Development of High-Fidelity Numerical Models for Supercritical CO2 Oxy-Combustion

Existing thermodynamic cycles used for electricity generation from fossil fuels are based on the steam-based Rankine cycle. The additional costs of carbon capture (i.e. CO2 capture), associated with add-on equipment to these existing generators, are significant and will ultimately limit the utilization of our nations’ vast resources of fossil fuels for future production of zero carbon emissions power. The Allam cycle, which relies on oxy-combustion of natural gas or coal-derived syngas in a highly CO2 diluted supercritical environment, has been identified to have high potential for improving overall plant efficiency, while producing a high-pressure, sequestration-ready stream of CO2. Due to the lack of available data for the high- pressure supercritical CO2 environments involved in these systems, advancement of this technology will require validated numerical models that can be used in conjunction with experimental test programs to reduce the cost and development time to market for this critical technology. The small business will collaborate with university researchers and a research center with relevant expertise with direct-fired supercritical CO2 environments to develop verified chemical mechanisms, real gas thermodynamic and transport properties, that can be implemented into an existing industrially-applied CFD model. The modified CFD model will be applied to an existing high-pressure test reactor for verification against data. The verified submodels will be used within the small business’ CFD model and in other commercial CFD software for direct oxy-fired supercritical CO2 combustor design and optimization. In the phase I effort, the small business will leverage an existing, industrially used CFD code that has been verified for simulation of atmospheric and elevated pressure air and oxy-combustion problems. The code will be modified to include real gas thermodynamic and transport properties appropriate for supercritical mixtures of CO2, and finite rate limitations associated with oxidation and emissions kinetics. The modified CFD code will be applied to an existing high-pressure combustor that has been developed to test conditions associated with the Allam cycle. The code modifications associated with real gas properties and chemical kinetics under supercritical CO2 conditions will be used by the small business and other equipment developers in CFD codes to develop and optimize combustor designs for the Allam cycle. Use of these CFD models in conjunction with experimental testing will reduce the demonstration and commercialization costs by decreasing the development time-scale to bring the Allam cycle based technology to market.