Multi-objective optimization of thermoeconomic and component size of supercritical carbon dioxide recompression cycle based on small-scale lead-cooled fast reactor

When the supercritical CO₂ power cycle is employed in confined spaces, such as nuclear-powered ships and spacecraft, its size should be given priority. To estimate the component size, the one-dimensional heat exchanger model developed in this study is used in a recompression supercritical CO₂ cycle integrated on a small-scale lead-cooled fast reactor. A parameter analysis was performed to study the influence of several key parameters on the levelized cost of electricity, thermal efficiency, and system size. Moreover, four types of multi-objective optimizations were conducted to provide optimization schemes for different scenarios. Results indicated that the increased turbine inlet temperature improved the thermoeconomic but augmented the system volume. The size of the low-temperature recuperator was observably enlarged near the optimal flow split ratio, thereby increasing the system volume. Pareto optimal solution of bi-objective optimization based on the levelized cost of electricity and system size reached the lowest system volume of 3.71 m³. Additionally, the best trade-off result of three-objective optimization was a thermal efficiency of 42.14%, a levelized cost of electricity of 56.30 $∙MWh⁻¹, and a system volume of 4.43 m³. Meanwhile, maximal and minimal pressure drops of CO₂ appeared in the cooler and intermediate heat exchanger, respectively.