太阳能辅助燃煤机组发电系统集热温度优化

为研究集热器工作温度对太阳能辅助燃煤机组发电系统中太阳能发电效率、成本的影响,从热力学第二定律出发,对用于太阳能辅助燃煤机组回热系统不同集成方式下太阳能热发电的火用效率进行分析,得出系统中太阳能发电的火用效率与集热器瞬时热效率及汽轮机抽汽效率之间的关系表达式,并结合LS-2槽式集热器(一种典型槽式集热器)的测试结果,对不同辐照条件下不同替代方式的热性能进行了比较。在此基础上,以太阳集热场辅助300MW燃煤机组发电系统为例对太阳能子系统的火用效率和发电成本(levelizedelectricity costs,LEC)进行分析,结果表明,当太阳直射辐射(direct normal irradiance,DNI)从300变化到1 000 W/m2时,对应的集热器最佳工作温度从277变化到317℃。

Optimization of Solar Collector Working Temperature for Solar Aided Coal-fired Power Generation Systems

In order to investigate the effect of solar collector working temperature on the efficiency of solar-to-electric and LEC(levelized electricity costs) in a solar aided coal-fired power generation system,based on the second law of thermodynamics,the exergy efficiencies of solar energy were analyzed under different replacements.The relationship between exergy efficiencies of solar energy and thermal efficiencies solar collector,extraction steam efficiencies of turbine was obtained.In the analysis,the thermal performance test results of LS-2(a typical PTC) were used.The performance of different replacements was compared under different direct normal irradiance(DNI).On this basis,the exergy efficiency and LEC of a PTC solar field aided a 300 MW unit were analyzed for an example.The results show that the optimum collector working temperature would change from 277 to 317 ℃ with the DNI from 300 to 1000 W/m2.