ACERC
Abstracts - 1991 |
ACERC
Abstracts - 1991 |
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Thrust Area 5: Comprehensive Model Development |
Smoot, L.D.
Coal and Char Combustion, Chapter 10
(W. Bartok and A.F. Sarofim, eds.), John Wiley and Sons, Inc., 1991. Funded
by Exxon Corp.
A comprehensive summary of 128 pages that treats reaction processes involving coal, char and other solid fossil fuels. Contents include coal processes and properties, fuel ignition, devolatilization, and oxidation. Practical flames are classified and their characteristics are discussed. Computerized models of these flames are reviewed and applied to industrial flames. The work cites 234 technical references, including 39 that report original combustion research work conducted at Brigham Young University.
Ma, K.-L.; Cohen, M.F. and
Painter, J.S.
Journal of Visualization and Computer Animation, 1991 (in press). Funded
by ACERC.
Ray-traced volume rendering has been shown to be an effective method for visualizing 3-D scalar data. However, with currently available workstation technology, interactive volume exploration using conventional volume rendering is still too slow to be attractive. This paper describes an enhanced volume rendering method that allows interactive changes of rendering parameters such as color and opacity maps. An innovative technique is provided which allows the user to plant a "seed" in the volume to rapidly modify local shading parameters. For a fixed viewing position, the user can interactively explore specific regions of interest. Furthermore, a virtual cutting technique with the exploratory seed allows the user to remove surfaces and see the internal structure of the volume. Examples demonstrate these techniques as an attractive option in many applications.
Solomon, P.R.; Hamblen,
D.G.; Serio, M.A.; Smoot, L.D. and Brewster, B.S.
Contractors Review Meeting, Morgantown, WV, August 1991. Funded by Morgantown
Energy Technology Center.
The overall objective of this program is to understand the chemical and physical mechanisms in coal conversion processes and incorporate this knowledge in computer-aided reactor engineering technology for the purposes of development, evaluation, design, scale up, simulation, control and feedstock evaluation in advanced coal conversion devices. To accomplish this objective, the study will: establish the mechanisms and rates of basic steps in coal conversion processes, incorporate this information into comprehensive computer models for coal conversion processes, evaluate these models, and apply them to gasification, mild gasification and combustion in heat engines.
Ma, K.-L. and Sikorski,
K.
5th SIAM Conference on Parallel Processing for Scientific Computing,
Houston, TX, March 1991. Funded by National Science Foundation and ACERC.
This paper describes a distributed algorithm for solving the 3-D unsteady compressible Navier-Stokes equations, and its implementation on the Inmos T800 transputer array, in particular, the IBM Victor Computer. Numerical experiments indicate that the algorithm offers the ultimate promise of supercomputer performance on relatively low-cost and highly scalable distributed memory parallel computers. In addition, we show the use of a visualization system that we have developed for observing flow structures and for verifying simulation results.
Clarksean, R. and Ma, K.-L.
AIAA 10th Computational Fluid Dynamics Conference, Honolulu, HI, July
1991. Funded by ACERC.
The coupling of the direct numerical simulation and visualization is useful because of the insight it provides into the development and formation of structures within the flow field. We discuss the use of a volume rendering technique for the visualization of a three-dimensional planar mixing layer. Graphical data in the form of color "snapshots" and a video will be presented to demonstrate the use of the volume rendering method as a better way to understand the physics of turbulent flow.
Solomon, P.R.; Hamblen,
D.G.; Serio, M.A.; Smoot, L.D. and Brewster, B.S.
5th Annual Report for the US Department of Energy, 1991. Funded by Morgantown
Energy Technology Center.
The overall objective of this program is the development of predictive capability for the design, scale up, simulation, control and feedstock evaluation in advanced coal conversion devices. This technology is important to reduce the technical and economic risks inherent in utilizing coal a feedstock whose variable and often unexpected behavior presents a significant challenge. This program will merge significant advances made at Advanced Fuel Research, Inc. (AFR) in measuring and quantitatively describing the mechanisms in coal conversion behavior, with technology being developed at Brigham Young University (BYU) in comprehensive computer codes for mechanistic modeling of entrained-bed gasification. Additional capabilities in predicting pollutant formation will be implemented and the technology will be expanded to fixed-bed reactors.
The foundation to describe coal-specific conversion behavior is AFR's Functional Group (FG) and Devolatilization, Vaporization, and Crosslinking (DVC) models, developed under previous and on-going METC sponsored programs. These models have demonstrated the capability to describe the time dependent evolution of individual gas species, and the amount and characteristics of tar and char. The combined FG-DVC model will be integrated with BYU's comprehensive two-dimensional reactor model, PCGC-2, which is currently the most widely used reactor simulation for combustion or gasification. The program includes: i) validation of the submodels by comparison with laboratory data obtained in this program, ii) extensive validation of the modified comprehensive code by comparison of predicted results with data from bench-scale and process scale investigations of gasification, mild gasification and combustion of coal or coal-derived products in heat engines, and iii) development of well documented user friendly software applicable to a "workstation" environment. Success in this program will be a major step in improving the predictive capabilities for coal conversion processes including: demonstrated accuracy and reliability and a generalized "first principles" treatment of coals based on readily obtained composition data. The progress during the fifth year of the program is summarized in the document.
Smith, P.J.; Smoot, L.D.;
Hill, S.C. and Eaton, A.M.
Advanced Combustion Engineering Research Center, 1991. Funded by US Department
of Energy, Consortium and ACERC.
The theoretical foundations, numerical approach and a guide for users of 90-PCGC-3 are presented. 90-PCGC-3 is a generalized, three-dimensional, steady state model that can be used to predict the behavior of a variety of reactive and non-reactive (isothermal) fluid flows. The model solves the Navier-Stokes equations in three-dimensional, Cartesian coordinates. Turbulence is accounted for in both the fluid mechanics equations and the combustion solution scheme. Major gas-phase reactions are modeled assuming local instantaneous equilibrium, and thus the reaction rates are limited by the turbulent rate of mixing. The gas phase is described by elliptic partial differential equations that are solved by an iterative line-by-line technique. Under-relaxation is used to achieve numerical stability.
Smoot, L.D.
Proceedings of the 2nd International Symposium on Coal Combustion Science
and Technology, 58-72, Beijing, China, October 1991. Funded by ACERC.
This invited paper describes an integrated, interdisciplinary research program at the Advanced Combustion Engineering Research Center in the United States. The program focuses on combustion research related to clean and efficient use of low-quality fossil fuels, particularly coal. About forty on-going experimental and modeling research projects in six thrust areas among 125 investigators are noted. Some specific projects in which the author participates are summarized, and results from two of these projects are presented and discussed. The first is development of a generalized NOx/SOx submodel for inclusion in a comprehensive combustion code, PCGC-2. The NOx model links, for the first time, thermal and fuel NOx with turbulence fluctuations. Thermal NOx measurements from an advanced, controlled-profile laboratory reactor agree generally with predictions and also support a key assumption used to estimate the radial concentration. Methods for predicting capture of SOx by limestone sorbents in coal combustion are outlined. Development and evaluation of an advanced, top-fed, counterflow, one-dimensional fixed bed gasification model is also summarized. Key assumptions and model parameters are identified. The model is based on solution of mass and energy balances for coal particles and gas with different axial temperature distributions. Pressure distribution varies with void fraction axially. Predictions of axial temperature and pressure variation compare well with reported measurements for several coals in a commercial atmospheric gasifier.
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