Seminars & Events
Argonne Leadership Computing Facility
"Gas Chemistry and Radiation Modeling for Syngas and Oxy-Fuel Combustion"
DATE: January 31, 2011
TIME: 1:30 PM - 2:30 PM
SPEAKER: Osama A. Marzouk, Research Engineer - Postdoctoral Fellow, National Energy Technology Laboratory, DOE and West Virgini
LOCATION: Building 240 / Conference Room 4301, Argonne National Laboratory
HOST: Tim Williams
Description:
With the increasing demand to reduce carbon dioxide as a greenhouse gas emitted from energy systems such as pulverized-coal power plants, attention is paid to retrofitting these energy systems with carbon capture technologies. Among these technologies, oxy-fuel combustion (where the fuel is burned in an atmosphere of oxygen and recycled flue gas rather than air) is a promising ‘easy-to-capture’ option. It is important, however, to predict and minimize any performance penalty due to oxy-fuel retrofitting before actual implementation. Computational fluid dynamics (CFD) simulations with accurate modeling enable us to predict the expected characteristics of combustion, mixing, and heat transfer, and therefore optimize the retrofitting process. These combustion simulations are challenging due to the large number of coupled phenomena and consequently the large number of models needed, which include turbulence, gas chemistry (turbulence-chemistry interaction, reaction kinetics, and chemistry solver), surface chemistry (heterogeneous reactions), gas-particle dynamics (particle tracking and turbulent dispersion), phase change (evaporation and devolatilization), and thermal radiation (radiative transfer equation and absorption coefficient). These models, in turn, warrant assessment/verification studies to identify applicability limitations, necessary modifications, and possible improvements. This is the main topic of the seminar.
From the various modeling aspects in combustion, the seminar considers gas chemistry and radiation. The seminar presents an assessment/verification study of reaction kinetics and chemistry solvers through the simulations of a turbulent syngas (carbon monoxide and hydrogen) flame, where two chemistry solvers (embedded Runge-Kutta and semi-implicit Bulirsch-Stoer) are used and predictions of eight reaction mechanisms (global and elementary) are compared. The seminar also presents a study analyzing four new weighted-sum-of-gas-gases models (WSGGMs) to evaluate the radiative absorption coefficient in oxy-fuel combustion, and how they perform differently from a classical air-fuel WSGGM. Two techniques (stepwise and interpolation) to implement the WSGGM are compared, through test cases with rectangular-box geometry and non-uniform temperature distribution.
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