Radial inflow turbine design for 1-MW supercritical carbon dioxide Brayton cycle using specific speed and specific diameter parameters

Supercritical carbon dioxide Brayton cycle is considered one of the most promising energy conversion cycles for energy sources such as solar thermal, coal, natural gas, nuclear, geothermal, biomass, waste heat, etc. Owing to its good efficiency at mild turbine inlet temperatures and potential to yield a compact system, turbomachinery design and development is an integral aspect for the successful deployment of this technology. This paper presents a meanline design methodology for the design of a radial inflow turbine for a 1-MW supercritical carbon dioxide Brayton cycle. The proposed methodology for the design of a radial inflow turbine with supercritical carbon dioxide as the working fluid is based on the selection of an appropriate combination of specific speed (N_S) and specific diameter (D_S) values from Balje’s N_S–D_S chart which is unique. CFD simulations are performed at design and off-design points for the developed turbine. The results from the meanline design are compared with the design point CFD simulation results. The 1-D meanline design based on the proposed methodology has yielded a total-to-total efficiency of 90.9% at the design point while the design point CFD simulation predicted a total-to-total efficiency of 91.2%.