基于NSGA-II的多效蒸发海水淡化系统优化研究

中文关键词: 海水淡化  多效蒸发  热力蒸汽压缩  多目标优化  带精英策略的非支配排序遗传算法

中文摘要:

      热压缩多效蒸发（MEE-TVC）海水淡化系统在工程中易于实现大型化应用，因此装置的优化设计极为必要。基于热力学第一、二定律，建立系统能质平衡模型和㶲分析模型。基于总收益需求法，建立系统经济性模型。以造水比最大（GORmax）/比㶲耗最小（ed min）和单位造水成本最低（Cp,tot min）为目标，建立系统多目标优化模型，利用带有精英策略的非支配排序遗传算法（NSGA-II）求解得到Pareto最优解集，并将单目标和多目标优化方案进行对比分析。结果表明：与初始方案相比，热力性能单目标优化方案（ed min或GORmax）的单位造水成本增加约20%，而多目标优化方案则对三个目标均有改善。优化结果显示，所采用的优化方法可满足工程设计精度要求，且可为决策者提供基于不同偏好的优化方案。

英文摘要:

      Multi-effect evaporation with thermal vapor compression (MEE-TVC) desalination system is easy to realize large-scale application in engineering, so optimal design of the plant is extremely necessary. Energetic and exergic analysis models of MEE-TVC were established based on the first and second laws of thermodynamics. Based on the total revenue requirement method, the economic model was established. Maximizing the gained output ratio (GORmax)/minimizing the specific exergy consumption (ed min) and minimizing the unit cost of water production (Cp,tot min) were taken as the objectives to establish the multi-objective optimization model of MEE-TVC. The non-dominant sorting genetic algorithm with elite strategy (NSGA-II) was adopted to solve the multi-objective optimization problem considering thermodynamic and economic performances simultaneously. The optimal design schemes selected from the pareto optimal front were analyzed by comparing with the base case. Results indicate that compared with the base case, both the optimal schemes of single objective (ed min或GORmax) lead to about 20% rise of Cp,tot, while the optimal schemes of multi-objective have varying degrees of improvement for all the objectives. The optimization results show that the proposed optimization method can meet the requirements of engineering design accuracy, and provide decision-makers with optimization schemes based on different preferences.