Irreversible losses, characteristic sizes and efficiencies of sCO2 axial turbines dependent on power capacities

• Published in: Energy (Oxford) Vol. 275; p. 127437
• Main Authors: Wang, Tianze, Xu, Jinliang, Wang, Zhaofu, Zheng, Haonan, Qi, Jianhui, Liu, Guanglin
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 15.07.2023
• Subjects: Irreversible loss; Scaling law; sCO2 cycle; Turbine efficiency; sCO2 cycle; Scaling law; Turbine efficiency; Irreversible loss
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2023.127437

Supercritical carbon dioxide (sCO2) cycle can be driven by fossil energy and solar/nuclear energy. Available references maximize cycle efficiency by fixing turbine efficiencies ηtt in advance. Here, we provide turbine efficiencies dependent on power capacities WT which are in the range of (50–450) MW. After examination of working mechanism and special characteristic of sCO2 turbines, a comprehensive model was presented to predict characteristic sizes, irreversible losses and efficiencies of turbines. Characteristic size of turbines (lc) is found to obey the scale law of lc∼WT0.5. Profile loss Yp, secondary loss Ys, clearance loss Ycl and trailing edge loss Yte obey the scaling laws of Yp∼WT−0.075,Ys∼WT−0.075,Ycl∼WT−0.39,Yte∼WT−1. These scaling laws agree with the correlations based on numerical simulations. With continuous increase of WT, ηtt increases but the slope of the curves become gentle. Efficiency maps are provided based on inlet pressures Pin and temperatures Tin. By fixing WT, ηtt decreases with increase of Pin and Tin. The scaling laws regarding irreversible losses provide the guidance to optimize the turbine design. The efficiency maps can be integrated in the cycle analysis for accurate estimate of system performance, and help to select suitable power capacity. •A comprehensive model is presented to predict the performances of sCO2 axial turbines.•Scaling laws of characteristic sizes and irreversible losses are theoretically developed.•Turbine efficiencies quickly increase and then the slope of the curve decreases, with increase of WT.•Turbine efficiencies show parabolic variation with respect to expansion pressure ratios.•Efficiency maps are presented based on inlet pressures and temperatures.