Turbomachine Design for Supercritical Carbon Dioxide Within the sCO₂-HeRo.EU Project

The paper aims to give an overview over the keystones of design of the turbomachine for a supercritical CO₂ (sCO2) Brayton cycle. The described turbomachine is developed as part of a demonstration cycle on a laboratory scale with a low through flow. Therefore the turbomachine is small and operates at high rotational speed. To give an overview on the development the paper is divided into two parts regarding the aerodynamic and mechanical design. The aerodynamic design includes a detailed description on the steps from choosing an appropriate rotational speed to the design of the compressor impeller. For setting the rotational speed the expected high windage losses are evaluated considering the reachable efficiencies of the compressor. The final impeller design includes a description of the blading development together with the final geometry parameters and calculated performance. The mechanical analysis shows the important considerations for building a turbomachine with integrated design of the three major components turbine, alternator and compressor (TAC). It includes different manufacturing techniques of the impellers, the bearing strategy, the sealing components and the cooling of the generator utilising the compressor leakage. Concluding the final design of the TAC is shown and future work on the machine is introduced.