基于超临界CO2布雷顿循环的 塔式太阳能集热发电系统
A Towered Solar Thermal Power Plant Based on Supercritical CO2 Brayton Cycle

为了提高太阳能热发电系统的性能,建立了以熔融盐为传热介质、再压缩式超临界CO2布雷顿(SCO2)循环为动力循环的塔式太阳能集热发电系统的分析模型,分析了定日镜、腔式吸热器、再压缩式SCO2发电系统3个子系统的性能,并研究了太阳辐射强度和采用不同底循环的SCO2发电系统对整个电站性能的影响,最后对采用不同类型的蒸汽动力循环和SCO2循环为动力子系统的5种塔式太阳能集热发电系统进行了对比。结果显示:吸热器的能量损失率最小,但损失率最大;随着太阳辐射强度增大,吸热器和整个电站的热效率和效率均增大;采用有机朗肯循环和跨临CO2(TCO2)循环作为底循环对SCO2发电系统进行余热回收,可提高整个电站的热效率,并且SCO2？？TCO2循环具有更高的热效率;相同条件下,不同的SCO2循环均比蒸汽动力循环具有更高的热效率和效率,其中基于SCO2？？TCO2的塔式太阳能电站热效率最高。
A towered solar thermal power plant using a recompression supercritical CO2 Brayton (SCO2) cycle with molten salt as the heat transfer fluid was established to improve the performance of solar thermal power plant. The exergy analysis on the subsystems of the heliostat field, the cavity receiver and the recompression SCO2 power cycle was performed. The effects of direct normal irradiation(DNI) and the type of SCO2 power cycle with different bottoming cycles on the system performance were tested, and the performances of solar power plants using different power cycles of SCO2 and steam power cycles were compared. The results show that: although the heat receiver has a least energy loss, it has the largest exergy loss rate; as DNI increases, the thermal and exergy efficiencies of the receiver and the whole plant increase; and adding a bottoming cycle such as ORC or TCO2 cycle to recover the waste heat of SCO2 power cycle can increase the overall efficiency. Especially, the SCO2？？TCO2 cycle can achieve higher thermal efficiency, and various SCO2 cycles can achieve higher thermal and exergy efficiencies compared with steam power cycles under the same conditions. The towered solar thermal power plant using a SCO2？？TCO2 cycle has higher cycle efficiency compared with other configurations