NUMERICAL MODEL DEVELOPMENT FOR SUPERCRITICAL CO2 OXY-COMBUSTION

Supercritical CO2 (sCO2) power cycles operate at high pressures (300 bar) and high inlet temperatures (700°C), with the promise of higher efficiency and the potential to foster sequestration of CO2. Current plans are to operate these devices using natural gas or syngas, burning with oxygen at fairly low combustion temperatures (1100 °C). However, there are gaps in the understanding of oxy-fuel combustion with CO2 under supercritical conditions. In addition, trace amounts of NOx and SOx impurities in the flow will also have significant impacts on the chemical kinetics. At these conditions, limited experimental data (especially at high-pressures) exist for validation of thermo, transport and reaction models that are essential for the simulation of the sCO2 combustion. Therefore, improved models for chemical kinetics and equations of state (EOS) are needed for high fidelity Computational Fluid Dynamics (CFD) simulations to aid the development and design of sCO2 power cycles. In this proposed work, existing models for natural gas and syngas with NOx chemistry will be extended to include a reaction scheme for SOx-fuel interaction. New experimental data for syngas and natural gas fuels will be acquired using existing high-pressure shock tube facility to measure ignition delay times of oxy- fuels with CO2 dilution up to 300 atm with NOx and SOx additives relevant to the sCO2 power cycle. These experimental data will be used to test and validate the detailed chemical kinetic mechanism to improve the model predictions at sCO2 power cycle conditions. This detailed kinetics model will be the basis to develop reduced kinetic models needed for turbulent combustion simulations. The model accuracy and computational efficiency of the reduced kinetics models will be evaluated by simulating one-dimensional turbulent flames at sCO2 power cycle conditions using a stand-alone linear-eddy mixing (LEM) model. The end-product of this project will be reduced and detailed kinetic models for sCO2 combustion of syngas and natural gas fuels validated by experimental data for high-pressure conditions and LEM numerical tool of sCO2 turbulent combustion with improved EOS.