Configurations Optimization and Application Analysis on S-CO₂ Power System for Multi-scenario Industrial Waste Heat Recovery

This study focuses on the configuration optimization of supercritical carbon dioxide (S-CO₂) power cycles for multi-scenario industrial waste heat recovery, aiming to enhance power generation performance and improve adaptability across a wide range of heat source temperature conditions. With the gradual commercialization of S-CO₂ power systems, their application is expanding from nuclear energy systems with relatively stable heat sources to industrial waste heat recovery scenarios characterized by strong temperature variability. Conventional configurations, such as the simple recuperated cycle (SRC) and recompression cycle (RC), often show limited adaptability under different thermal conditions, making it difficult to achieve efficient waste heat utilization across a broad operating range. To address this issue, a unified thermodynamic evaluation framework was developed to systematically compare and optimize multiple S-CO₂ cycle configurations, with particular emphasis on improving both energy conversion efficiency and waste heat recovery capability. The methodology was based on thermodynamic and exergy modeling of key components, including compressors, turbines, recuperators, heaters, and coolers. Three non-split cycle configurations and eight flow-splitting configurations were investigated. The flue gas outlet temperature of the heater (T_hout) was treated as the primary independent variable, and a parametric optimization strategy was employed. For each fixed T_hout, cycle parameters were optimized to maximize net power output, and the corresponding optimal cycle efficiency was obtained. By continuously varying T_hout, performance maps of different cycle configurations were established, revealing the coupling relationship between heat source temperature levels and optimal cycle selection. The results show that the preheating cycle (PHC) significantly improves temperature matching in the recuperator via flow-splitting, thereby reducing exergy destruction and increasing net power output. In contrast, RC exhibits higher efficiency under high-temperature conditions but limited capability for deep recovery of low-grade waste heat. The dual-turbine cascade cycle (DTC) maintains relatively stable turbine inlet temperatures via split-expansion, demonstrating improved performance at low T_hout conditions, although at the cost of increased system complexity. Furthermore, for coke dry quenching waste heat recovery, a newly proposed hybrid configuration combining split-expansion, recompression, and preheating (DTC_RC_PHC) shows enhanced thermodynamic performance at low T_hout conditions (≤200 ℃). However, the system complexity significantly increases. Overall, no single S-CO₂ cycle configuration is universally optimal across all operating conditions, as performance is strongly governed by heat source characteristics. The performance maps developed in this study provide a systematic basis for cycle selection under different industrial waste heat scenarios and offer useful guidance for the engineering application of S-CO₂ power generation systems in multi-scenario waste heat recovery.