Abstract: In view of the large fluctuation of the gas turbine load in the distributed energy system, the current researches on Organic Rankine Cycle (ORC) pay more attention to the comparison of the thermal performance of the same heat absorption with the initial parameters, but rarely consider the impacts of decrease in both flue gas temperature and mass flow rate on system performance causing by the gas turbine load reduction. Based on the characteristic model constructed by HYSYS platform, optimization scheme of the variable working condition ORC working medium was studied using the narrow⁃point temperature difference in the heat exchanger as the constraint condition. Under the variable load condition of gas⁃fired power plants, the operating parameters of the maximum net output power of the system are optimized. The cycle performances of varies working fluids with different compositions were compared of the characteristics of heat rate, mass flow and AP. The net output of R152a system shows obvious advantages on the heat rate and mass flow rate, compared with that in the mixed working medium in the selected working condition range, while the condenser AP value and the system heat recovery rate exhibit opposite performance. This work provides a reference database for the studying of the binary non⁃azeotropic mixture of ORC system.

Key words: Organic rankine cycle, Off?design performance, Waste heat recovery, Non?azeotropic mixture

摘要： 鉴于分布式能源系统中燃气轮机负荷波动较大，而目前对有机朗肯循环（Organic Rankine Cycle，ORC）研究更注重相同吸热量及其热力性能随初始参数变化的对比，很少考虑燃气轮机负荷降低时导致烟气温度和质量流量均下降对系统性能的影响。通过HYSYS平台构建特性模型，以换热器内窄点温差为约束条件，研究变工况特性ORC工质优选方案。在燃气电厂变负荷工况下，寻求对应系统最大净输出功的最佳运行参数，从热耗率、质量流量和AP值等特性比较，采用不同组分工质的循环性能，经对比发现R152a系统净输出功、热耗率、质量流量在所选工况区间内相比混合工质具有明显优势，而冷凝器AP值及系统热回收率却相反。研究结果为ORC系统二元非共沸混合工质优选提供参考。

关键词: 有机朗肯循环, 变工况特性, 余热回收, 非共沸混合工质