Aerodynamic Design and Off-design Performance Analysis of a Multi-Stage S-CO2 Axial Turbine Based on Solar Power Generation System

Solar energy is an inexhaustible source of clean energy. Meanwhile, supercritical carbon dioxide has excellent characteristics such as easy access to critical conditions, high density, and low viscosity, making it one of the most popular circulating working fluids in solar power generation technology. However, solar power generation systems are severely affected by geographical distribution, seasonal variations and day-night cycles. Therefore, efficient and adaptable turbine design is the key to realize supercritical carbon dioxide solar power generation technology. In this paper, the initial thermodynamic design of 10 MW S-CO2 three-stage axial turbine is completed by self-developed thermodynamic design software, and the key thermodynamic and structural parameters are obtained. The optimal design of turbine and its aerodynamic performance at rated operating conditions are obtained by using a three-dimensional aerodynamic numerical analysis and optimization method. At last, nine off-design conditions are analyzed in detail. The results show that the designed turbine output power is 10.37 MW and the total-total efficiency is 91.60%. It can operate efficiently and steadily in the range of output power from 16.2% to 155.9%. It can adapt to the variable operating conditions of solar power generation system and meet the design requirements.