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Upstream-flow-based mechanisms for global flow regime transition of gas/liquid two-phase flow in pipeline-riser systems

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CHEMICAL engineering SCIENCE 2021年 240卷 116542-116542页

作者： Zou, Suifeng Guo, Liejin Yao, Tian Wuhan Second Ship Design & Res Inst Wuhan 430064 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China CNPC Tubular Goods Res Inst Xian 710077 Peoples R China

In order to develop the transition models for undesirable two-phase flow regimes in a pipeline-riser system in offshore oil and gas production systems, the relation between the upstream flow condition in the pipeline and the global flow regime is analysed. The transition of local flow pattern along the upstream pipeline, especially the slug dissipation behaviour, is found to be related to global flow regime transition. The mechanisms for the transition from stable flow regime to different undesirable flow regimes are proposed separately. A set of hybrid criteria is established and validated by experimental data. The proposed criteria can predict the transition to undesirable conditions which are less severe but more common than the typical cases, compared with existing uniform criteria. The findings can help for better understanding of flow regime transition in a pipeline-riser system with more complex layout of pipeline, and also the possible extension of laboratorial experimental results. (c) 2021 Elsevier Ltd. All rights reserved.

关键词： Pipeline-riser system Two-phase flow Global flow regime flow regime transition Transition criteria Slug dissipation

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A multi-criteria comprehensive evaluation method for distributed energy system 10

A multi-criteria comprehensive evaluation method for distrib...

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10th International Conference on Applied Energy (ICAE)

作者： Dai, Haibo Wang, Jinshi Li, Gen Chen, Weixiong Qiu, Binbin Yan, Junjie Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

As the evaluation of distributed energy system (DES) is a complex problem, multi-criteria is necessary to fully evaluate the performance for different systems. In this paper, a novel multi-criteria evaluation method was established to assess the comprehensive performance of DES from economic, energy and environment criterions. Before constructing a multi-level indexes system, index correlation analysis was carried out to ensure the independence of indexes. Considering the advantages and disadvantages of subjective and objective methods, AHP-entropy method was proposed by integrating analytic hierarchy process (AHP) and information entropy method together to assign weights to the indexes. Finally, the technique for order preference by similarity to ideal solution (TOPSIS) method was applied to determine the optimal DES scheme. The case study indicated that the evaluation results of this method were in accordance with the reality, which could provide a reference for the selection of DES solutions. (C) 2019 The Authors. Published by Elsevier Ltd.

关键词： DES comprehensive evaluation AHP-entropy method TOPSIS method

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A new simulation method for laser speckle imaging to investigate hemodynamics 12

A new simulation method for laser speckle imaging to investi...

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12th International Conference on Computational Heat, Mass and Momentum Transfer (ICCHM2T)

作者： Sang, X. Li, D. Chen, B. Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

Speckle simulation is a powerful protocol to investigate the properties of speckle and evaluate image processing method. However, only static speckle images can be simulated by available methods without considering time-integrated effect of CCD. A time-integrated dynamic speckle simulation method based on coherent imaging was developed. Through the new simulation method, the effect of speckle size on LSCI was investigated. The smaller the speckle size is, the higher the spatial resolution become. But the one-dimensional speckle size should exceed two pixels to sample the speckle pattern. The characteristics of existing speckle contrast imaging methods were studied based on spatial statistics, and optimal parameters are given to obtain accurate and less noisy image. In general, the new simulation method for laser speckle imaging is a powerful tool to monitor blood flow in vivo and lay a solid foundation for the study of hemodynamics.

关键词： Hemodynamics

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Numerical modeling and performance comparison of high-temperature metal hydride reactor equipped with bakery system for solar thermal energy storage

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2020年第56期45卷 31612-31631页

作者： Ayub, Iqra Nasir, Muhammad Salman Liu, Yang Munir, Anjum Wu, Zhen Yang, Fusheng Zhang, Zaoxiao Xi An Jiao Tong Univ Sch Chem Engn & Technol State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Peoples R China Xi An Jiao Tong Univ Sch Energy & Power Engn Xian 710049 Peoples R China Univ Agr Faisalabad Dept Energy Syst Engn Faisalabad 38040 Pakistan Univ Agr Faisalabad Dept Struct & Environm Engn Faisalabad 38040 Pakistan

The current study provides an optimal design strategy for the metal hydride reactor for the thermal energy storage system for solar bakery applications. The sensitivity analysis of the annular truncated hollow conical fins type reactor was conducted by using COMSOL Multiphysics 5.3a software. The gravimetric exergy output rate and exergy output of different designs were compared. It was found that the optimal geometric parameters and operating conditions for the annular truncated hollow conical fins type reactor are fin angle (theta) = 20 degrees, fin radius (R-f) = 0.07 m, number of fins (N-f)= 32 and fin spacing (S-f) = 0.02 m, fin thickness (th(f)) = 0.008 m, hydrogen supply pressure (P-in,P-H2) = 5 MPa and inlet heat transfer fluid velocity (V-HTF,V-in) = 20 m/s. Finally, it was concluded that the Deign IV is the most favorable design, which has a uniform reaction, faster reaction time (15,000 s), and higher values of gravimetric exergy output rate and exergy output (1.23 W/kg, 0.028 kW). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Solar thermal energy Storage (MgH2+V2O5) reactor Optimal design strategy Reduction of reaction time and non-uniform reaction An increase of gravimetric exergy output rate

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A rapid method for composition tracking in hydrogen-blended pipeline using Fourier neural operator

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PHYSICS OF FLUIDS 2024年第11期36卷

作者： Gong, Junhua Shi, Guoyun Fan, Ziying Yu, Bo Chen, Yujje Chen, Bin Li, Jingfa Wang, Bohong Li, Zongze Jiang, Weixin Varbanov, Petar Sabev Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Beijing Inst Petrochem Technol Sch Mech Engn Beijing 102617 Peoples R China Beijing Acad Safety Engn & Technol Beijing 102617 Peoples R China China Petr Pipeline Engn Co Ltd Langfang Peoples R China Zhejiang Ocean Univ Natl & Local Joint Engn Res Ctr Harbor Oil & Gas S Zhejiang Prov Key Lab Petrochem Pollut Control Zhoushan 316022 Peoples R China Beijing Univ Technol Fac Environm & Life Beijing 100124 Peoples R China Brno Univ Technol VUT Brno Fac Mech Engn NETME Ctr Sustainable Proc Integrat Lab SPIL Technicka 2896-2 Brno 61669 Czech Republic

Blending hydrogen into natural gas for transportation is a crucial approach for achieving the widespread utilization of hydrogen. Tracking the concentration of the hydrogen within the pipeline is important for monitoring gas quality and managing pipeline operations. This study develops a rapid computational model to predict the hydrogen and natural gas concentrations within the pipeline during transportation based on the Fourier Neural Operator (FNO), an operator neural network capable of learning the differential operator in the partial differential equation. In the proposed model, the numerical method is employed to generate datasets, with the spline interpolation used to enhance data smoothness. The initial and boundary conditions are taken as the inputs to accommodate varying transportation scenarios. Comparison results indicate that the proposed model can notably reduce the time needed to predict the hydrogen and natural gas concentrations while maintaining prediction accuracy. The accuracy of the proposed model is validated by comparing its calculated results with the analytical solution and the concentrations of hydrogen and natural gas within the pipeline under two transportation scenarios, with relative errors of 0.49%, 0.31%, and 0.45%, respectively. Notably, the trained model demonstrates strong grid invariance, a type of model generalization. Trained on data generated from a coarse grid of 101 x 41 spatial-temporal resolution, the proposed model can accurately predict results on a fine grid of 401 x 81 spatial-temporal resolution with a relative error of only 0.38%. Regarding the prediction efficiency, the proposed model achieves an average 17.7-fold speedup compared to the numerical method. The positive results indicate that the proposed model can serve as a rapid and accurate solver for the composition transport equation.

关键词： Natural gas transportation

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Electrochemically-mediated amine regeneration of CO2 capture: From electrochemical mechanism to bench-scale visualization study

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APPLIED ENERGY 2021年 302卷 117554-117554页

作者： Wu, Xiaomei Fan, Huifeng Sharif, Maimoona Yu, Yunsong Wei, Keming Zhang, Zaoxiao Liu, Guangxin Xi An Jiao Tong Univ Sch Chem Engn & Technol 28 Xianning West Rd Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn 28 Xianning West Rd Xian 710049 Peoples R China

Electrochemically-mediated amine regeneration (EMAR) is a new CO2 capture technology with the potential to exploit the excellent removal efficiencies of thermal amine scrubbers while reducing parasitic energy losses and capital costs. To achieve higher efficiency and explore the industrial application of the promising EMAR system, a home-designed bench-scale modular flowing-through electrolysis cells (MFTECs) is proposed. The MFTECs with MEA solvent is carefully analyzed from electrochemical mechanism to bench-scale demonstration. Firstly, a series of electrochemical experiments were conducted in an H-cell to study the unknown electrochemical behaviors under various complex concentrations and temperatures, which provided a guidance to enhance the electrochemical performance. Subsequently, a visualization study of the CO2 desorption process in MFTECs was conducted at different operating conditions (current, complex concentration, electrode position, and reaction time) to investigate the desorption performance of the proposed MFTECs system. This framework allowed for direct observation and comprehension of the CO2 desorption process, as well as the movement and interaction of CO2 bubbles in MFTECs. Finally, results indicated that the proposed MFTECs enables higher electrode active surface area and lower cell resistance. This will contribute to enhancing the regeneration performance and promoting industrial application of CO2 desorption based on EMAR.

关键词： Carbon dioxide capture EMAR H-cell Electrochemical mechanism Bench-scale study

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Formation of persistent free radicals in sludge biochar by hydrothermal carbonization

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ENVIRONMENTAL CHEMISTRY LETTERS 2021年第3期19卷 2705-2712页

作者： Tang, Zheng Zhao, Song Qian, Yajie Jia, Hanzhong Gao, Pin Kang, Yanming Lichtfouse, Eric Donghua Univ Coll Environm Sci & Engn 2999 North Renmin Rd Shanghai 201620 Peoples R China Northwest A&F Univ Coll Resources & Environm Yangling 712100 Shaanxi Peoples R China Guangdong Acad Sci Natl Reg Joint Engn Res Ctr Soil Pollut Control & Guangdong Key Lab Integrated Agroenvironm Pollut Guangdong Inst Ecoenvironm & Soil Sci Guangzhou 510650 Peoples R China Aix Marseille Univ CEREGE Coll France CNRSIRDINRAE F-13100 Aix En Provence France Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

The uses of biochar as soil fertilizer can offset global warming and reduce dependence on limited mineral resources in the future circular economy, yet biochar may contain contaminants that can ultimately enter the food chain. In particular, persistent free radicals are emerging contaminants previously detected in biochar but underlying mechanisms of radical formation are not yet established. Here we studied radical generation during hydrothermal carbonization of waste sludge at 160-220 oC for 0.5-2 h with solid weight ratios of 10%w-40%w using electron paramagnetic resonance and Fourier transform infrared spectrometry. Results reveal that radical concentration increases with temperature, reaction time, and weight ratio in sludge biochars, reaching a content of 47.2 x 10(15) spins/g for 220 oC, 2 h heating, and 40%w solid ratio. Moreover, low temperature of about 160 oC favors the production of oxygen-centered radicals, whereas higher temperature of 220 oC produces carbon-centered radicals. Our findings imply that biochar ecotoxicity should be assessed prior applications to prevent adverse health effects.

关键词： Persistent free radicals Waste sludge biochar Hydrothermal carbonization

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Spatial Heterogeneity of Point Defect Properties in Refractory Multi-Principal Element Alloy with Short-Range Order: A First-Principles Study

SSRN

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SSRN 2022年

作者： Shi, Tan Lyu, Sixin Su, Zhengxiong Wang, Yunpeng Qiu, Xi Sun, Dan Xin, Yong Li, Wenjie Cao, Jiang Peng, Qing Li, Yuanming Lu, Chenyang School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China School of Electronic and Optical Engineering Nanjing University of Science and Technology Nanjing210094 China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The short-range order is inherently present in the multi-principal element alloys and has a profound impact on the defect behaviour. The effect of short-range order on vacancy and interstitial formation and migration was studied in body-centered cubic multi-principal element alloy NbZrTi by first-principles calculations. Two short-range order structures created by density functional theory and Monte Carlo method at 500 K and 800 K were compared with the random solid solution structure. Both vacancy and interstitial formation energies increase with the degree of short-range order. Point defect formation energies tend to be higher in region enriched in Nb and lower in region enriched in Zr and Ti. Both vacancies and interstitials prefer to migrate towards Zr,Ti-rich regions and away from Nb-rich regions, suggesting that Zr,Ti-rich region can act as recombination center for point defect annihilation. Compared to the random solid solution, the short-range order increases the spatial heterogeneity of point defect energy landscape. Tuning the degree of short-range order can be a viable strategy to optimize the point defect behaviour to achieve enhanced radiation resistance in multi-principal element alloys. © 2022, The Authors. All rights reserved.

关键词： Monte Carlo methods

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Numerical investigation on erosion characteristics of coplanar elbows connection for gas-solid flow 10

Numerical investigation on erosion characteristics of coplan...

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10th International Conference on Applied Energy (ICAE)

作者： Wang, Yu Liu, Rongtang Liu, Ming Yan, Junjie Xi An Jiao Tong Univ Sch Energy & Power Engn State Key Lab Multiphase Flow Power Engn Xian Shaanxi Peoples R China

Elbows are used widely in power plants. The erosive problems of the pipelines influence the performance of pipe system. Continuous arrangement of elbows is often necessary due to the limit of external space and connection length between elbows is short under the circumstance. The interaction between two elbows has influence on the flow field and erosion characteristics of elbows connection. The erosion distribution in coplanar elbow connection was presented and erosion characteristics of two kinds of coplanar elbows connection were obtained. The effects of inlet velocity and mass loading rate on maximum erosion rate were investigated. Results suggested the maximum wear rate increased exponentially with inlet velocity and increased linearly with mass loading rate. (C) 2019 The Authors. Published by Elsevier Ltd.

关键词： Elbows connection Erosion characteristics Numerical simulation Gas-solid flow

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Light-Enhanced Thermochemical Production of Solar Fuels from Methane Via Nickel-Based Redox Cycle

SSRN

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SSRN 2022年

作者： Liu, Mingkai Zhang, Jinrui Yang, Tianlong Rao, Qiong Gai, Zhongrui Zhao, Jianxiong Pan, Ying Su, Dong Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China University of Chinese Academy of Sciences Beijing100049 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University 710049 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China

Thermochemical methane reforming driven by solar energy is one of the efficient ways to store the renewable energy and to simultaneously reduce greenhouse gas emission. We report reaction reactivity of steam reforming of methane using nickel-based oxygen carrier driven by pure thermal heating and direct light irradiation in the same reactor. We find that the light-driven steam methane reforming system show improved conversion and reaction rate compared to that driven by pure thermal heating. We observed that illuminated NiO/NiAl2O4 achieved the same methane conversion rates and the H2 production rate comparable to those obtained on the same samples operated with only a thermal energy input, but at temperatures up to ~50 K lower. Based on in situ diffuse reflectance Infrared Fourier transform spectroscopy (DRIFTs) experiments, we postulate that light on the nickel oxide surface act to activate CH4 desorption and facilitate CHxO species evolution. By the combined effects of selection of chemical looping reactions and operation conditions, the solar-to-fuel efficiency of 16% was achieved. The results showcase the design of more energy-efficient chemical processes with a significant fraction of energy input provided in the form of direct sunlight irradiation as a potent pathway that can complement extremely high-temperature thermochemistry efforts in the quest for more efficient solar fuel production. © 2022, The Authors. All rights reserved.

关键词： Fourier transform infrared spectroscopy

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