431695 A Comprehensive NOx Kinetic Model for Predicting Emissions during High Hydrogen Content Fuel Combustion at Elevated Pressure

Tuesday, November 10, 2015: 9:30 AM
355F (Salt Palace Convention Center)
Sheikh F Ahmed, Department of Mechanical Engineering, University of South carolina, Columbia, SC, Nazli Asgari, University of South carolina, Columbia, SC, Bihter Padak, Chemical Engineering, University of South Carolina, Columbia, SC and Tanvir I Farouk, Department of Mechanical Engineering, University of South Carolina, Columbia, SC

High hydrogen content (HHC) fuel and synthesis gas combustion in gas turbine and other applications is an important aspect of many energy conversion scenarios for generating power and producing alternative transportation liquid fuels. Developing/testing predictive models for NOx formation continues to be important to evaluation/design of high efficiency, low emission technologies for HHC fuel and syngas combustion applications.  The present study investigates comprehensive detailed chemical kinetic models for describing the oxidation of CO/H2/NOx mixtures and limited amounts of small hydrocarbon species with the full implementation of NOx evolution pathways, including thermal, prompt, N2O and NNH paths. Model predicted behaviors are compared against multiple experimental datasets over a wide range of venues and operating conditions.  The experimental venues include shock tube, laminar-premixed flame, plug flow reactor, and perfectly stirred reactor experiments that cover pressures from 1 to 100 bar and equivalence ratios from 0.5 to 1.5. The Burke C0 [Intl. J. of Chemical Kinetics 44, (2012), 444 – 474) and Aramco C1-C4 [Intl. J. of Chemical Kinetics 45, (2013), 638 – 675] models are integrated to describe the fuel kinetics. The NOx kinetic components are developed based on a critical review of NOx production, and NO-NO2 interconversion sub- models presently available in the literature.  The NOx sub-model includes NxHy reaction paths as well as updated rate expressions and species, such as HNO2 and HONO2 and the related paths are found to contribute to NOx production significantly. In general, the overall model predictions are in good agreement with global combustion targets (shock tube ignition delay and premixed laminar burning velocity) as well as with more detailed target data including plug flow reactor reactivity, speciation, and perfectly stirred reactor measurements reported in the literature. Besides the data available in the literature, experiments are also conducted with a McKenna burner for generating additional model validation targets. The model was found to predict reasonably well these new experimental data. In addition, simulations are conducted for a wide range of reacting mixtures (H2/O2/N2, CO/H2/O2 and CO/H2O/O2/N2) with initial NO and NO2 perturbations to consider exhaust gas recirculation (EGR) conditions.

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