The flow distribution and mixing performance of the laminar flow in the PBT impeller-stirred tank were investigated in this study.The variation along with mixing time of the flow distribution and concentration at the ...The flow distribution and mixing performance of the laminar flow in the PBT impeller-stirred tank were investigated in this study.The variation along with mixing time of the flow distribution and concentration at the selected positions was visualized by means of the CFD and experiment methods.The CFD simulations results had a good agreement with the experimental results.In order to minish the Segregated Regions,the PBT impeller was optimally designed by means of orthogonal factorial experiment with selecting theθ99 mixing time as evaluation criteria.With the aim to increase the mixing efficiency,the optimal design results were obtained with the geometrical parameters of impeller diameter of 0.084 m,discharge angle of 45º,blade width of 0.018 m,and clearance of 0.05 m,and the mixing time of the optimal impeller-stirred flow was about 180 s,so this optimal design PBT impeller is more proper for the agricultural industries.展开更多
Robustness in most of the literature is associated with rain-max or min-max regret criteria. However, these criteria of robustness are conservative and therefore recently new criteria called, lexicographic a- robust m...Robustness in most of the literature is associated with rain-max or min-max regret criteria. However, these criteria of robustness are conservative and therefore recently new criteria called, lexicographic a- robust method has been introduced in literature which defines the robust solution as a set of solutions whose quality orjth largest cost is not worse than the best possible jth largest cost in all scenarios. These criteria might be significant for robust optimization of single objective optimization problems. However, in real optimization problems, two or more than two conflicting objectives are desired to optimize concurrently and solution of multi objective optimization problems exists in the form of a set of solutions called Pareto solutions and from these solutions it might be difficult to decide which Pareto solution can satisfy rain-max, min-max regret or lexico- graphic a-robust criteria by considering multiple objectives simultaneously. Therefore, lexicographic a-robust method which is a recently introduced method in literature is extended in the current research for Pareto solutions. The proposed method called Pareto lexicographic a-robust approach can define Pareto lexicographic a-robust solu- tions from different scenarios by considering multiple objectives simultaneously. A simple example and an application of the proposed method on a simple problem of multi objective optimization of simple assembly line balancing problem with task time uncertainty is presented to get their robust solutions. The presented method can be significant to implement on different multi objective robust optimization problems containing uncertainty.展开更多
基金This study was financially supported by the National Special Fund Program for Major Scientific Instruments and Equipment Development(2011YQ160002)Open Research Fund Program of Hubei Provincial Key Laboratory of Chemical Equipment Intensification and Intrinsic Safety(2015KA03).
文摘The flow distribution and mixing performance of the laminar flow in the PBT impeller-stirred tank were investigated in this study.The variation along with mixing time of the flow distribution and concentration at the selected positions was visualized by means of the CFD and experiment methods.The CFD simulations results had a good agreement with the experimental results.In order to minish the Segregated Regions,the PBT impeller was optimally designed by means of orthogonal factorial experiment with selecting theθ99 mixing time as evaluation criteria.With the aim to increase the mixing efficiency,the optimal design results were obtained with the geometrical parameters of impeller diameter of 0.084 m,discharge angle of 45º,blade width of 0.018 m,and clearance of 0.05 m,and the mixing time of the optimal impeller-stirred flow was about 180 s,so this optimal design PBT impeller is more proper for the agricultural industries.
文摘Robustness in most of the literature is associated with rain-max or min-max regret criteria. However, these criteria of robustness are conservative and therefore recently new criteria called, lexicographic a- robust method has been introduced in literature which defines the robust solution as a set of solutions whose quality orjth largest cost is not worse than the best possible jth largest cost in all scenarios. These criteria might be significant for robust optimization of single objective optimization problems. However, in real optimization problems, two or more than two conflicting objectives are desired to optimize concurrently and solution of multi objective optimization problems exists in the form of a set of solutions called Pareto solutions and from these solutions it might be difficult to decide which Pareto solution can satisfy rain-max, min-max regret or lexico- graphic a-robust criteria by considering multiple objectives simultaneously. Therefore, lexicographic a-robust method which is a recently introduced method in literature is extended in the current research for Pareto solutions. The proposed method called Pareto lexicographic a-robust approach can define Pareto lexicographic a-robust solu- tions from different scenarios by considering multiple objectives simultaneously. A simple example and an application of the proposed method on a simple problem of multi objective optimization of simple assembly line balancing problem with task time uncertainty is presented to get their robust solutions. The presented method can be significant to implement on different multi objective robust optimization problems containing uncertainty.
