Fast Turbomachinery Design Tools for Multi-Good Plants Based on sCO2 Cycles: the MUSIC Project Experience

Global warming and the impact of greenhouse gas emissions are currently one of the main topics of the international policy and scientific community. In the context of EU and national energy strategies, one of the most interesting research areas is the use of supercritical carbon dioxide (sCO2) as a working fluid to achieve high performance energy systems. With this aim the paper presents the development and the validation of mean-line tools for the design of centrifugal compressors and radial inflow expanders. The target plant is a multi-good system that uses concentrated solar power (CSP) to produce both electricity and green hydrogen (H2), conceived in the framework of the MUSIC project funded by the Italian Ministry of University and Research. The mean-line approach is essential during the preliminary phase of turbomachinery sizing as it quickly provides geometric and performance quantities. In particular, the choice of sCO2 as the working fluid complicates the study of the compressor since the fluid is close to its critical point at the compressor inlet. For this reason, it is needed to have a reliable tool that provides preliminary solutions for compressor design. The mean-line tools are based on enthalpy loss correlations which account for the sources of entropy generation. Since the performance of turbomachinery is a key enabler for the success of the developed solutions, the impact of main design parameters, such as the size parameter (SP), the pressure ratio (PR), and the volume expansion ratio (VR), is scrutinized in order to assess their effect on efficiency. The results of the parametric analysis are used to quantify the influence of turbomachinery performance on the overall cycle under nominal conditions.