In the middle of a heat wave it’s too hot to be writing too much. So, just a short one to advertise the latest paper that I have been involved in which was recently published in Applied Sciences as part of the Special Issue on Recent Advancement of Thermal Fluid Engineering in the Supercritical CO2 Power Cycle.

The paper explores the design of single-stage axial turbines for small-scale supercritical carbon dioxide power cycles, and has been conducted as part of the SCARABEUS project.

Download the open-access article for free here.

Mean-Line Design of a Supercritical CO2 Micro Axial Turbine

Supercritical carbon dioxide (sCO2) power cycles are promising candidates for concentrated-solar power and waste-heat recovery applications, having advantages of compact turbomachinery and high cycle efficiencies at heat-source temperature in the range of 400 to 800 degrees Celsius. However, for distributed-scale systems (0.1–1.0 MW) the choice of turbomachinery type is unclear. Radial turbines are known to be an effective machine for micro-scale applications. Alternatively, feasible single-stage axial turbine designs could be achieved allowing for better heat transfer control and improved bearing life. Thus, the aim of this study is to investigate the design of a single-stage 100 kW sCO2 axial turbine through the identification of optimal turbine design parameters from both mechanical and aerodynamic performance perspectives. For this purpose, a preliminary design tool has been developed and refined by accounting for passage losses using loss models that are widely used for the design of turbomachinery operating with fluids such as air or steam. The designs were assessed for a turbine that runs at inlet conditions of 923 K, 170 bar, expansion ratio of 3 and shaft speeds of 150k, 200k and 250k RPM respectively. It was found that feasible single-stage designs could be achieved if the turbine is designed with a high loading coefficient and low flow coefficient. Moreover, a turbine with the lowest degree of reaction, over a specified range from 0 to 0.5, was found to achieve the highest efficiency and highest inlet rotor angles.

Acknowledgement

The SCARABEUS project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 814985.