Session: 30-11 Testing 2 and Systems 2

Submission Number: 178237

Performance Evaluation for Design and Off-Design Operation of Supercritical CO2 Gas Turbine Cycles 

In order to respond to the rapidly changing energy demand while utilizing intermittent renewable energy sources, energy generation systems able to efficiently follow such rapid changes are needed. As supercritical CO₂ gas turbine systems with oxy-fuel (methanol, hydrogen and methane) combustion are able to quickly follow a wide range of power demands, they are complementary with renewable generation systems. Therefore, this paper investigates the design and off-design performance characteristics of supercritical CO₂ gas turbines, with the goal of achieving high thermal efficiency for a wide range of power output.

This paper presents thermodynamic models for the evaluation of performance characteristics of supercritical CO₂ gas turbine cycle in design and off-design operation conditions. Hereby, thermal characteristics of the gas turbine cycle, such as thermodynamic states of the cycle, flow rates of recirculated CO₂, fuel and combustion products (CO₂ and H₂O), thermal and power capacities of the combustion chamber, gas turbine, regenerator, cooler and compressor, conditions for extraction of combustion CO₂ and H₂O from recirculated CO₂ and temperature differences in recuperator, are given. Their influence on the thermal efficiency of the system for design and off-design operation conditions (variable compressor inlet temperature, variable gas turbine inlet temperature, variable compressor pressure ratio, variable rotational speed) is evaluated. The gas turbine dynamic characteristics under varying rotational speed to adjust the system power generation are assessed, showing the resulting effect on the cycle parameters (pressure ratio, gas turbine inlet temperature), mass flows (compressor, gas turbine, fuel), recuperator heat capacity, temperature profiles in the recuperator, power output and thermal efficiency.

Results of the investigation show the interdependences between the gas turbine thermal characteristics. The results show that high thermal efficiency (approaching 60%) can be achieved for high pressures (up to 30 MPa) and high gas turbine inlet temperatures (up to 1473 K). If the rotational speed is reduced from n/n_d = 1 to n/n_d = 0.8, this causes a decrease of the power from 10 MW to 5.7 MW and a decrease of the thermal efficiency from 59% to 56%. Overall, this study demonstrates that supercritical CO₂ gas turbines achieve high thermal efficiency across a wide range of power outputs, confirming their potential to respond to varying power demand and align with renewable energy systems.

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