Preliminary design and sensitivity analysis of centrifugal compressor train for a 50 MWe sCO2 Brayton power cycle for CSP applications

One of the major factors affecting the efficiency of supercritical carbon dioxide (sCO2) Brayton power cycles is the design of the turbomachinery. It has been shown that marginal increases in the efficiencies of the compressors and turbines can significantly reduce the size of the costly recuperators, thereby lowering cycle costs and further enhancing overall cycle efficiency. The focus of this work is on the preliminary design of highpressure compressors (HPC), low-pressure compressors (LPC) and recompression compressors (RCC) for a 50 MWe partial cooling sCO2 Brayton power cycle. The design calculations utilise an in-house developed real-gas mean-line analysis approach along with aerodynamic and parasitic loss models accounting for phenomena such as incidence and disk friction losses. Once the reference compressors have been designed, a sensitivity study is conducted to assess the impact of various design parameters on compressor geometries and thermodynamic performance. For each of the generated samples, the mean-line analysis code, developed in the Engineering Equation Solver (EES) software, is utilised to calculate compressor geometries and thermodynamic performance of the machines. The impact of the various design variables are therefore determined, and finally a compressor train is designed for the partial cooling power cycle. The sensitivity analysis yielded compressor design configurations with isentropic efficiencies ranging from 75% to 90% and rotor tip diameters between 210 mm and 250 mm, demonstrating the potential for high efficiency and compact designs in sCO₂ Brayton power cycles.