Preliminary Test Results of Supercritical CO2 Brayton Cycle Integral Experiment Loop (SCIEL)

Abstract

A supercritical CO2 (S-CO2) Brayton cycle has a great potential to become one of the future power conversion systems to improve economics and thermal efficiency compared with the conventional technology. This can be realized through high thermal efficiency at relatively moderate turbine inlet temperature (450~650oC), a simple cycle layout, and small component size (i.e. turbomachineries and heat exchangers), alleviation of turbine blade erosion issue. In spite of these merits, still some issues need to be resolved some technical challenges to achieve the theoretical thermal efficiency. The development of Supercritical CO2 Brayton Cycle Integral Experiment Loop (SCIEL) was started to overcome the technical issues, such as the operation near the critical point, bearings and seal technologies, and establishing control strategies. SCIEL is planned to be constructed with step by step approach to gradually reduce uncertainties of the system operation. Due to high uncertainties of the operation near the critical point (30.98oC, 7377kPa), the compressor performance test loop which consists of a compressor and a pre-cooler was constructed as the first step. To fundamentally remove the thrust bearing issue, the concepts of double suction configuration and shrouded impeller were newly adopted to the SCIEL compressor instead of the conventional Turbo-Alternator-Compressor (TAC) configuration. Currently SCIEL is at the second stage of the low pressure ratio power generation loop, which has the indirect heating system and a power turbine to the compressor performance test loop. The SCIEL is in Korea Atomic Energy Research Institute (KAERI). This loop can conduct not only the turbine power generation test but also the compressor performance test by maneuvering control valves. This paper summarizes the current technical challenges that authors face and the preliminary results of compressor performance tests and turbine power generation tests are discussed.