Design and testing of a compressor and turbine for a 2MW sCO2 Power System in Waste Heat Recovery Applications

Due to concerns of global warming resulting from excessive greenhouse gas emissions, there has been growing interest in improving energy efficiency and developing carbon-free energy sources. In particular, a substantial amount of waste heat and energy remain unused worldwide. The development of energy conversion technologies capable of utilising waste heat could significantly reduce greenhouse gas emissions. Among these technologies, supercritical CO2 power generation has attracted significant attention. The intrinsic characteristics of CO2 make it environmentally friendly and suitable for operation in the supercritical regime. The sCO2 power system features a compact design, low pressure ratios, and adaptability to various heat sources. For these reasons, KEPCO (Korea Electric Power Corporation) has initiated the development of a 2MW sCO2 power system that utilises waste heat from gas engines to enhance energy efficiency. In sCO2 power systems, compressor operation poses considerable challenges due to substantial fluid property alterations occurring in the vicinity of the critical point during the compression process. To address this challenge, KEPCO has adopted a near-commercial compressor and employed an integrally geared compander to facilitate a successful demonstration and subsequent commercialisation. The present study focuses on the strategies adopted to ensure that the compressor operates smoothly at the low temperature inlet to improve cycle efficiency. Additionally, the start-up sequence is implemented with the aim of avoiding the dome and two-phase region. In addition to these points, the paper presents conceptual designs and configurations, manufacturing status, and test results of the compressor and turbine for KEPCO’s 2MW sCO2 power system, which has been under development since 2016.