City Research Online

Abstract

Recent studies suggest that CO2 mixtures can reduce the costs of concentrated solar power plants. Radial inflow turbines (RIT) are considered suitable for small to medium-sized CO2 power plants (100 kW to 10 MW) due to aerodynamic and cost factors. This paper quantifies the impact of CO2 doping on RIT design by comparing 1D mean-line designs and aerodynamic losses of pure CO2 RITs with three CO2 mixtures: titanium tetrachloride (TiCl4), sulfur dioxide (SO2), and hexafluorobenzene (C6F6). Results show that turbine designs share similar rotor shapes and velocity diagrams for all working fluids. However, factors like clearance-to-blade height ratio, turbine pressure ratio, and fluid viscosity cause differences in turbine efficiency. When normalized for these factors, differences in total-to-static efficiency become less than 0.1%. However, imposing rotational speed limits reveals greater differences in turbine designs and efficiencies. The imposition of rotational speed limits reduces total-to-static efficiency across all fluids, with a maximum 15% reduction in 0.1 MW CO2 compared to a 3% reduction in CO2/TiCl4 turbines of the same power. Among the studied mixtures, CO2/TiCl4 turbines achieve the highest efficiency, followed by CO2/C6F6 and CO2/SO2. For example, 100 kW turbines achieve total-to-static efficiencies of 80.0%, 77.4%, 78.1%, and 75.5% for CO2/TiCl4, CO2/C6F6, CO2/SO2, and pure CO2, respectively. In 10 MW turbines, efficiencies are 87.8%, 87.3%, 87.5%, and 87.2% in the same order.

Publication Type:	Article
Additional Information:	Copyright © 2024 by ASME; reuse license CC-BY 4.0.
Publisher Keywords:	radial inflow turbine, CO2 mixtures, transcritical CO2 cycles, turbine aerodynamic design, loss analysis
Subjects:	T Technology > TJ Mechanical engineering and machinery T Technology > TL Motor vehicles. Aeronautics. Astronautics
Departments:	School of Science & Technology School of Science & Technology > Engineering
SWORD Depositor:	Symplectic Administrator

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