Chemical reactor networks for combustion systems modeling

This study shows the development and application of chemical reactor networks (CRN) for several combustion systems. The CRN development is based on results from computational fluid dynamics (CFD) simulations.; The University of Washington eight-step global kinetic mechanism for methane oxidation and NO formation is updated and validated in the CFD code for an experimental bluff body combustor. The CFD predicted emissions for the bluff body combustor are found to be in a good agreement with the experimental data. The eight-step global mechanism is then used in CFD modeling of generic and industrial gas turbine combustors.; The flow information from CFD modeling is analyzed and represented as an arrangement of chemical reactor elements. The CRN element arrangement, element volumes, and flow splits between the elements are adjusted based on the best agreement with CFD output over the range of pilot fuel flow rates for different premixer fuel-air ratio distributions. The resulting chemical reactor network consists of 31 elements representing zones typical of the generic swirl stabilized combustor: main premixer flame, pilot flame, post-flame, and center and dome recirculation zones. The NOx emissions predicted by CFD and CRN are in good agreement with one another for different injector configurations and for a range of pilot fuel flow rates.; By taking advantage of this detailed information for the generic combustor, the methodology for CFD to CRN translation is then developed. This methodology is applied to the industrial lean-premixed gas combustor. This CRN is applied to two test rig engine configurations for different engine sizes and injector circuit setups. The predicted NOx emissions are compared to the test rig emissions data for a range of pilot fuel flow rates and fuel types. Good agreement between the predicted NOx and the experiment data is found using both the GRI 3.0 mechanism and the global mechanism.; The CRN is able to handle complex chemical mechanisms and can provide significant insight into pollutant formation. Because of its small computational time requirement, the CRN can be used as tool for analysis of combustion systems and can be integrated into combustor design.