Reduzierte kinetische Modelle für die Abscheidung von Kohlenstoff aus der Gasphase

• Applicant: Professor Dr. Ulrich Maas
• Subject Area: Physical Chemistry of Molecules, Liquids and Interfaces, Biophysical Chemistry
• Term: from 2008 to 2012
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 58345291

• Final Report Year: 2012

Final Report Abstract

During the reported period the method of model reduction has been developed and applied to realistic mechanisms of chemical kinetics developed to describe the processes of chemical vapor deposition, infiltration and pyrolysis of high hydrocarbons. Two supplementary approaches were developed and applied to analyze the properties of the reference chemical reaction mechanism. The first one is indicated as a local approach. It is based on the previously developed ILDM approach and allows to access the local time scales of the process being calculated along the detailed system trajectory. This approach and detailed simulations of the original systems in typical regimes fully cover the first paragraph of the working program. The method of the global analysis has been further developed to simplify the implementation part and to make use of the presence of the different time scales. The method uses the global linearization approach based on the recently developed coordinate free singular perturbation theory. Explicit coordinate transformation into fast/slow subsystems is the main technical instrument for the analysis and for formulation of the reduced model. A combination of both approaches allowed to access to the system decomposition depending on different time scales. Moreover, using the constant transformation matrix (namely, their columns, which are eignevectors of the GQL matrix) the information about lumped species becomes available. This closes the second and third paragraphs of the project plan. All the methods for coupling reaction with the transport have been developed and ready to be implemented to simplify the detailed model simulation. An extensive use of these methods for the simulation of the overall CVI processes has, however, not been performed within the project period. The developed methods were implemented in FORTRAN codes. The program can be used to supply the user with the explicit matrix transformation (new coordinate system); it allows test integration of both reduced (as slow and fast subsystems) and detailed systems and can be used as a validation and investigation tool of the kinetic mechanisms. This finishes the last paragraph of the project plan. Both methods were implemented for typical regimes of the CVD process. Homogeneous system describing gas phase chemical kinetics was investigated for initial conditions typically used in the original experimental and modeling studies. The result shows the great potential of characteristic time scales analysis and global decomposition to yield an accurate reduced model.

Publications

• 2009, From Detailed Kinetics to Simplified Kinetics – Hierarchical Models for Combustion Chemistry, Proc. of the Australian Combustion Symposium, Brisbane, Australia
  Bykov, V., Maas, U.
  
• 2009, Hierarchical Modelling of Combustion Processes, High Performance Computing on Vector Systems 2008, Springer, Vol. 4, pp. 111-127
  Maas, U., Bykov, V., Rybakov, A., Stauch, R.
  
• 2009, Investigation of the hierarchical structure of kinetic models in ignition problems, Z. Phys. Chem., 223 (4-5), 461-479
  Bykov, V., Maas, U.
  
• 2010, Reaction-Diffusion Manifolds and Global Quasilinearization: Two Complementary Methods for Mechanism Reduction, The Open Thermodynamics Journal, 4, 92-100
  Bykov, V., Maas, U.
  
• 2010, Scaling Invariant Interpolation for Singularly Perturbed Vector Fields (SPVF), Lecture Notes in Computational Science and Engineering, Springer, Vol. 75, pp. 106-130
  Bykov, V., Gol'dshtein, V., Maas, U.
  
• 2011, Hierarchy System Analysis and Reduction of Reacting Flow Models, Computational Science and High Performance Computing IV, Notes on Numerical Fluid, Mechanics and Multidisciplinary Design, v. 115/2011, pp. 233-252
  Bykov, V., Maas, U.
  
• 2011, On Investigation of Internal Hierarchy of Chemical Kinetics Mechanisms, Proc. of the 13th International Conference on Numerical Combustion, Corfu Greece, April 27-29
  Bykov, V., Maas, U.
  
• 2011, On transformation to the Singularly Perturbed System, J. Phys.: Conf. Ser., 268, 012003
  Bykov, V.