超临界CO_2布雷顿循环的太阳能热发电系统分析

Analysis of solar thermal power generation system with supercritical CO_2 Brayton cycle

超临界CO_2(S-CO_2)循环系统在塔式太阳能热发电领域的应用潜力巨大。建立了基于闭式布雷顿循环的S-CO_2热发电系统模型,通过仿真计算比较了S-CO_2、空气、CO_2和He等4种工质在系统稳态运行时的工作性能,分析了各部分的损情况;研究了S-CO_2热发电系统随辐照强度变化的变工况特性。结果表明:S-CO_2系统热功性能好于另外3种工质;冷却器为系统损最大的部件;日间模式下,太阳辐照强度越高,系统热效率和输出净功率越大;系统的总效率在全年不同季节中相差不大;辐射强度突变时,系统热效率和效率表现出一定的滞后性。

The supercritical CO 2(S-CO 2)has high potential in tower solar thermal power generation industries.The S-CO 2 thermal power generation system model based on the closed Brayton cycle is established.By simulation calculation,the system performance in steady-state with four working materials(S-CO 2,air,CO 2,He)are compared.The exergy loss of each part is analyzed.By simulation calculation,the system performance in unsteady-state changing with radiation intensity is studied.The results show that S-CO 2 cycle has better system performance than other working fluid;cooler is the component with the largest system exergy loss;the better the solar irradiation condition is,the higher the thermal efficiency and the cumulative output power of the system is in the daytime mode;the overall efficiency of the system has little difference in different seasons in full year.When the radiation intensity suddenly changes,the thermal efficiency and exergetic efficiency exhibit hysteresis.