Computational studies in catalytic combustion of methyl chloride and methane.

摘要

This study investigates the advantages and disadvantages of utilization of progressively complex models for computational studies in catalytic combustion. Several computational models from simple one-dimensional to detailed two-dimensional models are developed for studying non-catalytic/catalytic ignition of methane over a flat plate and catalytic incineration of methyl-chloride inside a tube. Finite difference and modified damped Newton's method are implemented to solve the coupled non-linear parabolic and elliptic partial differential equations for the conservation of total mass, momentum energy and species.; Catalytic incineration of CH{dollar}sb3{dollar}Cl inside a tube is investigated with a plug flow and boundary layer model. For the experimental conditions investigated in this study, the prediction from the computationally inexpensive plug flow model is similar to a computationally expensive parabolic model. The models correctly predict the lower temperature requirement of the catalyst stabilized combustion for complete destruction of the CH{dollar}sb3{dollar}Cl. Surface reactions responsible for coupling gas-phase reactions with the surface are identified. The predictions for the product profiles by both models qualitatively match the experimental data.; Predictions from a boundary layer model and a full two-dimensional elliptic model are compared for both non-catalytic and catalytic ignition over a flat plate. Depending on the equivalence ratio and temperature maintained at the wall, the predictions far downstream from the leading edge are either similar or different. Very close to the leading edge the predictions differ. Criteria based on the wall temperature and inlet fuel equivalence ratio are developed to aid in the determination of which model to utilize for catalytic combustion of methane. For fuels other than methane, a qualitative criterion of flame penetration prediction by the boundary layer model can be utilized to determine whether or not to use fully elliptic two-dimensional model.; Several global surface reaction models are utilized to explore the impact of the uncertainty in the rate over a catalytic Pt-surface, found in the literature on prediction of combustion characteristics. Catalytic consumption of fuel in the boundary layer has been identified as the principal reason for delay in the gas-phase ignition of methane for the catalytic problem.