Multiscale Modeling of Supercritical Combustion with Two-Level Simulation on Adaptive Beamlets

Supercritical carbon dioxide (sCO2) based power cycles is a promising technological venue that can potentially increase the power cycle efficiency in power plant operations. In addition to higher efficiency, the direct-fired sCO2 cycle, in particular, offers other benefits including the facilitation of CO2 capture and sequestration, and potentially simpler designs. In order to develop the next-generation of low-emission supercritical combustors operating in a highly CO2-diluted environment, high-fidelity computational tools are needed that could enable engineers to maximize efficiency of their designs in a minimal time frame. The aim of the proposed project is to develop a multiscale modeling tool that provides distinct advantages over the presently used computational models, in order to simulate turbulent reacting flows in sCO2-based combustors. To circumvent the necessity and difficulty of modeling of many nonlinearities arising at super- critical conditions, a multiscale modeling concept of the two-level simulation (TLS) is explored and applied to supercritical reacting flows. In the TLS, all small-scale fields are simulated explicitly, albeit on one-dimensional (1D) domains – beamlets represented by a collection of lines embedded in a three-dimensional (3D) computational domain. The present Phase I research is focused on the demonstration of the TLS approach for a 1D variable-density advection-reaction- diffusion system and 3D supercritical nonreacting jets. In addition, a series of simplified Direct Numerical Simulation (DNS) studies of premixed flame propagation in a highly CO2-diluted environment is performed, in order to elucidate the effects of supercritical conditions and lay the foundation for computationally tractable TLS of a prototypical sCO2 combustor. The economical and environmental impacts of sCO2 power cycles are high, and affect important applications in multi-billion dollar energy production and power generation industries. The direct fired sCO2 cycle based on oxy-combustion of syngas is directly suitable for implementation in zero emission fossil fuel plants utilizing pulverized coal. The overall goal of the present project is to deliver a high-fidelity simulation tool that will be used to develop, optimize, or upgrade the supercritical CO2 based combustion technology through high-performance computing simulations.