A comprehensive study on the impact of turbomachinery synergy on the thermodynamic performance of supercritical carbon dioxide reheated recompression cycle

Turbomachinery synergy has significant influence on the thermodynamic performance of the state-of-the-art supercritical carbon dioxide Brayton cycles. To develop cycles with high efficiency, realizability and reliability, in-depth understanding of the effect of turbomachinery synergy are required, especially at the system conceptual design process. In this paper, a comprehensive investigation on the effect of turbomachinery synergy was carried out. A strategy and methodology based on one-dimensional turbomachinery models was firstly proposed. The effect of different turbomachinery synergy configurations on the performance of the reheated recompression cycle was quantitatively analyzed. Moreover, some considerations on selecting synergy configuration were put forward, as well as a reasonable scheme with high cycle efficiency and low axial thrust was proposed. Results indicate that turbomachinery synergy could lead to 2.81% maximum variation in cycle efficiency, from 45.10% to 42.29%. The negative effect on cycle efficiency could be weakened by proper selection of turbomachinery synergy configurations. Besides, from the perspective of high cycle efficiency, low turbomachinery rotating speed and small axial thrust on turbomachinery rotor system, C22:MR-HL which contains a coaxial compressors assembly and a coaxial turbines assembly is the most favorable and practical turbomachinery synergy configuration for the reheated recompression cycle. This study is expected to provide some useful guidance for the conceptual design of high-performance supercritical carbon dioxide Brayton cycles.