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Prediction of the severe slugging period in gas-liquid two-phase pipeline-riser systems using an artificial neural network

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Energy 2025年 331卷

作者： Yingjie Chang Qiang Xu Bo Huang Xuemei Zhang Haiyang Yu Hao Chen Dominique Thévenin Liejin Guo Shaanxi Key Laboratory of New Transportation Energy and Automotive Energy Saving School of Energy and Electrical Engineering Chang'an University 710064 Xi'an China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 Xi'an China Laboratory of Fluid Dynamics and Technical Flows Otto-von-Guericke-Universität Magdeburg 39106 Magdeburg Germany

Severe slugging flow (SS) is a very harmful flow regime found during oil and gas transportation. An accurate prediction of the SS period would help to obtain the needed conditions for regime transition models, which are essential when designing and operating an oil and gas field. However, previous empirical correlations are limited to specific flow and structural conditions, resulting in significant errors whenever these parameters deviate. Gas-liquid two-phase flow experiments in a pipeline-riser system were carried out and used as additional training data. The analysis of scatter matrix and correlation coefficient was used to determine the most relevant features impacting SS period. Then, a prediction model based on an artificial neural network (ANN) was established with one single output (the SS period) and seven input features, including five pipeline structural parameters and two flow parameters. The prediction errors coming with previous empirical models are much larger than those of our ANN model. While the relative errors of the empirical models range from −95 % to 3000 %, the ANN has a prediction error within a range of 25 % and a mean absolute error of only 11.3 %, showing a significant improvement over previous predictions.

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Control of two-phase flow around a cylinder with a cylindrical attachment: A numerical study

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Ocean engineering 2025年 334卷

作者： Wang, Ziqing Hu, Yu Huang, Shengxian Zhang, Yongxing Moghtaderi, Behdad Wang, Ying Shanghai Key Laboratory of Multiphase Flow and Heat Transfer of Power Engineering School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China National Engineering Laboratory for Pipeline Safety/MOE Key Laboratory of Petroleum Engineering/Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum – Beijing Beijing102249 China Centre for Innovative Energy Technologies The University of Newcastle CallaghanNSW2308 Australia

Mitigating flow separation, vortex shedding and sediment-induced erosion around cylindrical structures is critical for enhancing marine engineering safety. This study investigates the hydrodynamic performance of a two-phase flow around a cylinder equipped with an auxiliary cylinder under realistic ocean conditions. key parameters include the clearance ratio (G/D), particle characteristics (size and concentration), and vibration modes of the auxiliary body. This study investigates real ocean conditions, focusing on the influence of clearance ratio (G/D) and an auxiliary cylinder on flow field changes with varying particle characteristics. The results demonstrate that: (1) A clearance ratio G/D = 0.1 yields the optimal drag reduction (57.18 %) for the primary cylinder in single-phase flow;(2) Larger particles weaken vortex-particle interactions, while higher particle concentrations exacerbate uneven deposition near the cylinder;(3) Transverse vibration of the auxiliary body (amplitude ratio = 0.025, frequency ratio = 0.65) reduces drag by 18.7 % compared to stationary configurations. These findings provide insights into flow control strategies for offshore structures subjected to sediment-laden flows. © 2025 Elsevier Ltd

关键词： Marine safety

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Function-switchable metal/semiconductor junction enables efficient photocatalytic overall water splitting with selective water oxidation products

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Science Bulletin 2020年第16期65卷 1389-1395,M0004页

作者： Daixing Wei Yubo Tan Yiqing Wang Tingting Kong Shaohua Shen Samuel S.Maoc International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an 710049China College of Chemistry and Chemical Engineering Xi'an Shiyou UniversityXi'an 710054China Department of Mechanical Engineering University of California at BerkeleyBerkeleyCA 94720USA

A novel metal/semiconductor photocatalyst,Cu nanoparticles(NPs)modified TiO2 hollow spheres(Cu/TiO2),was designed for efficient photocatalytic overall water splitting(POWS)under both ultraviolet(UV)and visible(Vis)*** Cu/TiO2 photocatalyst possesses excellent POWS performance under Vis light at the highest level among the reported TiO2-based ***,the metal/semiconductor junction formed between Cu and TiO2 enables controlled water-oxidation product selectivity(H2O2 or O2)via different reaction pathways regulated by irradiation *** UV light,the electrons excited in TiO2 are captured by Cu NPs through the Cu/TiO2 Schottky interface for H2 production,with the photoholes in TiO2 producing H2O2 through a two-electron process;whilst under Vis light,Cu NPs act as plasmon to inject hot electrons to TiO2 for H2 production,while O2 is produced by hot holes on Cu NPs via a four-electron *** rational design of function-switchable metal/semiconductor junction may be helpful to understand the mechanisms for POWS with desired gas/liquid water-oxidation products.

关键词： Photocatalysis Water splitting Product selectivity Reaction pathway Metal/semiconductor junction

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A subcooled boiling model developed for narrow rectangular channels based on the CFD method 18

A subcooled boiling model developed for narrow rectangular c...

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18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Li, Linfeng Wang, Mingjun Zhang, Dalin Tian, Wenxi Su, G.H. Qiu, Suizheng State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

The accurate prediction of subcooled boiling phenomena in narrow rectangular channels is of great importance for the plate type fuel reactor core safety analysis during some critical scenarios. Serious of experimental studies on subcooled boiling in narrow rectangular channels indicate that a bubble may slide on the heating surface after nucleation and then lift to the main flow, merging with not-yet-fully-grown bubble and disrupting local boundary layer. In this paper, the influence of sliding bubbles is taken into consideration in wall boiling model and implanted into the CFD code to simulate boiling in narrow rectangular channel. Bubble dynamics is used in calculating the relevant bubble diameters during ebulletin cycle. The feasibility of this proposed model is validated with existed experimental data by comparing wall superheat. This work could promote the development of CFD two-phase flow simulation capacity in the plate type fuel nuclear reactor. © 2019 American Nuclear Society. All rights reserved.

关键词： Computational fluid dynamics

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Performance of different flocculants for harvesting Chlorella vulgaris by dissolved air flotation and sedimentation

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Bioresource technology 2025年 433卷 132743页

作者： X Wei N R H Rao S Tyagi W Thielemans W Cao L J Guo K Muylaert State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China Laboratory of Aquatic Biology KU Leuven Campus Kulak Kortrijk 8500 Kortrijk Belgium. Laboratory of Aquatic Biology KU Leuven Campus Kulak Kortrijk 8500 Kortrijk Belgium Sustainable Materials Laboratory Department of Chemical Engineering KU Leuven Campus Kulak Kortrijk 8500 Kortrijk Belgium. Electronic address: n.hanumanthrao@unsw.edu.au. Sustainable Materials Laboratory Department of Chemical Engineering KU Leuven Campus Kulak Kortrijk 8500 Kortrijk Belgium. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China. Electronic address: caowenxjtu@***. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China. Electronic address: lj-guo@***. Laboratory of Aquatic Biology KU Leuven Campus Kulak Kortrijk 8500 Kortrijk Belgium. Electronic address: koenraad.muylaert@kuleuven.be.

This study systematically evaluated the performance of dissolved air flotation and sedimentation for harvesting Chlorella vulgaris using eight different flocculants. Significant variation was observed in both the maximum harvesting efficiency and the minimum effective flocculant dose across different flocculant-process combinations. Among the tested flocculants, pyridinium modified cellulose nanocrystals achieved the highest harvesting efficiency of 99 % in both dissolved air flotation and sedimentation, while chitosan required the lowest minimum flocculant dose (∼2 mg·g) to induce flocculation. The impact of floc size formed during the flocculation step on harvesting performance was also investigated, revealing that large flocs significantly favored sedimentation-based microalgae harvesting. A preliminary cost analysis highlighted the importance of integrating economic considerations into the selection of both flocculant and harvesting method. The findings suggest that optimal flocculant and process selection should be based not only on harvesting efficiency but also on cost-effectiveness for microalgal biomass recovery.

关键词： Cationic flocculants Dissolved air flotation optimization Floc size distribution Microalgal recovery Water treatment

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Low to intermediate temperature ignition delay times of nitromethane 12

Low to intermediate temperature ignition delay times of nitr...

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12th Asia-Pacific Conference on Combustion, ASPACC 2019

作者： Yang, Meng Tang, Chenglong Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xianning West Road Xi'an Shaanxi710049 China

In this work, the auto-ignition experiments of nitromethane at the low to intermediate temperature, fuel concentration of 2%, pressure of 30 bar and different equivalence ratios have been investigated by using rapid compression machine. The pressure profiles of nitromethane ignition were observed. Results show that a distinct two-stage heat release process is found at ? = 0.5. And multi-stage heat release is also observed with temperature decreasing. Subsequently, the effect of equivalence ratio on the nitromethane ignition is performed. The results show that the dependence of nitromethane ignition on the equivalence ratio is weak. In addition, the experimental data are used to validate the recent developed mechanisms of nitromethane. Relative large deviations are observed between experiments and predictions. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Combustion

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Lattice Boltzmann simulation on adsorption of sulfuric acid vapor by ash particles

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Fuel 2025年 401卷

作者： Jiyun Ren Chongjun Jiang Fangfang Hu Hui Wang Yunhao Shao Xinyu Liu Zhang Wu Feng Pan Qidong Yang Lei Deng Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China China University of Petroleum-Beijing Beijing 102249 China China Energy Engineering Group Shaanxi Electric Power Design Institute Co. Ltd. Xi’an 710054 China West Pipeline Company of PipeChina Urumchi 830000 China

In the low-low temperature flue gas systems, sulfuric acid vapor is adsorbed onto the ash particles. Based on the SEM images of ash particles, the OpenCV library in C++ is employed for image binarization, which aids in developing a lattice Boltzmann method (LBM) that incorporates convection–diffusion and surface adsorption. The adsorption process of sulfuric acid vapor by ash particles with different chemical compositions is simulated and evaluated. The results indicate that sulfuric acid vapor exits through the ash particles at 5.1 μs, and stabilizes after 51 μs, reaching a maximum velocity of 0.29 m s –1 . Without chemical additives, the ash particles undergo a rapid adsorption phase within the initial 1000 μs, achieving nearly 78.92 % saturation with an average adsorption amount of 1.31 mg g –1 . At 10200 μs, most ash particles approach saturation adsorption, ranging from 1.6 to 1.8 mg g –1 . For all ash particles with added chemical components, adsorption preferentially occurs on the left side at both 5.1 μs and 51 μs. At 510 μs, nearly half of the ash particles with 7.1 % K 2 CO 3 reach adsorption saturation, while approximately one-half of those with 9.2 % Na 2 CO 3 achieve the same. Following the addition of 18.4 % Na 2 CO 3 , smaller ash particles approach saturation at a faster adsorption rate compared to those with 14.2 % K 2 CO 3 , with less than half of the region reaching an adsorption amount of 3.5mg g −1 . At 1000 μs, the ash particles containing 9.2 % and 18.4 % Na 2 CO 3 , along with 7.1 % and 14.2 % K 2 CO 3 , achieve saturation adsorption amounts of 96.14, 96.73 %, 95.45 %, and 93.87 %, respectively. The adsorption rate is high during the first 1000 μs but significantly declines after 1500 μs, nearing saturation by 3000 μs. The addition of 18.4 % Na 2 CO 3 results in porosity of up to 73.65 % and fewer large particles, allowing for faster mainstream velocity and mass transfer within the pores, thereby facilitating the vapor adsorption. By integrat

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PRELIMINARY NEUTRONIC/THERMAL-HYDRAULIC AND SAFETY ASSESSMENT OF PRESSURIZED WATER REACTOR LOADED WITH FULLY CERAMIC MICROENCAPSULATED FUEL

PRELIMINARY NEUTRONIC/THERMAL-HYDRAULIC AND SAFETY ASSESSMEN...

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2020 International Topical Meeting on Advances in Thermal Hydraulics, ATH 2020

作者： Wu, Di Gui, Minyang Zhang, Dalin Wang, Chenglong Wu, Yingwei Su, G.H. Qiu, Suizheng Tian, Wenxi Yang, Hongfa Peng, Jingyang Shanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi'an Jiaotong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an710049 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China Nuclear and Radiation Safety Center Ministry of Ecology and Environment of the People's Republic of China Beijing100082 China

ISBN: (纸本)9780894487774

As one of the accident tolerant fuels (ATFs), fully ceramic microencapsulated (FCM) fuel shows superior safety performance in accidents, which has the characteristics of high melting point, excellent heat transfer ability and strong nuclear proliferation resistance. Based on the neutronic analysis of Chinese advanced three loop pressurized water reactor (PWR), the assemblies and cores of FCM-SiC and UO2-Zr were designed, power distributions and cycle lengths were obtained, and the power was adjusted to ensure the annual refueling requirements. By using system analysis code, station blackout (SBO) accident in FCM-SiC and UO2-Zr was analyzed, where the steam-driven auxiliary feedwater (AFW) in secondary loop failed to be supplied in time. Assuming that the AFW system couldn't be put into operation immediately after accident, the critical time could be calculated, that is to say, fuel centerline temperature (FCT) and peak cladding temperature (PCT) wouldn't exceed corresponding limits during accident once the AFW was provided within the critical time. It is found that the critical time of FCM-SiC is 9000s and higher than that of UO2-Zr (7000s), which shows the advantages of ATFs. This work could provide reference for the optimized design of the reactor safety system in the future. © ATH 2020 - International Topical Meeting on Advances in Thermal *** rights reserved.

关键词： Silicon carbide

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Exploring Geometric Chirality in Nanocrystals for Boosting Solar-to-Hydrogen Conversion

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Angewandte Chemie 2024年第45期136卷

作者： Wenlong Fu Qi Gao Chunyang Zhang Lili Tan Biao Jiang Chengyu Xiao Prof. Maochang Liu Prof. Peng-peng Wang State Key Laboratory for Mechanical Behavior of Materials Shaanxi International Research Center for Soft Matter School of Materials Science and Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 PR China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 PR China

Advancing catalyst design is pivotal for the enhancement of photocatalytic processes in renewable energy conversion. The incorporation of structural chirality into conventional inorganic solar hydrogen nanocatalysts promises a significant transformation in catalysis, a feature absent in this field. Here we unveil the unexplored potential of geometric chirality by creating a chiral composite that integrates geometric chiral Au nanoparticles (NPs) with two-dimensional C 3 N 4 nanosheets, significantly boosting photocatalytic H 2 evolution beyond the achiral counterparts. The superior performance is driven by the geometric chirality of Au NPs, which facilitates efficient charge carrier separation through the favorable C 3 N 4 -chiral Au NP interface and chiral induced spin polarization, and exploits high-activity facets within the concave surfaces of chiral Au NPs. The resulting synergistic effect leads to a remarkable increase in photocatalytic H 2 evolution, with an apparent quantum yield of 44.64 % at 400 nm. Furthermore, we explore the selective polarized photo-induced carrier separation behavior, revealing a distinct chiral-dependent photocatalytic HER performance. Our work advances the design and utilization of chiral inorganic nanostructures for superior performance in energy conversion processes.

关键词： Geometric chirality Nanoparticles Photocatalytic hydrogen evolution reaction Chiral effect

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Cyclone separation in a supercritical water circulating fluidized bed reactor for coallbiomass gasification： Structural design and numerical analysis

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Particuology 2018年第4期16卷 55-67页

作者： Guoxing Li Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China

A new concept of a supercritical water （SCW） circulating fiuidized bed reactor is proposed to produce hydrogen from coal/biomass gasification. The cyclone is a key component of the reactor system, in this paper, cyclones with a single circular inlet （SCI） or a double circular inlet （DCI） were designed to adapt to the supercritical conditions. We evaluated the separation performance of the two cyclones using numerical simulations. A three-dimensional Reynolds stress model was used to simulate the turbulent flow of the fluid, and a stochastic Lagrangian model was used to simulate the particle motion. The flow fields of both cyclones were three-dimensionally unsteady and similar to those of traditional gas-solid cyclones. Secondary circulation phenomena were discovered and their influence on particle separation was estimated. Analyzing the distribution of the turbulence kinetic energy revealed that the most intensive turbulence existed in the zone near the vortex finder while the flow in the central part was relatively stable. The particle concentration distribution was non-uniform because of centrifugal forces. The distribution area can be divided into three parts according to the motion of the particles. In addition, the separation efficiency of both cyclones increased with the inlet SCaN velocity. Because of its perturbance flow, the DCI separator had higher separation efficiency than the SCI separator under comparable simulations. However, this was at the expense of a higher pressure drop across the cyclone.

关键词： CycloneStructural design Supercritical water-solid flow Separation performance Circulating fluidized bed Computational fluid dynamics

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