777 Matching Results

Search Results

Advanced search parameters have been applied.

Tables of thermodynamic functions for analysis of aircraft-propulsion systems

Description: Report presenting tables of thermodynamic functions for 42 substances containing argon, aluminum, boron, carbon, chlorine, fluorine, hydrogen, lithium, nitrogen, and oxygen. The functions examined included the specific heat at constant pressure, sensible enthalpy, sum of sensible enthalpy and chemical energy, molar entropy, enthalpy change due to formation of substance from elements in atomic gas state divided by gas constant times temperature, and the logarithm of the equilibrium constant at designated temperatures.
Date: August 1950
Creator: Huff, Vearl N. & Gordon, Sanford
Partner: UNT Libraries Government Documents Department

Fundamental Study of Low NOx Combustion Fly Ash Utilization

Description: This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over forty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives.
Date: May 1, 1997
Creator: Suubert, E. M.; Kuloats, I.; Smith, K.; Sabanegh, N.; Hurt, R.H.; Lilly, W. D. et al.
Partner: UNT Libraries Government Documents Department

Influence of sample composition on aerosol organic and black carbon determinations

Description: In this paper we present results on characterization of filter-collected redwood (Sequoia sempevirens)-needle and eucalyptus smoke particles by thermal, optical, and solvent extraction methods. Our results demonstrate that organic and black carbon concentrations determined by thermal and optical methods are not only method dependent, but also critically influenced by the overall chemical composition of the samples. These conclusions are supported by the following: (1) the organic fraction of biomass smoke particles analyzed includes a component, ranging in concentration from about 6-20% of total carbon or from 16-30% of organic carbon, that is relatively non-volatile and has a combustion temperature close to that of black carbon; (2) presence of K or Na in biomass smoke samples lowers the combustion temperatures of this organic component and of black carbon, making their combustion properties indistinguishable; (3) about 20% of total organic material is nonvolatile when heated to 550{degrees}C in an inert atmosphere. Consequently, thermal methods that rely on a specific temperature to separate organic from black carbon may either underestimate or overestimate the black and organic carbon concentrations, depending on the amounts of Na and K and on the composition and concentration of organic material present in a sample. These analytical uncertainties and, under some conditions, absorption by organic material may contribute to the variability of empirically derived proportionality between light transmission through filter deposits and black carbon concentrations.
Date: July 1, 1995
Creator: Novakov, T. & Corrigan, C.E.
Partner: UNT Libraries Government Documents Department

Fundamental Study of Low-Nox Combustion Fly Ash Utilization

Description: This study is principally concerned with characterizing the organic part of coal combustion fly ashes. High carbon fly ashes are becoming more common as by-products of low-NOx combustion technology, and there is need to learn more about this fraction of the fly ash. The project team consists of two universities, Brown and Princeton, and an electrical utility, New England Power. A sample suite of over forty fly ashes has been gathered from utilities across the United States, and includes ashes from a coals ranging in rank from bituminous to lignite. The characterizations of these ashes include standard tests (LOI, Foam Index), as well as more detailed characterizations of their surface areas, porosity, extractability and adsorption behavior. The ultimate goal is, by better characterizing the material, to enable broadening the range of applications for coal fly ash re-use beyond the current main market as a pozzolanic agent for concretes. The potential for high carbon-content fly ashes to substitute for activated carbons is receiving particular attention. The work performed to date has already revealed how very different the surfaces of different ashes produced by the same utility can be, with respect to polarity of the residual carbon. This can help explain the large variations in acceptability of these ashes as concrete additives.
Date: November 1, 1997
Creator: Suuberg, E. M.; Kuloats, I.; Smith, K.; Sabanegh, N.; Hurt, R. H.; Lilly, W. D. et al.
Partner: UNT Libraries Government Documents Department

Residues From Coal Comversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagensesis

Description: The goals of the project are two-fold: 1) to upgrade semi-quantitative X-ray diffraction(QXRD) methods presently used in analyzing complex coal combustion by-product (CCB)systems, with the quantitative Rietveld method, and 2) to apply this method to a set of by-product materials that have been disposed or utilized for a long period (5 years or more) in contact with the natural environment, to further study the nature of CCB diagenesis. The project is organized into three tasks to accomplish these two goals: 1) thorough characterization of a set of previously analyzed disposed by-product materials, 2) development of a set of CCB specific protocols for Rietveld QXRD, and 3) characterization of an additional set of disposed CCB materials, including application of the protocols for Rietveld QXRD developed in Task 2.
Date: December 4, 1998
Creator: McCarthy, Gregory J.
Partner: UNT Libraries Government Documents Department

Zinc Bromide Combustion: Implications for the Consolidated Incinerator Facility

Description: In the nuclear industry, zinc bromide (ZnBr2) is used for radiation shielding. At Savannah River Site (SRS) zinc bromide solution, in appropriate configurations and housings, was used mainly for shielding in viewing windows in nuclear reactor and separation areas. Waste stream feeds that will be incinerated at the CIF will occasionally include zinc bromide solution/gel matrices.The CIF air pollution systems control uses a water-quench and steam atomizer scrubber that collects salts, ash and trace metals in the liquid phase. Water is re-circulated in the quench unit until a predetermined amount of suspended solids or dissolved salts are present. After reaching the threshold limit, "dirty liquid", also called "blowdown", is pumped to a storage tank in preparation for treatment and disposal. The air pollution control system is coupled to a HEPA pre-filter/filter unit, which removes particulate matter from the flue gas stream (1).The objective of this report is to review existing literature data on the stability of zinc bromide (ZnBr2) at CIF operating temperatures (>870 degrees C (1600 degrees F) and determine what the combustion products are in the presence of excess air. The partitioning of the combustion products among the quencher/scrubber solution, bottom ash and stack will also be evaluated. In this report, side reactions between zinc bromide and its combustion products with fuel oil were not taken into consideration.
Date: December 16, 1998
Creator: Oji, L.N.
Partner: UNT Libraries Government Documents Department

Equation of state for detonation products

Description: To be useful, an equation of state for detonation products must allow rapid computation. The constraints applied by this requirement have surprising thermodynamic effects. Some of these are discussed here. A simple, complete equation of state is proposed, and its properties are discussed. With the form assumed here, all the useful integrals (except for the Riemann integral) can be written simply and explicitly, so the behavior of the important variables can be easily seen. The complete equation of state is calibrated for PBX9404 and PBX9501.
Date: December 31, 1998
Creator: Davis, W.C.
Partner: UNT Libraries Government Documents Department

Cycle-by-cycle combustion variations in spark-ignited engines

Description: Under constant nominal operating conditions, internal combustion engines can exhibit substantial variation in combustion efficiency from one cycle to the next. Previous researchers have attempted to explain these variations as resulting from stochastic, linear, or chaotic physical processes. Our investigations indicate that cyclic combustion variations can be explained as the result of interactions between a global low-dimensional nonlinearity and small-scale, high-dimensional processes that perturb the nonlinearity. Using this approach, we have proposed a simple model that accurately simulates experimentally observed patterns in cyclic combustion variations. Our model also explains the apparent discrepancies among previous investigators regarding the basic nature of cyclic variations. Further, it appears that symbol dynamics are useful for characterizing the observed model and experimental behavior.
Date: September 1, 1997
Creator: Daw, C.S.; Finney, C.E.A. & Connolly, F.T.
Partner: UNT Libraries Government Documents Department

Phenyl radical thermolysis and rate constants for phenyl + O{sub 2}

Description: The thermal decomposition of C{sub 6}H{sub 5}I has been used to prepare in-situ known initial concentrations of phenyl radicals at high temperatures. These can be degraded by direct decomposition at T > 1350 K giving H + C{sub 6}H{sub 4}. Using H-atom ARAS, rate constants for C{sub 6}H{sub 5} dissociation have been measured. Using the same ARAS technique, constants for C{sub 6}H{sub 5} dissociation have been measured. Using the same ARAS technique, the H- and O-atoms formed from the reaction, C{sub 6}H{sub 5} + O{sub 2}, have both been measured. The rate constant results are discussed along with lower T measurements in terms of RRKM calculations using published ab initio electronic structure determinations of transition states.
Date: August 1, 1997
Creator: Kumaran, S.S. & Michael, J.V.
Partner: UNT Libraries Government Documents Department

Residues From Coal Conversion and Utilization: Advanced Mineralogical Characterization and Disposed Byproduct Diagenesis

Description: The goals of the project are two-fold: 1) to upgrade semi-quantitative X-ray diffraction(QXRD) methods presently used in analyzing complex coal combustion by-product (CCB)systems, with the quantitative Rietveld method, and 2) to apply this method to a set of by-product materials that have been disposed or utilized for a long period (5 years or more) in contact with the natural environment, to further study the nature of CCB diagenesis. The project is organized into three tasks to accomplish these two goals: 1) thorough characterization of a set of previously analyzed disposed by-product materials, 2) development of a set of CCB specific protocols for Rietveld QXRD, and 3) characterization of an additional set of disposed CCB materials, including application of the protocols for Rietveld QXRD developed in Task 2.
Date: December 4, 1998
Creator: McCarthy, Gregory J.
Partner: UNT Libraries Government Documents Department

SILICON CARBIDE MICRO-DEVICES FOR COMBUSTION GAS SENSING UNDER HARSH CONDITIONS

Description: A sensor based on the wide bandgap semiconductor, silicon carbide (SiC), has been developed for the detection of combustion products in power plant environments. The sensor is a catalytic gate field effect device that can detect hydrogen containing species in chemically reactive, high temperature environments. Robust metallization and electrical contacting techniques have been developed for device operation at elevated temperatures. To characterize the time response of the sensor responses in the millisecond range, a conceptually new apparatus has been built. Software has been developed to cope with the requirements of fast sensor control and data recording. In addition user friendly software has been developed to facilitate use of the SiC sensors for industrial process control applications.
Date: April 1, 2004
Creator: Ghosh, Ruby N.; Tobias, Peter & Tobin, Roger G.
Partner: UNT Libraries Government Documents Department

SENSITIZATION AND EXACERBATION OF ALLERGIC DISEASES BY DIESEL ENGINE PARTICLES

Description: Most studies of the health effects of diesel exhaust have focused on the controversial issue of its role in cancer. However, recently the role of combustion products such as diesel exhaust particles (DEP) in modulating the immune response has garnered much attention. In particular the effect of DEP on allergic and asthmatic diseases has been the focus of many studies. A link between industrialization and allergic disease has long been presumed. Indeed, only 50 years after the first recorded reported case of allergy in 1819, Charles Blackely wrote that the ''hay-fever epidemic'' was associated with the movement of people from the country into the cities. Ishizaki et al. (1987) found that people in Japan living on busy roads lined with cedar trees have more allergies to cedar than residents living on similar streets with much less traffic. Since that time other epidemiological studies have reported similar findings. Kramer, et al., showed that hay fever is greater in residential areas with heavy truck traffic, while Weiland, et al., reported that allergic symptoms correlate with the distance of residences to roads with heavy traffic.
Date: August 20, 2000
Creator: Diaz-Sanchez, David
Partner: UNT Libraries Government Documents Department

The role of pore structure on char reactivity. Quarterly progress report, October 1994--December 1994

Description: In order to examine the role of pore structure, studies will be conducted on coal chars in the electrodynamic balance. Larger particles will also be examined using a fluidized bed to examine diffusion control reactions, and soot will also be investigated to examine the role of meso- and micro-pores without macro-pore interference. These studies will allow a full range of particles sizes and temperatures to be investigated and eventually modeled.
Date: January 1, 1995
Creator: Sarofim, A. F.
Partner: UNT Libraries Government Documents Department

Nitrogen release during coal combustion

Description: Experiments in entrained flow reactors at combustion temperatures are performed to resolve the rank dependence of nitrogen release on an elemental basis for a suite of 15 U.S. coals ranging from lignite to low-volatile bituminous. Data were obtained as a function of particle conversion, with overall mass loss up to 99% on a dry, ash-free basis. Nitrogen release rates are presented relative to both carbon loss and overall mass loss. During devolatilization, fractional nitrogen release from low-rank coals is much slower than fractional mass release and noticeably slower than fractional carbon release. As coal rank increases, fractional nitrogen release rate relative to that of carbon and mass increases, with fractional nitrogen release rates exceeding fractional mass and fractional carbon release rates during devolatilization for high-rank (low-volatile bituminous) coals. At the onset of combustion, nitrogen release rates increase significantly. For all coals investigated, cumulative fractional nitrogen loss rates relative to those of mass and carbon passes through a maximum during the earliest stages of oxidation. The mechanism for generating this maximum is postulated to involve nascent thermal rupture of nitrogen-containing compounds and possible preferential oxidation of nitrogen sites. During later stages of oxidation, the cumulative fractional loss of nitrogen approaches that of carbon for all coals. Changes in the relative release rates of nitrogen compared to those of both overall mass and carbon during all stages of combustion are attributed to a combination of the chemical structure of coals, temperature histories during combustion, and char chemistry.
Date: February 1, 1995
Creator: Baxter, L. L.; Mitchell, R. E.; Fletcher, T. H. & Hurt, R. H.
Partner: UNT Libraries Government Documents Department

Coolside waste management research. Quarterly progress report, January 1, 1994--March 31, 1994

Description: The objective of this work is to investigate the nature of Coolside waste in order to allow the design and construction of physically stable and environmentally safe landfills. Work in this period was initiated to determine if dry-FBC material could be used as a soil stabilizing material.
Date: August 1, 1994
Partner: UNT Libraries Government Documents Department

Methylmercury risk assessment issues

Description: This paper reviews the general background of health risks associated with mercury (Hg), primarily methylmercury (MeHg), with a view towards application to advanced technologies that could reduce any contributions from coal combustion. The need for accurate assessment of such risks is discussed, since Hg is now widely dispersed in the environment and cannot easily be eliminated. The primary pathway of MeHg intake is through eating contaminated fish. The issues of concern include identification of critical health outcomes (various neurological indices) and their confounding factors, accurate assessment of MeHg intake rates, and appropriate use of dose-response functions. Ultimately, such information will be used to evaluate alternative coal combustion systems.
Date: July 1, 1996
Creator: Lipfert, F.W. & Saroff, L.
Partner: UNT Libraries Government Documents Department

Quantifying magnitudes and distributions of CO sources

Description: We use a simplified version of the GRANTOUR chemical tracer model to analyze emissions of CO from various sources. The GRANTOUR model has been simplified to include the eigenvalue chemistry solution method of Prather (1994). The analysis includes fossil fuel combustion, biomass burning, hydrocarbon oxidation, ocean, and terrestrial sources of CO. We also present a 1{degree} x 1{degree} emissions inventory of CO from fossil fuel combustion.
Date: March 1, 1998
Creator: Dignon, J.; Penner, J. E. & Walton, J. J.
Partner: UNT Libraries Government Documents Department

Flamelet/flow interaction in premixed turbulent flames: simultaneous measurements of gas velocity and flamelet position

Description: An experimental technique for obtaining simultaneous measurements of fluid velocity and flamelet position in premixed flames is described and applied in a turbulent V-flame. The flamelet position information is used to calculate conditional velocity statistics, conditional on both zone (reactants or products) as well as conditional on distance from the flamelet. The conditional zone statistics demonstrate that increases (or decreases) in turbulence across the flame are dependent on axial position and location within the flame brush. The product- zone conditional covariance, coupled with the measured conditional mean velocity profiles, indicate that turbulence generation by shear may be a significant contribution to product zone turbulence levels. Velocity statistics conditional on distance from the flamelet demonstrate a considerable interaction between the flamelet and velocity field. Man and rms velocities vary significantly with proximity to the flamelet, such that differences in velocities which which occur just across the flamelet surface. The change in rms velocities just across the flamelet is found to be anisotropic, with the largest increase (smallest decrease) occurring in the axial velocity component. Rms velocities conditional on flamelet position further support the hypothesis that increased product gas velocity fluctuations may have a significant component associated with turbulence generation by mean shear.
Date: December 1, 1996
Creator: Miles, P.C. & Gouldin, F.C.
Partner: UNT Libraries Government Documents Department

Toxic substances from coal combustion -- a comprehensive assessment. Quarterly technical progress report, 1 April 1996--30 June 1996

Description: Before electric utilities can plan or implement emissions minimization strategies for hazardous pollutants, they must have an accurate and site-specific means of predicting emissions in all effluent streams for the broad range of fuels and operating conditions commonly utilized. Development of a broadly applicable emissions model useful to utility planners first requires a sound understanding of the fundamental principles controlling the formation and partitioning of toxic species during coal combustion (specifically in Phase I, As, Se, Cr, and possibly Hg). PSI Technologies (PSIT) and its team members will achieve this objective through the development of an {open_quotes}Engineering Model{close_quotes} that accurately predicts the formation and partitioning of toxic species as a result of coal combustion. The {open_quotes}Toxics Partitioning Engineering Model{close_quotes} (ToPEM) will be applicable to all conditions including new fuels or blends, low-NO{sub x} combustion systems, and new power systems being advanced by DOE in the Combustion 2000 program. This report describes the mineralogy and chemical analysis of bituminous coal samples.
Date: July 1, 1996
Creator: Bool, L.E. III; Senior, C.L.; Huggins, F.; Huffman, G.P. & Shah, N.
Partner: UNT Libraries Government Documents Department

A study of the overdriven behaviors of PBX 9501 and PBX 9502

Description: The author presents the Hugoniot pressure and sound speed data in the overdriven regime for both PBX 9501 and PBX 9502. The overdriven release experiments are also given. The failure of the standard Jones-Wilkins-Lee equation of state in modeling both the Hugoniot data and the overdriven release experiments for both high explosives are identified and remedy is made by including additional terms to steepen the slope of the Hugoniot in the high pressure regime. However, an anomaly presented itself as a kink in the release wave of PBX 9502 is observed. A careful examination of the Hugoniot data indicates similar behavior. A possible explanation is suggested for this peculiarity to the phase transition of carbon in the products.
Date: December 31, 1998
Creator: Tang, P.K.
Partner: UNT Libraries Government Documents Department

Computational modeling and experimental studies on NO{sub x} reduction under pulverized coal combustion conditions. Technical progress report, sixth quarter, April 1--June 30, 1996

Description: During this quarter, the experiments for nitric oxide reburning with a combination of methane and acetylene were conducted successfully. With the failure of ozonator lamp in the NOx analyzer shortly thereafter, the experimental study of nitric oxide reburning with a combination of methane and ammonia could not be completed. In the meantime, a coal feeder was designed and a purchase order was sent out for the building of the coal feeder. Presented herein are the experimental results of NO reburning with methane/acetylene. The results are consistent with model predictions.
Date: December 31, 1996
Creator: Kumpaty, S.K.; Subramanian, K.; Nokku, V.P. & Hodges, T.L.
Partner: UNT Libraries Government Documents Department

Suppression of fine ash formation in pulverized coal flames. Final technical report, September 30, 1992--January 31, 1996

Description: Coal ash, and particularly fine fly ash, remain one of the principal practical and environmental problems in coal-based power generation. In particular, submicron aerosols are identified with direct inhalation risk. Submicron ash is thought to arise from mineral vaporization during char combustion, followed by nucleation, condensation and coagulation to yield an aerosol. While aerosols are predominantly made out of volatile alkali minerals, they also can include refractory oxides that are chemically reduced to more volatile forms within the char particle and vaporized. Most of the ash of size greater than 1 {mu}m is generated by agglomeration of mineral as the char particle bums out. These two principal mechanisms are thought to account for most of the ash generated in coal combustion. Previous research has shown that various forms of coal treatment can influence the yields of fine ash from combustion. The research reported here investigates various forms of treatment, including physical coal cleaning, aerodynamic sizing, degree of grinding, and combinations of these on both aerosol yields and on yields of fine residual ash (1-4 {mu}m). The work also includes results from the combustion of artificial chars that include individual mineral elements. This research shows that these various forms of coal treatment can significantly change ash characteristics. While none of the treatments affected the bulk of the residual ash size distribution significantly, the yield of the ash aerosol mode (d<0.5 {mu}m) and fine residual ash mode (1-4 {mu}m) are changed by the treatments.
Date: July 19, 1996
Creator: Kramlich, J.C.; Chenevert, B.; Park, Jungsung; Hoffman, D.A. & Butcher, E.K.
Partner: UNT Libraries Government Documents Department

A theoretical equation of state for detonation products

Description: A theoretical equation of state for detonation products is described that places particular emphasis on the characterization of small carbon clusters (20{angstrom}--50{angstrom} in diameter) in the products. Diamond clusters are modeled with the dangling bonds on the surface atoms (up to 30% of the cluster) capped by various radicals composed of C, H, N, and O from the background molecular fluid mixture. Free energy methods for the surface groups are used to determine the chemical equilibrium composition of the cluster surface as well as the surrounding molecular fluid mixture. The surface composition shows dramatic changes in composition over some regions and varies slowly in others. A perturbation theory approach is used for the mixture of molecular fluids that also includes features based on Monte Carlo simulations.
Date: December 31, 1998
Creator: Shaw, M.S.
Partner: UNT Libraries Government Documents Department