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arXiv 2019年

作者： Qian, Yanxia Wu, Shuonan Wang, Fei Wang, Fei School of Mathematics and Statistics Xi'An Jiaotong University Xi'an Shaanxi710049 China School of Mathematical Sciences Peking University Beijing100871 China School of Mathematics and Statistics State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an Shaanxi710049 China

The Brinkman equations can be regarded as a combination of the Stokes and Darcy equations which model transitions between the fast flow in channels (governed by Stokes equations) and the slow flow in porous media (governed by Darcy?fs law). The numerical challenge for this model is the designing of a numerical scheme which is stable for both the Stokes-dominated (high permeability) and the Darcy-dominated (low permeability) equations. In this paper, we solve the Brinkman model in n dimensions (n = 2, 3) by using the mixed discontinuous Galerkin (MDG) method, which meets this challenge. This MDG method is based on the pseudostress-velocity formulation and uses a discontinuous piecewise polynomial pair PSk+1-Pk(k ≥ 0), where the stress field is symmetric. The main unknowns are the pseudostress and the velocity, whereas the pressure is easily recovered through a simple postprocessing. A key step in the analysis is to establish the parameter-robust inf-sup stability through specific parameter-dependent norms at both continuous and discrete levels. Therefore, the stability results presented here are uniform with respect to the permeability. Thanks to the parameter-robust stability analysis, we obtain optimal error estimates for the stress in broken H(div)-norm and velocity in L2-norm. Furthermore, the optimal L2 error estimate for pseudostress is derived under certain conditions. Finally, numerical experiments are provided to support the theoretical results and to show the robustness, accuracy, and flexibility of the MDG method. Copyright © 2019, The Authors. All rights reserved.

关键词： Stability

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Effect of proppant impingement on flow-induced corrosion of tubular steel super 13Cr via CFD and experiment

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Egyptian Journal of Petroleum 2018年第4期27卷 633-640页

作者： Cheng, J.R. Zhang, N.S. Cao, Y.P. Li, Z. Dou, Y.H. State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No. 28 Xianning West Road Xi'an 710049 Shaanxi Province China Department of Petroleum Engineering Xi'an Shiyou University Xi'an 710065 Shaanxi Province China Department of Mechanical Engineering Xi'an Shiyou University Xi'an 710065 Shaanxi Province China

Data from a standard laboratory test including open-circuit potential (OCP) and current density monitoring is used to study the effect of fracturing proppant impingement on corrosion of tubular steel. A solid-liquid flow simulation is performed to obtain some parameters of particle movement and oxygen mass transfer near the metal surface. The results show that the electrochemical reaction includes passivation, activation and repassivation during a particle impact on the metal surface. Once the metal surface is in the activated state, the potential and anode current density is controlled by the oxygen concentration in the boundary layer and repassivation rate of metal surface. The increase of particle impact velocity accelerates the transmission of corrosion reactants and creates deeper impact craters on metal surface, resulting in the increase of current density. Meanwhile, the high speed particle impingement causes some platelets and extruding lips and thus weakens the surface corrosion resistance of stainless steel. © 2017

关键词： flow-induced corrosion Particle impingement Passive films Repassivation Tubular steel

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Co2 Capture Performance and Energy Recovery in Pilot-Scale Thermal Electrochemical Co-Drive System

SSRN

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SSRN 2019年

作者： Ding, Wancheng Yu, Yunsong Zhang, Zaoxiao Wang, Geoff School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China School of Chemical Engineering The University of Queensland St LuciaQLD4072 Australia

关键词： Greenhouse gases

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power-Grid Dispatching Method Considering Heat-power Coupling Characteristics of CHP Units

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IOP Conference Series: Earth and Environmental Science 2020年第3期440卷

作者： Sensen Guan Kun Wang E Zhijun Qingbo Hu Shan Wang Jiuwen Fang Rong Chen Fei Lu Bangyu Yang Ming Liu Tianjin Electric Power Science & Research Institute Tianjin 300384 State Grid Tianjin Electric Power Company Tianjin 300010 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Tianjin Guodian Jinneng Binhai Co-generation co. LTD 300459.

The dispatching optimization of power grid is to obtain the greatest benefits on the basis of safe and stable operation of the power grid, which is of great significance for the energy-saving, reliability of the power grid. Therefore, a multi-objective model of power grid dispatching which considers the heat-power coupling characteristics of CHP units is developed in this study. The economic benefit and minimum wind power abandonment are taken as optimizing targets in the model. Meanwhile, the detail operation characteristics of condensing power plants and CHP units are considered in this model based on off-design models of power plant. Besides, the regional heat load and power load are scheduled together. Finally, the AHP-entropy method is used to obtain the weights of the two optimizing targets of economic benefit and wind power abandonment, and the multi-objective is converted into a single-objective.

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Energy and exergy recovery from exhaust hot water using organic Rankine cycle and a retrofitted configuration

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Journal of Central South University 2018年第6期25卷 1464-1474页

作者： SUN Wen-qiang YUE Xiao-yu WANG Yan-hui CAI Jiu-ju Department of Thermal Engineering School of MetallurgyNortheastern UniversityShenyang 110819China State Environmental Protection Key Laboratory of Eco-Industry Northeastern UniversityShenyang 110819China State Key Laboratory of Multiphase Flow in Power Engineering Xi＇an Jiaotong UniversityXi＇an 710049China ~ Central South University Press and Springer-Verlag GmbH Germanypart of Springer Nature 2018

Exhaust hot water （EHW） is widely used for various industrial processes. However, the excess heat carried by EHW is typically ignored and discharged into the environment, resulting in heat loss and heat pollution. An organic Rankine cycle （ORC） is an attractive technology to recycle heat from low-temperature energy carriers. Herein, ORC was used to recycle the heat carried by EHW. To investigate the energy and exergy recovery effects of EHW, a mathematical model was developed and a parametric study was conducted. The energy efficiency and exergy efficiency of the EHW-driven ORC system were modeled with R245fa, Rl13 and R123 as the working fluids. The results demonstrate that the EHW and evaporation temperatures have significant effects on the energy and exergy efficiencies of the EHW-driven ORC system. Under given EHW conditions, an optimum evaporation temperature exists corresponding to the highest exergy efficiency. To further use the low-temperature EHW, a configuration retrofitted to the ORC by combining with flash evaporation （FE） was conducted. For an EHW at 120 ~C and 0.2 MPa, the maximum exergy efficiency of the FE-ORC system is 45.91% at a flash pressure of 0.088 MPa. The FE-ORC performs better in exergy efficiency than the basic FE and basic EHW-driven ORC.

关键词： exhaust hot water （EHW） organic Rankine cycle （ORC） energy efficiency exergy efficiency flashevaporation （FE）

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New model for measuring stratified gas-liquid flow by Chisholm-model-based V-cone flowmeter

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Huagong Xuebao/CIESC Journal 2018年第8期69卷 3428-3435页

作者： He, Denghui Chen, Senlin Bai, Bofeng State Key Laboratory of Eco-hydraulic in Northwest Arid Region Xi’an University of Technology Xi'anShaanxi710048 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi'anShaanxi710049 China

Large errors are usually observed when Chisholm model is used in V-cone flowmeter to measure stratified gas-liquid flow rate. Three V-cone flowmeters with throttle ratios of 0.55, 0.65 and 0.75 were used to study stratified gas-liquid flowat gas volume fraction of more than 95%. The effects of gas and liquid flow rates, operating pressure and throttle ratio on correction factor C of the Chisholm model were analyzed and new modelfor measuring stratified gas-liquid flow was developed. Correction factor C was monotonically decreased with increase of Lockhart-Martinelli, XLM, but was hardly affected by pressure and the gas densiometric Froude number. However, C was somehow affected by throttle ratio. The relationship between C and XLM was obtained and new models for three V-cone flowmeters to measure stratified flow were developed. The relative standard error of the predicted gas flow rate was with ±3.0% for V-cone flowmeters with throttle ratios of 0.55 and 0.65 under confidence level of 94.6% and 88.6%, respectively, while that was with ±4.0% under 91.7% confidence level forV-cone flowmeter with throttle ratio of 0.75. © All Right Reserved.

关键词： Two phase flow

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Numerical Study of the Effect of Nozzle Configuration on Supersonic Condensation Jet

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2018年第1期39卷 207-212页

作者： Zhou, Lun Liu, Jia Ma, Qiran Chong, Dao-Tong Liu, Ji-Ping Yan, Jun-Jie MOE key Laboratory of Thermal Fluid Science and Engineering Xi'an Jiaotong University Xi'an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Three-dimensional steady method was employed to simulate the condensation process of supersonic steam condensed into subcooled water pool by embedding the phase change model based on thermal equilibrium into Ansys platform. By comparing the shape of steam plume between numerical and experimental results, good agreements were observed. When steam pressure, water temperature and the diameter of nozzle throat were 300 kPa, 20℃ and 8 mm, the diameters of nozzle exit were set as 8.8, 9.6, 10.4 11.2 and 12.0 mm, respectively. The effect of nozzle pressure ratio on the shape of steam plume and the internal flow process was revealed. © 2018, Science Press. All right reserved.

关键词： Condensation

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Structure engineering of Graphitic Carbon Nitride for Efficient Photocatalytic Water Splitting

Structure Engineering of Graphitic Carbon Nitride for Effici...

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中国化学会第三届中国能源材料化学研讨会

作者：沈少华 International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong University

Photocatalytic overall water splitting without using sacrificial agents is very appealing for converting solar energy into chemical ***,polymer photocatalysts with tunable molecular structures have emerged as promisin... 详细信息

关键词： Structure engineering of Graphitic Carbon Nitride for Efficient Photocatalytic Water Splitting

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Numerical Study on flow Field of a Diameter-varying Spray Tower for Amine-based CO2 Absorption 14

Numerical Study on Flow Field of a Diameter-varying Spray To...

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14th International Conference on Greenhouse Gas Control Technologies, GHGT 2018

作者： Wu, Xiaomei Yu, Yunsong Zhang, Zaoxiao Wang, Geoff Rudolph, Victor School of Chemical Engineering and Technology Xi’an Jiaotong University No.28 Xianning West Road Xi’an710049 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China School of Chemical Engineering The University of Queensland St LuciaQLD4072 Australia

Our group proposed a diameter-varying spray tower and a new spray mode of dual-nozzle opposed impinging spray to enhance the absorption performance of CO2 spray absorption process and some interesting results have been obtained. However, the detailed information (flow field distribution) inside the tower is hard to be obtained by experimental work. In this work, to specifically explain the performance inside the proposed diameter-varying spray tower, ANSYS Fluent17.2 software was used to simulate gas-liquid two-phase flow inside the proposed diameter-varying spray tower. Two different spray methods are discussed in this work. One is the dual-nozzle opposed impinging spray method proposed by our research group, the other is mostly literature discussed spray in the middle method. The flow field of continuous gas phase and dispersed liquid phase has been carefully discussed to illustrate the better spray method, which do more good to the CO2 absorption performance. © 2018 GHGT 2018 - 14th International Conference on Greenhouse Gas Control Technologies. All rights reserved.

关键词： Carbon dioxide

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Experimental Study on Combustion Adjustment for Dense-dilute Burning through Swirling Burner with Variable Flaring Angle

Experimental Study on Combustion Adjustment for Dense-dilute...

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2018 3rd International Conference on Automation, Mechanical and Electrical engineering (AMEE 2018)

作者： Ya-fei ZHANG Rui LUO Yi-hua DOU Mechanical Engineering College Xi'an Shiyou University Thermal Power Research Institute State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

A swirling burner with adjustable inner secondary air flaring angle is proposed and a laboratory-scale opposed-firing furnace is built. The effects of burner flaring angle on dense-dilute low-NO burning are experimentally studied. The temperature distributions along the depth and height direction of furnace are emphatically illustrated. NO emission and char burnout are compared and discussed. Experiment results indicate that under the dense-dilute burning conditions,variation of burner inner secondary air flaring promotes ignition conditions. Under different conditions of dense-dilute ratio, variation of burner flaring angle can help decreasing NO emission and improving char burnout. Finally the optimum flaring angle of swirling burner under different dense-dilute ratios is summarized in the form of curves, which could provide reference for exquisite and novel combustion adjustment.

关键词： Swirling burner Flaring angle Dense-dilute burning Coal combustion

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