Design methodology of supercritical carbon dioxide brayton cycle turbomachinery for SMART application

Abstract

The Supercritical Carbon Dioxide(S-CO2) Brayton cycle has been gaining attention due to its compactness and high efficiency at moderate turbine inlet temperature. Previous S-CO2 cycle research works in the field of nuclear engineering were focused on its application to the next generation reactor with higher turbine inlet temperature than the existing conventional water-cooled nuclear power plants. However, it was shown in authors’ previous paper that the advantages of the S-CO2 Brayton cycle can be also further applied to the water-cooled Small Modular Reactor (SMR) with success, since SMR requires minimal overall footprint while retaining high plant performance. One of the major issues in the S-CO2 Brayton cycle is the selection and design of appropriate turbomachineries for the cycle. Since most of the existing turbomachineries in the nuclear industries operate with either incompressible fluid or ideal gas, it is not appropriate to choose the S-CO2 Brayton cycle turbomachineries under existing framework. This is because the S-CO2 Brayton cycle high efficiency is the result of the non-linear properties variation near the CO2 critical point, and turbomachineries have to operate near the critical point. Thus, the major focus of this paper is to suggest the design methodology of the turbomachineries necessary for the S-CO2 Brayton cycle coupled to water-cooled SMR conditions. The suggested design methodology was first tested with the existing experimental data to verify its capability. After then, it was applied to the suggested system to demonstrate its capability and to provide fundamental information for the future design of the suggested system.