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Effect of Slug flow on CO2 Corrosion

AIP Conference Proceedings 2010年第1期1207卷 403-409页

作者： Y. B. Zhang K. Yan D. F. Che State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

multiphase flow induced CO2 corrosion has resulted in serious losses in oil and gas production. In this paper, gas‐liquid two‐phase vertical upward slug flow has been analyzed from aspects containing flow structure, hydrodynamic characteristics, mass transfer characteristics and their effects on pipe wall and corrosion product film, and it is found that slug flow has a distinct effect on transports of corroding species to and of corrosion products from the wall, momentum interchange between fluid and wall and the formation and damage of corrosion product film. In addition, the transports of corrosive species and corrosion product are also an important step in CO2 corrosion process. It is assumed that the slug flow induced CO2 corrosion of pipeline is dependent on the non‐linear coupling of the characteristics including the shear stress, the normal stress, the mass transfer coefficient, and the electrochemical reaction.

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On the effects of shear and compositional inhomogeneities in turbulent, lean, premixed flames 11

On the effects of shear and compositional inhomogeneities in...

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11th Asia-Pacific Conference on Combustion, ASPACC 2017

作者： Steinmetz, S.A. Juddoo, M. Jin, W. Masri, A.R. School of Aerospace Mechanical and Mechatronic Engineering University of Sydney NSW2006 Australia State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xian710049 China

This paper presents some initial results on the separate effects of shear and compositional inhomogeneities on the global structure of turbulent lean piloted premixed flames. Shear is introduced by injecting the mixture in two streams through two concentric tubes at different velocities. Compositional inhomogeneity, for the same shear rate, is obtained by injecting air in the annulus and fuel or rich fuel-air mixtures through the inner jet which may be recessed upstream of the jet exit plane. It is found that increasing the shear inhomogeneity can lead to a shorter flame where the tip may transition from "open" to "closed". The latter refers to a "Bunsen-like" flame while an "open" flame has reacting edges that do not close at the tip. Compositional inhomogeneity seems to have little effects on the global structure despite the presence of mixture fraction gradients a noted from Rayleigh scattering performed the jet exit plane. Measurements of velocity fields and imaging of reaction zones will be performed to enable a better understanding of the structure of these flames and to locate them on the premixed flames regime diagram. © 2018 Combustion Institute. All Rights Reserved.

关键词： Mixtures

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Numerical study on the laminar flame characteristics of acetylene-methanol blends 11

Numerical study on the laminar flame characteristics of acet...

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11th Asia-Pacific Conference on Combustion, ASPACC 2017

作者： Li, Qianqian Zhang, Yemiao Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No. 28th Xianning West Road Xi’anShaanxi710049 China

Laminar flame characteristics of the blends of acetylene and methanol were numerically studied at 0.1 MPa and 363 K. A model was adopted to do the simulations with the accuracy validated with published laminar flame speeds data of methanol and acetylene. Simulation results showed that the methanol addition into acetylene leads to the significant increase of laminar flame speed with the equivalence ratio corresponding the maximum value shifting to the rich side. The reasons behind were analyzed and found the thermal and chemical kinetic effects both contribute the laminar flame speed variation while the contribution of the diffusion effect can be ignored. Besides, the equivalence ratio shift is found to be closely related to the adiabatic temperature and OH concentrations.

关键词： Acetylene

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Shock tube study on ignition delay of multi-component syngas mixtures - Effect of equivalence ratio

Shock tube study on ignition delay of multi-component syngas...

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作者： Thi, Luong Dinh Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an 710049 China Le Quy Don Technical University Hanoi Viet Nam

Ignition delays were measured in a shock tube for syngas mixtures with argon as diluent at equivalence ratios of 0.3, 1.0 and 1.5, pressures of 0.2, 1.0 and 2.0 MPa and temperatures from 870 to 1350 K. Results show that the influences of equivalence ratio on the ignition of syngas mixtures exhibit different tendency at different temperatures and pressures. At low pressure, the ignition delay increases with an increase in equivalence ratio at tested temperature. At high pressures, however, an opposite behavior is presented, that is, increasing equivalence ratio inhibits the ignition at high temperature and vice versa at intermediate temperature. The affecting degree of equivalence ratio on ignition delay is different for each mixture at given condition, especially for the syngas with high CO concentration. Sensitivity analyses demonstrate that reaction H + O2 = O + OH (R1) dominates the syngas oxidation under all conditions. With the increase of CO mole fraction, reactions CO + OH = CO2 + H (R27) and CO + HO2 = CO2 + OH (R29) become more important in the syngas ignition kinetics. With the increase of pressure, the reactions related to HO2 and H 2O2 play the dominate role. The opposite influence of equivalence ratio on ignition delay at high- and intermediate-temperatures is chemically interpreted through kinetic analyses. © 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Shock tubes

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Influence of Salts on Morphology of Structures in Surfactant-Polymer Solutions Explored by Coarse Grained Dynamic Simulation

Influence of Salts on Morphology of Structures in Surfactant...

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作者： Liu, Dongjie Liu, Fei Zhou, Wenjing Chen, Fei Wei, Jinjia State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China School of Chemical Engineering and Technology Xi’an Jiaotong University Xi’an710049 China

In this study, a coarse-grained molecular dynamic simulation was employed to test the influence of salts in morphology of structures in surfactant-polymer solutions. The surfactant was cetyltrimethyl ammonium chloride (CTAC) and the polymer was polyacrylamide (PAM). Six different salt concentrations were studied in the mixed surfactant-polymer solutions, and pure surfactant solutions with salts were also tested as control groups. By analyzing the shapes of micelles and the CTA+ aggregation number of micelles, we noted that the proper salt concentration can facilitate the formation of large micelles. In too high or too low salt concentration solutions only spherical or short rodlike micelles exist. The existence of PAM can also facilitate the formation of large micelles because polymers act as "bridges" and increase the probability of touch and coalescence of micelles. © Springer Nature Switzerland AG 2020.

关键词： Morphology

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Premixed combustion of diluted hydrogen-air mixtures in a constant volume bomb

Premixed combustion of diluted hydrogen-air mixtures in a co...

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作者： Miao, Haiyan Huang, Qian Hu, Erjiang Huang, Zuohua Jiang, Deming State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Energy and Powar Engineering Xi an Jiaotong University Xi an 710049 China

Combustion characteristics of diluted hydrogen-air premixed combustion were studied in a constant volume bomb over wide ranges of diluent ratios and equivalence ratios using two kinds of diluent gases. A two-zone model was applied to calculate the heat release rate and combustion duration based on the pressure data. The study showed that, by adding diluent gas into the hydrogen-air mixture, both the combustion development duration and the combustion duration are lengthened. Increasing the diluent ratio reduces the value of the peak pressure, and the reduction is larger on the rich mixture than on the lean one. CO2 diluent gas has greater effects on the normalized mass burning rate, the combustion development duration, and the combustion duration than nitrogen. Within the experimental range of this study, the minimum value of both the combustion development duration and the combustion duration lies within the range of ø = 1.4-1.6. © 2009 American Chemical Society.

关键词： Combustion

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Numerical investigation on thermoacoustic onset

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2009年第8期30卷 1279-1282页

作者： Wang, Yong He, Ya-Ling Li, Qing Tao, Wen-Quan State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 China

Thermoacoustic phenomena are almost nonlinear, which features self-excited onset. In this paper, a closed-open Rijke tube with the heat source placed at the middle of the tube is modeled. Based on parallel computation, onset of the Rijke tube is carried out numerically. Onset phenomena with various initial fields are observed. Oscillating frequency of the gas within limit cycle is obtained. The gas flow and heat transfer characteristics are studied. These numerical results agree well with those from previous numerical simulations. Such work is helpful for better understanding on the thermoacoustic phenomena, and offers a reference for the study of the thermoacoustic problems with mesoscopic methods such as the lattice Boltzmann method.

关键词： Thermoacoustics

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Performance comparison and analysis of typical energy conversion cycle

Performance comparison and analysis of typical energy conver...

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International Conference on Computer Distributed Control and Intelligent Environmental Monitoring

作者： Wang, Yuqi Zheng, Lan Yang, Fusheng Meng, Xiangyu Zhang, Zaoxiao School of Chemical Engineering Northwest University Xi'an Shaanxi 710069 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an Shaanxi 710049 China

ISBN: (纸本)9780769543505

The performance of 3 types of energy utilization cycles including the organic Rankine cycle, the single stage static hydrogen compression cycle, and the new multistage continuous hydrogen compression cycle were analyzed. A multi-element valued model was used to evaluate the performance holistically, and the result showed that the integrated superiority achieved 0.721, which indicated the continuous hydrogen compression cycle is considered the best option among the typical compression energy utilization cycles and deserves thorough studying. © 2011 IEEE.

关键词： Energy utilization

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CFD study on the optimal nozzle exit position in a CO2 two-phase ejector 24

CFD study on the optimal nozzle exit position in a CO2 two-p...

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24th IIR International Congress of Refrigeration, ICR 2015

作者： He, Yang Deng, Jianqiang Zhang, Zaoxiao Zheng, Lixing State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China School of Chemical Engineering and Technology Xi'an Jiaotong University Xi'an710049 China

ISBN: (纸本)9782362150128

The nozzle exit position (NXP) is a significant parameter for an ejector. In this work, a two dimensional (2D) homogeneous CFD model is developed to simulate the two-phase ejector used in transcritical CO2 refrigeration cycle and NXP is focused on. After model validation, the flow fields in ejectors with different NXPs are simulated and an optimal NXP is obtained. According to the numerical results, with the increase of the NXP, a higher velocity and lower pressure are achieved for the primary fluid in the suction chamber which enhances the entrainment of the secondary fluid. Oppositely, the flow area of the primary fluid at the mixer inlet increases with the NXP which reduces the secondary flow rate. A compromise between these two factors leads to the optimal NXP with the highest entrainment ratio under the same operating condition. The results are helpful to the optimal design and control of the ejector.

关键词： Carbon dioxide

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Numerical Study on Combustion and NOx Emission Characteristics of Co-Firing Semi-Coke and Coal in a Tangentially-Fired Utility Boiler 9th

Numerical Study on Combustion and NOx Emission Characteristi...

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9th International Symposium on Coal Combustion, ISCC 2019

作者： Feng, Qinqin Wang, Chang’an Wang, Pengqian Wang, Zhichao Yao, Wei Zhao, Lei Du, Yongbo Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Xi’an Thermal Power Research Institute Co. LTD Xi’an710054 China

ISBN: (纸本)9789811616563

With the booming coal industry and the increasing production of semi-coke, a large number of small particles and powder pyrolysis semi-coke are urgent to be exploited. Co-firing semi-coke with coal is a potential approach to achieve clean and efficient utilization of such low-volatile fuel. In this paper, the co-combustion performance of semi-coke and coal in a 135 MW tangentially-fired boiler was investigated by numerical simulation. The influences of semi-coke blending ratio, blending mode and injection position on the combustion efficiency and NOx generation characteristics of the utility boiler were extensively analyzed. The simulation results indicated that the NOx emission at the furnace outlet was elevated and the burn-out ratio declined with an increase in semi-coke blending ratio. Different heights of semi-coke injected position could lead to different combustion efficiency and NOx emissions. The semi-coke was recommended to be injected from the middle layer of burners to obtain low carbon content in fly ash. The blending methods (in-furnace versus out-furnace) had certain impacts on the NOx emission and carbon content in fly ash. High burn-out ratio could be obtained when the semi-coke and coal were injected from different burners. © 2022, Tsinghua University Press.

关键词： Coal

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