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transient analysis and optimization of passive residual heat removal heat exchanger in advanced nuclear power plant

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Nuclear Science and Techniques 2022年第8期33卷 147-162页

作者： Yan-Bin Liu Xiang-Yu Meng Xue-Sheng Wang Qi-Ming Men Yu-Yang Yuan Jia-Ming Cao Key Laboratory of Pressure Systems and Safety Ministry of EducationEast China University of Science and TechnologyShanghai 200237China Shanghai Nuclear Engineering Research and Design Institute State Power Investment CorporationShanghai 200233China

The transient performance and optimization of a passive residual heat removal heat exchanger(PRHR HX)were ***,a calculation method was developed for predicting the heat transfer of the PRHR *** calculation results were validated through comparisons with ROSA experimental *** heat-transfer performance of the AP1000 PRHR HX in the initial period was predicted,and it satisfied the design ***,the distributions of the heat flux,tube-inside/outside heattransfer coefficients,and heat load for the AP1000 PRHR HX over 2000 s were ***,an optimization study was conducted by adjusting the horizontal length and tube *** effects on the four main heat-transfer parameters and the heat-transfer area were ***,the influence of the initial in-containment refueling water storage tank(IRWST)temperature was investigated using an established simulation *** results indicated that it significantly affected the trends of the IRWST temperature and reactor outlet ***,the minimum required flow rates over time to maintain the reactor outlet temperature at the safety line were determined for different start-up *** trends of the minimum required flow rate and the peak flow rate were analyzed.

关键词： Heat transfer PRHR HX transient analysis Optimization investigation

transient analysis of 1D inhomogeneous media by dynamic inhomogeneous finite element method

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Earthquake Engineering and Engineering Vibration 2013年第4期12卷 569-576页

作者： Yang Zailin Wang Yao Hei Baoping College of Aerospace and Civil Engineering Harbin Engineering University

The dynamic inhomogeneous finite element method is studied for use in the transient analysis of one dimensional inhomogeneous media. The general formula of the inhomogeneous consistent mass matrix is established based on the shape function. In order to research the advantages of this method, it is compared with the general finite element method. A linear bar element is chosen for the discretization tests of material parameters with two fictitious distributions. And, a numerical example is solved to observe the differences in the results between these two methods. Some characteristics of the dynamic inhomogeneous finite element method that demonstrate its advantages are obtained through comparison with the general finite element method. It is found that the method can be used to solve elastic wave motion problems with a large element scale and a large number of iteration steps.

关键词： inhomogeneous media elastic wave transient analysis dynamic inhomogeneous finite element method discretization

transient analysis of a fluid bu er driven by a birth and death process

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Transient analysis of a fluid bu er driven by a birth and de...

transient analysis of lossy multiconductor transmission Line in multilayered dielectric media under interfering field

The 19th International Teletraffic Congress-ITC19

作者： Fabrice Guillemin Bruno Sericola Fabrics Guillemin France Telec:om 2 Avenue Pierre Marzin 22300 Lannion France Bruno Sericola INRIA-IRISA Campus de Beaulieu 35042 Rennes Cedex Prance

＜正＞We analyze the transient behavior of a uid queue when the instantaneous rate of the input process is governed by a general birth and death process. These uid ows models are widely used in the performance analysis of telecommunication systems. The transient analysis of such models has already been considered in earlier works with a nite state space background process. We consider in this paper a in nite state space driving process and we study the uid queue by using results from spectral theory.

关键词： Fluid bu er spectral theory orthogonal polynomials transient analysis

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Transient analysis of lossy multiconductor transmission Line...

An Early-Stop Adjoint transient Sensitivity analysis Method for Objective Functions Associated with Many Time Points

1999 International Conference on Computational Electromagnetics and Its Applications(ICCEA’99)

作者： Peijinming Zhu shouzheng An tongyi Dept.of electronic science and tech East China Normal University

ISBN: (纸本)0780358023

＜正＞The calculation of C,L,R,G for a multiconductor transmission line in multilayered dielectric media is given by solving the integrated equation with moment *** transmission line equation including interfere field is solved by characteristic current wave variable mode expansion and is fitted in *** transient response is obtained by NILT and Euler *** result is well consistent with the reported ones.

关键词： multiconductor transmission lines transient analysis transient response capacitance inductance electric resistance electric admittance transmission line theory integral equations method of moments transient analysis lossy multiconductor transmission lines multilayered dielectric media capacitance inductance resistance conductance interfering field integral equation moment method transmission line equation current wave variable mode expansion transient response numerical inverse Laplace transform Euler transformation

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Tsinghua Science and Technology 2023年第3期28卷 566-579页

作者： Wenfei Hu Sen Yin Liang Wang Chunxue Liu Zhikai Wang Zuochang Ye Yan Wang School of Integrated Circuits Tsinghua UniversityBeijing 100084China Beijing Microelectronics Technology Institute(BMTI) Beijing 100076China Beijing Innovation Center for Future Chips Tsinghua UniversityBeijing 100084China Beijing National Research Center for Information Science and Technology Tsinghua UniversityBeijing 100084China

transient sensitivity analysis aims to obtain the gradients of objective functions(circuit performance)with respect to design or variation parameters in a simulator,which can be widely used in yield analysis and circuit optimization,among ***,the traditional method has a computational complexity of O(N^(2))for objective functions containing circuit states at N time *** computational complexity is too expensive for large N,especially in time-frequency *** paper proposes a many-time-point sensitivity method to reduce the computational complexity to O(N)in multiparameter many-time-point *** paper demonstrates a derivation process that improves efficiency by weighting the transfer chain and multiplexing the backpropagation *** also proposed an early-stop method to improve efficiency further under the premise of ensuring *** algorithm enables sensitivity calculation of performances involving thousands of time points,such as signal-to-noise and distortion ratio and total harmonic distortion,with significant speed improvements.

关键词： adjoint sensitivity Fourier transformation transient analysis many time point sensitivity(MTPS) early-stop

Reduced Model of Droop-controlled Converters for transient Simulation analysis

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Chinese Journal of Electrical Engineering 2022年第3期8卷 112-122页

作者： Yingjie Tan Yang Shen Min Xu Chao Shen Jinyong Lei Electric Power Research Institute CSGGuangzhou 510663China College of Electrical and Information Engineering Hunan UniversityChangsha 410082China

In recent years,the transient stability problems encountered by power grids have increasingly attracted interest due to the connection of renewable energy *** of the effective methods for studying the transient characteristics of a system is transient simulation *** reduce the simulation time,especially in a system with numerous renewable energy resources,model reduction has been widely ***,when a general reduced model is adopted to analyze different transient characteristics,a tradeoff between accuracy and simulation speed *** this study,reduced model selection is implemented to resolve this *** the droop-controlled converter as an example,this approach allows the transient simulation analysis of voltage,frequency,and power angle ***,a full-order model of the droop-controlled inverter is ***,the singular perturbation method is applied to derive different reduced-order ***,considering accuracy and simulation speed simultaneously,the most suitable reduced models for transient angle,voltage,and frequency simulation analyses are determined through time-domain simulation ***,the simulation results based on Matlab/Simulink are used to verify the correctness of the reduced model selection.

关键词： Droop-controlled inverter transient analysis reduced-order model singular perturbation

transient Squeal analysis of a Non Steady State Manoeuvre

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Journal of Mechanics Engineering and Automation 2017年第5期7卷 269-277页

作者： Oliver Stump Maximilian Konning Wolfgang Seemann Daimler AG Group Research & MBC Development Sindelfingen 71059 Germany Institute of Engineering Mechanies-Karlsruhe Institute of Technology (KIT) Karlsruhe 76131 Germany

Brake squeal is one of the main NVH （vibration harshness） challenges in the brake development of passenger cars. The conflict of goals in the development process and the late testability leads to the need of a deeper basic understanding of the squeal phenomenon and definition of design rules. On the other hand, brake squeal is still a very interesting field of research also for the universities because of its combination of different fundamentals, such as friction and stability behaviour of systems with local nonlinearities. Major nonlinearities of the brake system are the joints, especially the contact areas formed by the oscillating brake pad and the caliper. The state-of-the-art calculation method, which still is the ＂complex eigenvalue analysis＂, linearizes these joints, hence, neglecting its nonlinear influence in the stability analysis. Vehicle and bench experiments show that special driving manoeuvres like parking, where the brake pad often leaves the steady state, are likely causing brake squeal. The system in these manoeuvres sometimes behaves opposed to the linearized stability analysis, indicating a limit cycle beyond the Hopf point. Therefore, these states must be investigated more closely. This paper investigates the nonlinear influence of the pad caliper joint in a fixed brake caliper, also called abutment. Bench tests with pressure foils at the abutment of the brake caliper and mode shape analysis were done and a simple FE （finite element） model for a transient simulation is proposed. It is shown that the joint activity varies with driving manoeuvres, leading to different stability behaviours and limiting cycle amplitudes.

关键词： Brake squeal transient analysis nonlinear joint stability analysis finite element method.

A transient Multidimensional CFD Approach to the analysis of a Control Valve Using Non-Newtonian Fluids

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Journal of Energy and Power Engineering 2012年第9期6卷 1398-1407页

作者： Fabrizio Grasselli Massimo Milani Luca Montorsi Fabrizio Paltrinieri Department of Sciences and Methods for Engineering University of Modena and Reggio Emilia Reggio Emilia 42122 Italy

In this paper the flow through a control directional valve is studied by means of a CFD （computational fluid-dynamics） analysis under transient operating conditions. The mesh motion is resolved on a time basis as a function of the external actuation system In the analysis, an open source fluid-dynamics code is used and both cavitation and turbulence are accounted for in the modeling. Moreover, the numerical model of the working fluid is modified in order to account also for the non-Newtonian fluids. The effects of the shear rate on the shear stress are accounted for both by using experimental measurements and correlations available in literature, such as the Herschel-Bulkley model. The analysis determines the performance of the control directional valve under different operating conditions when using either Newtonian or non-Newtonian fluids. In particular, the discharge coefficient, the recirculating regions, the flow acceleration angle and the pressure and velocity fields are investigated.

关键词： CFD hydraulic valve transient analysis moving mesh non-Newtonian fluid.

Hydrodynamics and Lateral Gas Dispersion in a High-Density Circulating Fluidized Bed Reactor with Bluff Internals

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Chinese Journal of Chemical Engineering 2001年第3期9卷 291-296页

作者：杨艳辉贾新莉魏飞金涌 Tsing Hua Univ Dept Chem Engn Beijing 100084 Peoples R China

Effect of bluff internals on the hydrodynamics and lateral gas mixing was studied in a 0.186m ID high-density riser. With the bluff internals, the extremely non-uniform radial profiles of solid fraction and particle velocity become flat and the dense downflow layer near the wall disappears, indicating the significant enhancement of solid turbulence introduced by the internals. The fluctuation velocity and solid fraction transient signal analysis indicates a significant increase in fluctuation intensity near the wall region. The length influenced by the internals on the flow structure is about 1 meter. The lateral gas dispersion coefficient increases significantly as the bluff internals exist in the riser.

关键词： high-density riser bluff internal solid fraction particle velocity transient analysis gas mixing gas dispersion model