Development of operation strategy for recompression supercritical CO₂ cycle with intercooled main compressor under off-design condition

¹ MOE Key Laboratory of Thermal Fluid Science and Engineering, Xi’an Jiaotong University, Xianning West Road. 28, Xi’an 710049, PR China
² Institute for Energy Engineering, Technische Universität Berlin, Marchstr. 18, 10587 Berlin, Germany

Abstract

The supercritical carbon dioxide (S-CO₂) cycle is regarded as a potential option for the next generation power conversion system. Concentrated solar power (CSP) plant is one of the promising scenarios to adopt the S-CO₂ cycle due to the appealing thermal efficiency and the ability to integrate thermal storage and dry cooling. Among various cycle configurations of S-CO₂ cycle, the recompression S-CO₂ cycle with intercooled main compressor is one of the optimal choices that can provide superior efficiency and a large enough temperature differential for thermal input, which together contribute to the minimization of the overall levelized cost of electricity (LCOE) of the whole CSP plant. The off-design performance and the associated control scheme have important effects on the CSP plant. This paper develops an off-design model for the recompression S-CO₂ cycle with intercooled main compressor for the commercialized hundred-megawatt CSP plant. The effects of different off-design conditions on cycle performance are first evaluated. Different operating strategies regarding the control of cycle maximal pressure and preventing abnormal compressor conditions during off-design operation are then presented and compared. This work is expected to provide knowledge for the optimal control of recompression S-CO₂ cycle with intercooled main compressor during the real operation of the CSP plant.