating a need for improvements in computational methodology. Nonetheless, the 90-reaction mechanism showed the ability to reproduce many of the trends seen in experimental studies of this very complicated kinetic system. This work highlights reactions that may govern the system evolution and branching behavior critical to the stability of the system. We hope that this analysis will guide experimental investigations to reduce the uncertainties in the critical rate coefficients and thermochemistry, allowing an unambiguous determination of the dominant reaction pathways in the system. Advances in efficient and accurate solvation models that effectively separate entropic and enthalpic contributions will most directly benefit solution-phase modeling efforts. Methods for more accurately estimating activity coefficients, including at infinite dilution in multicomponent mixtures, are needed for modeling high ionic strength aqueous systems. A detailed derivation of the solution-phase equilibrium and transition state theory rate expressions in solution is included in the Supporting Information. PMID:18652432

  19. Measures for a quality combustion (combustion chamber exit and downstream); Mesures pour une combustion de qualite (sortie de chambre de combustion et en aval)

    Energy Technology Data Exchange (ETDEWEB)

    Epinat, G. [APAVE Lyonnaise, 69 (France)

    1996-12-31

    After a review of the different pollutants related to the various types of stationary and mobile combustion processes (stoichiometric, reducing and oxidizing combustion), measures and analyses than may be used to ensure the quality and efficiency of combustion processes are reviewed: opacimeters, UV analyzers, etc. The regulation and control equipment for combustion systems are then listed, according to the generator capacity level

  20. Computational Modeling of Turbulent Spray Combustion

    NARCIS (Netherlands)

    Ma, L.

    2016-01-01

    The objective of the research presented in this thesis is development and validation of predictive models or modeling approaches of liquid fuel combustion (spray combustion) in hot-diluted environments, known as flameless combustion or MILD combustion. The goal is to combine good physical insight, a

  1. Combustible and incombustible speciation of Cl and S in various components of municipal solid waste.

    Science.gov (United States)

    Watanabe, Nobuhisa; Yamamoto, Osamu; Sakai, Mamoru; Fukuyama, Johji

    2004-01-01

    Chlorine (Cl) and sulfur (S) in municipal solid waste (MSW) are important reactive elements during combustion. They generate the acidic pollutants HCl and SOx, and, furthermore, produce and suppress organic chlorinated compounds. Nevertheless, few practical reports about Cl and S content in MSW have been published. In combustion and recycling processes, both combustible Cl and S, and incombustible Cl and S species are equally important. This paper presents the results of a comprehensive study about combustible and incombustible Cl and S in MSW components, including kitchen garbage, paper, textiles, wood and leaves, plastics and small chips. By integrating this collected data with data about MSW composition, not only the overall content of Cl and S in MSW, but also the origins of both combustible and incombustible Cl and S were estimated. The average Cl content in bulk MSW was 3.7 g/kg of raw MSW, of which 2.7 and 1.0 g/kg were combustible and incombustible, respectively. The Cl contribution from plastics was 76% and 27% with respect to combustible and incombustible states. The average S content in bulk MSW was 0.81 g/kg of raw MSW, of which 0.46 g/kg was combustible and 0.35 g/kg was incombustible. Combustible S was mainly due to synthetic textiles, while incombustible S was primarily from paper.

  2. Tuning the degradation rate of calcium phosphate cements by incorporating mixtures of polylactic-co-glycolic acid microspheres and glucono-delta-lactone microparticles.

    Science.gov (United States)

    Sariibrahimoglu, Kemal; An, Jie; van Oirschot, Bart A J A; Nijhuis, Arnold W G; Eman, Rhandy M; Alblas, Jacqueline; Wolke, Joop G C; van den Beucken, Jeroen J J P; Leeuwenburgh, Sander C G; Jansen, John A

    2014-11-01

    Calcium phosphate cements (CPCs) are frequently used as synthetic bone graft materials in view of their excellent osteocompatibility and clinical handling behavior. Hydroxyapatite-forming CPCs, however, degrade at very low rates, thereby limiting complete bone regeneration. The current study has investigated whether degradation of apatite-forming cements can be tuned by incorporating acid-producing slow-resorbing poly(D,L-lactic-co-glycolic) acid (PLGA) porogens, fast-resorbing glucono-delta-lactone (GDL) porogens, or mixtures thereof. The physicochemical, mechanical, and degradation characteristics of these CPC formulations were systematically analyzed upon soaking in phosphate-buffered saline (PBS). In parallel, various CPC formulations were implanted intramuscularly and orthotopically on top of the transverse process of goats followed by analysis of the soft tissue response and bone ingrowth after 12 weeks. In vitro degradation of GDL was almost completed after 2 weeks, as evidenced by characterization of the release of gluconic acid, while PLGA-containing CPCs released glycolic acid throughout the entire study (12 weeks), resulting in a decrease in compression strength of CPC. Extensive in vitro degradation of the CPC matrix was observed upon simultaneous incorporation of 30% PLGA-10% GDL. Histomorphometrical evaluation of the intramuscularly implanted samples revealed that all CPCs exhibited degradation, accompanied by an increase in capsule thickness. In the in vivo goat transverse process model, incorporation of 43% PLGA, 30% PLGA-5% GDL, and 30% PLGA-10% GDL in CPC significantly increased bone formation and resulted in higher bone height compared with both 10% GDL and 20% GDL-containing CPC samples.

  3. Multidimensional modeling of Dimethyl Ether(DME) spray combustion in DI diesel engine

    Institute of Scientific and Technical Information of China (English)

    WEN Hua; LIU Yong-chang; WEI Ming-rui; ZHANG Yu-sheng

    2005-01-01

    In the present study a modified CFD code KIVA3V was used to simulate the spray combustion in a small DI diesel engine fueled with DME. The improved spray models consider more spray phenomena such as cavitation flow in nozzle hole, jet atomization, droplet second breakup and spray wall interaction. Otherwise, a reduced DME reaction mechanism is implemented in the combustion model, and a new turbulent combustion model-Partial Stirred Reactor (PaSR) model is selected to simulate the spray combustion process, the effects of turbulent mixing on the reaction rate are considered. The results of engine modeling based on those models agreed well with the experimental measurements. Study of temperature fields variation and particle traces in the combustion chamber revealed that the engine combustion system originally used for diesel fuel must be optimized for DME.

  4. FINE PARTICLE EMISSIONS FROM RESIDUAL FUEL OIL COMBUSTION: CHARACTERIZATION AND MECHANISMS OF FORMATION

    Science.gov (United States)

    The paper gives results of a comparison of the characteristics of particulate matter (PM) emitted from residual fuel oil combustion in two types of combustion equipment. A small commercial 732-kW-rated fire-tube boiler yielded a weakly bimodal PM size distribution (PSD) with over...

  5. Investigation on in vitro dissolution rate enhancement of indomethacin by using a novel carrier sucrose fatty acid ester

    Directory of Open Access Journals (Sweden)

    Murthy Kolapalli Venkata

    2012-07-01

    Full Text Available Abstract Background and the purpose of the study The purpose of the present investigation was to characterize and evaluate solid dispersions (SD of indomethacin by using a novel carrier sucrose fatty acid ester (SFE 1815 to increase its in vitro drug release and further formulating as a tablet. Methods Indomethacin loaded SD were prepared by solvent evaporation and melt granulation technique using SFE 1815 as carrier in 1:0.25, 1:0.5 1:0.75 and 1:1 ratios of drug and carrier. Prepared SD and tablets were subjected to in vitro dissolution studies in 900 mL of pH 7.2 phosphate buffer using apparatus I at 100 rpm. The promising SD were further formulated as tablets using suitable diluent (DCL 21, Avicel PH 102 and pregelatinised starch to attain the drug release similar to that of SD.. The obtained dissolution data was subjected to kinetic study by fitting the data into various model independent models like zero order, first order, Higuchi, Hixon-Crowell and Peppas equations. Drug and excipient compatibility studies were confirmed by fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and scanning electron microscopy. Results The in vitro dissolution data exhibited superior release from formulation S6 with 1:0.5 drug and carrier ratio using solvent evaporation technique than other SDs prepared at different ratio using solvent evaporation and melt granulation technique. The in vitro drug release was also superior to that of the physical mixtures prepared at same ratio and also superior to SD prepared using common carriers like polyvinyl pyrollidone and PEG 4000 by solvent evaporation technique. Tablets (T8 prepared with DCL21 as diluent exhibited superior release than the other tablets. The tablet formulation (T8 followed first order release with Non-Fickian release. Conclusion SFE 1815 a novel third generation carrier can be used for the preparation of SD for the enhancement of in vitro drug release of

  6. Flow and combustion characteristics of a 2-dimensional spouted bed

    Science.gov (United States)

    Sawyer, R. F.; Hart, J. R.; Ohtake, K.

    1982-03-01

    A two dimensional spouted bed laboratory combustor was designed and constructed with the objective of studying the interaction among the gas flow, particle flow, and combustion. The facility, designed for a maximum thermal power of 20 kW, has a quartz front wall providing full optical access to particle flows and combustion processes. The combustor was characterized in terms of pressure, temperature, gas velocity, and particle velocity profiles and operating limits. Initial studies employed premixed propane and air and a fixed bed height, bed material, injector slot width, and combustor geometry. As in previous investigations of axisymmetric spouted beds, the ratio of particle mass circulation rate to jet mass flow rate was observed to be about ten. Combustion increased this ratio by about 10%. A pulsating mode of operation was noted with a characteristic frequency of about 10 Hz, controlled by the interaction of the particle and gas flows.

  7. Combustion of Micro- and Nanothermites under Elevating Pressure

    Science.gov (United States)

    Monogarov, K.; Pivkina, Alla; Muravyev, N.; Meerov, D.; Dilhan, D.

    Non-equilibrium process of combustion-wave propagation of thermite compositions (Mg/Fe2O3) inside the sealed steel tube have been investigated to study the burning rate at elevating pressure. Under confinement the hot gas-phase products, formed during thermite combustion result in considerable overpressure inside the tube that reverses the gas flow and leads to pressure-driven preheating effect of the burned-gas permeation. Convective origin of this preheating effect is discussed. The pressure-time dependency is obtained experimentally. The composition was pressed inside the steel tube in pellets; the size of each part was measured to obtain burning rate - pressure dependency. Both micro- and nanosized components were used to prepare thermite compositions under study. The significant difference in burning parameters of micron- and nanosized thermites is observed and analyzed. Based on obtained results, the combustion mechanism of thermites with the micro- and nanosized components is discussed.

  8. Use of the graphical analytic methods of studying the combustion processes in the internal combustion engine combustion chamber on the basis of similarity criterion

    Directory of Open Access Journals (Sweden)

    S. V. Krasheninnikov

    2014-10-01

    Full Text Available The task of improving the economic and ecological parameters of the internal combustion engines remains topical within the frameworks of the modern engine-building technology. Since a combustion engine is a complex system combining such units as an intake manifold, combustion chamber, exhaust manifold, one of directions of the engine development is adjustment of the joint operation of its units. The specified adjustment should better be performed with the use of the so-called integral characteristics. The author means under an integral characteristic the rating plate of a unit (engine containing information about all the possible modes and conditions of its use, specifies the optimal operating range and indicates all the basic values of efficiency – reliability – environmental friendliness at each point of its field. As a rule, integral characteristics are multi-parametric. It is common practice to coordinate the field of such characteristic by similarity criteria determining the unit or engine behavior in whole.

  9. Controlling pollution by controlling combustion

    Energy Technology Data Exchange (ETDEWEB)

    Orrin, John (South Bank Univ., London (United Kingdom))

    1994-05-04

    Modern control theory is now being used to reduce pollution from fossil fuel combustion. Powerful microprocessors using digital control algorithms are now used to make combustion systems, such as industrial furnaces and car engines, operate with optimal performance. These systems operate to achieve a balance between lean fuel burning with the reduced pollution produced, but more engine noise and vibration, and an air/fuel mixture that produces good engine performance but worse pollution. (UK)

  10. Study of Second Generation Biofuels in Internal Combustion Engines

    Energy Technology Data Exchange (ETDEWEB)

    Kannan, Dhandapani

    2012-07-01

    fuel, vis-a-vis neat diesel fuel (DF). The CO, THC, smoke and TPM emissions were reduced significantly, while NOx emissions were somewhat higher with BD blended fuels compared to neat FT fuel. The reductions in CO, THC, smoke and TPM emissions with BD blends were mainly due to the oxygen content in the BD blended fuel, while the increases in NOx emissions with BD fuels were due to advances in injection timing, higher percentages of fatty acids with double bonds in the carbon chain and higher heat release in the pre-mixed combustion. Secondly, a four-stroke, single-cylinder, naturally-aspirated (NA), direct-injection (DI) diesel engine with 8 BHP at 1500 rpm coupled with water-cooled, eddy current dynamometer was used for the experiments. Ethanol (5% by volume) was injected into the intake manifold by the port injection method with the assistance of a mechanical fuel injection pump. Therefore, the volumetric blending percentages of ethanol, BD and diesel fuels (E:D:JME) are (0:100:0), (5:95:0), (5:75:20), (5:55:40), (5:35:60), (5:15:80) (5:0:95) and (0:0:100) respectively. Ethanol pre-mixed with intake air, assisted in improving combustion in both diesel and the JME blends. The addition of ethanol to high-viscosity Jatropha methyl ester (JME) through port injection is investigated in order to determine its effect on the fuels viscosity and thereby on the diesel engine performance. In addition to viscosity alteration, the impact of ethanol addition on combustion characteristics such as combustion duration, ignition delay and emissions levels from diesel engines fuelled with blends of ethanol, diesel and JME was studied in particular. It was found that blending of oxygenated fuels with diesel modifies the chemical structure and physical properties which in turn, alter the engines operating conditions, combustion parameters and emissions levels. However, the injection of only 5% ethanol through port injection allows for up to 25% blending of diesel with biofuels, while

  11. Analysis of combustion process of dual burning rate grain with series embedded metal wires and calculation of motor internal ballistics%嵌金属丝串装双燃速药柱燃烧分析及发动机内弹道计算

    Institute of Scientific and Technical Information of China (English)

    张明; 熊波; 涂四华; 曹晓利

    2016-01-01

    The combustion process of dual burning rate grain with series embedded metal wires was analysed and the basic law of combustion area variation was obtained.Based on the PRO/E,the complex burning area of the grain was calculated precisely.To calculate the internal ballistics for the special structure of the motor,a group of differential equation was established and solved by the Runge-Kutta method.The calculation results agree with test data very well.The calculation method of the complex internal ballis-tics is precise and reliable,which could meet the engineering requirements.%针对嵌金属丝、串装双燃速装药燃烧过程进行了分析,得到了燃面变化的基本规律。基于PRO/E软件,实现了嵌多根金属丝、双燃速推进剂串装药柱复杂燃面的精确推移计算。为精确计算发动机复杂的内弹道,建立了内弹道微分方程组,并通过Runge-Kutta法进行了求解。结果表明,该数值计算方法计算结果与实测数据吻合度较高,计算方法精确可靠,满足工程预示要求。

  12. Materials for High-Temperature Catalytic Combustion

    OpenAIRE

    Ersson, Anders

    2003-01-01

    Catalytic combustion is an environmentally friendlytechnique to combust fuels in e.g. gas turbines. Introducing acatalyst into the combustion chamber of a gas turbine allowscombustion outside the normal flammability limits. Hence, theadiabatic flame temperature may be lowered below the thresholdtemperature for thermal NOXformation while maintaining a stable combustion.However, several challenges are connected to the application ofcatalytic combustion in gas turbines. The first part of thisthe...

  13. Fe2+ oxidation rate drastically affect the formation and phase of secondary iron hydroxysulfate mineral occurred in acid mine drainage

    International Nuclear Information System (INIS)

    During the processes of secondary iron hydroxysulfate mineral formation, Fe2+ ion was oxidized by the following three methods: (1) biooxidation treatment by Acidithiobacillus ferrooxidans (A. ferrooxidans); (2) rapid abiotic oxidation of Fe2+ with H2O2 (rapid oxidation treatment); (3) slow abiotic oxidation of Fe2+ with H2O2 (slow oxidation treatment). X-ray diffraction (XRD) patterns, element composition, precipitate weight and total Fe removal efficiency were analyzed. The XRD patterns and element composition of precipitates synthesized through the biooxidation and the slow oxidation treatments well coincide with those of potassium jarosite, while precipitates formed at the initial stage of incubation in the rapid oxidation treatment showed a similar XRD pattern to schwertmannite. With the ongoing incubation, XRD patterns and element composition of the precipitates that occurred in the rapid oxidation treatment were gradually close to those in the biooxidation and the slow oxidation treatments. Due to the inhibition of A. ferrooxidans itself and its extracellular polymeric substances (EPS) in aggregation of precipitates, the amount of precipitates and soluble Fe removal efficiency were lower in the biooxidation treatment than in the slow oxidation treatment. Therefore, it is concluded that Fe2+ oxidation rate can greatly affect the mineral phase of precipitates, and slow oxidation of Fe2+ is helpful in improving jarosite formation. - Highlights: ► Slow oxidation of Fe2+ is helpful in jarosite formation. ► The already-formed schwertmannite can be gradually transformed to jarosite. ► Precipitates formation can be inhibited probably by EPS from A. ferrooxidans.

  14. Results of a model for premixed combustion oscillation

    Energy Technology Data Exchange (ETDEWEB)

    Janus, M.C.; Richards, G.A.

    1996-12-31

    Combustion oscillations are receiving renewed research interest due to the increasing application of lean premix (LPM) combustion to gas turbines. A simple, nonlinear model for premixed combustion is described in this paper. The model was developed to help explain specific experimental observations, and to provide guidance for the development of active control schemes based on nonlinear concepts. The model can be used to quickly examine instability trends associated with changes in equivalence ratio, mass flow rate, geometry, ambient conditions, and other pertinent factors. The model represents the relevant processes occurring in a fuel nozzle and combustor which are analogous to current LPM turbine combustors. Conservation equations for the fuel nozzle and combustor are developed from simple control volume analysis, providing a set of ordinary differential equations that can be solved on a personal computer. Combustion is modeled as a stirred reactor, with a bi- molecular reaction rate between fuel and air. A variety of numerical results and comparisons to experimental data are presented to demonstrate the utility of the model. Model results are used to understand the fundamental mechanisms which drive combustion oscillations, the effects of inlet air temperature and nozzle geometry on instability, and the effectiveness of active control schemes. The technique used in the model may also be valuable to understand oscillations in low NO{sub x} industrial burners.

  15. Omega-3 Fatty Acid Supplementation for 12 Weeks Increases Resting and Exercise Metabolic Rate in Healthy Community-Dwelling Older Females.

    Directory of Open Access Journals (Sweden)

    Samantha L Logan

    Full Text Available Critical among the changes that occur with aging are decreases in muscle mass and metabolic rate and an increase in fat mass. These changes may predispose older adults to chronic disease and functional impairment; ultimately resulting in a decrease in the quality of life. Research has suggested that long chain omega-3 fatty acids, found predominantly in fatty fish, may assist in reducing these changes. The objective of this study was to evaluate the effect of fish oil (FO supplementation in a cohort of healthy, community-dwelling older females on 1 metabolic rate and substrate oxidation at rest and during exercise; 2 resting blood pressure and resting and exercise heart rates; 3 body composition; 4 strength and physical function, and; 5 blood measures of insulin, glucose, c-reactive protein, and triglycerides. Twenty-four females (66 ± 1 yr were recruited and randomly assigned to receive either 3g/d of EPA and DHA or a placebo (PL, olive oil for 12 wk. Exercise measurements were taken before and after 12 wk of supplementation and resting metabolic measures were made before and at 6 and 12 wk of supplementation. The results demonstrated that FO supplementation significantly increased resting metabolic rate by 14%, energy expenditure during exercise by 10%, and the rate of fat oxidation during rest by 19% and during exercise by 27%. In addition, FO consumption lowered triglyceride levels by 29% and increased lean mass by 4% and functional capacity by 7%, while no changes occurred in the PL group. In conclusion, FO may be a strategy to improve age-related physical and metabolic changes in healthy older females. Trial registration: ClinicalTrials.gov NCT01734538.

  16. Effects of homeopathic arsenicum album, nosode, and gibberellic acid preparations on the growth rate of arsenic-impaired duckweed (Lemna gibba L.).

    Science.gov (United States)

    Jäger, Tim; Scherr, Claudia; Simon, Meinhard; Heusser, Peter; Baumgartner, Stephan

    2010-01-01

    This study evaluated the effects of homeopathically potentized Arsenicum album, nosode, and gibberellic acid in a bioassay with arsenic-stressed duckweed (Lemna gibba L.). The test substances were applied in nine potency levels (17x, 18x, 21x-24x, 28x, 30x, 33x) and compared with controls (unsuccussed and succussed water) regarding their influence on the plant's growth rate. Duckweed was stressed with arsenic(V) for 48 h. Afterwards, plants grew in either potentized substances or water controls for 6 days. Growth rates of frond (leaf) area and frond number were determined with a computerized image analysis system for different time intervals (days 0-2, 2-6, 0-6). Five independent experiments were evaluated for each test substance. Additionally, five water control experiments were analyzed to investigate the stability of the experimental setup (systematic negative control experiments). All experiments were randomized and blinded. The test system exhibited a low coefficient of variation (approximately equal to 1%). Unsuccussed and succussed water did not result in any significant differences in duckweed growth rate. Data from the control and treatment groups were pooled to increase statistical power. Growth rates for days 0-2 were not influenced by any homeopathic preparation. Growth rates for days 2-6 increased after application of potentized Arsenicum album regarding both frond area (p gibba impaired by arsenic(V) was stable and reliable. It yielded evidence for specific effects of homeopathic Arsenicum album preparations and it will provide a valuable tool for future experiments that aim at revealing the mode of action of homeopathic preparations. It may also be useful to investigate the influence of external factors (e.g., heat, electromagnetic radiation) on the effects of homeopathic preparations. PMID:21057725

  17. Acid Deposition Phenomena

    International Nuclear Information System (INIS)

    Acid deposition, commonly known as acid rain, occurs when emissions from the combustion of fossil fuels and other industrial processes undergo complex chemical reactions in the atmosphere and fall to the earth as wet deposition (rain, snow, cloud, fog) or dry deposition (dry particles, gas). Rain and snow are already naturally acidic, but are only considered problematic when less than a ph of 5.0 The main chemical precursors leading to acidic conditions are atmospheric concentrations of sulfur dioxide (SO2) and nitrogen oxides (NOx). When these two compounds react with water, oxygen, and sunlight in the atmosphere, the result is sulfuric (H2SO4) and nitric acids (HNO3), the primary agents of acid deposition which mainly produced from the combustion of fossil fuel and from petroleum refinery. Airborne chemicals can travel long distances from their sources and can therefore affect ecosystems over broad regional scales and in locations far from the sources of emissions. According to the concern of petroleum ministry with the environment and occupational health, in this paper we will discussed the acid deposition phenomena through the following: Types of acidic deposition and its components in the atmosphere Natural and man-made sources of compounds causing the acidic deposition. Chemical reactions causing the acidic deposition phenomenon in the atmosphere. Factors affecting level of acidic deposition in the atmosphere. Impact of acid deposition. Procedures for acidic deposition control in petroleum industry

  18. Determination of human muscle protein fractional synthesis rate

    DEFF Research Database (Denmark)

    Bornø, Andreas; Hulston, Carl J; van Hall, Gerrit

    2014-01-01

    labeled amino acid will be incorporated within the few hours of a typical laboratory experiment. GC combustion isotope ratio MS (GC-C-IRMS) has thus far been considered the 'gold' standard for the precise measurements of these low enrichment levels. However, advances in liquid chromatography-tandem MS (LC......-MS/MS) and GC-tandem MS (GC-MS/MS) have made these techniques an option for human muscle FSR measurements. Human muscle biopsies were freeze dried, cleaned, and hydrolyzed, and the amino acids derivatized using either N-acetyl-n-propyl, phenylisothiocyanate, or N......In the present study, different MS methods for the determination of human muscle protein fractional synthesis rate (FSR) using [ring-(13)C6 ]phenylalanine as a tracer were evaluated. Because the turnover rate of human skeletal muscle is slow, only minute quantities of the stable isotopically...

  19. Combustion Byproducts Recycling Consortium

    Energy Technology Data Exchange (ETDEWEB)

    Paul Ziemkiewicz; Tamara Vandivort; Debra Pflughoeft-Hassett; Y. Paul Chugh; James Hower

    2008-08-31

    The Combustion Byproducts Recycling Consortium (CBRC) program was developed as a focused program to remove and/or minimize the barriers for effective management of over 123 million tons of coal combustion byproducts (CCBs) annually generated in the USA. At the time of launching the CBRC in 1998, about 25% of CCBs were beneficially utilized while the remaining was disposed in on-site or off-site landfills. During the ten (10) year tenure of CBRC (1998-2008), after a critical review, 52 projects were funded nationwide. By region, the East, Midwest, and West had 21, 18, and 13 projects funded, respectively. Almost all projects were cooperative projects involving industry, government, and academia. The CBRC projects, to a large extent, successfully addressed the problems of large-scale utilization of CCBs. A few projects, such as the two Eastern Region projects that addressed the use of fly ash in foundry applications, might be thought of as a somewhat smaller application in comparison to construction and agricultural uses, but as a novel niche use, they set the stage to draw interest that fly ash substitution for Portland cement might not attract. With consideration of the large increase in flue gas desulfurization (FGD) gypsum in response to EPA regulations, agricultural uses of FGD gypsum hold promise for large-scale uses of a product currently directed to the (currently stagnant) home construction market. Outstanding achievements of the program are: (1) The CBRC successfully enhanced professional expertise in the area of CCBs throughout the nation. The enhanced capacity continues to provide technology and information transfer expertise to industry and regulatory agencies. (2) Several technologies were developed that can be used immediately. These include: (a) Use of CCBs for road base and sub-base applications; (b) full-depth, in situ stabilization of gravel roads or highway/pavement construction recycled materials; and (c) fired bricks containing up to 30%-40% F

  20. Combustion Instabilities Modeled

    Science.gov (United States)

    Paxson, Daniel E.

    1999-01-01

    NASA Lewis Research Center's Advanced Controls and Dynamics Technology Branch is investigating active control strategies to mitigate or eliminate the combustion instabilities prevalent in lean-burning, low-emission combustors. These instabilities result from coupling between the heat-release mechanisms of the burning process and the acoustic flow field of the combustor. Control design and implementation require a simulation capability that is both fast and accurate. It must capture the essential physics of the system, yet be as simple as possible. A quasi-one-dimensional, computational fluid dynamics (CFD) based simulation has been developed which may meet these requirements. The Euler equations of mass, momentum, and energy have been used, along with a single reactive species transport equation to simulate coupled thermoacoustic oscillations. A very simple numerical integration scheme was chosen to reduce computing time. Robust boundary condition procedures were incorporated to simulate various flow conditions (e.g., valves, open ends, and choked inflow) as well as to accommodate flow reversals that may arise during large flow-field oscillations. The accompanying figure shows a sample simulation result. A combustor with an open inlet, a choked outlet, and a large constriction approximately two thirds of the way down the length is shown. The middle plot shows normalized, time-averaged distributions of the relevant flow quantities, and the bottom plot illustrates the acoustic mode shape of the resulting thermoacoustic oscillation. For this simulation, the limit cycle peak-to-peak pressure fluctuations were 13 percent of the mean. The simulation used 100 numerical cells. The total normalized simulation time was 50 units (approximately 15 oscillations), which took 26 sec on a Sun Ultra2.

  1. Combustion Characteristics of Coated Nano Aluminum in Composite Propellants

    Directory of Open Access Journals (Sweden)

    Yunlan Sun

    2006-10-01

    Full Text Available The effects of coated nano-sized aluminum (Al powder (n-Al and micron-sized Al powder(g-Al in propellants on the burning rate and pressure exponent have been investigated. Theresults show that the burning rates of propellants increase as the n-Al content increases, butthe burning rate pressure exponents tend to decrease. Compared with propellant containing-Al, the increments of burning rates of propellants containing n-Al powder reduce graduallywith increase in the pressure because of the differences of the combustion characteristics andignition performances of n-Al powder and g-Al powder. Single short distance photograph, scanningelectron microscopy, x-ray fluorescence analysis were used to characterise the flame image,combustion phenomena, the quenched surface image, and surface elements. A substantialdifference in combustion characteristics of n-Al powder has been found in comparison with-Al powder. In addition, oxygen-bomb combustion heat, ignition temperature, and recoveryratio of residues were measured.

  2. The purification of internal combustion engine exhaust emissions

    Energy Technology Data Exchange (ETDEWEB)

    Davies, M.J.; Jorgensen, Norman; Carlow, J.S.; Raybone, David.

    1994-03-02

    In this patent, improved catalytic reduction of exhaust gas pollutants from internal combustion engines is described. During the warm-up phase of the cycle, a plasma discharge is initiated in the exhaust gases upstream of the catalytic converter. The plasma is controlled using sensors which detect the catalyst temperature and gas pressure and flow rate. (UK)

  3. TRENDS OF INDEXES IMPROVEMENT OF MODERN INTERNAL COMBUSTION EGNINE

    Directory of Open Access Journals (Sweden)

    Motlokhov, A.

    2013-01-01

    Full Text Available The author of this scientific paper has suggested an effective method of indexes improvement of engines with spark ignition by means of complete fuel combustion that allows to in-crease economy, remove detonation, and use a high rate of compression and cheap low octane gaso-line as well as BFC fuel.

  4. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    Science.gov (United States)

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C. PMID:27295338

  5. Plasma-Enhanced Atomic Layer Deposition of SiN-AlN Composites for Ultra Low Wet Etch Rates in Hydrofluoric Acid.

    Science.gov (United States)

    Kim, Yongmin; Provine, J; Walch, Stephen P; Park, Joonsuk; Phuthong, Witchukorn; Dadlani, Anup L; Kim, Hyo-Jin; Schindler, Peter; Kim, Kihyun; Prinz, Fritz B

    2016-07-13

    The continued scaling in transistors and memory elements has necessitated the development of atomic layer deposited (ALD) of hydrofluoric acid (HF) etch resistant and electrically insulating films for sidewall spacer processing. Silicon nitride (SiN) has been the prototypical material for this need and extensive work has been conducted into realizing sufficiently lower wet etch rates (WERs) as well as leakage currents to meet industry needs. In this work, we report on the development of plasma-enhanced atomic layer deposition (PEALD) composites of SiN and AlN to minimize WER and leakage current density. In particular, the role of aluminum and the optimum amount of Al contained in the composite structures have been explored. Films with near zero WER in dilute HF and leakage currents density similar to pure PEALD SiN films could be simultaneously realized through composites which incorporate ≥13 at. % Al, with a maximum thermal budget of 350 °C.

  6. Numerical modeling of sodium fire – Part II: Pool combustion and combined spray and pool combustion

    International Nuclear Information System (INIS)

    Highlights: • A CFD based method is proposed for the simulation of sodium pool combustion. • A sodium evaporation based model is proposed to model sodium pool evaporation. • The proposed method is validated against sodium pool experiments of Newman and Payne. • The results obtained using the proposed method are in good agreement with the experiments. - Abstract: The risk of sodium-air reaction has received considerable attention after the sodium-fire accident in Monju reactor. The fires resulting from the sodium-air reaction can be detrimental to the safety of a sodium fast reactor. Therefore, predicting the consequences of a sodium fire is important from a safety point of view. A computational method based on CFD is proposed here to simulate sodium pool fire and understand its characteristics. The method solves the Favre-averaged Navier-Stokes equation and uses a non-premixed mixture fraction based combustion model. The mass transfer of sodium vapor from the pool surface to the flame is obtained using a sodium evaporation model. The proposed method is then validated against well-known sodium pool experiments of Newman and Payne. The flame temperature and location predicted by the model are in good agreement with experiments. Furthermore, the trends of the mean burning rate with initial pool temperature and oxygen concentration are captured well. Additionally, parametric studies have been performed to understand the effects of pool diameter and initial air temperature on the mean burning rate. Furthermore, the sodium spray and sodium pool combustion models are combined to simulate simultaneous spray and pool combustion. Simulations were performed to demonstrate that the combined code could be applied to simulate this. Once sufficiently validated, the present code can be used for safety evaluation of a sodium fast reactor

  7. Toxicology of drinking water disinfection byproducts from nutrients. Rate studies of destruction of polyunsaturated fatty acids in vitro by chlorine-based disinfectants.

    Science.gov (United States)

    Bercz, J P

    1992-01-01

    As model reactions between unsaturated fats and water disinfectants in the GI tract, relative rates of destruction of seven polyunsaturated fatty acids (L, alpha Ln, gamma Ln, Ara, EPA, DH, and DT) by OCl- and NH2Cl were investigated in vitro. Using millimolar solutions of seven PUFAs combined with various OCl- mole ratios, disappearance of PUFAs was followed by UV spectrophotometry at pH = 9.5 and at 35 degrees C via conjugated hydroperoxydienes at 234 nm. While OCl- rapidly destroyed all PUFAs, NH2Cl was inert. Overall second-order rate constants computed for L at increasing times disclosed that the attack on the cis-CH=CHCH2CH=CH moiety by OCl- does not follow simple second-order kinetics. Using a logit-log transform and second-order polynomial regression analysis of L's disappearance in a stoichiometric ([L] = 1.2 mM; [ClO-] = 2.4 mM) mix, data were analyzed by the time ratio method of Schwemer and Frost. These agreed with a sequential system of at least two irreversible second-order reactions having k1 = 15.6 L.mol-1.s-1 and k2 = 2.6 L.mol-1.s-1. Preliminary GC/MS analysis indicated that the initial product is a mix of chlorohydrin isomers. These undergo second addition of HOCl and/or lose halogens and polymerize. Additional minor products were also C5-C9 mono- and bifunctional carboxylates and mixed acid aldehydes. Studies with mol equiv of Cl- - free 36ClO- allowed estimation of covalent binding of Cl by L at various times, supporting the kinetic findings. For other PUFAs of higher degree unsaturation, the complexity of feasible reactions precluded an analogous approach.(ABSTRACT TRUNCATED AT 250 WORDS)

  8. Combustion behaviours of tobacco stem in a thermogravimetric analyser and a pilot-scale fluidized bed reactor.

    Science.gov (United States)

    Yang, Zixu; Zhang, Shihong; Liu, Lei; Li, Xiangpeng; Chen, Hanping; Yang, Haiping; Wang, Xianhua

    2012-04-01

    Despite its abundant supply, tobacco stem has not been exploited as an energy source in large scale. This study investigates the combustion behaviours of tobacco stem in a thermogravimetric analyser (TGA) and a pilot-scale fluidized bed (FB). Combustion characteristics, including ignition and burnout index, and combustion reaction kinetics were studied. Experiments in the FB investigated the effects of different operating conditions, such as primary air flow, secondary air flow and feeding rates, on the bed temperature profiles and combustion efficiency. Two kinds of bed materials cinder and silica sand were used in FB and the effect of bed materials on agglomeration was studied. The results indicated that tobacco stem combustion worked well in the FB. When operation condition was properly set, the tobacco stem combustion efficiency reached 94%. In addition, compared to silica sand, cinder could inhibit agglomeration during combustion because of its high aluminium content.

  9. Twenty-fifth symposium (international) on combustion

    International Nuclear Information System (INIS)

    Approximately two-thirds of the papers presented at this conference are contained in this volume. The other one-third appear in special issues of ''Combustion and Flame'', Vol. 99, 1994 and Vol. 100, 1995. Papers are divided into the following sections: Supersonic combustion; Detonations and explosions; Internal combustion engines; Practical aspects of combustion; Incineration and wastes; Sprays and droplet combustion; Coal and organic solids combustion; Soot and polycyclic aromatic hydrocarbons; Reaction kinetics; NOx; Turbulent flames; Turbulent combustion; Laminar flames; Flame spread, fire and halogenated fire suppressants; Global environmental effects; Ignition; Two-phase combustion; Solid propellant combustion; Materials synthesis; Microgravity; and Experimental diagnostics. Papers have been processed separately for inclusion on the data base

  10. INVESTIGATION OF SPONTANEOUS COMBUSTION TENDENCY

    Directory of Open Access Journals (Sweden)

    Ivan HRUŠOVSKÝ

    2015-12-01

    Full Text Available The potential of vegetable oils to undergo violent thermal oxidation is long-known problem. The process of this oxidation is investigated by the means of differential thermal analysis. Polyurethane foam was saturated with Tung oil rich in unsaturated fatty acids at three different mass rations, and airfl ow at three different rates is introduces to the sample to ensure suffi cient volume of air for oxidation. The samples were thermally stressed both dynamically and isothermally. The results were compared to results of standard differential Mackey test.

  11. Numerical simulation of three-dimensional combustion flows

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    A finite-rate method is used to simulate the three-dimensional combustion process in a plasma generator with CH4 as the fuel. The simulation was run with RNG k-ε model to simulate turbulence, with eddy-dissipation-concept (EDC) model to simulate the combustion and with discrete ordinates model to simulate radiation. The numerical results show that the flow field characteristics and the parameter distributions are under the condition of rich fuels, and these results provide valuable information when optimizing the plasma generator design and organizing its flow fields.

  12. Oxygen isotopic signature of CO2 from combustion processes

    Directory of Open Access Journals (Sweden)

    H. G. Jansen

    2008-11-01

    Full Text Available For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires, and human induced (fossil fuel combustion, biomass burning in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects in the order of about 26‰ became obvious, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature, sample geometries (e.g. texture and surface-volume ratios and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original 18O signature of the material appeared to have little or no influence.

  13. The combustion properties analysis of various liquid fuels based on crude oil and renewables

    Science.gov (United States)

    Grab-Rogalinski, K.; Szwaja, S.

    2016-09-01

    The paper presents results of investigation on combustion properties analysis of hydrocarbon based liquid fuels commonly used in the CI engine. The analysis was performed with aid of the CRU (Combustion Research Unit). CRU is the machine consisted of a constant volume combustion chamber equipped with one or two fuel injectors and a pressure sensor. Fuel can be injected under various both injection pressure and injection duration, also with two injector versions two stage combustion with pilot injection can be simulated, that makes it possible to introduce and modify additional parameter which is injection delay (defined as the time between pilot and main injection). On a basis of this investigation such combustion parameters as pressure increase, rate of heat release, ignition delay and combustion duration can be determined. The research was performed for the four fuels as follows: LFO, HFO, Biofuel from rape seeds and Glycerol under various injection parameters as well as combustion chamber thermodynamic conditions. Under these tests the change in such injection parameters as injection pressure, use of pilot injection, injection delay and injection duration, for main injection, were made. Moreover, fuels were tested under different conditions of load, what was determined by initial conditions (pressure and temperature) in the combustion chamber. Stored data from research allows to compare combustion parameters for fuels applied to tests and show this comparison in diagrams.

  14. Chemical Looping Combustion Reactions and Systems

    Energy Technology Data Exchange (ETDEWEB)

    Sarofim, Adel; Lighty, JoAnn; Smith, Philip; Whitty, Kevin; Eyring, Edward; Sahir, Asad; Alvarez, Milo; Hradisky, Michael; Clayton, Chris; Konya, Gabor; Baracki, Richard; Kelly, Kerry

    2011-07-01

    Chemical Looping Combustion (CLC) is one promising fuel-combustion technology, which can facilitate economic CO2 capture in coal-fired power plants. It employs the oxidation/reduction characteristics of a metal, or oxygen carrier, and its oxide, the oxidizing gas (typically air) and the fuel source may be kept separate. This work focused on two classes of oxygen carrier, one that merely undergoes a change in oxidation state, such as Fe3O4/Fe2O3 and one that is converted from its higher to its lower oxidation state by the release of oxygen on heating, i.e., CuO/Cu2O. This topical report discusses the results of four complementary efforts: (1) the development of process and economic models to optimize important design considerations, such as oxygen carrier circulation rate, temperature, residence time; (2) the development of high-performance simulation capabilities for fluidized beds and the collection, parameter identification, and preliminary verification/uncertainty quantification (3) the exploration of operating characteristics in the laboratory-scale bubbling bed reactor, with a focus on the oxygen carrier performance, including reactivity, oxygen carrying capacity, attrition resistance, resistance to deactivation, cost and availability (4) the identification of mechanisms and rates for the copper, cuprous oxide, and cupric oxide system using thermogravimetric analysis.

  15. Oxy-Fuel Combustion of Coal

    DEFF Research Database (Denmark)

    Brix, Jacob

    This Ph.D. thesis describes an experimental and modeling investigation of the thermal conversion of coal and an experimental investigation of the emission of NO from char combustion in O2/N2 and O2/CO2 atmospheres. The motivation for the work has been the prospective use of the technology “Oxy......-Fuel Combustion” as a mean of CO2 abatement in large scale energy conversion. Entrained Flow Reactor (EFR) experiments have been conducted in O2/N2 and O2/CO2 mixtures in the temperature interval 1173 K – 1673 K using inlet O2 concentrations between 5 – 28 vol. %. Bituminous coal has been used as fuel in all....... % it was found that char conversion rate was lowered in O2/CO2 compared to O2/N2. This is caused by the lower diffusion coefficient of O2 in CO2 (~ 22 %) that limits the reaction rate in zone III compared to combustion in O2/N2. Using char sampled in the EFR experiments ThermoGravimetric Analyzer (TGA...

  16. The combined effect of administration of intravenous and topical tranexamic acid on blood loss and transfusion rate in total knee arthroplasty

    Science.gov (United States)

    Yuan, Z. F.; Yin, H.; Xing, D. L.

    2016-01-01

    Objectives Tranexamic acid (TXA) is an antifibrinolytic agent used as a blood-sparing technique in total knee arthroplasty (TKA), and is routinely administered by intravenous (IV) or intra-articular (IA) injection. Recently, a novel method of TXA administration, the combined IV and IA application of TXA, has been applied in TKA. However, the scientific evidence of combined administration of TXA in TKA is still meagre. This meta-analysis aimed to investigate the efficacy and safety of combined IV and IA TXA in patients undergoing TKA. Materials and Methods A systematic search was carried out in PubMed, the Cochrane Clinical Trial Register (Issue12 2015), Embase, Web of Science and the Chinese Biomedical Database. Only randomised controlled trials (RCT) evaluating the efficacy and safety of combined use TXA in TKA were identified. Two authors independently identified the eligible studies, extracted data and assessed the methodological quality of included studies. Meta-analysis was conducted using Review Manager 5.3 software. Results A total of ten RCTs (1143 patients) were included in this study. All the included studies were randomised and the quality of included studies still needed improvement. The results indicated that, compared with either placebo or the single-dose TXA (IV or IA) group, the combination of IV and IA TXA group had significantly less total blood loss, hidden blood loss, total drain output, a lower transfusion rate and a lower drop in haemoglobin level. There were no statistically significant differences in complications such as wound infection and deep vein thrombosis between the combination group and the placebo or single-dose TXA group. Conclusions Compared with placebo or the single-dose TXA, the combined use of IV and IA TXA provided significantly better results with respect to all outcomes related to post-operative blood loss without increasing the risk of thromboembolic complications in TKA. Cite this article: Z. F. Yuan, H. Yin, W. P. Ma

  17. Explosion limits for combustible gases

    Institute of Scientific and Technical Information of China (English)

    TONG Min-ming; WU Guo-qing; HAO Ji-fei; DAI Xin-lian

    2009-01-01

    Combustible gases in coal mines are composed of methane, hydrogen, some multi-carbon alkane gases and other gases. Based on a numerical calculation, the explosion limits of combustible gases were studied, showing that these limits are related to the concentrations of different components in the mixture. With an increase of C4H10 and C6H14, the Lower ExplosionLimit (LEL) and Upper Explosion-Limit (UEL) of a combustible gas mixture will decrease clearly. For every 0.1% increase in C4H10 and C6H14, the LEL decreases by about 0.19% and the UEL by about 0.3%. The results also prove that, by increasing the amount of H2, the UEL of a combustible gas mixture will increase considerably. If the level of H2 increases by 0.1%, the UEL will increase by about 0.3%. However, H2 has only a small effect on the LEL of the combustible gas mixture. Our study provides a theoretical foundation for judging the explosion risk of an explosive gas mixture in mines.

  18. Turbulent Combustion in SDF Explosions

    Energy Technology Data Exchange (ETDEWEB)

    Kuhl, A L; Bell, J B; Beckner, V E

    2009-11-12

    A heterogeneous continuum model is proposed to describe the dispersion and combustion of an aluminum particle cloud in an explosion. It combines the gas-dynamic conservation laws for the gas phase with a continuum model for the dispersed phase, as formulated by Nigmatulin. Inter-phase mass, momentum and energy exchange are prescribed by phenomenological models. It incorporates a combustion model based on the mass conservation laws for fuel, air and products; source/sink terms are treated in the fast-chemistry limit appropriate for such gasdynamic fields, along with a model for mass transfer from the particle phase to the gas. The model takes into account both the afterburning of the detonation products of the C-4 booster with air, and the combustion of the Al particles with air. The model equations were integrated by high-order Godunov schemes for both the gas and particle phases. Numerical simulations of the explosion fields from 1.5-g Shock-Dispersed-Fuel (SDF) charge in a 6.6 liter calorimeter were used to validate the combustion model. Then the model was applied to 10-kg Al-SDF explosions in a an unconfined height-of-burst explosion. Computed pressure histories are compared with measured waveforms. Differences are caused by physical-chemical kinetic effects of particle combustion which induce ignition delays in the initial reactive blast wave and quenching of reactions at late times. Current simulations give initial insights into such modeling issues.

  19. Effect of organic loading rate on methane and volatile fatty acids productions from anaerobic treatment of palm oil mill effluent in UASB and UFAF reactors

    Directory of Open Access Journals (Sweden)

    Sumate Chaiprapat

    2007-05-01

    Full Text Available Anaerobic treatment of palm oil mill effluent (POME with the separation of the acidogenic and methanogenic phase was studied in an up-flow anaerobic sludge blanket (UASB reactor and an up-flowanaerobic filter (UFAF reactor. Furthermore, the effect of OLR on methane and volatile fatty acid productions in UASB and UFAF reactors was investigated. In this research, UASB as acidogenic reactor wasused for volatile fatty acid production and UFAF as methanogenic reactor was used for methane production. Therefore, POME without pH adjustment was used as influent for the UASB reactor. Moreover, the syntheticwastewater with pH adjustment to 6.00 was fed into the UFAF reactor. The inoculum source for both reactors was the combination of POME sludge collected from the CSTR of a POME treatment plant and granulesludge collected from the UASB reactor of a frozen sea food industry treatment plant. During experimental operation, the organic loading rate (OLR was gradually increased from 2.50 to 17.5 g COD/l/day in theUASB reactor and 1.10 to 10.0 g COD/l/day in the UFAF reactor. Consequently, hydraulic retention time (HRT ranged from 20.0 to 2.90 days in the UASB reactor and from 13.5 to 1.50 days in the UFAF reactor.The result showed that the COD removal efficiency from both reactors was greater than 60.0%. In addition, the total volatile fatty acids increased with the increasing OLR. The total volatile fatty acids and acetic acidproduction in the UASB reactor reached 5.50 g/l and 4.90 g/l, respectively at OLR of 17.5 g COD/l/day and HRT of 2.90 days before washout was observed. In the UFAF reactor, the methane and biogas productionincreased with increasing OLR until an OLR of 7.50 g COD/l/day. However, the methane and biogas production significantly decreased when OLR increased up to 10.0 g COD/l/day. Therefore, the optimum OLR inthe laboratory-scale UASB and UFAF reactors were concluded to be 15.5 and 7.50 g COD/l/day, respectively.

  20. Premixed combustion of coconut oil in a hele-shaw cell

    Directory of Open Access Journals (Sweden)

    Hadi Saroso

    2014-12-01

    Full Text Available Coconut oil combustion characteristic is observed experimentally by evaporating oil in the boiler then mix it with air before being burned at various equivalence ratios in the Hele-shaw cell. The result shows that, coconut oil tends to break into glycerol and fatty acid due to hydrolysis reaction producing the flame propagation, where the fatty acid flame propagates first then glycerol flame. Micro-explosion occurs when moisture from fatty acid combustion is absorbed by glycerol and higher heating due to higher flame speed produces more micro-explosion.

  1. Study of agglomeration behavior of combustion-synthesized nano-crystalline ceria using new fuels

    Energy Technology Data Exchange (ETDEWEB)

    Mukherjee, Srirupa T.; Bedekar, Vinila [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Patra, A.; Sastry, P.U. [Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India); Tyagi, A.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, Maharashtra (India)], E-mail: aktyagi@barc.gov.in

    2008-10-20

    Ceria powders were prepared by gel combustion process using cerium nitrate and hitherto unexplored amino acid fuels such as aspartic acid, glutamic acid, arginine, tryptophan, phenyl alanine, valine, etc. These powders were characterized by X-ray diffraction, surface area analysis, sinterability, dynamic light scattering, scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS). The combustion-synthesized powders were agglomerates of nano-crystallites. SAXS profiles of the powders prepared using tryptophan, phenyl alanine and dimethyl urea exhibited fractal behavior.

  2. Effects of volatile coatings on the morphology and optical detection of combustion-generated black carbon particles.

    Energy Technology Data Exchange (ETDEWEB)

    Bambha, Ray.; Dansson, Mark A; Schrader, Paul E.; Michelsen, Hope A.

    2013-09-01

    We have measured time-resolved laser-induced incandescence (LII) from combustion-generated mature soot extracted from a burner and (1) coated with oleic acid or (2) coated with oleic acid and then thermally denuded using a thermodenuder. The soot samples were size selected using a differential mobility analyser and characterized with a scanning mobility particle sizer, centrifugal particle mass analyser, and transmission electron microscope. The results demonstrate a strong influence of coatings particle morphology and on the magnitude and temporal evolution of the LII signal. For coated particles higher laser fluences are required to reach LII signal levels comparable to those of uncoated particles. This effect is predominantly attributable to the additional energy needed to vaporize the coating while heating the particle. LII signals are higher and signal decay rates are significantly slower for thermally denuded particles relative to coated or uncoated particles, particularly at low and intermediate laser fluences.

  3. Comprehensive study of biodiesel fuel for HSDI engines in conventional and low temperature combustion conditions

    Energy Technology Data Exchange (ETDEWEB)

    Tormos, Bernardo; Novella, Ricardo; Garcia, Antonio; Gargar, Kevin [CMT-Motores Termicos, Universidad Politecnica de Valencia, Valencia, ES, Campus de Vera, s/n, Edificio 6D. Camino de Vera s/n, 46022 Valencia (Spain)

    2010-02-15

    In this research, an experimental investigation has been performed to give insight into the potential of biodiesel as an alternative fuel for High Speed Direct Injection (HSDI) diesel engines. The scope of this work has been broadened by comparing the combustion characteristics of diesel and biodiesel fuels in a wide range of engine loads and EGR conditions, including the high EGR rates expected for future diesel engines operating in the low temperature combustion (LTC) regime. The experimental work has been carried out in a single-cylinder engine running alternatively with diesel and biodiesel fuels. Conventional diesel fuel and neat biodiesel have been compared in terms of their combustion performance through a new methodology designed for isolating the actual effects of each fuel on diesel combustion, aside from their intrinsic differences in chemical composition. The analysis of the results has been sequentially divided into two progressive and complementary steps. Initially, the overall combustion performance of each fuel has been critically evaluated based on a set of parameters used as tracers of the combustion quality, such as the combustion duration or the indicated efficiency. With the knowledge obtained from this previous overview, the analysis focuses on the detailed influence of biodiesel on the different diesel combustion stages known ignition delay, premixed combustion and mixing controlled combustion, considering also the impact on CO and UHC (unburn-hydrocarbons) pollutant emissions. The results of this research explain why the biodiesel fuel accelerates the diesel combustion process in all engine loads and EGR rates, even in those corresponding with LTC conditions, increasing its possibilities as alternative fuel for future DI diesel engines. (author)

  4. Characteristics of combustion products: a review of the literature

    Energy Technology Data Exchange (ETDEWEB)

    Chan, M.K.W.; Mishima, J.

    1983-07-01

    To determine the effects of fires in nuclear-fuel-cycle facilities, Pacific Northwest Laboratory (PNL) has surveyed the literature to gather data on the characteristics of combustion products. This report discusses the theories of the origin of combustion with an emphasis on the behavior of the combustible materials commonly found in nuclear-fuel-cycle facilities. Data that can be used to calculate particulate generation rate, size, distribution, and concentration are included. Examples are given to illustrate the application of this data to quantitatively predict both the mass and heat generated from fires. As the final result of this review, information gaps are identified that should be filled for fire-accident analyses in fuel-cycle facilities. 29 figures, 32 tables.

  5. 3rd International Workshop on Turbulent Spray Combustion

    CERN Document Server

    Gutheil, Eva

    2014-01-01

    This book reflects the results of the 2nd and 3rd International Workshops on Turbulent Spray Combustion. The focus is on progress in experiments and numerical simulations for two-phase flows, with emphasis on spray combustion. Knowledge of the dominant phenomena and their interactions allows development of predictive models and their use in combustor and gas turbine design. Experts and young researchers present the state-of-the-art results, report on the latest developments and exchange ideas in the areas of experiments, modelling and simulation of reactive multiphase flows. The first chapter reflects on flame structure, auto-ignition and atomization with reference to well-characterized burners, to be implemented by modellers with relative ease. The second chapter presents an overview of first simulation results on target test cases, developed at the occasion of the 1st International Workshop on Turbulent Spray Combustion. In the third chapter, evaporation rate modelling aspects are covered, while the fourth ...

  6. Time varying voltage combustion control and diagnostics sensor

    Science.gov (United States)

    Chorpening, Benjamin T.; Thornton, Jimmy D.; Huckaby, E. David; Fincham, William

    2011-04-19

    A time-varying voltage is applied to an electrode, or a pair of electrodes, of a sensor installed in a fuel nozzle disposed adjacent the combustion zone of a continuous combustion system, such as of the gas turbine engine type. The time-varying voltage induces a time-varying current in the flame which is measured and used to determine flame capacitance using AC electrical circuit analysis. Flame capacitance is used to accurately determine the position of the flame from the sensor and the fuel/air ratio. The fuel and/or air flow rate (s) is/are then adjusted to provide reduced flame instability problems such as flashback, combustion dynamics and lean blowout, as well as reduced emissions. The time-varying voltage may be an alternating voltage and the time-varying current may be an alternating current.

  7. Citric acid aided synthesis, characterization, and high-rate electrochemical performance of LiNi0.5Mn1.5O4

    International Nuclear Information System (INIS)

    The citric acid aided synthesis, physico-chemical and electrochemical characterization of the nanosized nickel-doped lithium manganese spinel, LiNi0.5Mn1.5O4 having excellent high-rate properties is described. An optimal electrode material represented by perfectly shaped, well-faceted particles of 100-400 nm size containing crystallites of the 15-22 nm size could be obtained upon the thermal treatment at 700 °C. In spite of a reduced specific capacity (102 mAh·g−1) it is able to retain a half of it upon the discharge current of 4400 mA·g−1 (30 C) and to endure the current load of 5870 mAh·g−1 (40 C) delivering the reversible specific capacity of 25 mAh·g−1. It is suggested that the reduced specific capacity is determined primarily by the aggregation of material's particles, whereas the good high-rate capability is governed not only by the size of crystallites but also by the perfectness of crystals, and imperfections in big, well-shaped crystals (like dislocations, grain boundaries, etc.) less retard the diffusion of lithium ions than particle boundaries in small, randomly oriented, accreted crystals

  8. The activity of ascorbic acid and catechol oxidase, the rate of photosynthesis and respiration as related to plant organs, stage of development and copper supply

    Directory of Open Access Journals (Sweden)

    St. Łyszcz

    2015-06-01

    Full Text Available Some experiments were performed to investigate the physiological role of copper in oat and sunflower and to recognize some effects of copper deficiency. Oat and sunflower plants were grown in pots on a peat soil under copper deficiency conditions (–Cu or with the optimal copper supply (+Cu. In plants the following measurements were carried out: 1 the activity of ascorbic acid oxidase (AAO and of catechol oxidase (PPO in different plant organs and at different stages of plant development, 2 the activity and the rate of photosynthesis, 3 the activity of RuDP-carboxylase, 4 the intensity of plant respiration. The activity of AAO and of PPO, and also the rate and the activity of photosynthesis were significantly lower under conditions of copper deficiency. The activity of both discussed oxidases depended on: 1 the plant species, 2 plant organs, 3 stage of plant development. Copper deficiency caused decrease of the respiration intensity of sunflower leaves but it increased to some extent the respiration of oat tops. Obtained results are consistent with the earlier suggestion of the authors that the PPO activity in sunflower leaves could be a sensitive indicator of copper supply of the plants, farther experiments are in progress.

  9. A projection method for LES of incompressible turbulent combustion

    Institute of Scientific and Technical Information of China (English)

    LIU Yi; GUO Yincheng

    2004-01-01

    In this paper, the "incompressible" property of a turbulent combustion with Ma<<1 is analyzed, and a projection method for simulation of low Ma number turbulent combustions is discussed. The density is calculated explicitly,and the projection is only applied to the momentum equations and thus greatly saves the calculation cost. Large eddy simulation of methane-air turbulent planar jet combustion is performed using this projection method. A reduced four-step chemical kinetic mechanism is applied for the simulation of methane-air combustion. A dynamic eddy viscosity model is utilized for the sub-grid scales turbulence modulation. The SGS model for the filtered reaction rate is a dynamic similarity model. Simulation results depict the detailed coherent structures in the jet flame along with the vortex-flame interactions in the flow field. Besides, it is found that the chemical reaction has the effect of "energy rearrangement" in the flow field, which may greatly reduce the turbulence. Simulation results show the satisfactory performance of this projection method in simulating turbulent combustion under the condition of Ma<<1.

  10. Premixed combustion under electric field in a constant volume chamber

    KAUST Repository

    Cha, Min Suk

    2012-12-01

    The effects of electric fields on outwardly propagating premixed flames in a constant volume chamber were experimentally investigated. An electric plug, subjected to high electrical voltages, was used to generate electric fields inside the chamber. To minimize directional ionic wind effects, alternating current with frequency of 1 kHz was employed. Lean and rich fuel/air mixtures for both methane and propane were tested to investigate various preferential diffusion conditions. As a result, electrically induced instability showing cracked structure on the flame surface could be observed. This cracked structure enhanced flame propagation speed for the initial period of combustion and led to reduction in flame initiation and overall combustion duration times. However, by analyzing pressure data, it was found that overall burning rates are not much affected from the electric field for the pressurized combustion period. The reduction of overall combustion time is less sensitive to equivalence ratio for methane/air mixtures, whereas the results demonstrate pronounced effects on a lean mixture for propane. The improvement of combustion characteristics in lean mixtures will be beneficial to the design of lean burn engines. Two hypothetical mechanisms to explain the electrically induced instability were proposed: 1) ionic wind initiated hydrodynamic instability and 2) thermodiffusive instability through the modification of transport property such as mass diffusivity. © 2012 IEEE.

  11. Optical investigation of heat release and NOx production in combustion

    International Nuclear Information System (INIS)

    Two novel optical techniques are presented for non-intrusive, spatially resolved study of combustion, both based on passive Optical Emission Tomography (OET). Firstly, OET is used for non-intrusive study of heat release through the detection of chemiluminescence by the hydroxyl radical that is generated in the burning process. The OET technique presented here is based on a passive fibre-optic detection system, which allows spatially resolved high-frequency detection of the flame front in a combustion flame, where all fibres detect the emission signals simultaneously. The system withstands the high pressures and temperatures typically encountered in the harsh environments of gas turbine combustors and IC engines. The sensor-array is non-intrusive, low-cost, compact, simple to configure and can be quickly set up around a combustion field. The maximum acquisition rate is 2 kHz. This allows spatially resolved study of the fast phenomena in combustion. Furthermore, a method is presented for study of the production of NOx through chemiluminescence from tri-methyl-borate (TMB). In combustion, the tri-methyl-borate produces green luminescence in locations where NOx would be produced. Combining the green luminescence visualisation with UV detection of the hydroxyl radical allows monitoring of heat release and of NOx production areas, thus giving a means of studying both the burning process and the resulting NOx pollution

  12. A Reduced Order Model for the Design of Oxy-Coal Combustion Systems

    Directory of Open Access Journals (Sweden)

    Steven L. Rowan

    2015-01-01

    Full Text Available Oxy-coal combustion is one of the more promising technologies currently under development for addressing the issues associated with greenhouse gas emissions from coal-fired power plants. Oxy-coal combustion involves combusting the coal fuel in mixtures of pure oxygen and recycled flue gas (RFG consisting of mainly carbon dioxide (CO2. As a consequence, many researchers and power plant designers have turned to CFD simulations for the study and design of new oxy-coal combustion power plants, as well as refitting existing air-coal combustion facilities to oxy-coal combustion operations. While CFD is a powerful tool that can provide a vast amount of information, the simulations themselves can be quite expensive in terms of computational resources and time investment. As a remedy, a reduced order model (ROM for oxy-coal combustion has been developed to supplement the CFD simulations. With this model, it is possible to quickly estimate the average outlet temperature of combustion flue gases given a known set of mass flow rates of fuel and oxidant entering the power plant boiler as well as determine the required reactor inlet mass flow rates for a desired outlet temperature. Several cases have been examined with this model. The results compare quite favorably to full CFD simulation results.

  13. Novel Active Combustion Control Valve

    Science.gov (United States)

    Caspermeyer, Matt

    2014-01-01

    This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

  14. Bioactivity studies of calcium magnesium silicate prepared from eggshell waste by sol–gel combustion synthesis

    OpenAIRE

    Rajan Choudhary; Sivasankar Koppala; Sasikumar Swamiappan

    2015-01-01

    The present study focused on the synthesis of calcium magnesium silicate (akermanite, Ca2MgSi2O7) using eggshell biowaste (as calcium source), magnesium nitrate and tetraethyl orthosilicate (TEOS) as starting materials. Sol–gel combustion method was adopted to obtain calcium magnesium silicate. Citric acid was used as a fuel (reducing agent) and nitrate ions present in the metal nitrates acts as an oxidizing agent during combustion process. The characterization of synthesized calcium magnesiu...

  15. THE COMBUSTION PERFORMANCE OF MEDIUM DENSITY FIBERBOARD TREATED WITH FIRE RETARDANT MICROSPHERES

    Directory of Open Access Journals (Sweden)

    Lichao Sun,

    2011-12-01

    Full Text Available Fire retardant particles (guanylurea phosphate and boric acid with a morphological characteristic of large crystal or fine microsphere, were respectively applied to wood fibers to make medium density fiberboard (MDF. The effects of particle size of the fire retardant on the combustion performance of the resulting MDF samples were determined using a thermogravimetric (TG analyzer and cone calorimeter (CONE. The scanning electron microscopy and laser particle size analysis showed that the microspheric particles of fire retardant had a mean size of approximately 20 µm, which was smaller than the crystal (260 um. Incorporation of the fire retardant either in the crystal or microsphere shape reduced the weight loss of the resulting MDF, as evidenced by the TG analysis and the CONE test; the release rate and total amount of both the heat and smoke were apparently inhibited as compared to the untreated MDF samples. Treatments caused an increase in both the ignition time and charring ratio of the MDF. Compared with the fire retardant crystals, the fine microspheric particles exhibited greater ability in inhibiting the release of heat and smoke through the combustion processes.

  16. Combustion synthesis method and products

    Science.gov (United States)

    Holt, J.B.; Kelly, M.

    1993-03-30

    Disclosed is a method of producing dense refractory products, comprising: (a) obtaining a quantity of exoergic material in powder form capable of sustaining a combustion synthesis reaction; (b) removing absorbed water vapor therefrom; (c) cold-pressing said material into a formed body; (d) plasma spraying said formed body with a molten exoergic material to form a coat thereon; and (e) igniting said exoergic coated formed body under an inert gas atmosphere and pressure to produce self-sustained combustion synthesis. Also disclosed are products produced by the method.

  17. Fundamentals of premixed turbulent combustion

    CERN Document Server

    Lipatnikov, Andrei

    2012-01-01

    Lean burning of premixed gases is considered to be a promising combustion technology for future clean and highly efficient gas turbine engines. This book highlights the phenomenology of premixed turbulent flames. The text provides experimental data on the general appearance of premixed turbulent flames, physical mechanisms that could affect flame behavior, and physical and numerical models aimed at predicting the key features of premixed turbulent combustion. The author aims to provide a simple introduction to the field for advanced graduate and postgraduate students. Topics covered include La

  18. Autodesk Combustion 4 fundamentals courseware

    CERN Document Server

    Autodesk,

    2005-01-01

    Whether this is your first experience with Combustion software or you're upgrading to take advantage of the many new features and tools, this guide will serve as your ultimate resource to this all-in-one professional compositing application. Much more than a point-and-click manual, this guide explains the principles behind the software, serving as an overview of the package and associated techniques. Written by certified Autodesk training specialists for motion graphic designers, animators, and visual effects artists, Combustion 4 Fundamentals Courseware provides expert advice for all skill le

  19. Combustion enhancing additives for coal firing

    Energy Technology Data Exchange (ETDEWEB)

    Katherine Le Manquais; Colin Snape; Ian McRobbie; Jim Barker [University of Nottingham, Nottingham (United Kingdom). School of Chemical, Environmental and Mining Engineering (SChEME)

    2007-07-01

    For pulverised fuel (pf) combustion, the level of unburnt carbon in fly ash is now considerably more problematic worldwide than a decade ago, because of the introduction of low NOx burners and the increased level of high inertinite in internationally traded coals. Thus, there is a major opportunity to develop an effective additive to improve carbon burnout and obviate the need for post-treatment of fly ash, which endeavours to meet specifications for filler/building materials applications and thereby avoid landfill. A robust comparison of the reactivity of different coals and their corresponding chars is necessary, in order to estimate the effects of such an additive on pf combustion. Coal chars have been generated on a laboratory scale using thermal gravimetric analysis (TGA) and on a larger scale using a drop tube furnace (DTF), which is more representative of the rapid heating rates and mixing achieved on pf combustion. The TGA results indicate that chars have varying levels of reactivity, dependent on the parent coal properties. When physically mixed with a propriety metal additive, the degree of enhancement to the reactivity of these chars also appeared reliant on the parent coal characteristics. Additionally it was demonstrated that DTF chars, whilst showing similar reactivity trends, are less reactive than the equivalent coal chars produced by the TGA. However, when mixed with the metal additive the DTF chars show a significantly greater improvement in reactivity than their analogous TGA chars, indicating the additive may have the greatest impact on the most unreactive carbon in the coal. 42 refs., 6 figs., 1 tab.

  20. Development of a Premixed Combustion Capability for Scramjet Combustion Experiments

    Science.gov (United States)

    Rockwell, Robert D.; Goyne, Christopher P.; Rice, Brian E.; Chelliah, Harsha; McDaniel, James C.; Edwards, Jack R.; Cantu, Luca M. L.; Gallo, Emanuela C. A.; Cutler, Andrew D.; Danehy, Paul M.

    2015-01-01

    Hypersonic air-breathing engines rely on scramjet combustion processes, which involve high speed, compressible, and highly turbulent flows. The combustion environment and the turbulent flames at the heart of these engines are difficult to simulate and study in the laboratory under well controlled conditions. Typically, wind-tunnel testing is performed that more closely approximates engine testing rather than a careful investigation of the underlying physics that drives the combustion process. The experiments described in this paper, along with companion data sets being developed separately, aim to isolate the chemical kinetic effects from the fuel-air mixing process in a dual-mode scramjet combustion environment. A unique fuel injection approach is taken that produces a nearly uniform fuel-air mixture at the entrance to the combustor. This approach relies on the precombustion shock train upstream of the dual-mode scramjet combustor. A stable ethylene flame anchored on a cavity flameholder with a uniformly mixed combustor inflow has been achieved in these experiments allowing numerous companion studies involving coherent anti-Stokes Raman scattering (CARS), particle image velocimetry (PIV), and planar laser induced fluorescence (PLIF) to be performed.

  1. Application of the first combustion model to spray combustion

    NARCIS (Netherlands)

    Jager, de B.; Kok, J.B.W.

    2004-01-01

    Liquid fuel is of interest to apply to gas turbines. The large advantage is that liquids are easily storable as compared to gaseous fuels. Disadvantage is that liquid fuel has to be sprayed, vaporized and mixed with air. Combustion occurs at some stage of mixing and ignition. Depending on the effici

  2. Experimental investigation of wood combustion in a fixed bed with hot air

    Energy Technology Data Exchange (ETDEWEB)

    Markovic, Miladin, E-mail: m.markovic@utwente.nl; Bramer, Eddy A.; Brem, Gerrit

    2014-01-15

    the primary air speed, fuel moisture and inert content on the combustion characteristics (ignition rate, combustion rate, ignition front speed and temperature of the reaction zone) is evaluated. The upward combustion concept decouples the drying, devolatilization and burnout phase. In this way the moisture and inert content of the waste have almost no influence on the combustion process. In this paper an experimental comparison between conventional and reversed combustion is presented.

  3. Combustion characteristics of SMX and SMX based propellants

    Science.gov (United States)

    Reese, David A.

    This work investigates the combustion of the new solid nitrate ester 2,3-hydroxymethyl-2,3-dinitro-1,4-butanediol tetranitrate (SMX, C6H 8N6O16). SMX was synthesized for the first time in 2008. It has a melting point of 85 °C and oxygen balance of 0% to CO 2, allowing it to be used as an energetic additive or oxidizer in solid propellants. In addition to its neat combustion characteristics, this work also explores the use of SMX as a potential replacement for nitroglycerin (NG) in double base gun propellants and as a replacement for ammonium perchlorate in composite rocket propellants. The physical properties, sensitivity characteristics, and combustion behaviors of neat SMX were investigated. Its combustion is stable at pressures of up to at least 27.5 MPa (n = 0.81). The observed flame structure is nearly identical to that of other double base propellant ingredients, with a primary flame attached at the surface, a thick isothermal dark zone, and a luminous secondary flame wherein final recombination reactions occur. As a result, the burning rate and primary flame structure can be modeled using existing one-dimensional steady state techniques. A zero gas-phase activation energy approximation results in a good fit between modeled and observed behavior. Additionally, SMX was considered as a replacement for nitroglycerin in a double base propellant. Thermochemical calculations indicate improved performance when compared with the common double base propellant JA2 at SMX loadings above 40 wt-%. Also, since SMX is a room temperature solid, migration may be avoided. Like other nitrate esters, SMX is susceptible to decomposition over long-term storage due to the presence of excess acid in the crystals; the addition of stabilizers (e.g., derivatives of urea) during synthesis should be sufficient to prevent this. the addition of Both unplasticized and plasticized propellants were formulated. Thermal analysis of unplasticized propellant showed a distinct melt

  4. Free Energy and Internal Combustion Engine Cycles

    CERN Document Server

    Harris, William D

    2012-01-01

    The performance of one type (Carnot) of Internal Combustion Engine (ICE) cycle is analyzed within the framework of thermodynamic free energies. ICE performance is different from that of an External Combustion Engine (ECE) which is dictated by Carnot's rule.

  5. Scramjet Combustion Stability Behavior Modeling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A recent breakthrough in combustion stability analysis (UCDS) offers the potential to predict the combustion stability of a scramjet. This capability is very...

  6. Scramjet Combustion Stability Behavior Modeling Project

    Data.gov (United States)

    National Aeronautics and Space Administration — A recent breakthrough in combustion stability analysis (UCDS) offers the means to accurately predict the combustion stability of a scramjet. This capability is very...

  7. Optimization of Post Combustion in Steelmaking (TRP 9925)

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Richard J. Fruehan; Dr. R. J. Matway

    2004-03-31

    In the electric arc furnace (EAF), and the basic oxygen furnace (BOF) for producing steel, the major off gas is carbon monoxide (CO). If the CO can be combusted to CO{sub 2}, and the energy transferred to the metal, this reaction will reduce the energy consumed in the EAF and allow for more scrap melting in the BOF which would significantly lower the energy required to produce steel. This reaction is referred to as post combustion. In order to optimize the post combustion process, computational fluid dynamic models (CFD) of the two steelmaking processes were developed. Before the models could be fully developed information on reactions affecting post combustion had to be obtained. The role of the reaction of CO{sub 2} with scrap (iron) was measured at the temperatures relevant to post combustion in laboratory experiments. The experiments were done to separate the effects of gas phase mass transfer, chemical kinetics, and solid state mass transfer through the iron oxide formed by the reaction. The first CFD model was for the EAF using the FIDAP-CFD{trademark} code. Whereas this model gave some useful results it was incomplete due to problems with the FIDAP program. In the second EAF model, the CFX{trademark} code was used and was much more successful. The full 3-D model included all forms of heat transfer and the back reactions of CO{sub 2} with the metal and scrap. The model for the EAF was a full 3-D model and consisted of a primary oxygen lance with side wall injectors for post combustion. The model could predict the degree of post combustion and heat transfer. The BOF model was a slice of the BOF for which there was symmetry. The model could predict post combustion, heat transfer, temperature profiles and the effect of operating variables such as oxygen flow rates and distribution. The present research developed several new models such as limited combustion and depostcombustion. These were all documented by MSA Pass as a sub-contract. Instruction manuals were

  8. High Frequency Combustion Instabilities of LOx/CH4 Spray Flames in Rocket Engine Combustion Chambers

    NARCIS (Netherlands)

    Sliphorst, M.

    2011-01-01

    Ever since the early stages of space transportation in the 1940’s, and the related liquid propellant rocket engine development, combustion instability has been a major issue. High frequency combustion instability (HFCI) is the interaction between combustion and the acoustic field in the combustion c

  9. Combustion Chemistry Diagnostics for Cleaner Processes.

    Science.gov (United States)

    Kohse-Höinghaus, Katharina

    2016-09-12

    Climate change, environmental problems, urban pollution, and the dependence on fossil fuels demand cleaner, renewable energy strategies. However, they also ask for urgent advances in combustion science to reduce emissions. For alternative fuels and new combustion regimes, crucial information about the chemical reactions from fuel to exhaust remains lacking. Understanding such relations between combustion process, fuel, and emissions needs reliable experimental data from a wide range of conditions to provide a firm basis for predictive modeling of practical combustion processes.

  10. Smouldering Combustion Phenomena in Science and Technology

    OpenAIRE

    Rein, Guillermo

    2009-01-01

    Smouldering is the slow, low-temperature, flameless form of combustion of a condensed fuel. It poses safety and environmental hazards and allows novel technological application but its fundamentals remain mostly unknown to the scientific community. The terms filtering combustion, smoking problem, deep seated fires, hidden fires, peat or peatlands fires, lagging fires, low oxygen combustion, in-situ combustion, fireflood and underground gasification, all refer to smouldering com...

  11. Combustion Chemistry Diagnostics for Cleaner Processes.

    Science.gov (United States)

    Kohse-Höinghaus, Katharina

    2016-09-12

    Climate change, environmental problems, urban pollution, and the dependence on fossil fuels demand cleaner, renewable energy strategies. However, they also ask for urgent advances in combustion science to reduce emissions. For alternative fuels and new combustion regimes, crucial information about the chemical reactions from fuel to exhaust remains lacking. Understanding such relations between combustion process, fuel, and emissions needs reliable experimental data from a wide range of conditions to provide a firm basis for predictive modeling of practical combustion processes. PMID:27440049

  12. Potential of methanol in dual fuel combustion

    OpenAIRE

    Tuominen, Tino

    2016-01-01

    Depleting oil resources together with the climate change due to the use of fossil fuels are motivating to investigate alternative fuels and new combustion strategies used with them. At the moment, dual fuel combustion is one of the most promising new combustion strategies. Combining it to the use of renewable methanol as a primary fuel, it offers an interesting option for the conventional combustion engine. This thesis focuses on investigating the theoretical potential of methanol in dua...

  13. Combustion performance of flame-ignited high-speed train seats via full-scale tests

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    2015-10-01

    Full Text Available Determining the combustion characteristics of combustibles in high-speed trains is the foundation of evaluating the fire hazard on high-speed trains scientifically, and establishing effective active and passive fire precautions. In this study, the double seats in the compartments of CRH1 high-speed trains were used as the main research object. Under different test conditions, including the power of ignition sources and ventilation rates, full-scale furniture calorimeter tests were conducted to study important fire combustion characteristics such as the ignition characteristics of seats, heat release rate, mass loss rate, total heat release, temperature variation, and smoke release rate. The relationships among these parameters were analyzed and summarized into combustion behavior and characteristics, thus providing fundamental data and reference for the development of fire precautions and safety design of high-speed trains. The results in this test are as follows: (i The double seats of high-speed trains are relatively easy to ignite and susceptible to the fire ground environment. (ii The combustion temperature in the test apparatus exceeded 600 °C in only 2 min for the larger ignition source. (iii The heat release rate exceeded 800 kW. (iv The total heat release resulted mainly from flame combustion. (v The final mass loss rate was ∼30%. (vi The lowest light transmittance was <25%. (vii The change process of temperature with time has the same trend as the change process of heat release rate. (viii Suppressing flame combustion and controlling the smoke generated from the seat materials themselves played key roles in retarding the combustion of high-speed train seats.

  14. Combustion aerosols from potassium-containing fuels

    Energy Technology Data Exchange (ETDEWEB)

    Balzer Nielsen, Lars

    1998-12-31

    The scope of the work presented in this thesis is the formation and evolution of aerosol particles in the submicron range during combustion processes, in particular where biomass is used alone or co-fired with coal. An introduction to the formation processes of fly ash in general and submicron aerosol in particular during combustion is presented, along with some known problems related to combustion of biomass for power generation. The work falls in two parts. The first is the design of a laboratory setup for investigation of homogeneous nucleation and particle dynamics at high temperature. The central unit of the setup is a laminar flow aerosol condenser (LFAC), which essentially is a 173 cm long tubular furnace with an externally cooled wall. A mathematical model is presented which describes the formation and evolution of the aerosol in the LFAC, where the rate of formation of new nuclei is calculated using the so-called classical theory. The model includes mass and energy conservation equations and an expression for the description of particle growth by diffusion. The resulting set of nonlinear second-order partial differential equations are solved numerically using the method of orthogonal collocation. The model is implemented in the FORTRAN code MONAERO. The second part of this thesis describes a comprehensive investigation of submicron aerosol formation during co-firing of coal and straw carried out at a 380 MW{sub Th} pulverized coal unit at Studstrup Power Plant, Aarhus. Three types of coal are used, and total boiler load and straw input is varied systematically. Straw contains large amounts of potassium, which is released during combustion. Submicron aerosol is sampled between the two banks of the economizer at a flue gas temperature of 350 deg. C using a novel ejector probe. The aerosol is characterized using the SMPS system and a Berner-type low pressure impactor. The chemical composition of the particles collected in the impactor is determined using

  15. Straw combustion on slow-moving grates

    DEFF Research Database (Denmark)

    Kær, Søren Knudsen

    2005-01-01

    Combustion of straw in grate-based boilers is often associated with high emission levels and relatively poor fuel burnout. A numerical grate combustion model was developed to assist in improving the combustion performance of these boilers. The model is based on a one-dimensional ‘‘walking...

  16. 30 CFR 56.4104 - Combustible waste.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Combustible waste. 56.4104 Section 56.4104... Control Prohibitions/precautions/housekeeping § 56.4104 Combustible waste. (a) Waste materials, including... properly, waste or rags containing flammable or combustible liquids that could create a fire hazard...

  17. Thermogravimetric investigation of the co-combustion between the pyrolysis oil distillation residue and lignite.

    Science.gov (United States)

    Li, Hao; Xia, Shuqian; Ma, Peisheng

    2016-10-01

    Co-combustion of lignite with distillation residue derived from rice straw pyrolysis oil was investigated by non-isothermal thermogravimetric analysis (TGA). The addition of distillation residue improved the reactivity and combustion efficiency of lignite, such as increasing the weight loss rate at peak temperature and decreasing the burnout temperature and the total burnout. With increasing distillation residue content in the blended fuels, the synergistic interactions between distillation residue and lignite firstly increased and then decreased during co-combustion stage. Results of XRF, FTIR, (13)C NMR and SEM analysis indicated that chemical structure, mineral components and morphology of samples have great influence on the synergistic interactions. The combustion mechanisms and kinetic parameters were calculated by the Coats Redfern model, suggesting that the lowest apparent activation energy (120.19kJ/mol) for the blended fuels was obtained by blending 60wt.% distillation residue during main co-combustion stage. PMID:27416511

  18. An analysis of combustion studies in shock expansion tunnels and reflected shock tunnels

    Science.gov (United States)

    Jachimowski, Casimir J.

    1992-01-01

    The effect of initial nonequilibrium dissociated air constituents on the combustion of hydrogen in high-speed flows for a simulated Mach 17 flight condition was investigated by analyzing the results of comparative combustion experiments performed in a reflected shock tunnel test gas and in a shock expansion tunnel test gas. The results were analyzed and interpreted with a one-dimensional quasi-three-stream combustor code that includes finite rate combustion chemistry. The results of this study indicate that the combustion process is kinetically controlled in the experiments in both tunnels and the presence of the nonequilibrium partially dissociated oxygen in the reflected shock tunnel enhances the combustion. Methods of compensating for the effect of dissociated oxygen are discussed.

  19. EMISSION AND COMBUSTION CHARACTERISTICS OF DIFFERENT FUELS IN A HCCI ENGINE

    Directory of Open Access Journals (Sweden)

    S. Sendilvelan

    2011-06-01

    Full Text Available Different intake valve timings and fuel injection amounts were tested in order to identify their effects on exhaust emissions and combustion characteristics using variable valve actuation (VVA in a Homogeneous Charge Compression Ignition (HCCI engine. The HCCI engine is a promising concept for future automobile engines and stationary power plants. The two-stage ignition process in a HCCI engine creates advanced ignition and stratified combustion, which makes the ignition timing and combustion rate controllable. Meanwhile, the periphery of the fuel-rich zone leads to fierce burning, which results in slightly high NOx emissions. The experiments were conducted in a modified single cylinder water-cooled diesel engine. In this experiment we use diesel, bio-diesel (Jatropha and gasoline as the fuel at different mixing ratios. HCCI has advantages in high thermal efficiency and low emissions and could possibly become a promising combustion method in internal combustion engines.

  20. Analysis of irrationality of coal susceptibility to spontaneous combustion determination method with fluid oxygen adsorption

    Institute of Scientific and Technical Information of China (English)

    HE Qi-lin

    2008-01-01

    Based on experiment results and theoretical analysis,pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidation process and oxidation reaction.The method is incorrect,paying attention at one aspect and ignoring the rest.The method is not reasonable for coal susceptibility to spontaneous combustion determination.Susceptibility to spontaneous combustion of coal reflects chemical property of coal oxidation with oxygen absorption and heat release at low temperature.Coal's susceptibility to spontaneous combustion is mainly decided by the number of molecules with reaction activation energy and activation molecule production rate at certain temperature.Therefore,index of susceptibility to spontaneous combustion should adopt accumulative value or trend of heat release or oxygen adsorption during oxidation process.

  1. Analysis of irrationality of coal susceptibility to spontaneous combustion determination method with fluid oxygen adsorption

    Institute of Scientific and Technical Information of China (English)

    HE Qi-lin

    2008-01-01

    Based on experiment results and theoretical analysis, pointed out that the method of coal susceptibility to spontaneous combustion determination with fluid oxygen adsorption can not present the essence of coal oxidation process and oxidation reaction. The method is incorrect, paying attention at one aspect and ignoring the rest. The method is not reasonable for coal susceptibility to spontaneous combustion determination. Sus-ceptibility to spontaneous combustion of coal reflects chemical property of coal oxidation with oxygen absorption and heat release at low temperature. Coal's susceptibility to spon-taneous combustion is mainly decided by the number of molecules with reaction activation energy and activation molecule production rate at certain temperature. Therefore, index of susceptibility to spontaneous combustion should adopt accumulative value or trend of heat release or oxygen adsorption during oxidation process.

  2. Numerical Simulation of Combustion and Rotor-Stator Interaction in a Turbine Combustor

    Directory of Open Access Journals (Sweden)

    Dragos D. Isvoranu

    2003-01-01

    Full Text Available This article presents the development of a numerical algorithm for the computation of flow and combustion in a turbine combustor. The flow and combustion are modeled by the Reynolds-averaged Navier-Stokes equations coupled with the species-conservation equations. The chemistry model used herein is a two-step, global, finite-rate combustion model for methane and combustion gases. The governing equations are written in the strong conservation form and solved using a fully implicit, finite-difference approximation. The gas dynamics and chemistry equations are fully decoupled. A correction technique has been developed to enforce the conservation of mass fractions. The numerical algorithm developed herein has been used to investigate the flow and combustion in a one-stage turbine combustor.

  3. Experimental Investigation of Oxygen Enriched air intake on Combustion Parameters of a Single Cylinder Diesel Engine

    Directory of Open Access Journals (Sweden)

    K.RAJKUMAR

    2010-08-01

    Full Text Available In the present experimental work a computerized Single cylinder Diesel engine with data acquisition system was used to study the effects of oxygen enriched air intake on combustion parameters. Increasing the oxygen content with the air leads to faster burn rates and the ability to burn more fuel at the same stoichiometery. Addedoxygen in the combustion air leads to shorter ignition delays and offers more potential for burning diesel. Oxy-fuel combustion reduces the volume of flue gases and reduces the effects of green house effect also. Engine test has been carried out in the above said engine for different loads and the following combustion parameters like Ignition delay, Combustion duration, Heat release and Cylinder pressure was discussed.

  4. Sulfur Chemistry in Combustion II

    DEFF Research Database (Denmark)

    Johnsson, Jan Erik; Kiil, Søren

    2000-01-01

    Several options are available to control the emission of SO2 from combustion processes. One possibility is to use a cleaner technology, i.e. fuel switching from oil and coal to natural gas or biomass, or to desulphurize coal and oil. Another possibility is to change to a different technology...

  5. Low-Temperature Combustion Technology

    OpenAIRE

    Osintsev, Konstantin

    2012-01-01

    Any coal-fired boiler is always designed on a certain kind of coal. In the EU and Russia in the old coal mines can be mined coal with a high content of moisture and ash. In order to use coal with different characteristics in the same steam generator, it is necessary to create a new coal combustion technology.

  6. OXYGEN ENHANCED COMBUSTION FOR NOx CONTROL

    International Nuclear Information System (INIS)

    Increased environmental regulations will require utility boilers to reduce NO(sub x) emissions to less than 0.15lb/MMBtu in the near term. Conventional technologies such as Selective Catalytic Reduction (SCR) and Selective Non-Catalytic Reduction (SNCR) are unable to achieve these lowered emission levels without substantially higher costs and major operating problems. Oxygen enhanced combustion is a novel technology that allows utilities to meet the NO(sub x) emission requirements without the operational problems that occur with SCR and SNCR. Furthermore, oxygen enhanced combustion can achieve these NO(sub x) limits at costs lower than conventional technologies. The objective of this program is to demonstrate the use of oxygen enhanced combustion as a technical and economical method of meeting the EPA State Implementation Plan for NO(sub x) reduction to less than 0.15lb/MMBtu for a wide range of boilers and coal. The oxygen enhanced coal combustion program (Task 1) focused this quarter on the specific objective of exploration of the impact of oxygen enrichment on NO(sub x) formation utilizing small-scale combustors for parametric testing. Research efforts toward understanding any limitations to the applicability of the technology to different burners and fuels such as different types of coal are underway. The objective of the oxygen transport membrane (OTM) materials development program (Task 2.1) is to ascertain a suitable material composition that can be fabricated into dense tubes capable of producing the target oxygen flux under the operating conditions. This requires that the material have sufficient oxygen permeation resulting from high oxygen ion conductivity, high electronic conductivity and high oxygen surface exchange rate. The OTM element development program (Task 2.2) objective is to develop, fabricate and characterize OTM elements for laboratory and pilot reactors utilizing quality control parameters to ensure reproducibility and superior performance

  7. Optimal Bayesian Experimental Design for Combustion Kinetics

    KAUST Repository

    Huan, Xun

    2011-01-04

    Experimental diagnostics play an essential role in the development and refinement of chemical kinetic models, whether for the combustion of common complex hydrocarbons or of emerging alternative fuels. Questions of experimental design—e.g., which variables or species to interrogate, at what resolution and under what conditions—are extremely important in this context, particularly when experimental resources are limited. This paper attempts to answer such questions in a rigorous and systematic way. We propose a Bayesian framework for optimal experimental design with nonlinear simulation-based models. While the framework is broadly applicable, we use it to infer rate parameters in a combustion system with detailed kinetics. The framework introduces a utility function that reflects the expected information gain from a particular experiment. Straightforward evaluation (and maximization) of this utility function requires Monte Carlo sampling, which is infeasible with computationally intensive models. Instead, we construct a polynomial surrogate for the dependence of experimental observables on model parameters and design conditions, with the help of dimension-adaptive sparse quadrature. Results demonstrate the efficiency and accuracy of the surrogate, as well as the considerable effectiveness of the experimental design framework in choosing informative experimental conditions.

  8. Magnetic Field Control of Combustion Dynamics

    Science.gov (United States)

    Barmina, I.; Valdmanis, R.; Zake, M.; Kalis, H.; Marinaki, M.; Strautins, U.

    2016-08-01

    Experimental studies and mathematical modelling of the effects of magnetic field on combustion dynamics at thermo-chemical conversion of biomass are carried out with the aim of providing control of the processes developing in the reaction zone of swirling flame. The joint research of the magnetic field effect on the combustion dynamics includes the estimation of this effect on the formation of the swirling flame dynamics, flame temperature and composition, providing analysis of the magnetic field effects on the flame characteristics. The results of experiments have shown that the magnetic field exerts the influence on the flow velocity components by enhancing a swirl motion in the flame reaction zone with swirl-enhanced mixing of the axial flow of volatiles with cold air swirl, by cooling the flame reaction zone and by limiting the thermo-chemical conversion of volatiles. Mathematical modelling of magnetic field effect on the formation of the flame dynamics confirms that the electromagnetic force, which is induced by the electric current surrounding the flame, leads to field-enhanced increase of flow vorticity by enhancing mixing of the reactants. The magnetic field effect on the flame temperature and rate of reactions leads to conclusion that field-enhanced increase of the flow vorticity results in flame cooling by limiting the chemical conversion of the reactants.

  9. MECHANISMS AND OPTIMIZATION OF COAL COMBUSTION

    Energy Technology Data Exchange (ETDEWEB)

    Kyriacos Zygourakis

    2000-10-31

    The completed research project has made some significant contributions that will help us meet the challenges outlined in the previous section. One of the major novelties of our experimental approach involves the application of video microscopy and digital image analysis to study important transient phenomena (like particle swelling and ignitions) occurring during coal pyrolysis and combustion. Image analysis was also used to analyze the macropore structure of chars, a dominant factor in determining char reactivity and ignition behavior at high temperatures where all the commercial processes operate. By combining advanced experimental techniques with mathematical modeling, we were able to achieve the main objectives of our project. More specifically: (1) We accurately quantified the effect of several important process conditions (like pyrolysis heating rate, particle size, heat treatment temperature and soak time) on the combustion behavior of chars. These measurements shed new light into the fundamental mechanisms of important transient processes like particle swelling and ignitions. (2) We developed and tested theoretical models that can predict the ignition behavior of char particles and their burn-off times at high temperatures where intraparticle diffusional limitations are very important.

  10. Incorporating advanced combustion models to study power density in diesel engines

    Science.gov (United States)

    Lee, Daniel Michael

    A new combustion model is presented that can be used to simulate the diesel combustion process. This combustion process is broken into three phases: low temperature ignition kinetics, premixed burn and high temperature diffusion burn. The low temperature ignition kinetics are modeled using the Shell model. For combustion limited by diffusion, a probability density function (PDF) combustion model is utilized. In this model, the turbulent reacting flow is assumed to be an ensemble of locally laminar flamelets. With this methodology, species mass fractions obtained from the solution of laminar flamelet equations can be conditioned to generate a flamelet library. For kinetically limited (premixed) combustion, an Arrhenius rate is used. To transition between the premixed and diffusion burning modes, a transport equation for premixed fuel was implemented. The ratio of fuel in a computational cell that is premixed is used to determine the contribution of each combustion mode. Results show that this combustion model accurately simulates the diesel combustion process. Furthermore, the simulated results are in agreement with the recent conceptual picture of diesel combustion based upon experimental observations. Large eddy simulation (LES) models for momentum exchange and scalar flux were incorporated into the KIVA solver. In this formulation, the turbulent viscosity, μt, is determined as a function of the sub- grid turbulent kinetic energy, which is in turn determined from a one equation model. The formulation for the scalar transfer coefficient, μs, is similar to that of the turbulent viscosity, yet is made to be consistent with scalar transport. Test cases were run verifying that both momentum and scalar flux can be accurately predicted using LES. Once verified, these LES models were used to simulate the diesel combustion process for a Caterpillar 3400 series engine. Results for the engine simulations were in good agreement with experimental data.

  11. Environmental optimisation of waste combustion

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Robert [AaF Energikonsult, Stockholm (Sweden); Berge, Niclas; Stroemberg, Birgitta [TPS Termiska Processer AB, Nykoeping (Sweden)

    2000-12-01

    The regulations concerning waste combustion evolve through R and D and a strive to get better and common regulations for the European countries. This study discusses if these rules of today concerning oxygen concentration, minimum temperature and residence time in the furnace and the use of stand-by burners are needed, are possible to monitor, are the optimum from an environmental point of view or could be improved. No evidence from well controlled laboratory experiments validate that 850 deg C in 6 % oxygen content in general is the best lower limit. A lower excess air level increase the temperature, which has a significant effect on the destruction of hydrocarbons, favourably increases the residence time, increases the thermal efficiency and the efficiency of the precipitators. Low oxygen content is also necessary to achieve low NO{sub x}-emissions. The conclusion is that the demands on the accuracy of the measurement devices and methods are too high, if they are to be used inside the furnace to control the combustion process. The big problem is however to find representative locations to measure temperature, oxygen content and residence time in the furnace. Another major problem is that the monitoring of the operation conditions today do not secure a good combustion. It can lead to a false security. The reason is that it is very hard to find boilers without stratifications. These stratifications (stream lines) has each a different history of residence time, mixing time, oxygen and combustible gas levels and temperature, when they reach the convection area. The combustion result is the sum of all these different histories. The hydrocarbons emission is in general not produced at a steady level. Small clouds of unburnt hydrocarbons travels along the stream lines showing up as peaks on a THC measurement device. High amplitude peaks has a tendency to contain higher ratio of heavy hydrocarbons than lower peaks. The good correlation between some easily detected

  12. High-normal serum uric acid is associated with albuminuria and impaired glomerular filtration rate in Chinese type 2 diabetic patients

    Institute of Scientific and Technical Information of China (English)

    CAI Xiao-ling; HAN Xue-yao; JI Li-nong

    2011-01-01

    Background Recently,some studies had shown that elevated serum uric acid (SUA) itself may increase the risk for development of renal disease in patients with diabetes.This study aimed to explore whether SUA was a predictor of microalbuminuria and impaired renal function in type 2 diabetes in Chinese patients.Methods This cross-sectional study included 2108 type 2 diabetic patients.Kidney function was estimated using the simplified modification of diet in renal disease (MDRD) equation to obtain estimated glomerular filtration rate.The urine samples were obtained for measuring the albumin-to-creatinine ratio (ACR).Results According to the ACR level,these patients were divided into two groups,normal ACR (NA) and non-normal ACR (non-NA).Both SUA and creatinine were significantly higher in the non-NA group than those in the NA group ((318.89+107.52) vs.(283.44±88.64) μmol/L,and (95.08±53.24) vs.(79.63±18.20) μmol/L,respectively).Logistic regression analysis showed that diabetic duration,systolic blood pressure,creatinine and SUA were the independent predictors of albuminuria.Furthermore,to identify the factors associated with renal function,these patients were divided into two groups according to the MDRD level (MDRD<90 or MDRD>90).Both SUA and creatinine were significantly higher in the lower MDRD group than those in the higher MDRD group ((301.90±96.46) vs.(264.07+84.74) μmol/L,and (89.10±31.00) vs.(66.37±11.15) μ mol/L,respectively).Logistic regression analysis showed that only age and SUA were the independent predictors of MDRD.Conclusion High-normal SUA was associated with albuminuria and impaired glomerular filtration rate in Chinese type 2 diabetic patients.

  13. Thermal analysis and combustion kinetic of heavy oils

    Energy Technology Data Exchange (ETDEWEB)

    Santos, R.G. [Centre for Petroleum Studies, State University of Campinas(Brazil); Vargas, J.A.V.; Trevisan, O.V. [Department of Petroleum Engineering, Faculty of Mechanical Engineering, State University of Campinas (Brazil)

    2011-07-01

    In the oilfield sector, a thermal method named in-situ combustion (ISC) is used as an enhanced recovery method. ISC consists of the injection of gas into the reservoir, a combustion front is created producing heat which reduces the oil viscosity. For this method to be successful, understanding of the thermal and kinetic parameters involved is required; the aim of this paper is to evaluate those parameters for different crude oils. Experiments were conducted using accelerating rate calorimetry on Brazilian heavy oil samples under a heat-wait-seek-mode. Results showed that accelerating rate calorimetry is efficient in resolving the three main regions of reaction of the oil and that between 200 degree C and 300 degree C oxygen addition reactions are dominant while bond scission reactions dominate from 350 degree C. This study demonstrated that accelerating rate calorimetry is an efficient method to determine thermal and kinetic parameters of oxidation reaction of heavy oil.

  14. Coal combustion waste management study

    International Nuclear Information System (INIS)

    Coal-fired generation accounted for almost 55 percent of the production of electricity in the United States in 1990. Coal combustion generates high volumes of ash and flue gas desulfurization (FGD) wastes, estimated at almost 90 million tons. The amount of ash and flue gas desulfurization wastes generated by coal-fired power plants is expected to increase as a result of future demand growth, and as more plants comply with Title IV of the 1990 Clean Air Act Amendments. Nationwide, on average, over 30 percent of coal combustion wastes is currently recycled for use in various applications; the remaining percentage is ultimately disposed in waste management units. There are a significant number of on-site and off-site waste management units that are utilized by the electric utility industry to store or dispose of coal combustion waste. Table ES-1 summarizes the number of disposal units and estimates of waste contained at these unites by disposal unit operating status (i.e, operating or retired). Further, ICF Resources estimates that up to 120 new or replacement units may need to be constructed to service existing and new coal capacity by the year 2000. The two primary types of waste management units used by the industry are landfills and surface impoundments. Utility wastes have been exempted by Congress from RCRA Subtitle C hazardous waste regulation since 1980. As a result of this exemption, coal combustion wastes are currently being regulated under Subtitle D of RCRA. As provided under Subtitle D, wastes not classified as hazardous under Subtitle C are subject to State regulation. At the same time Congress developed this exemption, also known as the ''Bevill Exclusion,'' it directed EPA to prepare a report on coal combustion wastes and make recommendations on how they should be managed

  15. Use of gadolinium diethylene triamine penta-acetic acid, as measured by ELISA, in the determination of glomerular filtration rates in cats.

    Science.gov (United States)

    Sox, Erika M; Chiotti, Ruthanne; Goldstein, Richard E

    2010-10-01

    The goal of this study was to evaluate a commercially available assay for gadolinium diethylene triamine penta-acetic acid (Gd-DTPA) for use in estimating glomerular filtration rate (GFR) in cats (Gd-DTPA GFR) with a wide range of GFRs. Eighteen adult cats (11 healthy and seven with chronic kidney disease) were included. Plasma concentrations of Gd-DTPA following intravenous injection were measured with an ELISA kit (FIT-GFR). Results for Gd-DTPA GFR were compared with simultaneously obtained values for plasma clearance of iohexol (iohexol GFR), plasma blood urea nitrogen (BUN) and creatinine concentrations. A negative correlation existed between iohexol GFR and plasma concentrations of BUN and creatinine. A positive correlation existed between Gd-DTPA GFR and iohexol GFR. There was no correlation between Gd-DTPA GFR and plasma concentrations of BUN and creatinine. In this study plasma clearance of Gd-DTPA assayed by FIT-GFR did not appear to provide a sufficiently accurate estimation of GFR in cats when compared with plasma clearance of iohexol, and plasma concentrations of BUN and creatinine. PMID:20724186

  16. Central metal ion exchange in a coordination polymer based on lanthanide ions and di(2-ethylhexyl)phosphoric acid: exchange rate and tunable affinity.

    Science.gov (United States)

    Tasaki-Handa, Yuiko; Abe, Yukie; Ooi, Kenta; Tanaka, Mikiya; Wakisaka, Akihiro

    2014-01-01

    In this paper the exchange of lanthanide(III) ions (Ln(3+)) between a solution and a coordination polymer (CP) of di(2-ethylhexyl)phosphoric acid (Hdehp), [Ln(dehp)3], is studied. Kinetic and selectivity studies suggest that a polymeric network of [Ln(dehp)3] has different characteristics than the corresponding monomeric complex. The reaction rate is remarkably slow and requires over 600 h to reach in nearly equilibrium, and this can be explained by the polymeric crystalline structure and high valency of Ln(3+). The affinity of the exchange reaction reaches a maximum with the Ln(3+) possessing an ionic radius 7% smaller than that of the central Ln(3+), therefore, the affinity of the [Ln(dehp)3] is tunable based on the choice of the central metal ion. Such unique affinity, which differs from the monomeric complex, can be explained by two factors: the coordination preference and steric strain caused by the polymeric structure. The latter likely becomes predominant for Ln(3+) exchange when the ionic radius of the ion in solution is smaller than the original Ln(3+) by more than 7%. Structural studies suggest that the incoming Ln(3+) forms a new phase though an exchange reaction, and this could plausibly cause the structural strain.

  17. Effect of feeding guanidinoacetic acid and L-arginine on the fertility rate and sperm penetration in the perivitelline layer of aged broiler breeder hens.

    Science.gov (United States)

    Sharideh, H; Esmaeile Neia, L; Zaghari, M; Zhandi, M; Akhlaghi, A; Lotfi, L

    2016-04-01

    Two experiments were conducted to evaluate the effects of feeding guanidinoacetic acid (GAA) and L-arginine (ARG) on fertility and sperm penetration (SP) rate of broiler breeder hens. In the first experiment, a total of 200 broiler breeder hens (Ross 308) aged 53 weeks were randomly allotted to four dietary treatments (0, 0.6, 1.2 and 1.8 g GAA/kg diet) with five replicates of 10 birds each. In the second experiment, 320 broiler breeder hens (Ross 308) were used from 53 to 62 weeks of age in a 2 × 4 factorial arrangement (0 or 1.2 g GAA/kg diet along with 0, 3, 6 or 9 g ARG/kg diet). The hens received a diet containing 2800 kcal ME/kg and 14% CP. Sixteen sexually mature Ross 308 breeder roosters (34 weeks old) were used to artificially inseminate the hens. Fertility of the hens was determined in 61 and 62 weeks of age. The sperm penetration holes in the inner perivitelline layer (IPL) overlying the germinal disc were enumerated on days 3 and 7 following each insemination. Adding GAA to the breeder diet increased the number of SPs in the IPL and fertility in both experiments (p hens at the later phase of the egg production period.

  18. Dioxin emissions from small-scale combustion of bio-fuel and household waste

    Energy Technology Data Exchange (ETDEWEB)

    Hedman, Bjoern

    2005-09-01

    This thesis deals with emissions of persistent organic pollutants, primarily dioxins, from the combustion of solid biofuels and dry combustible household waste in relatively small facilities, 5-600 kW, without advanced air pollution controls. Co-combustion of waste and biofuel in effective small boilers was tested as an alternative to prevailing large-scale management and combustion strategies for handling municipal solid waste. This approach includes no advanced air pollution control systems, but offers two advantages: limiting transport and providing scope to use local biofuel resources. Source-sorted, dry, combustible household waste was collected from households in a sparsely populated area and co-combusted as briquettes together with reed canary-grass in 150-600 kW biofuel boilers. Most trials showed difficulties to meet regulative limits for the emissions of dioxins valid for incineration of MSW and the regulated limits for emissions of hydrochloric acid were exceeded manifold. It was concluded that additional flue-gas cleaning will be needed to ensure that emissions are sufficiently low. Dioxins were also found in the waste, especially in the textile fraction. The mass of dioxins in the flue-gas emissions was generally lower than the mass in the fuel input. Intermittent combustion of wood pellets in a residential boiler resulted in an unexpectedly high dioxin emissions factor of 28 ng (WHO-TEQ)/kg fuel. Combustion of wood in a modern environmentally certified boiler yielded considerably lower dioxin emissions than combustion in an old boiler, and combustion with a full air supply, i.e. with use of heat storage tank, resulted in up to 90% reductions in dioxin emission factors compared to combustion with reduced air supply. Combustion of plastic waste in a residential wood boiler resulted in high emissions of dioxins. Tests of uncontrolled combustion of garden and household waste in barrels or open fires, 'backyard burnings', resulted in emissions

  19. Severe Accident Analysis for Combustible Gas Risk Evaluation inside CFVS

    Energy Technology Data Exchange (ETDEWEB)

    Lee, NaRae; Lee, JinYong; Bang, YoungSuk; Lee, DooYong [FNC Technology Co. Ltd., Yongin (Korea, Republic of); Kim, HyeongTaek [KHNP-Central Research Institute, Daejeon (Korea, Republic of)

    2015-10-15

    The purpose of this study is to identify the composition of gases discharged into the containment filtered venting system by analyzing severe accidents. The accident scenarios which could be significant with respect to containment pressurization and hydrogen generation are derived and composition of containment atmosphere and possible discharged gas mixtures are estimated. In order to ensure the safety of the public and environment, the ventilation system should be designed properly by considering discharged gas flow rate, aerosol loads, radiation level, etc. One of considerations to be resolved is the risk due to combustible gas, especially hydrogen. Hydrogen can be generated largely by oxidation of cladding and decomposition of concrete. If the hydrogen concentration is high enough and other conditions like oxygen and steam concentration is met, the hydrogen can burn, deflagrate or detonate, which result in the damage the structural components. In particularly, after Fukushima accident, the hydrogen risk has been emphasized as an important contributor threatening the integrity of nuclear power plant during the severe accident. These results will be used to analyze the risk of hydrogen combustion inside the CFVS as boundary conditions. Severe accident simulation results are presented and discussed qualitatively with respect to hydrogen combustion. The hydrogen combustion risk inside of the CFVS has been examined qualitatively by investigating the discharge flow characteristics. Because the composition of the discharge flow to CFVS would be determined by the containment atmosphere, the severe accident progression and containment atmosphere composition have been investigated. Due to PAR operation, the hydrogen concentration in the containment would be decreased until the oxygen is depleted. After the oxygen is depleted, the hydrogen concentration would be increased. As a result, depending on the vent initiation timing (i.e. vent initiation pressure), the important

  20. Measurement and simulation of swirling coal combustion

    Institute of Scientific and Technical Information of China (English)

    Liyuan Hu; Lixing Zhou; Yonghao Luo; Caisong Xu

    2013-01-01

    Particle image velocimetry (PIV),thermocouples and flue gas analyzer are used to study swirling coal combustion and NO formation under different secondary-air ratios.Eulerian-Lagrangian large-eddy simulation (LES) using the Smagorinsky-Lilly sub-grid scale stress model,presumed-PDF fast chemistry and eddy-break-up (EBU) gas combustion models,particle devolatilization and particle combustion models,are simultaneously used to simulate swirling coal combustion.Statistical LES results are validated by measurement results.Instantaneous LES results show that the coherent structures for swirling coal combustion are stronger than those for swirling gas combustion.Particles are shown to concentrate along the periphery of the coherent structures.Combustion flame is located in the high vorticity and high particle concentration zones.Measurement shows that secondary-air ratios have little effect on final NO formation at the exit of the combustor.

  1. Potential applications of renewable energy sources, biomass combustion problems in boiler power systems and combustion related environmental issues

    International Nuclear Information System (INIS)

    This paper describes the potential applications of renewable energy sources to replace fossil fuel combustion as the prime energy sources in various countries, and discusses problems associated with biomass combustion in boiler power systems. Here, the term biomass includes organic matter produced as a result of photosynthesis as well as municipal, industrial and animal waste material. Brief summaries of the basic concepts involved in the combustion of biomass fuels are presented. Renewable energy sources (RES) supply 14% of the total world energy demand. RES are biomass, hydropower, geothermal, solar, wind and marine energies. The renewables are the primary, domestic and clean or inexhaustible energy resources. The percentage share of biomass was 62.1% of total renewable energy sources in 1995. Experimental results for a large variety of biomass fuels and conditions are presented. Numerical studies are also discussed. Biomass is an attractive renewable fuel in utility boilers. The compositions of biomass among fuel types are variable. Ash composition for the biomass is fundamentally different from ash composition for the coal. Especially inorganic constituents cause to critical problems of toxic emissions, fouling and slagging. Metals in ash, in combination with other fuel elements such as silica and sulfur, and facilitated by the presence of chlorine, are responsible for many undesirable reactions in combustion furnaces and power boilers. Elements including K, Na, S, Cl, P, Ca, Mg, Fe, Si are involved in reactions leading to ash fouling and slagging in biomass combustors. Chlorine in the biomass may affect operation by corrosion. Ash deposits reduce heat transfer and may also result in severe corrosion at high temperatures. Other influences of biomass composition are observed for the rates of combustion and pollutant emissions. Biomass combustion systems are non-polluting and offer significant protection of the environment. The reduction of greenhouse gases

  2. Combustion chamber analysis code

    Science.gov (United States)

    Przekwas, A. J.; Lai, Y. G.; Krishnan, A.; Avva, R. K.; Giridharan, M. G.

    1993-05-01

    A three-dimensional, time dependent, Favre averaged, finite volume Navier-Stokes code has been developed to model compressible and incompressible flows (with and without chemical reactions) in liquid rocket engines. The code has a non-staggered formulation with generalized body-fitted-coordinates (BFC) capability. Higher order differencing methodologies such as MUSCL and Osher-Chakravarthy schemes are available. Turbulent flows can be modeled using any of the five turbulent models present in the code. A two-phase, two-liquid, Lagrangian spray model has been incorporated into the code. Chemical equilibrium and finite rate reaction models are available to model chemically reacting flows. The discrete ordinate method is used to model effects of thermal radiation. The code has been validated extensively against benchmark experimental data and has been applied to model flows in several propulsion system components of the SSME and the STME.

  3. TOXIC SUBSTANCES FROM COAL COMBUSTION-A COMPREHENSIVE ASSESSMENT

    Energy Technology Data Exchange (ETDEWEB)

    C.L. Senior; F. Huggins; G.P. Huffman; N. Shah; N. Yap; J.O.L. Wendt; W. Seames; M.R. Ames; A.F. Sarofim; S. Swenson; J.S. Lighty; A. Kolker; R. Finkelman; C.A. Palmer; S.J. Mroczkowski; J.J. Helble; R. Mamani-Paco; R. Sterling; G. Dunham; S. Miller

    2001-06-30

    UU focused on the behavior of trace metals in the combustion zone by studying vaporization from single coal particles. The coals were burned at 1700 K under a series of fuel-rich and oxygen-rich conditions. The data collected in this study will be applied to a model that accounts for the full equilibrium between carbon monoxide and carbon dioxide. The model also considers many other reactions taking place in the combustion zone, and involves the diffusion of gases into the particle and combustion products away from the particle. A comprehensive study has been conducted at UA to investigate the post-combustion partitioning of trace elements during large-scale combustion of pulverized coal combustion. For many coals, there are three distinct particle regions developed by three separate mechanisms: (1) a submicron fume, (2) a micron-sized fragmentation region, and (3) a bulk (>3 {micro}m) fly ash region. The controlling partitioning mechanisms for trace elements may be different in each of the three particle regions. A substantial majority of semi-volatile trace elements (e.g., As, Se, Sb, Cd, Zn, Pb) volatilize during combustion. The most common partitioning mechanism for semi-volatile elements is reaction with active fly ash surface sites. Experiments conducted under this program at UC focused on measuring mercury oxidation under cooling rates representative of the convective section of a coal-fired boiler to determine the extent of homogeneous mercury oxidation under these conditions. In fixed bed studies at EERC, five different test series were planned to evaluate the effects of temperature, mercury concentration, mercury species, stoichiometric ratio of combustion air, and ash source. Ash samples generated at UA and collected from full-scale power plants were evaluated. Extensive work was carried out at UK during this program to develop new methods for identification of mercury species in fly ash and sorbents. We demonstrated the usefulness of XAFS spectroscopy for

  4. Mechanism and optimization of fuel injection parameters on combustion noise of DI diesel engine

    Institute of Scientific and Technical Information of China (English)

    张庆辉; 郝志勇; 郑旭; 杨文英; 毛杰

    2016-01-01

    Combustion noise takes large proportion in diesel engine noise and the studies of its influence factors play an important role in noise reduction. Engine noise and cylinder pressure measurement experiments were carried out. And the improved attenuation curves were obtained, by which the engine noise was predicted. The effect of fuel injection parameters in combustion noise was investigated during the combustion process. At last, the method combining single variable optimization and multivariate combination was introduced to online optimize the combustion noise. The results show that injection parameters can affect the cylinder pressure rise rate and heat release rate, and consequently affect the cylinder pressure load and pressure oscillation to influence the combustion noise. Among these parameters, main injection advance angle has the greatest influence on the combustion noise, while the pilot injection interval time takes the second place, and the pilot injection quantity is of minimal impact. After the optimal design of the combustion noise, the average sound pressure level of the engine is distinctly reduced by 1.0 dB(A) generally. Meanwhile, the power, emission and economy performances are ensured.

  5. Combustion stability assessment for utility pulverized coal-fired boilers under low loads

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, H.-C.; Huang, Y.-L.; Li, J.; Liu, Z.-H.; Zheng, C.-G. [Huazhong University of Science and Technology, Wuhan (China). National Lab. of Coal Combustion, Dept. of Power Engineering

    2000-08-01

    Based on the influence of chemical equivalence ratio on the combustion stability of utility pulverized coal-fired boilers and the control theory about system stability, a combustion stability index, CSI, which refers to the maximum reduction ratio of the fuel mass flow rate that can be overcome by the stable combustion process under a constant air mass flow rate, was proposed to assess quantitatively the combustion stability in the boilers. MLO, the Minimum Load of Operation with stable combustion not supported by firing oil, and MCQ, the Minimum Coal Quality, which gives the lowest heat values of coals with different volatile matter contents for stable operation of boilers, are defined on the basis of CSI. In order to predict MLO and MCQ, a simple chemical reaction system model has been modified by means of the concept of lean flammability of gaseous fuels. A three-dimensional combustion simulation code integrated with the modified model was used to study the stability of combustion process in a 200 MWe pulverized coal fired utility boiler. The predictions of MLO and MCQ agreed confidently with operational experiences. 16 refs., 7 figs.

  6. Influence of drop size distribution and fuel vapor fraction on premixed spray combustion

    Science.gov (United States)

    Machiroutu, Sridhar Venkatabojji

    Premixed spray combustion is affected by fuel and oxidizer properties, mixture equivalence ratio and spray quality. The spray quality is characterized by a mean droplet diameter (SMD) and a droplet size distribution (DSD). Prior experimental studies have considered only the influence of SMD, in part due to the difficulty in controlling the DSD independently. The present work provides experimental evidence demonstrating the effect of the fuel droplet size distribution and fuel vapor fraction on premixed spray combustion. Combustion experiments were performed in a pilot-ignited, continuous flow, tubular, vertical test rig wherein fuel sprays were injected into an air stream. A novel twin-atomizer technique that allowed control over overall equivalence ratio, SMD, DSD, and fuel vapor fraction of the premixed spray was used to generate test sprays. A line-of-sight, infrared (IR) extinction technique was developed to quantify the fuel vapor fraction in premixed sprays. Radial distributions of fuel vapor were evaluated using an 'onion peeling' deconvolution technique. Combustion of test sprays indicated flame propagation among regions of high fuel vapor fraction to generate a high rate of combustion. In lean premixed sprays, the presence of a low fuel vapor concentration does not impact the combustion process. Experimental evidence demonstrating the enhancement of flame propagation velocity for optimal SMDs of ethanol sprays has been found. It was observed that test sprays with narrower DSDs have faster burning rates and more complete combustion. The DSD of the sprays were characterized with a droplet surface-area-based standard deviation of the DSD.

  7. The role of nozzle convergence in diesel combustion

    Energy Technology Data Exchange (ETDEWEB)

    J. Benajes; S. Molina; C. Gonzaalez; R. Donde [CMT-Motores Termicos, Universidad Politecnica de Valencia, Valencia (Spain)

    2008-08-15

    An experimental study has been performed for identifying the role of injector nozzle hole convergence and cavitation in diesel engine combustion and pollutant emissions. For doing so, five nozzles were tested under different operating and experimental conditions. The critical cavitation number of each nozzle was analyzed. With this value, an estimation of the mixing process at different conditions obtained. This data is used to explain the combustion results which are analyzed in terms of the apparent combustion time, rate of heat release, in-cylinder pressures, adiabatic temperatures and soot and NOx emissions. Special emphasis is put in developing an expression to explicitly link the mixing process and the injection rate with the rate of heat release. The results show that the fuel-air mixing process can be improved by the use of both convergent and cavitating nozzles, thus lowering the soot emissions. The NOx production, being dependent of the injection rate and the mixing process, does not necessarily increase with the use of more convergent nozzles. 40 refs., 8 fig., tabs.

  8. Operation related on-line measurements of low temperature fire side corrosion during co-combustion of biomass and oil; Driftrelaterad direktmaetning av laagtemperaturkorrosion i en braensleeldad kraftvaermeanlaeggning

    Energy Technology Data Exchange (ETDEWEB)

    Eriksson, Thomas [Studsvik Nuclear AB, Nykoeping (Sweden)

    2000-05-01

    A number of combustion plants have experienced corrosion attack on air preheaters and economisers when fired with biomass fuels. In certain plants the problems are great and reconstruction has been performed so that exposed components can be exchanged during operation. The electrochemical techniques offer on-line measurements of the changes in corrosion rate in the low temperature region in a waste incinerator. The purpose with this study was to evaluate the technique in a biomass fired boiler where the corrosion rate is considerable lower compared to a waste incinerator. Experiments were performed at the Haesselby plant, boiler 3, which was fired with pure biomass as well as a mixture of biomass and oil during the test period. It was found that the electrochemical technique is a useful tool for on-line measurements of the changes in corrosion rate in biomass fired utilities. Since the corrosion rate in the low temperature region is dependent on the boiler construction, electrochemical measurements give valuable information on the corrosion rate during optimisation of the fuel mixture, SNCR and temperature or the low temperature components. This is of special importance when introducing new fuels or fuel mixtures. Soot blowing is of prime importance for the total corrosion. During a few minutes an individual soot blower can initiate such a high corrosion rate that it represents the total corrosion. The material temperature is another important parameter. Above a certain temperature the corrosion rate is negligible. During co-combustion this temperature was found to be in the region 65-85 deg C. The influence of the SNCR with ammonia, with respect to corrosion, is dependent on the fuel mixture used. In utilities where acidic combustion products are formed, ammonia has a neutralising effect e.g. in Hoegdalen. At the Haesselby plant this neutralising effect was not found. During cocombustion with oil the ammonia forms ammoniahydrosulphate which increases the corrosion

  9. Dynamical issues in combustion theory

    International Nuclear Information System (INIS)

    This book looks at the world of combustion phenomena covering the following topics: modeling, which involves the elucidation of the essential features of a given phenomenon through physical insight and knowledge of experimental results, devising appropriate asymptotic and computational methods, and developing sound mathematical theories. Papers in this book describe how all of these challenges have been met for particular examples within a number of common combustion scenarios: reactive shocks, low Mach number premixed reactive flow, nonpremixed phenomena, and solid propellants. The types of phenomena examined are also diverse: the stability and other properties of steady structures, the long time dynamics of evolving solutions, properties of interfaces and shocks, including curvature effects, and spatio-temporal patterns

  10. Oxy-coal Combustion Studies

    Energy Technology Data Exchange (ETDEWEB)

    Wendt, J. [Univ. of Utah, Salt Lake City, UT (United States); Eddings, E. [Univ. of Utah, Salt Lake City, UT (United States); Lighty, J. [Univ. of Utah, Salt Lake City, UT (United States); Ring, T. [Univ. of Utah, Salt Lake City, UT (United States); Smith, P. [Univ. of Utah, Salt Lake City, UT (United States); Thornock, J. [Univ. of Utah, Salt Lake City, UT (United States); Y Jia, W. Morris [Univ. of Utah, Salt Lake City, UT (United States); Pedel, J. [Univ. of Utah, Salt Lake City, UT (United States); Rezeai, D. [Univ. of Utah, Salt Lake City, UT (United States); Wang, L. [Univ. of Utah, Salt Lake City, UT (United States); Zhang, J. [Univ. of Utah, Salt Lake City, UT (United States); Kelly, K. [Univ. of Utah, Salt Lake City, UT (United States)

    2012-01-06

    The objective of this project is to move toward the development of a predictive capability with quantified uncertainty bounds for pilot-scale, single-burner, oxy-coal operation. This validation research brings together multi-scale experimental measurements and computer simulations. The combination of simulation development and validation experiments is designed to lead to predictive tools for the performance of existing air fired pulverized coal boilers that have been retrofitted to various oxy-firing configurations. In addition, this report also describes novel research results related to oxy-combustion in circulating fluidized beds. For pulverized coal combustion configurations, particular attention is focused on the effect of oxy-firing on ignition and coal-flame stability, and on the subsequent partitioning mechanisms of the ash aerosol.

  11. Fundamental studies of spray combustion

    Energy Technology Data Exchange (ETDEWEB)

    Li, S.C.; Libby, P.A.; Williams, F.A. [Univ. of California, San Diego, CA (United States)

    1997-12-31

    Our research on spray combustion involves both experiment and theory and addresses the characteristics of individual droplets and of sprays in a variety of flows: laminar and turbulent, opposed and impinging. Currently our focus concerns water and fuel sprays in two stage laminar flames, i.e., flames arising, for example from a stream of fuel and oxidizer flowing opposite to an air stream carrying a water spray. Our interest in these flames is motivated by the goals of reducing pollutant emissions and extending the range of stable spray combustion. There remains considerable research to be carried out in order to achieve these goals. Thus far our research on the characteristics of sprays in turbulent flows has been limited to nonreacting jets impinging on a plate but this work will be extended to opposed flows with and without a flame. In the following we discuss details of these studies and our plans for future work.

  12. Preparation of nanometer MgO by sol-gel auto-combustion

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Nanometer MgO was prepared via a sol-gel auto-combustion technique using magnesium nitrate as raw material and citric acid as chelating agent.IR spectra of the dried gel were used to investigate the structure of the precursors.By studying the different TG curves of magnesium citrate gel prepared by different methods,we found that a combustion process occurred and the nitrate ions acted as an oxidant in the combustion process.TEM photographs of synthesized powders from the sol-gel auto-combustion showed that the crystallites were uniform in size.In addition,the XRD pattern of this sample showed that the particle size was 8.9 nm.The BET curves,in turn,showed that the specific surface of the sample was 26.34 m2/g.The mechanism of the frothing process in restraining agglomeration is discussed.

  13. Particulate emissions from residential wood combustion: Final report: Norteast regional Biomass Program

    Energy Technology Data Exchange (ETDEWEB)

    1987-01-01

    The objective of this study was to provide a resource document for the Northeastern states when pursuing the analysis of localized problems resulting from residential wood combustion. Specific tasks performed include assigning emission rates for total suspended particulates (TSP) and benzo(a)pyrene (BaP) from wood burning stoves, estimating the impact on ambient air quality from residential wood combustion and elucidating the policy options available to Northeastern states in their effort to limit any detrimental effects resulting from residential wood combustion. Ancillary tasks included providing a comprehensive review on the relevant health effects, indoor air pollution and toxic air pollutant studies. 77 refs., 11 figs., 25 tabs.

  14. THE COMBUSTION CHARACTERISTICS OF A MOVABLE LINEAR FIRE SEAT IN MINE FIRES

    Institute of Scientific and Technical Information of China (English)

    王德明; 王省身

    1996-01-01

    Because of the difficulties of describing the process of combustion of underground mine fires, usually the fire seat is considered as a fixed point in the methods of mine fire computer simulation, however this is not in keeping with the feature of the distribution of the combustibles and the process of combustion in mine fires. A conception about movable linear fire seat is put forward first by the authors, together with the calculated models of the thermal decomposition rate, flame spreading velocity and the steady burning length of a linear fire seat etc. The paper also introduces the results of the application of these models.

  15. Modelling of NOx emissions from pressurized fluidized bed combustion - A parameter study

    DEFF Research Database (Denmark)

    Jensen, Anker; Johnsson, Jan Erik

    1997-01-01

    reactions and heterogeneous reactions catalyzed by bed material and char. Simulations of the influence of operating conditions: air staging, load, temperature, fuel particle size, bed particle size and mass of bed material on the NO emission is presented and compared to results from the literature...... velocity, the bubble size, the bubble rise velocity and the gas interchange coefficient between bubble and dense phase. The most important combustion parameters are the rates of CO and CH4 combustion and the CO/(CO + CO2) ratio from char combustion. (C) 1997 Elsevier Science Ltd....

  16. Combustion and Plasma Synthesis of High-Temperature Materials

    Science.gov (United States)

    Munir, Z. A.; Holt, J. B.

    1997-04-01

    , et al.). Combustion Synthesis in the Ti-C-Ni-Al System (S. Dunmead, et al.). Combustion Synthesis Dynamics Modeling (T. Kottke, et al.). Elementary Processes in SiO2-Al Thermite-Type Reactions Activated or Induced by Mechanochemical Treatment (G. Hida & I. Lin). Combustion Synthesis of Ceramic Preforms for Molten-Metal Infiltration (D. Halverson, et al.). Combustion Characteristics of Solid-Solid Systems: Experiments and Modeling (S. Kumar, et al.). Microstructure of TiB2 Sintered by the Self-Combustion Method (K. Urabe, et al..). A Laser-Ignition Study of Gasless Reactions Using Thermography (C. Chow & J. Mohler). Shock-Induced Reaction Synthesis-Assisted Processing of Ceramics (R. Ward, et al.). Summary Assessment of the Application of SPS and Related Reaction Processing to Produce Dense Ceramics (R. Rice). Shock Consolidation of Combustion-Synthesized Ceramics (A. Niiler, et al.). High-Pressure Burning Rate of Silicon in Nitrogen (M. Costantino & J. Holt). Preparation of a TiC Single Crystal by the Floating-Zone Method from a Self-Combustion Rod (S. Otani, et al.). PLASMA AND GAS-PHASE SYNTHESIS. Thermal Plasma Synthesis of Ceramic Powders and Coatings (T. Yoshida). A Theoretical Comparison of Conventional and Hybrid RF-Plasma Reactors (J. McKelliget & N. El-Kaddah). Homogeneous Nucleation and Particle Growth in Thermal Plasma Synthesis (S. Girshick & C.-P. Chiu). Formation of Refractory Aerosol Particles (R. Flagan, et al.). Ceramic-Powder Synthesis in an Aerosol Reactor (M. Alam, et al.). Silica-Particle Formation Using the Counter-Flow Diffusion Flame Burner (J. Katz, et al.). Synthesis and Properties of Low-Carbon Boron Carbides (C. Adkins, et al.). Synthesis of Si, SiC, and Si3N4 Powders Under High Number Density Conditions (J. Haggerty & J. Flint). Rapid Preparation of Titanium and Other Transition-Metal Nitride- and Carbide Powders by a Carbo-Reduction Method Using Arc-Image Heating (M. Yoshimura, et al.). Microwave Plasma Densification of Aluminum Nitride

  17. CSIR helps prevent spontaneous combustion

    Energy Technology Data Exchange (ETDEWEB)

    Vuuren, M. van (CSIR Energy Technology (South Africa))

    1992-03-01

    Heaps of stockpiled coal could present a fire hazard due to the risk of spontaneous combustion. Regular monitoring of stockpiles and bunker testing of coals help to prevent stockpile fires. This brief article describes the recent upgrading of the CSIR's bunker test facility that enables coal producers, users and exporters to test their products under simulated conditions that duplicate the actual conditions under which coal is stored. 2 photos.

  18. Combustion generated fine carbonaceous particles

    OpenAIRE

    Bockhorn, Henning; D'Anna, Andrea; Sarofim, Adel F.; Wang, Hai

    2009-01-01

    Soot is of importance for its contribution to atmospheric particles with their adverse health impacts and for its contributions to heat transfer in furnaces and combustors, to luminosity from candles, and to smoke that hinders escape from buildings during fires and that impacts global warming or cooling. The different chapters of the book adress comprehensively the different aspects from fundamental approaches to applications in technical combustion devices.

  19. ABB Combustion Engineering nuclear technology

    Energy Technology Data Exchange (ETDEWEB)

    Matzie, R.A.

    1994-12-31

    The activities of ABB Combustion Engineering in the design and construction of nuclear systems and components are briefly reviewed. ABB Construction Engineering continues to improve the design and design process for nuclear generating stations. Potential improvements are evaluated to meet new requirements both of the public and the regulator, so that the designs meet the highest standards worldwide. Advancements necessary to meet market needs and to ensure the highest level of performance in the future will be made.

  20. Effect of acid-catalyzed formation rates of benzimidazole-linked polymers on porosity and selective CO2 capture from gas mixtures.

    Science.gov (United States)

    Altarawneh, Suha; İslamoğlu, Timur; Sekizkardes, Ali Kemal; El-Kaderi, Hani M

    2015-04-01

    Benzimidazole-linked polymers (BILPs) are emerging candidates for gas storage and separation applications; however, their current synthetic methods offer limited control over textural properties which are vital for their multifaceted use. In this study, we investigate the impact of acid-catalyzed formation rates of the imidazole units on the porosity levels of BILPs and subsequent effects on CO2 and CH4 binding affinities and selective uptake of CO2 over CH4 and N2. Treatment of 3,3'-Diaminobenzidine tetrahydrochloride hydrate with 1,2,4,5-tetrakis(4-formylphenyl)benzene and 1,3,5-(4-formylphenyl)-benzene in anhydrous DMF afforded porous BILP-15 (448 m(2) g(-1)) and BILP-16 (435 m(2) g(-1)), respectively. Alternatively, the same polymers were prepared from the neutral 3,3'-Diaminobenzidine and catalytic amounts of aqueous HCl. The resulting polymers denoted BILP-15(AC) and BILP-16(AC) exhibited optimal surface areas; 862 m(2) g(-1) and 643 m(2) g(-1), respectively, only when 2 equiv of HCl (0.22 M) was used. In contrast, the CO2 binding affinity (Qst) dropped from 33.0 to 28.9 kJ mol(-1) for BILP-15 and from 32.0 to 31.6 kJ mol(-1) for BILP-16. According to initial slope calculations at 273 K/298 K, a notable change in CO2/N2 selectivity was observed for BILP-15(AC) (61/50) compared to BILP-15 (83/63). Similarly, ideal adsorbed solution theory (IAST) calculations also show the higher specific surface area of BILP-15(AC) and BILP-16(AC) compromises their CO2/N2 selectivity.