有机工质低温余热发电系统多目标优化设计

Multi-objective Optimization of Low-temperature Waste-heat ORC Power Generation Systems

针对现有有机朗肯循环单目标优化设计的局限性,从热力性、经济性等多方面对有机工质低温余热发电系统进行多目标优化设计.以系统效率最大和总投资费用最小为目标函数,选取透平进口温度、透平进口压力、余热锅炉节点温差、接近点温差和冷凝器端差等5个关键热力参数作为决策变量,利用非支配解排序遗传算法(NSGA-II)分别对采用R123、R245fa和异丁烷的有机工质余热发电系统进行多目标优化,获得不同工质的多目标优化的最优解集(Pareto最优前沿),并采用理想点辅助法从最优解集中选择出最优解及相应的系统最佳热力参数组合.结果表明:在给定余热条件下,从热力性能和经济性两方面考虑,R245fa是最优的有机工质,从多目标优化的最优解集中选择出的最佳效率为10.37%,最小总投资费用为455.84万元.

Owing to the limitations of single-objective optimization on existing organic Rankine cycle （ORC） power generation system, a multi-objective optimization design was conducted for the low-tempera- ture waste-heat ORC power generation system from the point of view of thermodynamic and economic as- pects, by taking maximum exergy efficiency and minimum investment of system as the objective functions, selecting 5 key thermal parameters as the decision variables, such as turbine inlet temperature, turbine in- let pressure, pinch temperature difference, approach temperature difference and condenser temperature difference, etc., optimizing the ORC power generation system with working fluids R123, R245fa and isobutane using non-dominated sorting genetic algorithm （NSGA-II）, and subsequently Pareto optimal so- lutions were obtained, from which the optimum design solution with optimal combinations of system ther- mal parameters was selected with the aid of an ideal point. Results show that under the given waste heat conditions, R245fa is the optimal working fluid in consideration of both the thermodynamic performance and the economic efficiency. The optimum solution shows an optimal exergy efficiency of 10.37% and a minimum investment of 4 558 400 Yuan.