基于变温度热源的ORC发电系统的优化分析

Optimization Analysis of ORC Power Generation System Based on Variable Temperature Heat Source

考虑到实际中较多中低温余热为不稳定热源,针对120℃~150℃的不稳定热源,建立了有机朗肯循环数学模型。选用4种工质,并以R1234ze为例,基于变温度热源,以蒸发温度、过热度以及蒸发器窄点温差为变量,分别对系统的热力性能与经济性能进行了分析。确立了由㶲效率与净现值构成的综合目标函数Fx,并利用遗传算法进行多参数的目标优化,找出4种工质变温度热源下的最优运行参数。结果表明:综合目标函数Fx可同时反映系统的热力性能与经济性能;4种工质的临界温度不同,对应性能最佳时的热源温度区间不同;给定条件下,R1234ze的综合经济性能最优,R245fa的热力性能最优,R1234yf的应用潜力最差。

Considering that a lot of waste heat at low-to-medium-temperature is unstable heat source in practice,this paper established an organic Rankine cycle mathematical model for unstable heat source at 120℃~150℃.Selecting four types of working medium and taking R1234ze as an example,based on the variable temperature heat source,the thermal and economic performance of the system are analyzed respectively by taking evaporation temperature,superheat and narrow point temperature difference as variables.The comprehensive objective function Fx composed of energy efficiency and net present value is established,and the genetic algorithm is used to carry out multi-parameter objective optimization to find the optimal operating parameters of four working medium under variable temperature heat source The results show that the generalized objective function Fx can reflect the thermal performance andeconomic performance of the system at the same time. The critical temperature of the four workingmedium is different, and the temperature range of the heat source corresponding to the best comprehensiveperformance is different. Under given conditions, R1234ze has the best comprehensive economicperformance;R245fa has the best thermal performance, and R1234yf has the worst application potential.