Research Of Transfer Process Intensification Based On Flow Pattern Structure Construction

Equipment optimization is an effective method to intensify transfer process inchemical engineering. Traditional chemical equipment optimization, based on thedesigner’s experience, usually proposes several possible suggestions or structures, andchooses the best one according to the experimental or numerical calculation results.Because of the difference in academic background and experience, designers havedifferent suggestions and obtain different structures, thus traditional equipmentoptimization often lacks theoretical basis. To establish a generally applicableequipment optimization method is a basic problem which urgently needs to be solved.Based on former researches, the paper put forward a novel equipmentoptimization which based on flow pattern structure construction method. For chemicaltransfer process, we introduced an objective function, the controlling equations werederived by the objective function and the constraints that satisfying the physicalmodel. Through solving the controlling equation by CFD software, the flow pattern inwhere the objective function take the minimum was obtained, the Equipment can beoptimized by the flow pattern structure.The mixing process was optimized by flow pattern construction method. Namely,the specific flow pattern was constructed to enhance the mixing process. To obtain thedesired flow pattern, a Lagrange multiplier equation, with the entropy generation asthe objective function and some global constraints, was constructed. The solution ofthe Lagrange equation represented the flow pattern extremizing the entropygeneration subject to a given rate of viscous dissipation rate. The simulation resultsrevealed that the flow pattern constructed by extremizing the entropy generationcontributed to an improvement in mixing performance. To demonstrate the validity ofthe flow pattern structure construction method, the mixing for a mixture ofammonia/air mixture involved in the flue gas denitration process was studied byconstructing the specific flow pattern in which the mixing performance was improved.Finally, according to the specific flow pattern, a static mixer with internal structurewas designed by employing the porous media model. The fluid transportation process was optimized by flow pattern constructionmethod in this paper. By introducing the calculus of variations，Lagrange multiplierequation, with the viscous dissipation rate in channel as the objective function andsome global constraints, was constructed. The solution of Lagrange equation denotedthe optimal flow field contributing to the minimum viscous dissipation rate subject toa given rate of input work. The optimization of fluid transport in straight channel,L-type channel, and U-type channel were studied to demonstrate the validity of themethod. According to the numerical results solved by the CFD software Fluent6.3,the optimal flow field could significantly reduce the viscous dissipation rate, and theglobal optimal flow field which can guide the design of fluid channel was achieved bysolving the Lagrange multiplier equation in different input external works.