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Experimental Study and Theoretical Development of Liquid Entrainment in T-Junction with Double Inlets and Single Inlet of Gas Phase

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SSRN 2023年

作者： Li, Kepiao Shi, Yanggen Zhang, Kui Tian, Wenxi Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology Xi'an Jiaotong University Xi’an710049 China

The liquid phase entrainment through vertical-up branch had been analyzed through scaled and full size of experiment since ADS-4 (the fourth-stage Automatic Depressurization System) valve adopted in advanced PWR (Pressurized Water Reactor). Most of the existed studies focus on the single inlet of gas whereas steam may flow from two sides of the T-junction during the blowdown of primary system. Hence the experimental study on liquid entrainment with double end inlets are carried out. The data on the onset of entrainment (OLE) turns out that double end inlets show small difference with single inlet, whereas the entrainment rate research have great difference with single inlet and there is more than 50% error between the data and existing theoretical models. According to the visible flow phenomenon and flow instability, a new entrainment rate model was proposed which can well predict the double-end inlets and single-inlet entrainment phenomenon with the error within ±20%. © 2023, The Authors. All rights reserved.

关键词： Pressurized water reactors

Experiments and Predictions for Severe Slugging of Gas-Liquid Two-Phase flows in a Long-Distance Pipeline-Riser System

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SSRN 2023年

作者： Chang, Yingjie Xu, Qiang Zou, Suifeng Zhao, Xiangyuan Wu, Quanhong Wang, Yechun Thévenin, Dominique Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universität Magdeburg Magdeburg39106 Germany

Experiments concerning the flow regimes observed in gas-liquid two-phase flows in a long pipeline-riser system have been carried out and are analyzed in this paper. The test loop with 0.075 m inner diameter consists of a 314 m horizontal pipeline, followed by a 25 m downward-inclined pipe, and finally a 21.5 m riser pipe. An industrial-scale global flow regime map is derived from differential pressure measurements in the riser. Electrical capacitance volume tomography installed in the horizontal section was used to reconstruct the phase interface in order to calculate the average gas void fraction (GVF). An appropriate model for this system is selected by comparing the experimental GVF with different, widely used models. The occurrence of a severe slugging flow (SS) can be well predicted using the model involving additional corrections (taking into account pipeline length, accurate GVF results, and gas density). This study supports the development of a suitable SS prediction model enabling safe design, operation, and control of practical systems. © 2023, The Authors. All rights reserved.

关键词： Pipelines

Optimization of Single-Hole Fender Design for Offshore Wind Turbine Foundation Under Ship Collision

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SSRN 2023年

作者： Wang, Yujin Li, Chun Yue, Minnan Liu, Qingsong Sun, Kang Yue, Xinzhi Han, Zhiwei School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai China Shanghai Electric Wind Power Group Co. Ltd. Shanghai200233 China

This paper proposes a new design of protective fender for offshore wind turbine foundations based on nonlinear dynamics theory. The traditional anti-collision design for marine engineering platforms is not well-suited to wind turbine foundations, so the study uses the internal dynamics method and LS-DYNA to simulate the collision between a tripod foundation fender and a ship. The study analyzes impact force, energy absorption, stress, strain, and acceleration of the wind turbine tower top using finite element simulations under 19 relative hole angles. Results indicate that the optimal anti-collision protection is achieved with a hole angle of 20°. The study also examines the dynamic response and acceleration of the fender under different hole outer diameters of 0.5 m, 0.6 m, and 0.7 m and finds that the fender with a 0.7 m outer diameter exhibits the best anti-collision characteristics. The study utilizes a Kriging approximation model and a multi-objective genetic optimization algorithm to optimize the single-hole fender's design for minimum collision force and maximum energy absorption. The optimal parameter configuration has an inner hole diameter size of 0.658 m and a relative angle of 0.22°, achieving the best fender collision resistance ability. © 2023, The Authors. All rights reserved.

关键词： Offshore wind turbines

Experimental Study on Deliquification with Atomizing Nozzle in Gas Well

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Experimental Study on Deliquification with Atomizing Nozzle ...

2020 International Conference on Green Energy, Environment and Sustainable Development, GEESD 2020

作者： Gao, Yutang Li, Xiaobai Chang, Peng Liu, Lei State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Shaanxi710049 China

Gas is a clean energy resource in comparison with oil and coal. Liquid-loading problem is frequently encountered in the process of gas production. It would directly cause the production of gas wells decreasing, even off production. A number of deliquification techniques have been suggested for solving this kind of problem, but the available techniques are not yet widely applicable. Based on the analysis, the method of deliquification with atomizing nozzle in gas wells was put forward. The test bench was designed for studying the atomization of nozzles and the liquid entrainment of gas flow. The size distribution of atomized droplets was measured by Malvern laser grain size analyzer. The Sauter mean diameters of atomized droplets were analysed under different two-phase flow conditions. The results indicate that the designed nozzles have good atomization performances and show potential application for reducing liquid loading in gas wells. © Published under licence by IOP Publishing Ltd.

关键词： Two phase flow

Evaluation of a Numerical Model for Predicting flow and Heat Transfer in a Hexagonal Helical Cruciform Seven-Rods Bundle and Analysis of Rod Bundle Size Independence

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SSRN 2024年

作者： Jiang, Dianqiang Deng, Jian Zhang, Dalin Zhou, Xingguang Xiao, Changzhi Tian, Wenxi Qiu, Suizheng Su, Guanghui H. State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China Science and Technology on Reactor System Design Technology Laboratory Chengdu610213 China China Institute of Atomic Energy Beijing611731 China

In this study, the accuracy and applicability of the numerical model are comprehensively evaluated based on the experimental data of a hexagonal helical cruciform (HC) seven-rods bundle. The STAR CCM+ is utilized as a tool to obtain predicted results of flow and heat transfer in different flow regions. The numerical results indicate that it is an improved method to set a negative heat flux on the hexagonal wall in the laminar flow region. The Reynolds stress transport model can accurately predict the experimental results of heat transfer in the transitional flow region, with an average wall temperature deviation of 2.8℃. The SST k-ω model with cubic constitutive option can accurately predict the experimental results of the flow resistance, and a relative error of f is 1.8%. In the turbulent flow region, the SST k-ω model with cubic constitutive option provides an accurate prediction, with an average wall temperature deviation of 3.7℃. The realizable k-Ε two-layer model can accurately predict the flow resistance, and the relative error of f is 0.1%. The preferred numerical model is used to analyze the size independence of the HC rod bundle. This work provides certain guidelines for the accurate simulation in the HC seven-rods bundle. © 2024, The Authors. All rights reserved.

关键词： Computational fluid dynamics

Numerical Study on Benchmark Analysis of NACIE-UP Facility with Uniform and Non-Uniform power Distribution

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SSRN 2024年

作者： Li, Haoyang Zhang, Dalin Zhou, Lei Deng, Jian Tian, Wenxi Su, Guanghui Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China

The NACIE-UP facility is located at the ENEA Brasimone Research Centre and is designed to investigate the thermo-hydraulic properties of LBE within a wire-spaced assembly under uniform and non-uniform power distribution conditions. In this study, the thermo-hydraulic characteristics of FPS are analyzed. ANSYS Fluent solver is applied with the COUPLE algorithm of RANS [[EQUATION]] model. Cheng&Tak correlation and computational conditions are implanted into Fluent in the form of UDFs. The results show that the RMSEs of ADP10SS1 and ADP10SS2 are 2.52 K and 3.69 K, 7.05 K and 8.48 K for ADP06SS1 and ADP06SS2, respectively, which indicate that the adopted models have good prediction ability for the temperature of the experimental conditions. Meanwhile, the heat transfer characteristics are investigated and compared with the correlations of Ushakov, Mikityuk, Kazimi and Carelli. Above all, this study provides quantitative and qualitative analysis for verification and validation of CFD/STH code and stand-alone CFD simulation. © 2024, The Authors. All rights reserved.

关键词： Heat transfer

On Accelerative Propagation of Premixed Hydrogen/Air Laminar and Turbulent Expanding Flames

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SSRN 2022年

作者： Zhao, Haoran Wang, Jinhua Cai, Xiao Dai, Hongchao Liu, Xiao Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong Universit Xi’an710049 China College of Power and Energy Engineering Harbin Engineering University Harbin150001 China

The accelerative propagation of laminar and turbulent premixed hydrogen/air flames are investigated using a constant volume combustion chamber. Turbulent burning velocity ( S T ) of hydrogen/air mixtures are determined in a wide range of conditions, more importantly the flame propagation dynamics and acceleration exponents are analyzed in detail. Results show that three distinct stages, namely quasi steady, transition acceleration and saturation acceleration stages are distinguished in laminar flame propagation process, and transient acceleration exponent ( a R ) increases in transition acceleration stage while nearly remains as a constant between 1.1~1.25 in saturation acceleration stage. Turbulent flame propagation follows a self-similar acceleration law, and transient acceleration exponent increases continuously as flame propagates outwardly. Furthermore, the empirical correlatio n is obtained to describe the development of turbulent flame acceleration with flame radius. Additionally, global acceleration exponents ( a ) of turbulent flames increase continuously with u ’ / S L and no significant trend variation occurs in different regimes. It appears that the accelerative propagation of turbulent expanding flames is mainly controlled by turbulence stretch, while the effect of flame intrinsic instability is nearly covered in current study. © 2022, The Authors. All rights reserved.

关键词： Acceleration

Mild Combustion of a Premixed Nh3/Air Jet Flame in Hot Coflow Versus its Ch4/Air Counterpart

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SSRN 2023年

作者： Li, Pengfei Wang, Guochang Liu, Xiangtao Shi, Guodong Cai, Xiao Liu, Zhaohui Mi, Jianchun State Key Laboratory of Coal Combustion School of Energy and Power Engineering Huazhong University of Science and Technology Wuhan430074 China College of Engineering Peking University Beijing100871 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Dalian Maritime University China

MILD combustion is very suitable for solving the problems of unstable flame and high NOx emission (ENOx ) for ammonia fuel, but the related studies are rare. This work numerically investigates the MILD combustion characteristics of a premixed NH3/air jet flame in hot coflow (JHC) under different jet equivalence ratio (ΦJ), coflow temperature (TC) and oxygen level (XO2,C). For comparison, the similar CH4/air MILD-JHC flames are also calculated. Results show that the NH3 flame generally has lower temperature rise and heat release as well as larger reaction zone than CH4. This may suggest that the former flame can develop to the MILD regime more easily. ENOx is two orders higher from the NH3 than CH4 flame at all TC and XO2,C for ΦJ 1, ENOx of the NH3 flame quickly drops to near zero, but ENH3 and EH2 are very high (~1000 ppm) and the combustion efficiency is low. Moreover, ENOx increases quickly (slowly) with XO2,C (TC) while ENH3 and EH2 are quite low at TC ≥ 1300 K and XO2,C ≥ 1% for the NH3 flame. ENOx mainly comes from NO but N2O is also important at low ΦJ and TC. Therefore, considering all ENOx , ENH3, EH2 and the burning efficiency, the optimal conditions for NH3 MILD combustion are ΦJ =1, TC ≥ 1500 K and XO2,C =1%-3%. In addition, compared to the conventional flame, the NH3 MILD combustion can reduce ENOx by 1-2 orders. © 2023, The Authors. All rights reserved.

关键词： Ammonia

Experimental study on the contribution of included/excluded minerals to particulate formation during coal char combustion

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Fuel 2023年第1期346卷

作者： Shang, Yimin Liu, Siqi Niu, Yanqing Zhu, Guangqing Cheng, Zening Hui, Shi'en State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Shaanxi710049 China China Nuclear Power Technology Research Institute Shenzhen518031 China Zhundong Energy Research Institute Xinjiang Tianchi Energy Co. Ltd. Xinjiang831100 China

The contributions of included and excluded minerals to particulate matter formation are quantified in this work. By devolatilization of three typical Chinese coals, three coal chars with low (LA), moderate (MA), and high ash (HA) content (with both included and excluded minerals) were prepared, from which three float coal chars with low (LA−), moderate (MA−), and high ash (HA−) content (without excluded minerals) were separated by density differentiation method. The coal chars before and after separation were burned in a drop-tube furnace at 1600 K, the results of three float coal chars can directly reveal the contribution of included minerals, and the comparison of two kinds of chars with and without excluded minerals would reveal the excluded mineral contribution to ash distribution. The size distributions of the combustion-generated ash particle were obtained from the combination of ELPI+ and laser particle-size analyzer. The fractions of included/excluded minerals were obtained from SEM images. The results from the combustion of the float chars indicate the physical transformation of included minerals, while the results from original coal chars involve the transformation of both included and excluded minerals. Results indicate that the distribution of ash particles from included minerals for HA− char possesses a single peak, while the ash distributions of MA− and LA− char show a bi-modal shape. The excluded minerals in LA and MA chars mainly contribute to the ash emissions with sizes larger than 80 μm. The contribution from excluded minerals reach 86% to the ash particles of 205 μm for HA char, 54% for MA char and 51% for LA char. The number fractions of included minerals continuously decrease with a transformation into excluded minerals during char dynamic combustion. © 2023 Elsevier Ltd

关键词： Minerals