多目标超临界CO2循环设计与优化

Multi-objective Designing and Optimization of Rankine Cycle Using Supercritical CO2

在分析再热、回热朗肯循环基本特性基础上,对压气机和回热器进行了理论分析,先后加入二次回热和分级压缩对循环进行优化。结果表明优化效果显著：优化后的循环在压气机出口压力为30MPa时,相对于再热–一次回热循环热效率和净输出功分别提高了17.69%、6.42%;较一次回热–再热–分级压缩循环热效率提高了22.28%,换热器中平均换热温差降低了70.78%,换热器中不可逆损失降低了69.82%,最高循环热效率达到了43.9%。最后选取压气机进、出口压力等5个参数作为决策变量,对循环热效率、循环净输出功、循环总不可逆损失进行多目标优化,并通过设定各目标贡献系数得到了相应最优循环参数。

On the base of analysing the characteristics of the reheat and regenerative Rankine cycle, the compressor and regenerator were analyzed theoretically. Then twice-regenerator and stage compression were added in the cycle for optimization. The results show significant optimization effect. At 30MPa （compressor outlet pressure）, the Cycle efficiency and net output work after optimization are increased respectively by 17.69% and 6.42% compared to the reheat-once-regenerative cycle; and compared to the reheat-once-regen cycle, the cycle efficiency is improved by 22.28%; the average heat transfer temperature difference in the heat exchanger and the energy loss are respectively reduced by 70.78% and 69.82%. The maximum cycle efficiency is up to 43.9%. Finally the compressor inlet pressure, outlet pressure and other 3 parameters are chosen as decision variables for the multi-objective optimization of the cycle efficiency, net output work and total irreversible lose, and optimal cycle parameters are obtained by setting different contribution factors of the objectives.