An improved self-condensing transcritical CO Rankine cycle (TCRC) with two-stage ejector on the basis of the preliminarily designed one with an ejector is proposed in this study, aiming to enable the condensation of CO using conventional cooling source and achieve desirable performance. Thermodynamic and economic mathematical models of the improved self-condensing TCRC are developed, and detailed parametric analysis is carried out to investigate the effect of main parameters on both thermodynamic and economic performances of the system. Then the multi-objective optimization is conducted to examine the potential for performance enhancement. Thereafter, a comparative analysis of the performances between the improved self-condensing TCRC and preliminary self-condensing TCRC is performed. Results show that the improved self-condensing TCRC with two-stage ejector outperforms the preliminary one with an ejector in both thermodynamic and economic aspects, achieving a 3.93% increase in maximum exergy efficiency and a 13.84% reduction in minimum unit net power cost through multi-objective optimization. Under optimal conditions, the exergy efficiency for the improved self-condensing TCRC is 45.48% with a unit net power cost of 0.1241$/kWh.

中文翻译：

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用于低品位热利用的改进型自冷凝跨临界二氧化碳朗肯循环的热力学、经济分析和多目标优化，具有两级喷射器

本研究在初步设计的带喷射器的基础上提出了一种改进的带两级喷射器的自冷凝跨临界CO朗肯循环（TCRC），旨在利用常规冷却源实现CO的冷凝并获得理想的性能。建立了改进的自冷凝TCRC的热力学和经济数学模型，并进行了详细的参数分析，以研究主要参数对系统热力学和经济性能的影响。然后进行多目标优化以检查性能增强的潜力。此后，对改进的自冷凝TCRC和初步自冷凝TCRC之间的性能进行了比较分析。结果表明，改进型两级喷射器自冷凝式TCRC在热力学和经济性方面均优于带喷射器的初级TCRC，通过多级优化，最大火用效率提高了3.93%，最小单位净电成本降低了13.84%。 - 客观优化。在最佳条件下，改进的自冷凝式TCRC的火用效率为45.48%，单位净电费为0.1241$/kWh。