TURBOMACHINERY FLOWPATH DESIGN AND PERFORMANCE ANALYSIS FOR SUPERCRITICAL CO2

The development of Supercritical CO2 (S-CO2) power cycles is currently a major focus of the engineering and scientific community. The reason for such a growing interest in this type of power can be explained by the significant benefits in size and efficiency of power cycles, which use S-CO2 as a working fluid, as compared to conventional steam power generation. Many areas of application such as nuclear, solar, waste heat, energy storage, and clean coal combustion, are being studied for S-CO2 power production. Most of the publications discussing S-CO2 are concentrated on optimization of the cycle's thermodynamic characteristics, topping and bottoming and have been conceptualized based on the heat source. At the same time, numerous aspects of turbomachinery design are often overlooked or are not well understood. This article discusses some specific engineering aspects of the design of turbine flow path which uses S-CO2 as a working fluid. The following design options have been studied to determine the best turbine configuration: number of stages, rotational speed, impulse versus reaction, types of stages, and radial clearance influence. The effect of larger bending loads, resulting from high power density on nozzles and blade chords size and, consequently, turbine length, has also been studied. The authors hope that the results presented in the article will help the engineering community design better S-CO2 turbomachinery.