WP2 – Novel radial turbomachinery for sCO2 applications (Leader POLIMI)

WP2 aims at studying the configuration of optimal radial turbomachinery for sCO2 power/storage systems of medium power range (1-10 MWe), targeting maximum efficiency, reliability, and addressing the novel application with particular reference to the turbomachinery used for the storage cycle, reaching TRL 3.
Application of the whole set of computational models and tools developed by POLIMI for turbomachinery design & analysis is envisioned, from the mean-line codes for preliminary sizing to the most advanced two-phase CFD models for turbomachinery flows in near-critical conditions, interacting with UNIGE regarding the feasibility of cycle operating points, as optimised in WP1. 

In T2.1 the mean-line codes will be applied systematically to obtain surrogate models and sizing of all the turbomachinery involved in the processes [Romei 2020], basing on the WP1 optimised operating points, and identifying feasibility boundary conditions for cycle layout (e.g. minimum pressure distance from critical point). Such surrogate models (POLIMI) will be employed in WP1 for preliminary sizing the turbomachinery and estimating the related capital costs (UNIGE) as well as for eco-design quantitative assessments (UNIFI).

T2.2 will focus on the aerodynamic design of high-temperature machines (e.g. 350-550°C), both on a novel hot compressor (charging phase) and expander (discharging phase) with special attention to the related technology challenges: structural integrity aspects will be considered in the shape-optimization [Persico 2019], both introducing geometric constraints and performing dedicated FEM analyses, as well as the performance impact of leakages of secondary flows. The resulting high-temperature machines will be analysed to obtain high-fidelity maps of machine performance and rangeability.

T2.3 will consider the design of near-critical machines, including both compressor (discharging phase) and a novel cold sCO2 turbine. The emphasis will be made on the interplay between aerodynamics and thermodynamics, since the proximity to saturation makes these machines prone to experience phase change. The optimization will be based on the CFD models developed by POLIMI and featuring advanced thermodynamic models for simulating two-phase flows, which can deal with both cavitation and condensation (which may both occur, depending on the thermodynamic state at the intake resulting from the cycle optimization). The resulting near-critical machines will be analysed to obtain high-fidelity maps of machine performance and rangeability.