为高效转换塔式太阳能系统的聚光热量,将混合工质（CO2/R290、CO2/R600a和CO2/R601a）应用于再压缩动力循环,建立塔式太阳能热发电系统的热力模型,并基于典型日（春分、夏至、秋分、冬至）的辐照条件对系统热力性能进行分析比较。结果表明：在混合工质不可燃的质量分数范围内,随着CO2质量分数的增加,3种混合工质的系统热效率、效率和发电量均先升高后降低,最优质量分数分别为0.7/0.3、0.8/0.2和0.8/0.2。在3种混合工质中,CO2/R290（0.7/0.3）的系统性能最佳,春分的系统热效率为18.99%,发电量为17.1 MWh。在不同典型日下,夏至系统热效率和效率略低于冬至,但其发电量最高。基于3种混合工质探究透平进口温度、循环最低温度、高温熔盐温度和分流比对系统性能的影响,结果表明,系统存在最佳分流比使热效率和发电量最高,相应分流比的范围为0.70~0.75。
Abstract
In order to efficiently convert the concentrated heat of solar power tower system, three mixtures （CO2/R290, CO2/R600a and CO2/R601a） are applied to the recompression power cycle. An integrated model is established for the solar power tower system, and the corresponding thermal performances are analyzed and compared under the irradiation conditions of typical days in four seasons（March 20, June 21, September 23 and December 21）. The obtained results show that： in the mass fraction range of CO2-based mixture with nonflammability, as the CO2 mass fraction increases, the system thermal efficiency, exergy efficiency and generated power of the mixtures increase first and then decrease. The optimal mass fractions are 0.7/0.3, 0.8/0.2 and 0.8/0.2, respectively. Among these three mixtures, CO2/R290 （0.7/0.3） has the best performances with the thermal efficiency 18.99% and generated power 17.1 MWh at Vernal Equinox. Under different typical days, the thermal efficiency and exergy efficiency of Summer Solstice are slightly lower than those of Winter Solstice, but the generated power is the highest. Furthermore, based on the three CO2-based mixtures, effects of turbine inlet temperature, minimum cycle temperature, hot molten salt temperature and split ratio on system performances are also investigated. It’s found that there exists an optimal split ratio to achieve the highest thermal efficiency and generated power. For the recompression power system, the optimal split ratio is in the range of 0.70-0.75.
关键词
塔式太阳能热发电系统 /
CO2混合工质 /
再压缩动力循环 /
热力性能
Key words
solar power tower system /
CO2 -based mixture /
recompression power cycle /
thermal performance
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基金
国家自然科学基金（52106037）; 福建省新能源发电与电能变换重点实验室开放基金（KLIF-202106）; 中国长江三峡集团项目（202003024）
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