The objective of the present work is the investigation of a regenerative supercritical Brayton cycle (SBC) and its combination with an organic Rankine cycle (ORC). The study includes assessment, comparison, and single-objective optimization of these systems which are driven by molten salt solar power tower (SPT). First, the performances of 13 different working fluids from 18 introduced gases in the supercritical regions are studied in SBC and 6 working fluids are selected for further analysis. Then, a parametric analysis is performed to assess the effects of the compressor pressure ratio (CPR) and the Brayton turbine inlet temperature (BTIT) variations on net power output, exergy efficiency and total exergy destruction rate. After that, the optimum operating points of system performance are reported. The results show that using ORC causes all three output parameters to be improved. The highest net power output is 177321 kW and the highest exergy efficiency is 21.23% which are obtained by Helium as the working fluid. Moreover, the minimum exergy destruction is found to be 70576 kW allocating Oxygen. Finally, by comparing the examined gases in SBC, it can be concluded that using Helium leads to the best thermodynamic performance of the system.

本工作的目的是研究再生超临界布雷顿循环（SBC）及其与有机朗肯循环（ORC）的组合。该研究包括对由熔融盐太阳能塔（SPT）驱动的这些系统的评估，比较和单目标优化。首先，在SBC中研究了来自18种超临界区域引入气体中的13种不同工作流体的性能，并选择了6种工作流体进行进一步分析。然后，进行参数分析以评估压缩机压力比（CPR）和布雷顿涡轮进口温度（BTIT）变化对净功率输出，火用效率和总火用破坏率的影响。之后，报告系统性能的最佳工作点。结果表明，使用ORC会改善所有三个输出参数。通过氦气作为工作流体，最高净功率输出为177321 kW，最高火用效率为21.23％。此外，发现分配氧气的最小火用破坏为70576 kW。最后，通过比较SBC中的检查气体，可以得出结论，使用氦气可以使系统具有最佳的热力学性能。