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Coupled simulation of recirculation zonal firebox model and detailed kinetic reactor model in an industrial ethylene cracking furnace

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Chinese Journal of Chemical Engineering 2017年第8期25卷 1091-1100页

作者： zhou fang Tong Qiu Weiguo zhou Department of Chemical Engineering Tsinghua University

A coupled system simulating both firebox and reactor is established to study the naphtha pyrolysis in an industrial tubular *** firebox model is based on zone method including combustion,radiation,and convection to simulate heat transfer in the furnace.A two-dimensional recirculation model is proposed to estimate the flow field in *** reactor model integrates the feedstock reconstruction model,an auto-generator of detail kinetic schemes,and the reactor simulation model to simulate the reaction process in the tubular *** coupled simulation result is compared with industrial process and shows agreement within short computation time.

关键词： Ethylene cracking Coupled simulation Tubular furnace Recirculation zone modeling Detailed reaction kinetic

Investigation of electropolishing characteristics of tungsten in ecofriendly sodium hydroxide aqueous solution

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Advances in Manufacturing 2020年第3期8卷 265-278页

作者： Wei Han Feng-zhou fang Centre of Micro/Nano manufacturing Technology(MNMTDublin) University College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Centre of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin 300072People’s Republic of China

In this study,an eco-friendly electrolyte for electropolishing tungsten and the minimum material removal depth on the electropolished tungsten surface are investigated using an electrochemical etching *** a concentrated acid electrolyte,the polarization curve and current density transient are *** a NaOH electrolyte,the effects of interelectrode gap and electrolyte concentration on electropolishing are *** differences in electropolishing characteristics are compared among different electrolyte *** are etched on the electropolished tungsten surface to determine the minimum material removal depth on the tungsten *** results indicate the color effect due to a change in the thickness of the oxide film on the tungsten surface after electropolishing with a concentrated acid *** surface roughness decreases with the interelectrode gap width owing to the increased current density when using the NaOH ***,the electropolishing effect is less prominent with a significantly smaller gap because the generated bubbles are unable to escape from the narrow working gap in time.A material removal depth of less than 10 nm is achieved on the tungsten surface in an area of diameter 300 lm,using the electrochemical etching method.

关键词： Electropolishing NaOH solution Surface roughness Tungsten Etching

Optimal tool design in micro-milling of difficult-to-machine materials

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Advances in Manufacturing 2023年第2期11卷 222-247页

作者： Lorcan O'Toole Feng-zhou fang Centre of Micro/Nano Manufacturing Technology(MNMT-Dublin) University College DublinDublin 4Ireland State Key Laboratory of Precision Measuring Technology and Instruments Laboratory of Micro/Nano Manufacturing Technology(MNMT)Tianjin UniversityTianjin300072People's Republic of China

The limitations of significant tool wear and tool breakage of commercially available fluted micro-end mill tools often lead to ineffective and inefficient manufacturing,while surface quality and geometric dimensions remain unacceptably *** is especially true for machining of difficult-to-machine(DTM)materials,such as super alloys and *** conventional fluted micro-tool designs are generally down scaled from the macro-milling tool ***,simply scaling such designs from the macro to micro domain leads to inherent design flaws,such as poor tool rigidity,poor tool strength and weak cutting edges,ultimately ending in tool ***,in this article a design process is first established to determine optimal micro-end mill tool designs for machining some typical DTM materials commonly used in manufacturing orthopaedic implants and micro-feature *** design process focuses on achieving robust stiffness and mechanical strength to reduce tool wear,avoid tool chipping and tool breakage in order to efficiently machine very hard ***,static stress and deflection finite element analysis(FEA)is carried out to identify stiffness and rigidity of the tool design in relation to the maximum deformations,as well as the Von Mises stress distribution at the cutting edge of the designed *** analysis and further optimisation of the FEA results,a verified optimum tool design is established for micro-milling DTM *** experimental study is then carried out to compare the optimum tool design to commercial tools,in regards to cutting forces,tool wear and surface quality.

关键词： Precision machining Micro-milling Difficult-to-machine(DTM) Tool wear Micro-tool design Surface quality

SIMULATION OF THERMAL TRANSPORT IN AQUIFER:A GWHP SYSTEM IN CHENGDU,CHINA

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Journal of Hydrodynamics 2009年第5期21卷 647-657页

作者： zhou Yan-zhang zhou Zhi-fang Institute of Groundwater Science and Engineering Hohai University Nanjing 210098 China

With an established convection-dispersion model for the thermal transport in aquifer, the thermal transport processes in an unconfined aquifer of a Groundwater Heat Pump （GWHP） system in Chengdu, China, are simulated with double-well intervals and cooling-load design fluctuations in summer running period under special groundwater flow and heat source conditions, and the stage-characteristics of the thermal transport in the aquifer are investigated in the running cycle （1 year） numerically. The results show that the thermal transport in the aquifer is closely related to the distance between pumping and injecting wells and the cooling-load design fluctuations, especially, to the cycling water volume. The thermal transport in the aquifer sees different characteristics in the two states in the pumping-recharging stages in summer/winter and the storing stages in spring/autumn. With the hydro-geologic theory and the numerical model, the effect of the groundwater-flow on the thermal transport in the unconfined aquifer is discussed.

关键词： Groundwater Heat Pump (GWHP) thermal transport in aquifer numerical simulation groundwater flow

Dynamical Feedback between Synoptic Eddy and Low-Frequency Flow as Simulated by BCC_CSM1.1(m)

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Advances in Atmospheric Sciences 2017年第11期34卷 1316-1332页

作者： fang zhou Hong-Li REN Laboratory for Climate Studies National Climate CenterChina Meteorological Administrationbeijing 100081china CMA-NJU Joint Laboratory for Climate Prediction Studies School of Atmospheric SciencesNanjing Universitynanjing 210093china Department of Atmospheric Science School of Environmental StudiesChina University of Geosciencewuhan 430074china

Since the interaction between atmospheric synoptic eddy （SE）（2-8 days） activity and low-frequency （LF）（monthly） flow （referred to as SELF） plays an essential role in generating and maintaining dominant climate modes, an evaluation of the performance of BCC_CSMI.I（m） in simulating the SE feedback onto the LF flow is given in this paper. The model captures well the major spatial features of climatological eddy vorticity forcing, eddy-induced growth rate, and patterns of SELF feedback for the climate modes with large magnitudes in cold seasons and small magnitudes in warm seasons for both the Northern and Southern Hemisphere. As in observations, the eddy-induced growth rate and SELF feedback patterns in the model also show positive SE feedback. Overall, the relationships between SE and LF flow show that BCC_CSM1. l（m） satisfactorily captures the basic features of positive SE feedback, which demonstrates the simulation skill of the model for LF variability. Specifically, such an evaluation can help to find model biases of BCC_CSM1.1 （m） in simulating SE feedback, which will provide a reference for the model＇s application.

关键词： model evaluation synoptic eddy feedback simulation eddy vorticity forcing eddy-induced growth rate patternsof synoptic eddy feedback

Bio-inspired Collision-free 4D Trajectory Generation for UAVs Using Tau Strategy

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Journal of Bionic Engineering 2016年第1期13卷 84-97页

作者： Zuqiang Yang zhou fang Ping Li School of Aeronautics and Astronautics Zhejiang University Hangzhou 310027 China

Inspired by the general tau theory in animal motion planning, a collision-free four-dimensional （4D） trajectory generation method is presented for multiple Unmanned Aerial Vehicles （UAVs）. This method can generate a group of optimal or near-optimal collision-free 4D trajectories, the position and velocity of which are synchronously planned in accordance with the arrival time. To enlarge the shape adjustment capability of trajectories with zero initial acceleration, a new strategy named intrinsic tau harmonic guidance strategy is proposed on the basis of general tau theory and harmonic motion. In the case of multiple UAVs, the 4D trajectories generated by the new strategy are optimized by the bionic Particle Swarm Optimization （PSO） algorithm. In order to ensure flight safety, the protected airspace zone is used for collision detection, and two collision resolution approaches are applied to resolve the remaining conflicts after global trajectory optimization. Numerous simulation results of the simultaneous arrival missions demonstrate that the proposed method can effectively provide more flyable and safer 4D trajectories than that of the existing methods.

关键词： bio-inspired 4D trajectory generation general tau theory multiple UAVs

Charge generation and electrostatic equilibrium for single granules during sliding

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Particuology 2016年第6期14卷 126-134页

作者： Jun Yao fang zhou Yanlin Zhao Beijing Key Laboratory of Process Fluid Filtration and Separation College of Mechanical and Transportation Engineering China University ofPetroleum-Beijing Beijing 102249 China College of Energy Xiamen University Xiamen 361005 China

Electrostatic phenomena are commonly observed in the processing of solids. However. the working mech- anism of electrostatic charge generation for single granules and particularly, their electrostatic equilibria have not been properly understood. In this work, repeated-sliding charging experiments with single granules were investigated for their electrostatic generation particularly from the perspective of tribo- electrification equilibrium. Factors including granule length-ratio, sliding face shape, sliding times, sliding area, sliding velocity, front-facing edge, and sliding-plate inclined-angle were found to have an obvious effect on granule charge generation. Length-ratio and sliding area have significant effects as the gran- ules evolved toward an equilibrium state. Equilibrium charge is suggested as a variable expressing the charging propensity of the material. In addition, under the same working conditions, a semi-cylindrical granule generates greater charge than a rectangular granule.

关键词： Granule Electrostatics Charge generation Equilibrium Granule shape

Molecular reconstruction model based on structure oriented lumping and group contribution methods

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Chinese Journal of Chemical Engineering 2018年第8期26卷 1677-1683页

作者： Jincai Chen zhou fang Tong Qiu Department of Chemical Engineering Tsinghua University

Molecular management is a promising technology to face challenges in the refining industry, such as more stringent requirements for product oil and heavier crude oil, and to maximize the value of every molecule in petroleum fractions. To achieve molecular management in refining processes, a novel model that is based on structure oriented lumping(SOL) and group contribution(GC) methods was proposed in this study. SOL method was applied to describe a petroleum fraction with structural increments, and GC method aimed to estimate molecular properties. The latter was achieved by associating rules between SOL structural increments and GC structures. A three-step reconstruction algorithm was developed to build a representative set of molecules from partial analytical data. First, structural distribution parameters were optimized with several properties. Then, a molecular library was created by using the optimized parameters. In the final step, maximum information entropy(MIE) method was applied to obtain a molecular fraction. Two industrial samples were used to validate the method, and the simulation results of the feedstock properties agreed well with the experimental data.

关键词： Molecular reconstruction Structure oriented lumping Group contribution Monte Carlo Maximum information entropy

Application of convolutional neural networks to large-scale naphtha pyrolysis kinetic modeling

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Chinese Journal of Chemical Engineering 2018年第12期26卷 2562-2572页

作者： Feng Hua zhou fang Tong Qiu Department of Chemical Engineering Tsinghua University Beijing 100084China Beijing Key Laboratory of Industrial Big Data System and Application Beijing 100084China

System design and optimization problems require large-scale chemical kinetic models. Pure kinetic models of naphtha pyrolysis need to solve a complete set of stiff ODEs and is therefore too computational expensive. On the other hand, artificial neural networks that completely neglect the topology of the reaction networks often have poor generalization. In this paper, a framework is proposed for learning local representations from largescale chemical reaction networks. At first, the features of naphtha pyrolysis reactions are extracted by applying complex network characterization methods. The selected features are then used as inputs in convolutional architectures. Different CNN models are established and compared to optimize the neural network *** the pre-training and fine-tuning step, the ultimate CNN model reduces the computational cost of the previous kinetic model by over 300 times and predicts the yields of main products with the average error of less than 3%. The obtained results demonstrate the high efficiency of the proposed framework.

关键词： Convolutional neural network Network motif Naphtha pyrolysis Kinetic modeling