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Study on the thermal and geometrical parameters of helical coil once-through steam generator system

International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 80-96页

作者： Yao, Hao Chen, Guo Lu, Kailin Liao, Haoyu Wu, Yingwei Tian, Wenxi Su, Guanghui Qiu, Suizheng School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China Nuclear Power Institute of China Chengdu610226 China

Due to the special structure, helical coil once-through steam generators (HCOTSGs) can withstand greater thermal expansion stress, have a larger heat exchange area, and cause the secondary flow phenomenon to improve the heat transfer capacity. Thus, it is inevitable to further study the thermal-hydraulic characteristics of the HCOTSG, a vital component of reactors. The optimal physical models were selected for different heat transfer areas by detailed investigation and comparison, to adopt in the TACS, a self-developed thermal-hydraulic analysis code that is accurate and widely-used in HCOTSG simulation. After verification with experiments of Santini, taking the IRIS reactor as the object, the TACS was employed to briefly study the thermal-hydraulic performances of the HCOTSG system at first, and then discuss the influences of thermal and geometric parameters on the HCOTSG. The analysis results showed that: the variation of the primary flow rate greatly affects the heat transfer coefficient of the primary side, while the maximum value of the heat transfer coefficient of the secondary side only changes drastically with the secondary flow rate;when the primary side flow drops to 70%, superheated steam is not generated on the secondary side;when the secondary mass flow rate decreases to a certain extent, the steam superheat degree increases by a small amplitude;the primary side inlet temperature has a little influence on the primary temperature difference, but significant influence on the two-phase zone length of the secondary side;the secondary inlet temperature has very little influence on the HCOTSG system;the inner diameter and the outer diameter of helical tubes have obvious influences, while the helical diameter has not. © 2021 Xi'an Jiaotong University

关键词： Heat transfer coefficients

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A framework of the transport model for high-order eddy viscosity tensor in two-dimensional turbulent flow

arXiv

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arXiv 2023年

作者： Zhou, Xingguang Zhang, Dalin Tian, Wenxi Su, Guanghui Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'An710049 China

Motivated by the concept of eddy viscosity tensor in improved Boussinesq hypothesis, a transport model of high-order eddy viscosity tensor in 2D-3C turbulence structure is derived from the second-order moment model by tensorial analysis. Compared with the previous high-order eddy viscosity tensor mathematical model [1-3] for turbulent flow under special operating conditions, we have obtained a general high-order eddy viscosity tensor transport model, which can show the anisotropy and transport characteristics of Reynolds stress. The transport equation of a high-order eddy viscosity tensor includes the transient term, convection term, production term, diffusion term, positive-definite source term, and dissipation term. In addition, when the components of high-order eddy viscosity tensor are positive or negative, the physical meaning of the source terms is also discussed. Two numerical simulation cases are also interpreted to verify the model. First, we apply the transport model of high-order eddy viscosity to the numerical calculation analysis of two-dimensional straight channel turbulent flow, and the results show that this model can effectively characterize the anisotropy of Reynolds stress. With a combination of analytical and numerical methods, we analyze the flow fields and the components of high-order eddy viscosity tensor to investigate the evolution law of high-order eddy viscosity tensor. The characteristics of the principal components and tensorial invariance of dimensionless Reynolds stress anisotropy tensor of two-dimensional straight channel turbulent flow also have been investigated with the Lumley triangle [4,5]. The results show that this model has a good agreement with the DNS calculation results for the characteristics of dimensionless Reynolds stress anisotropy tensor. Then, we make the numerical investigation for a two-dimensional planar asymmetric diffuser and compare the results with the experiments of Obi *** [6]. The transport model can reso

关键词： Tensors

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A Numerical Approach for Inlet-Outlet Boundary Conditions with Least-Square Moving Particle Explicit (Lsmpe) Method on Gpu

SSRN

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SSRN 2024年

作者： Ren, Qianyong Cao, Sheng Wang, Wenpeng Zhang, Bin Shan, Jianqiang Shaanxi Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

The study introduces a method for managing inlet and outlet boundary conditions using the Least-Square moving particle explicit method (LSMPE). A high-precision least squares discrete method was applied to the moving particle explicit method (MPE) based on predictive-corrected pressure. The code was accelerated using OpenACC for parallelization. Special boundary treatments were applied to minimize errors induced by boundaries, including particle number density correction for inlet particles, addressing slip or nonslip boundaries, and introducing concept particles at the outlet. The stability and accuracy of this method were validated through three cases. Simulation results for Poiseuille flow and circular flow demonstrated the method’s good precision, exhibiting stable pressure fields. Results from single-phase flow simulations through a porous medium bed agreed well with predictions from the Ergun equation, highlighting the method’s potential for practical engineering applications © 2024, The Authors. All rights reserved.

关键词： Porous materials

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Analysis of real-fluid thermodynamic effects on turbulent statistics in transcritical channel flows

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Physical Review Fluids 2023年第2期8卷 024605-024605页

作者： Fangbo Li Jack Guo Bofeng Bai Matthias Ihme State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi 710049 China Department of Mechanical Engineering Stanford University Stanford California 94305 USA

Wall-bounded turbulence at high-pressure transcritical conditions with intense density fluctuations are encountered in many technical applications. In this study, we analyze the turbulent energy transport in transcritical channel flows specifically focusing on dissipation rate, turbulent kinetic energy budgets, heat fluxes, and momentum-fluctuation statistics; results from this analysis are used to guide the development of turbulent scaling laws. We find that the dissipation rate of turbulent kinetic energy is dominated by the enstrophy in the logarithmic layer, and the fluctuating viscosity results in the reduced tilting of the vortical structures and the attenuation of streamwise vorticity in the near-wall layer; the fluctuating viscosity attenuates the dissipation rate by reducing the shear strain and the enstrophy production. Local equilibrium of the turbulent kinetic energy exists in the logarithmic layer. We show that the real-fluid thermodynamic effects significantly change the turbulent heat flux correlated with the sweep and the ejection events; the density changes alter the turbulent transport and result in noticeable magnitudes of density-fluctuation-related momentum-fluctuation statistics. From these results, scaling laws for the turbulent length scales and turbulent kinetic energy budgets are proposed, thereby contributing to improvement of the wall models in large-eddy simulations and Reynolds-averaged Navier-Stokes (RANS) simulations.

关键词： Channel flow

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CFD simulation of thermal hydraulic characteristics in a typical upper plenum of RPV

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Frontiers in Energy 2021年第4期15卷 930-945页

作者： Mingjun WANG Lianfa WANG Yingjie WANG Wenxi TIAN Jian DENG Guanghui SU Suizheng QI State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi’an Jiaotong UniversityXi’an 710049China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of ChinaChengdu 610213China

A comparative computational fluid dynamics(CFD)study was conducted on the three different types of pressurized water reactor(PWR)upper plenum,named TYPE 1(support columns(SCs)and control rod guide tubes(CRGTs)with two large windows),TYPE 2(SCs and CRGTs without windows),and TYPE 3(two parallel perforated barrel shells and CRGTs).First,three types of upper plenum geometry information were collected,simplified,and adopted into the BORA facility,which is a 1/5 scale system of the four-loop PWR ***,the geometry,including the upper half core,upper plenum region,and hot legs,was built using the Salome *** that,an unsteady calculation to simulate the reactor balance operation at hot full power scenario was ***,the differences of flowrate distribution at the core outlet and temperature distribution and transverse velocity inside the hot legs with different upper plenum internals were *** results suggest that TYPE 1 upper plenum internals cause the largest flowrate difference at the core outlet while TYPE 3 leads to the most even distributed *** distribution and evolution pattern of the tangential velocity inside hot legs is highly dependent on the upper plenum *** counter-rotating swirls exist inside the TYPE 1 hot leg and only one swirl revolving around the hog leg axis exist inside the TYPE 2 hot *** TYPE 3,two swirls like that of TYPE 1 rotating around the hot leg axis significantly increase the temperature homogenization *** research provides meaningful guidelines for the future optimization and design of advanced PWR upper plenum internal structures.

关键词： pressurized water reactor(PWR) upper plenum internal structures temperature distribution computational fluid dynamics(CFD)

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Development of a three-dimensional method for thermal-hydraulics/neutronics coupling analysis and its application on CFETR helium-cooled solid breeder blanket

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 154-165页

作者： Lian, Qiang Tian, Wenxi Qiu, Suizheng Su, G.H. Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Blankets are of practical importance in the fusion reactor due to their main functions for engineering application. As the fusion power designed for the Chinese Fusion engineering Test Reactor (CFETR) is increased from 200 MW to 1.5 GW during its phase II operation, more challenges are issued for blankets from the points of view of thermal-hydraulics, neutronics, mechanics, and safety. In this paper, the Coupling Analysis of Thermal-hydraulics and Neutronics Interface Code (CATNIC) was developed using the user-defined function (UDF) in the CFD software FLUENT. The explicit coupling scheme based on cell-to-cell mapping approach was adopted to transfer data between neutronics calculation and thermal-hydraulics simulation. Three-dimensional thermal-hydraulic model and neutronics model were established using Fluent and MCNP4C, respectively. The helium-cooled solid breeder (HCSB) blanket of CFETR was simplified as a slice model to reduce the computing resources. With the slice model of CFETR HCSB blanket, the coupling analysis was carried out using the developed CATNIC. The calculation results from coupling and non-coupling analyses were compared to verify the feasibility of the coupling method in this study. As the helium coolant was considered as the transparent medium for neutron, the thermal-hydraulic and neutronics analyses were both converged after two iterations. However, using the developed coupling method in this study, the detailed change of tritium production ratio (TPR) and nuclear heat deposition in different parts of the blanket was revealed, which could provide important guidance for the design of the distribution for both coolant and purge gas. © 2021 Xi'an Jiaotong University

关键词： Coolants

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Instantaneous mixing characteristics of binary mixtures differing in density in a gas-solid fluidised bed

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Particuology 2020年第6期18卷 63-71页

作者： Zhen Wan Youjun Lu Hao Wang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

Characterisations of instantaneous mixing behaviours in fluidised beds with binary mixtures has many *** studied the instantaneous mixing characteristics of binary mixtures in a 2-D quasi gas-solid fluidised bed using a capacitance probe *** method enabled the quantitative assessment of instantaneous mixing behaviours,including mixing index,rate,and *** kinds of binary mixtures of similar size but different density were used for the transient and steady fluidisation experiments in a bubbling fluidised *** mixing curves of initially segregated binary mixtures were acquired,and the instantaneous characteristics for the entire process were *** equation was proposed to describe the mixing process and predict the mixing degree over *** comparing experiments with different working conditions,the effects of superficial gas velocity and density ratio on the mixing in the centre and at the wall of the fluidised bed were *** the stable fluidisation stage,the axial concentration profiles of the mixtures were obtained,and the mechanisms of mixing were *** showed that the mixing level increased logarithmically with time and eventually reached a relatively stable *** the superficial gas velocity and reducing the density ratio promoted mixing and reduced mixing *** superficial gas velocities tended to mix the mixtures well and quickly,regardless of the density ratio of the two components.

关键词： Binary mixtures Fluidised bed Mixing Instantaneous characteristics

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Multiple load short-term forecasting model of integrated energy system based on multiple LSTM networks

Multiple load short-term forecasting model of integrated ene...

引用

International Conference on power engineering 2021, ICOPE 2021

作者： Cai, Yanchun Xu, Kaiwen Chong, Daotong Wang, Jinshi Yan, Junjie Liu, Ming State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Accurate short-term load forecasting of integrated energy system can optimize system operation and play an important role in improving system energy efficiency. In this paper, a multiple load short-term forecasting model of integrated energy system based on multiple LSTM networks is proposed. Firstly, the load influencing factors are divided into meteorological characteristic, delay characteristic and periodic characteristic, and the correlation is calculated based on Pearson coefficient. Secondly, a load forecasting model with multiple LSTM network coupling is established to explore the relationship between load and three characteristics, and excavate the complex coupling relationship among cooling, heating and power. The results show that the model has better prediction performance compared with other commonly used models. © 2021 The Japan Society of Mechanical Engineers.

关键词： Long short-term memory

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A computational particle fluid-dynamics simulation of hydrodynamics in a three-dimensional full-loop circulating fluidized bed: Effects of particle-size distribution

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Particuology 2020年第2期18卷 134-145页

作者： Hang Zhang Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049ShaanxiChina

A computational particle fluid-dynamics model coupled with an energy-minimization multi-scale(EMMS)drag model was applied to investigate the influence of particle-size distribution on the hydrodynamics of a three-dimensional full-loop circulating fluidized *** particle systems,including one monodisperse and two polydisperse cases,were *** numerical model was validated by comparing its results with the experimental axial voidage distribution and solid mass *** EMMS drag model had a high accuracy in the computational particle fluid-dynamics simulation of the three-dimensional full-loop circulating fluidized *** total number of parcels in the system(Np)influenced the axial voidage distribution in the riser,especially at the lower part of the *** numerical simulation results showed that axial segregation by size was predicted in the two polydisperse cases and the segregation size increased with an increase in the number of size *** axial voidage distribution at the lower portion of the riser was significantly influenced by particle-size ***,radial segregation could only be correctly predicted in the upper region of the riser in the polydisperse case of three solid species.

关键词： Circulating fluidized bed Computational particle fluid dynamics Particle-size distribution Energy-minimization multiscale model Three-dimensional full-loop simulation

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Thermal-hydraulic performance evaluation of annular fuel based on modified FROBA-ANNULAR

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International Journal of Advanced Nuclear Reactor Design and Technology 2021年 3卷 108-118页

作者： Li, Chenxi Liao, Haoyu Wu, Yingwei Tian, Wenxi Su, G.H. Qiu, Suizheng School of Nuclear Science and Technology Shanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In this study, based on the modification of the pellet cladding mechanical interaction, gap closure process, and the cladding water corrosion model, Fuel Rod Behavior Analysis-ANNULAR (FROBA-ANNULAR) was uprated. The modified code was verified with FRAPCON-ANNULAR and ABAQUS. The verification calculation was under low power density when both two gaps were open. The calculation results showed good agreement. The modified code was then utilized to evaluate the annular fuel behavior, compared with the original code FROBA-ANNULAR. In this study, the annular fuel exhibits a much lower peak fuel temperature(about 900K). The different results for heat flux fraction(0.55 for the original code, 0.66 for the modified code) indicated that the gap closure process strongly affected the movement of the adiabatic pellet line. The internal pressure results (7.5 MPa for the original code, 6 MPa for the modified code) were also affected by the different assumptions. The results also showed that Zr's oxidation thickness and hydrogen concentration were related to both time and temperature. The higher the temperature was, the larger the oxidation rate was when the transition thickness was reached. © 2021

关键词： Heat flux

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