A simultaneous synthesis method for optimizing supercritical CO2 power cycles integrating topological and heat exchanger network design

This study addresses two major limitations of existing superstructure-based and enhanced synthesis methods for supercritical CO2 (sCO2) cycle design: their reliance on a priori configurations and their inability to jointly optimize cycle topology and heat exchanger networks. To overcome these challenges, a novel simultaneous synthesis method is proposed, enabling integrated optimization of both the cycle structure and heat exchanger network. By employing thermal cut and superstructure methods, we disassemble basic cycles and reintegrate fundamental thermodynamic processes, establishing rigorous structural synthesis rules and a comprehensive control logic system. A mixed-integer nonlinear programming (MINLP) model is developed to optimize the sCO2 cycle structure. The proposed method is applied to the design of an sCO2 flue gas waste heat recovery system, where a tailored branch-priority algorithm is introduced to improve solution efficiency. Simultaneous optimization of system topology and heat exchanger networks is achieved under four operating conditions. The results show that the net output power of the system is reduced by 29.61 kW and 16.42 kW for the dry cooling condition compared to the wet cooling condition when the flue gas temperatures are 873.15 K and 673.15 K. Overall, the method not only improves net power output by 3.93 %–10.39 % and 9.49 %–18.98 % compared to two conventional sCO2 cycles but also reduces computational time and enhanced heat recovery efficiency.