Abstract
Industrial process heating is dominated by fossil-based energy sources, making energy consumption in this sector extremely carbon intensive. High-temperature heat pumps (HTHPs) represent an attractive technology to replace fossil-based heat production, enabling decarbonization combined with improved energy efficiency. This paper presents the evaluation of a 4-stage piston compressor geometry for a steam-based HTHP for different cycle layouts, designed for a temperature lift of 80 K and producing steam at 200 °C and 15.5 bara. The study is performed within the GEOSYN Horizon Europe project. The development of a novel compressor using steam as the working fluid, consisting of four compression stages, introduces design challenges related to correct sizing of the cylinder geometry to optimize COP, while also satisfying constraints such as maximum
discharge temperatures and the need for interstage steam bypass or recycling in different cycle layouts. The evaluation of different methods for interstage steam desuperheating and their impact on the compressor geometry is presented. Dynamic modelling of the HTHP has been carried out to investigate the operational performance under various conditions and constraints, from start-up using air as the working fluid to steadystate operation with steam. The results support the development of the overall system design and operational strategy of the HTHP, as well as the dimensioning of key components.