Thermodynamic evaluation and optimization of supercritical CO2 Brayton cycle considering recuperator types and designs

Abstract

The recompression supercritical carbon dioxide Brayton cycle (SCO2-BC) has great potential for bottoming cycles among future energy conversion systems with comparatively high thermal efficiency. However, the recuperator type selections and optimal designs are a long-standing bottleneck of realizing maximum cycle efficiency and minimum cost. Reasonable collocation of recuperator types remains challenging. In this study, the thermodynamic–economic evaluation and optimization of recompression cycle were performed considering different recuperator types and designs. Printed circuit recuperator channel types include straight, zigzag, S-shaped, and airfoil fins. The design parameters include recuperator enthalpy efficiency and recompression fraction. The results indicate that low-temperature recuperator (LTR) with zigzag channel and high-temperature recuperator (HTR) with zigzag channel exhibit the best comprehensive cycle performance. The cycle thermal efficiency is more sensitive to the HTR enthalpy efficiency compared with the LTR. There is a local inflection point of the recompression fraction where the cycle efficiency is maximum and the exergy loss is minimum. The optimal solution of three-objective optimization considering efficiency, total cost, and exergy loss is more comprehensive than that of the two-objective optimization considering efficiency and cost. In the application of concentrated solar power, the annual carbon dioxide emission can be directly reduced by 0.43 Gt through this optimization improvement. The results of the current study offer a promising route to high-efficiency and low-cost applications of SCO2-BC by rational selection of recuperator types and designs.