超临界有机朗肯循环地热发电系统性能及多目标优化研究

Abstract The supercritical Organic Rankine Cycle (ORC) stands out as a promising technology for thermal power conversion due to its high thermal efficiency, straightforward equipment requirements, and compact footprint. Despite its potential, existing optimization design methods for supercritical ORC systems face several limitations, such as focusing on single-objective optimization, and relying on empirically when defined pinch point temperature differences. These limitations often result in a restricted operating parameter range, which may lead to suboptimal solutions or even render the optimization process infeasible under complex constraints. To overcome these limitations, this study proposes a novel multi-objective optimization design method that introduces variable pinch point temperature differences into the optimization process. The system performance was evaluated using three optimization objectives: net output power, heat exchange area, and specific investment cost, and the comprehensive performance for each evaluated case was calculated using the Entropy Weight Method. Compared to traditional methods, this approach eliminates the reliance on empirical assumptions for selecting the pinch point temperature, and expands the feasible matching range between turbine inlet temperature and turbine inlet pressure​ by over 50%, enabling more accurate and flexible optimization. As a result, the optimized system achieves a 3.1% increase in net output power, a 4.3% reduction in heat exchanger area, and a 9.3% improvement in the comprehensive performance. Finally, the proposed strategy is applied to low-temperature, medium-temperature, and high-temperature geothermal power systems, demonstrating its broad applicability and offering valuable insights for the optimal design and deployment of supercritical ORC systems in geothermal energy utilization.