Design and Performance Analysis of a Solar-Coal-Fired Complementary Power System Based on the S-CO2 Brayton Cycle

To make solar energy conversion more effective and enable effective complementary utilization of multiple energy sources, two types of solar-coal-fired complementary power (SCCP) systems, which use the supercritical CO2 Brayton cycle, are investigated and their layouts are improved. In addition, a thermodynamic performance analysis is carried out. The results show that, as the amount of work done by the solar energy module increases, the coal saving rate increases linearly and proportionally in both SCCP systems. Also, the supplementary electric power generated by the solar field increases. The two improved layouts increase the net efficiency of the SCCP systems significantly (SCCP1: from 43.60% to 47.65%, SCCP2: from 43.60% to 47.67%). More specifically, the net efficiency of the improved layout for SCCP2 increases faster than that for SCCP1 (with its improved layout), when the second split ratio (SR2) exceeds 0.031. When the net efficiency remains unchanged, the SR2 for SCCP2 improved layout has a wide range. Furthermore, both the operation performance and operating mode conversion of the basic system are studied for varying sunlight conditions. The simulation results are consistent with the expectations, which underlines the development potential of the system to a certain extent.