Optimal Thermal Power Cycle Analysis of Concentrated Solar Power System with the Receiver Surface Radiation Characteristics

Abstract

Concentrated solar power (CSP) technology can provide stable and continuous power output, and has the potential to be the basic electricity supply. The focused solar energy is converted into the heat by the receiver of the CSP plant, and the high-temperature solar heat-absorbing surface is the core component of most existing receivers. However, the correlation between the radiation characteristics of the receiver surface and the CSP performance is not fully studied. Therefore, in this paper, the energy transfer path of the CSP power generation system was established based on steam Rankine cycle, air Brayton cycle and carbon dioxide Brayton cycle, and the coupling relationship between the radiation characteristics of the receiver surface and the important parameters of the CSP system was analyzed, as well as the impact on the overall thermal-electric conversion efficiency of the system. How to quantitatively select the cut-off wavelength of the selective coating is given for the first time. The overall thermal-electric conversion efficiency of CO2 Brayton cycle remained the highest among the three cycles in most situations. In the range of 1-100 kW/m2, the larger the solar incident energy flow is expected as it has the higher optimal heat collection temperature and the overall thermal-electric conversion efficiency. When the emissivity combination was improved from 0.65-0.25 to 1-0, the overall thermal-electric conversion efficiency can be improved by 18%-27%.

Keywords: CO2 Brayton cycle, concentrated solar power, efficiency, emissivity, solar receiver