Investigation of thermodynamics of the supercritical CO2 Brayton cycle used in solar power at off-design conditions

The performance degradation of solar-power used SCO2 Brayton cycle under off-design condition is always a serious problem for the solar power station. However, very rare investigations have paid attention on it. The paper focuses on the behavior of SCO2 (supercritical carbon dioxide) Brayton cycle used for solar power generation under off-design condition using MATLAB code. Both the regenerative and recompression models, which are believed to have more promising performance, are established and compared. The variation of cycle performance on both annual and daily scales are investigated. It has been observed that the recompression model with specific bypass fraction always has superior performance under off-design condition. Meanwhile, for both models, the compressor is presented as an important component which limits the cycle performance under the off-design condition. Moreover, to keep with the reality, the weather factors of cloud coefficient (CC) and cloud cover coefficient (CCF) are firstly led into the off-design analysis of cycle. The relationship model between the SCO2 cycle performance and the CC, characterized by an approximate parabolic equation, has been developed.

Automated summary

This paper investigates the performance degradation of solar-power used SCO2 Brayton cycle under off-design condition using MATLAB code. The results show that the recompression model with specific bypass fraction performs better than the regenerative model under off-design condition. The compressor is identified as an important component that limits the cycle performance. In addition, the paper introduces weather factors and develops a relationship model between the SCO2 cycle performance and cloud coefficient.