Performance analyses of a particularly designed turbine for a supercritical CO2-based solar Rankine cycle system

A centrifugal prototype turbine used in a supercritical CO2-based solar Rankine cycle system (SRCS) is proposed and investigated by both experimental and analytical methods. The basic operation of the turbine is checked, and its performance is also systematically analyzed based on the CO2 mass flow rate and temperature at the outlet of turbine, its rotational speed, and output torque. In addition, the choking phenomenon of the flow in the nozzle is also investigated when the inner diameter of nozzle in the turbine is increased from 0.5 to 1.0mm. The results show that the choked flow does not occur, and the CO2 flow can go smoothly in the nozzle when the inner diameter is bigger than 0.7mm. It is also found that the turbine output torques related with electric power generation increase with the increase of inner diameter of nozzle. Present study reveals that current turbine provides a well performance for this SRCS and is helpful for the further development of solar thermal-energy technologies. Copyright (c) 2015 John Wiley & Sons, Ltd.