Session: 30-14 Turbines 3 and Fluids 2

Submission Number: 178259

Radial Turbomachinery Design for Supercritical CO2 Gas Turbine Systems 

A supercritical CO₂ gas turbine cycle is a competitive power generation system, which is gaining significant research interest for numerous applications, due to its high thermal efficiency and compactness. It relies on the design of efficient and compact turbomachinery that can adapt to rapidly changing properties of the supercritical fluid. Due to the high pressure, high density and low volumetric flow rates of CO₂, the application of radial turbomachinery is promoted, especially in applications with lower gas turbine power output for distributed energy systems.

This paper evaluates and analyzes the design parameters of centrifugal compressors and radial expanders (gas turbines) as main components of the supercritical CO₂ gas turbine systems. Using the meanline concept, thermo-fluid characteristics of the flow fields in the compressor and expander are estimated and integrated into MATLAB models for determining optimal design parameters for the compressor and expander. Hereby, Coolprop is used to calculate the thermodynamic properties for CO₂. The models consider a wide range of published data obtained from theoretical and experimental investigations of centrifugal compressors and radial expanders, as well as the peculiarities of the supercritical CO₂ turbomachinery. The models are based on the dimensionless coefficients (flow rate coefficient and work coefficient), as well as on the influence of Reynolds number, Mach number and isentropic exponent on the compressor and expander efficiencies, and on the recommendations for some relative geometrical parameters (width of the flow field, diameters, and blade angles).

The results achieved with the model show that for a gas turbine system with power output up to 10 MW, the required impeller diameter is up to 75 mm, whereas the required rotational speed is high (up to 100000 rpm). The decrease of gas turbine capacity results in the requirement of extremely small impeller diameter and extremely high rotational speed. These findings confirm the compactness and the small size of the turbomachinery for supercritical CO₂ systems, significantly lower than conventional gas turbine systems. Finally, diagrams showing the dependency of turbomachinery diameters and rotational speed on the gas turbine capacity and gas turbine operating conditions, are given. Using these diagrams the range of application of the radial turbomachinery for the supercritical CO₂ gas turbine cycle is defined.

Presenting Author: Monika Sharevska Department of Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente

Presenting Author Biography: Monika Sharevska is a PhD Candidate at the Department of Thermal and Fluid Engineering, University of Twente. Her research focuses on modelling of supercritical CO2 gas turbine systems, integrated with renewable fuel generation systems. She holds a MSc in Mechanical Engineering from Saints Cyril and Methodius University in Skopje, Macedonia.

Authors:

Monika Sharevska Department of Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente
Maja Sharevska Department of Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente
Gerwin Hoogsteen Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente
Johann Hurink Faculty of Electrical Engineering, Mathematics and Computer Science, University of Twente
Artur Pozarlik Department of Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente
Yashar Hajimolana Department of Thermal and Fluid Engineering, Faculty of Engineering Technology, University of Twente