The optimal design of a compression refrigeration system(CRS) with multiple temperature levels is very important to chemical process industries and also represents considerable challenges in process systems engineerin...The optimal design of a compression refrigeration system(CRS) with multiple temperature levels is very important to chemical process industries and also represents considerable challenges in process systems engineering. In this paper, a general methodology for the optimal synthesis of the CRS, which simultaneously integrates CRS and Heat Exchanger Networks(HEN) to minimize the total compressor shaft work consumption based on an MINLP model, has been proposed. The major contribution of this method is in addressing the optimal design of refrigeration cycle with variable refrigeration temperature levels. The method can be used to make major decisions in the CRS design, such as the number of levels, temperature levels, and heat transfer duties. The performance of the developed methodology has been illustrated with a case study of an ethylene CRS in an industrial ethylene plant, and the optimal solution has been examined by rigorous simulations in Aspen Plus to verify its feasibility and consistency.展开更多
Steady-state non-dominated sorting genetic algorithm (SNSGA), a new form of multi-objective genetic algorithm, is implemented by combining the steady-state idea in steady-state genetic algorithms (SSGA) and the fitnes...Steady-state non-dominated sorting genetic algorithm (SNSGA), a new form of multi-objective genetic algorithm, is implemented by combining the steady-state idea in steady-state genetic algorithms (SSGA) and the fitness assignment strategy of non-dominated sorting genetic algorithm (NSGA). The fitness assignment strategy is improved and a new self-adjustment scheme of is proposed. This algorithm is proved to be very efficient both computationally and in terms of the quality of the Pareto fronts produced with five test problems including GA difficult problem and GA deceptive one. Finally, SNSGA is introduced to solve multi-objective mixed integer linear programming (MILP) and mixed integer non-linear programming (MINLP) problems in process synthesis.展开更多
In this paper, an improved hybrid differential evolution-estimation of distribution algorithm (IHDE-EDA) is proposed for nonlinear programming (NLP) and mixed integer nonlinear programming (MINLP) models in engineerin...In this paper, an improved hybrid differential evolution-estimation of distribution algorithm (IHDE-EDA) is proposed for nonlinear programming (NLP) and mixed integer nonlinear programming (MINLP) models in engineering optimization fields. In order to improve the global searching ability and convergence speed, IHDE-EDA takes full advantage of differential information and global statistical information extracted respectively from differential evolution algorithm and annealing mechanism-embedded estimation of distribution algorithm. Moreover, the feasibility rules are used to handle constraints, which do not require additional parameters and can guide the population to the feasible region quickly. The effectiveness of hybridization mechanism of IHDE-EDA is first discussed, and then simulation and comparison based on three benchmark problems demonstrate the efficiency, accuracy and robustness of IHDE-EDA. Finally, optimization on an industrial-size scheduling of two-pipeline crude oil blending problem shows the practical applicability of IHDE-EDA.展开更多
In this paper the MINLP method proposed in Part(Ⅰ)is illustrated by applying it tothe synthesis problem of non-sharp distillation sequences.A MINLP formulation for the synthesis ofdistillation sequences with non-shar...In this paper the MINLP method proposed in Part(Ⅰ)is illustrated by applying it tothe synthesis problem of non-sharp distillation sequences.A MINLP formulation for the synthesis ofdistillation sequences with non-sharp separation is proposed.In this formulation the recoveries of thekey components are introduced as optimization variables and this makes it possible to synthesize adistillation sequence with specified component recoveries,and at the same time,renders the MINLPproblem nonconvex.The solution procedure is illustrated with three example problems.展开更多
An algorithm for global optimization of a class of nonconvex MINLP problems is devel-oped and presented in this paper.By partitioning the variables,dual representation of the primal ofsubproblems and outer-approximati...An algorithm for global optimization of a class of nonconvex MINLP problems is devel-oped and presented in this paper.By partitioning the variables,dual representation of the primal ofsubproblems and outer-approximation strategy are used to develop a representative relaxed iterativeproblem.Then the original MINLP problem is replaced by a series of subproblems and relaxediterative problems.By exploiting the particular form of the nonconvex MINLP problem,the feasibleregion of this problem is explicitly included in the representative problem,thus the inconvenienceencountered with the GBD method can be avoided.The proposed method is illustrated andinterpreted geometrically with an example problem.展开更多
基金Supported by the National Natural Science Foundation of China(21676183)
文摘The optimal design of a compression refrigeration system(CRS) with multiple temperature levels is very important to chemical process industries and also represents considerable challenges in process systems engineering. In this paper, a general methodology for the optimal synthesis of the CRS, which simultaneously integrates CRS and Heat Exchanger Networks(HEN) to minimize the total compressor shaft work consumption based on an MINLP model, has been proposed. The major contribution of this method is in addressing the optimal design of refrigeration cycle with variable refrigeration temperature levels. The method can be used to make major decisions in the CRS design, such as the number of levels, temperature levels, and heat transfer duties. The performance of the developed methodology has been illustrated with a case study of an ethylene CRS in an industrial ethylene plant, and the optimal solution has been examined by rigorous simulations in Aspen Plus to verify its feasibility and consistency.
文摘Steady-state non-dominated sorting genetic algorithm (SNSGA), a new form of multi-objective genetic algorithm, is implemented by combining the steady-state idea in steady-state genetic algorithms (SSGA) and the fitness assignment strategy of non-dominated sorting genetic algorithm (NSGA). The fitness assignment strategy is improved and a new self-adjustment scheme of is proposed. This algorithm is proved to be very efficient both computationally and in terms of the quality of the Pareto fronts produced with five test problems including GA difficult problem and GA deceptive one. Finally, SNSGA is introduced to solve multi-objective mixed integer linear programming (MILP) and mixed integer non-linear programming (MINLP) problems in process synthesis.
基金Supported by the National Basic Research Program of China (2012CB720500)the National Natural Science Foundation of China (60974008)
文摘In this paper, an improved hybrid differential evolution-estimation of distribution algorithm (IHDE-EDA) is proposed for nonlinear programming (NLP) and mixed integer nonlinear programming (MINLP) models in engineering optimization fields. In order to improve the global searching ability and convergence speed, IHDE-EDA takes full advantage of differential information and global statistical information extracted respectively from differential evolution algorithm and annealing mechanism-embedded estimation of distribution algorithm. Moreover, the feasibility rules are used to handle constraints, which do not require additional parameters and can guide the population to the feasible region quickly. The effectiveness of hybridization mechanism of IHDE-EDA is first discussed, and then simulation and comparison based on three benchmark problems demonstrate the efficiency, accuracy and robustness of IHDE-EDA. Finally, optimization on an industrial-size scheduling of two-pipeline crude oil blending problem shows the practical applicability of IHDE-EDA.
基金Supported by National Natural Science Foundation of China
文摘In this paper the MINLP method proposed in Part(Ⅰ)is illustrated by applying it tothe synthesis problem of non-sharp distillation sequences.A MINLP formulation for the synthesis ofdistillation sequences with non-sharp separation is proposed.In this formulation the recoveries of thekey components are introduced as optimization variables and this makes it possible to synthesize adistillation sequence with specified component recoveries,and at the same time,renders the MINLPproblem nonconvex.The solution procedure is illustrated with three example problems.
基金Supported by the National Natural Science Foundation of China
文摘An algorithm for global optimization of a class of nonconvex MINLP problems is devel-oped and presented in this paper.By partitioning the variables,dual representation of the primal ofsubproblems and outer-approximation strategy are used to develop a representative relaxed iterativeproblem.Then the original MINLP problem is replaced by a series of subproblems and relaxediterative problems.By exploiting the particular form of the nonconvex MINLP problem,the feasibleregion of this problem is explicitly included in the representative problem,thus the inconvenienceencountered with the GBD method can be avoided.The proposed method is illustrated andinterpreted geometrically with an example problem.
