Design of a single-shaft compressor, generator, turbine for small-scale supercritical CO2 systems for waste heat to power conversion applications

Abstract

Waste heat to power conversion is a promising approach to reduce the carbon intensity in industry and manufactured goods. In this framework, bottoming thermodynamic cycles using supercritical carbon dioxide as working fluid (sCO2) might be a suitable and efficient technology to consider especially for heat sources characterized by streams at high temperatures (>300°C). The compactness of sCO2 turbomachinery is one of the advantages of sCO2 systems over the conventional technologies; on the other hand, the reduced dimensions limits the bottom end of the power size achievable with such systems. The scarce amount of scientific and industrial literature for electrical power sizes between 50 and 100 kW further demonstrates this. The current research work summarizes the design procedure as weil as the technical and technological challenges involved in the design of a single-shaft compressor, generator, turbine unit (CGT) for a sCO2 system with a 50kWe nominal power output. First an overview of the High Temperature Heat To power Conversion facility (HT2C) under construction at Brunel University London will be presented. Then, highlights of the CGT design are presented in terms of structural and packaging aspects as weil as with regards to the ancillary lubrication, drainage and cooling loops.