Design and Evaluation of Small-scale Supercritical Carbon Dioxide System with Solar Heat Source

This paper focuses on the design of a 12-kW small-scale supercritical CO2 test loop. A theoretical study, stabilization, and optimization of carbon dioxide were carried out with the application of a solar heat source based on solar thermal data in Pohang. The thermodynamic cycle of the test facility is a Rankine cycle (transcritical cycle), which contains liquid, gas, and supercritical CO2. The system is designed to achieve 6.98% efficiency at a maximum pressure of 12 MPa and a maximum temperature of 70°C. In addition, the optimum turbine inlet temperature and pressure were calculated to increase the cycle efficiency, and the application of an internal heat exchanger (IHX) was simulated. It was found that the maximum efficiency increases to 18.75%. The simulation confirmed that the efficiency of the cycle is 6.7% in May and 6.26% in June.