低温过热有机朗肯循环工质筛选及参数优化  

WORKING FLUID SELECTION AND PARAMETRIC OPTIMIZATION OF A SUPERHEAT ORGANIC RANKINE CYCLE FOR LOW TEMPERATURE WASTE HEAT RECOVERY

作　　者：李鹏[1] 韩中合[1] 梅中恺 韩旭[1] 王智[1] Li Peng, Han Zhonghe, Mei Zhongkai, Han Xu, Wang Zhi(Key Lab of Condition Monitoring and Control for Power Plant Equipment, North China Electric Power University Ministry of Education, Baoding 071003, China)

机构地区：[1]华北电力大学电站设备状态监测与控制教育部重点实验室

出　　处：《太阳能学报》2018年第9期2393-2402,共10页Acta Energiae Solaris Sinica

基　　金：国家自然科学基金(51306059);国家科技支撑计划(2014BAA06B01);中央高校基本科研业务费专项资金(2017XS120)

摘　　要：以低温烟气余热驱动的内回热有机朗肯（organic Rankine cycles，ORC）系统为例，分析系统净输出功、透平膨胀比、热效率、热回收率、炯损失、炯效率以及比净功等热力性能评价指标随蒸发温度和过热度的变化规律，确定系统最佳工质及最优蒸发温度和过热度。提出用预热系数、潜热系数、过热系数与内回热系数解释系统热效率随工质临界温度变化的原因。研究结果表明：随蒸发温度升高，系统净输出功先增大后减小，热回收率和总炯损减小，透平膨胀比、热效率和炯效率增大。适当过热对于ORC系统十分重要，不仅能降低透平膨胀比，提高系统运行稳定性，还可减小系统总炯损，提高系统炯效率，增大工质比净功。经对比发现，丁烷为适合该文所选热源的最佳工质，在蒸发温度为100℃、过热度为5℃工况下能取得最佳热力性能。Both working fluid selection and parametric optimization are two key issues in performance optimization of organic Rankine cycle system. In order to effectively recover the waste flue gas heat, an organic Rankine cycle （ORC） with internal heat exchanger was established. A thermodynamic model was established to analysis the variation of net power output, turbine expansion ratio, thermal efficiency, heat recovery efficiency, exergy destruction, exergy efficiency and specific net power output with increment in both evaporation temperature and superheat degree. Preheating coefficient, latent heat coefficient, superheating coefficient and internal heat coefficient were put forward to study the effect of critical temperature on the thermal efficiency. The calculated resultsed revealed that with increase in evaporation temperature the net output power increases firstly and then decreases. And the expansion ratio, heat recovery efficiency and exergy destruction decrease while the thermal and exergy efficieneies increase with the increment in evaporation temperature. A proper degree of superheat is not only propitious to reduce the expansion ratio and improve the operational stability but also beneficial to decreases the exergy destruction and increase the exergy efficiency and specific net power output. Therefore a proper degree of superheat is essential to ORC system. It was also concluded that butane is the most suitable working fluid, and optimal thermal performance can be obtained when evaporation temperature is 100℃ and superheat degree is 5 ℃.

关 键 词：有机朗肯循环 临界温度 膨胀比 稳定性 热力性能 

分 类 号：TK123[动力工程及工程热物理—工程热物理]