(547f) Optimal Design and Dynamic Modeling of Microtube Recuperators in an Indirect Supercritical Carbon Dioxide Recompression Brayton Power Cycle
With this motivation, a rigorous design model has been developed using Aspen Custom Modeler for high-temperature and low-temperature microtube recuperators in an indirect sCO2 Brayton recompression cycle with improved steady-state economic characteristics and preferred dynamic performance characteristics. Additionally, a dynamic model has been developed to simulate the operating conditions spanning normal design point, to startup, shut down and other off-design conditions. This model is imported to a system-level dynamic model of the entire sCO2 Brayton cycle to improve simulation accuracy when investigating the system dynamic behavior and developing advanced control strategies. In both models, the recuperators are discretized along the axes to handle the changing properties, and simulated with rigorous thermal-hydraulic correlations and commercially available microtube sizes. In this presentation, we will focus on the following aspects: (1) one-dimensional steady-state design approach of the recuperators in sCO2 Brayton cycle, (2) design optimization for better economics along with superior dynamic characteristics by considering various objectives such as maximization of the heat transfer area, maximization of the compactness, minimization of the metal mass, minimization of the thermal residence time, by using successive quadratic programming algorithm, (3) sensitivity studies of different values of the design parameters, such as minimum temperature approach and maximum allowable pressure drop, which highly impact the thermal efficiency and the economic performance of the entire sCO2 Brayton cycle, (4) two-dimensional dynamic model of the recuperators spanning both design and off-design conditions, and (5) re-design to obtain superior transient response of the recuperators.