Experimental and Numerical Studies of Supercritical CO2 Test Loop with GAMMA code

Abstract

A Supercritical CO2 (S-CO2) Brayton cycle is globally viewed as one of the strong candidate for the next generation power conversion system for numerous applications, including the next generation nuclear power system. The major advantages of the S-CO2 Brayton cycle are its high thermal efficiency with mild temperature heat source and compactness. These features of the S-CO2 Brayton cycle come from a small compressing work by operating the compressor near the critical point of CO2 (around 30.98°C, 7.38MPa). Therefore, S-CO2 Brayton cycles are typically designed to set the compressor inlet condition closes to the critical point for achieving the best use of the behavior of CO2 like an incompressible fluid near the critical point of CO2. This operating condition also means the compressor inlet can be operating under two-phase or liquid region during transient situations such as changes of cooling system performance , load variations, etc. This can cause degradation of the system performance and damage major components designed to operate under single phase, supercritical state conditions. The Korea Advanced Institute of Science and Technology (KAIST) research team has been testing a lab-scale S-CO2 test loop namely SCO2PE (Supercritical CO2 Pressurizing Experiment) to develop various driving strategies focusing on the compressor operation near the critical point of CO2. In this study, the research for the S-CO2 system operation analysis will be carried out under the conditions of the cooling heat transfer capability variation with the gas system transient analysis code GAMMA and experimental data of the S-CO2 test facility, SCO2PE.