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7th International Conference on Power engineering, ICOPE 2019

作者： Yan, Wenchen Han, Xiaoqu Chen, Nana Wu, Wenxiang Zhou, Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Air-cooling systems are widely used in coal-fired power plants, especially in areas rich in coal resources and short of water. To prompt its economic and safe operation, dynamic modeling is urgently required to acquire the power plant's characteristics under complex working conditions. In particular, the condensing pressure of the air-cooling unit is significantly affected by the ambient temperature, and the thermal power plant is a complicated energy system with serious nonlinearity. In many cases, it is difficult to establish the mathematical model of the system by traditional analytical methods. In the present work, a 1000 MW supercritical power plant thermal system was modeled and simulated by GSE simulation software. The model was developed according to the structural characteristics, incorporating boiler system, steam turbine system and direct air-cooling system. The simulation results were compared with the actual operation data of the power plant to validate the model. The relative errors of the simulation models under steady-state conditions were less than 3%, which indicates that the models have high accuracy. On this basis, the influence of condensing pressure on the standard coal consumption rate was obtained. It was shown that when the condensing pressure ranged between 5 kPa and 20 kPa, the coal rate increased by 1.6 g/kW∙h with 1 kPa increase in the condensing pressure. Then the boundary conditions of the system were changed. When the parameters changed, the changes of condensing pressure and power were monitored, so as to study the dynamic characteristics of the system. © ICOPE 2019 - 7th International Conference on Power engineering, Proceedings. All rights reserved.

关键词： Coal

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Numerical study on drop-on-demand droplet formation dynamics 7

Numerical study on drop-on-demand droplet formation dynamics

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7th International Conference on Power engineering, ICOPE 2019

作者： Zhu, Maoguo Chong, Daotong Zhao, Quanbin Chen, Weixiong Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Inkjet printing technology has been applied in many industrial fields for its significant usefulness. The drop-on-demand droplet formation dynamics was studied numerically based on the VOF and CSF method. Droplet formation was modeled by imposing a vertical velocity pulse waveform perturbation. The effects of printhead geometry and fluid properties on droplet ejection stability were analyzed. Simulation results make clear that choosing an appropriate printing fluid with relatively lower density and viscosity or higher surface tension can improve the droplet ejection stability. Designing the printhead with a larger inclination of outlet is also a key way to improve the droplet ejection stability. In addition, droplet ejection stability becomes better as Z increased or Ca decreased. © ICOPE 2019 - 7th International Conference on Power engineering, Proceedings. All rights reserved.

关键词： Stability

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Effect of the Density Difference on Fluid Distribution in Layered Rock Samples

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Energy & Fuels 2025年第9期39卷 4412-4420页

作者： Yongfei Yang Tonghui Liu Yingwen Li Weichen Sun Hai Sun Lei Zhang Junjie Zhong Kai Zhang Jun Yao State Key Laboratory of Deep Oil and Gas China University of Petroleum (East China) Qingdao 266580 P. R. China；Research Center of Multiphase Flow in Porous Media School of Petroleum Engineering China University of Petroleum (East China) Qingdao 266580 P. R. China Geosteering & Logging Research Institute Sinopec Matrix Corporation Qingdao 266071 P. R. China Research Center of Multiphase Flow in Porous Media School of Petroleum Engineering China University of Petroleum (East China) Qingdao 266580 P. R. China

During geological CO2storage, gravity segregation due to fluid density differences significantly affects the efficiency and safety of the process. This can result in premature CO2breakthrough, reduced storage efficiency, and increased leakage risks. This study aims to investigate how gas migrates in layered heterogeneous reservoirs over time due to prolonged density differences and to assess the resulting impact on fluid distribution. We use artificially layered heterogeneous sandstone cores for experimentation. After completing gas injection and water flooding experiments, the core was positioned with the low permeability layer (LPL) at the top and the high permeability layer (HPL) at the bottom for an extended period. Because the effects of density differences are not easily discernible during gas–water two-phase flow under typical driving forces, we applied micro-CT imaging technology to visualize and analyze how density differences influence gas flow within the core. The results demonstrate that during the static placement period following displacement, gas clusters exhibit different flow behaviors at the pore throats. Most gas clusters struggle to overcome the Jamin effect and enter into the upper pores; a few large-volume gas clusters, driven by density differences, partially pass through the throats into the upper pores, while the remaining portions are stranded within the throats, leading to a snap-off phenomenon; while some gas clusters successfully overcome the Jamin effect and enter the upper pores in significant numbers. The experimental findings indicate that the LPL effectively hinder the upward migration of the nonwetting phase gases from bottom and fluid density differences significantly influence gas–water distribution changes. This study provides critical insights for optimizing CO2storage and offers a new perspective on fluid behavior in layered heterogeneous reservoirs.

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Studies on high temperature corrosion behavior of water wall materials under cyclic temperature 7

Studies on high temperature corrosion behavior of water wall...

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7th International Conference on Power engineering, ICOPE 2019

作者： Liu, Zhuhan Wu, Zhengyu Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In this study, the corrosion behavior of water wall materials under cyclic temperature was studied. Corrosion products (XRD and EDS), corrosion morphology (SEM detection) and corrosion effects on residual matrix metal (SEM detection) were compared after different corrosion times to obtain the corrosion behavior under cyclic temperature conditions. There is no significant difference between the corrosion products of the sample at the circulating temperature and the corrosion products at the constant temperature. The corrosion surface layer is iron oxide, but according to the cross-sectional morphology it can be clearly observed that under the cyclic temperature condition, there is a certain increase in the corrosion layer thickness and the corrosion scales is broken with less protection. As the composition of T23, Cr didn't participate in the corrosion reactions to form a protective Cr2O3 protective layer, which is different in other materials. © ICOPE 2019 - 7th International Conference on Power engineering, Proceedings. All rights reserved.

关键词： High temperature corrosion

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Selectivity catalytic reduction of NO by CO over Fe-Cu oxides supported on rice hull Ash(Rha) 7

Selectivity catalytic reduction of NO by CO over Fe-Cu oxide...

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7th International Conference on Power engineering, ICOPE 2019

作者： Teng, Zhaohui Fu, Liang Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xian710049 China

The present work contains the studies of catalytic reduction of NO with CO over 20 wt.% bimetallic Fe-Cu transition metal oxides supported on rice hull ash (RHA) and γ-Al2O3, which were prepared by various procedures. All catalysts contained CuO and Fe2O3 alongside with CuFe2O4. The catalytic activity kinetics for NO and CO reduction reaction mechanism was obviously improved over the synthesized RHA when compared to alumina support. And bimetallic metal catalyst Fe2Cu1/RHA demonstrated a high conversion of NO at all the temperatures examined. This was due to the strong interaction of Cu-Fe with the amorphous silica and activated carbon in RHA and high dispersion on the supporter. NO was almost reacted to N2 over Fe2Cu1/RHA from room temperature to 500℃ and O2 has little influence on it in our experiment conditions. About 100% CO was oxidized after 150℃ over Fe2Cu1/RHA. All the materials showed an unchanged stability over the period of 20h. Metallic copper and iron were the active species. The present results suggest that bimetallic Fe-Cu transition metal oxides supported on rice hull ash (RHA) can be used as an applicable catalyst to selectively reduce NO and CO. © ICOPE 2019 - 7th International Conference on Power engineering, Proceedings. All rights reserved.

关键词： Reduction

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Effects of Combustor Wall Temperature on the Outer Recirculation Zone Combustion Modes Transition in Lean Premixed Dme/Air Swirl Flames

SSRN

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SSRN 2024年

作者： Lin, Wenjun Zhang, Weijie An, Zhenhua Wang, Jinhua Huang, Zuohua Zhang, Huangwei State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Department of Mechanical Engineering National University of Singapore 9 Engineering Drive 1 Singapore117576 Singapore Department of Mechanical Engineering and Science Kyoto University Kyoto daigakuKatsura Nishikyo-ku Kyoto615-8540 Japan

In this study, the effects of wall thermal conditions on the ORZ combustion modes transition in the DME/air swirl flames are investigated using the Large Eddy Simulation (LES) and Flamelet Generated Manifold (FGM) method. The results show that the ORZ chemistry and temperature are highly sensitive to the wall thermal condition. Based on the correlation between the temperature and species observed in the time-averaged numerical results, the relation between the combustion mode and temperature in the ORZ is discovered. Through temporal analysis of species and heat release rate in the ORZ, the stable Mode II and Mode IV as well as the unstable Mode III are identified. The chemical reaction pathway analysis for typical probe in the ORZ reveals that different combustion modes undergo distinct (lowtemperature or high-temperature) chemical reaction pathways. Afterwards, the definition of combustion modes used in experiments is refined by utilizing the chemical reaction data from the simulations. And it is applied to identify the combustion mode across the entire computational domain. The results confirm the consistency between the combustion modes determined in experiments based on OH and CH2O and those determined in simulations using chemical reaction rates. Finally, this explains the mechanism of the flickering flame in Mode III is the competition between the low-temperature and high-temperature reaction in the ORZ. Whereas the unstable Mode III can be stabilized by changing the wall temperature to reach the Mode II or Mode IV. © 2024, The Authors. All rights reserved.

关键词： Temperature

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Experimental study on preparation of amorphous SiO2 by fluidized bed combustion of rice husk 7

Experimental study on preparation of amorphous SiO2 by fluid...

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7th International Conference on Power engineering, ICOPE 2019

作者： Yao, Yashu Xu, Heng Tan, Jingkao Hu, Zhengtao Zhou, Qulan Li, Na State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

The rice husk ash (RHA) contains a large amount of amorphous silica having a large specific surface area and high activity, but after combustion of the rice husk the SiO2 is easily crystallized, which deteriorate the performance. Therefore, it is necessary to study the crystallization process of silica in combustion for the preparation of excellent rice husk ash. On the self-built fluidized bed experimental system, the combustion characteristics of rice husk and the pore characteristics of RHA under different excess air coefficients were studied. It was found that when the excess air ratio was between 0.8 and 0.9, the silica remained unchanged, and the specific surface area of rice husk ash is larger. Meanwhile, the furnace temperature is higher, which is conducive to the utilization of heat;when the excess air ratio is greater than 1, the crystallization of rice husk ash is more serious. In conclusion, it should be burned when the excess air ratio is less than 1 in order to prepare RHA with large specific surface area by direct combustion method. © ICOPE 2019 - 7th International Conference on Power engineering, Proceedings. All rights reserved.

关键词： Silica

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Large eddy simulation on the wake characteristics of linearly stratified flow past a sphere

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Scientific Reports 2025年第1期15卷 1-13页

作者： Xia, Tianci Wei, Na Shi, Liuliu School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai 200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093 China Key Laboratory of Power Machinery and Engineering of Ministry of Education Shanghai Jiao Tong University Shanghai 200240 China

In this study, Large Eddy Simulation (LES) has been employed to examine the influence of the Froude number (Fr) on the linearly stratified wake and internal waves behind a sphere at a subcritical Reynolds number of Re = 3700. Six distinct sets of models with varying Fr (Fr = 0.05, 0.25, 0.5, 1, 2, ∞) have been chosen to establish density linear stratification through the use of a User Defined Function (UDF). The analysis focuses on the impact of stratification on wake characteristics, velocity distribution, and the structure of internal waves within stratified flow. It is evident that density stratification plays a pivotal role in shaping wake structure. Notably, in stratified flows, wakes exhibit unique characteristics including the generation of internal waves, suppression of vertical velocity, and the emergence of oscillating wake patterns. The study reveals that a decrease in the Froude number leads to heightened vertical suppression of the wake and increased anisotropy of the velocity distribution. Furthermore, as the Froude number ascends from 0.05 to 2, the wake undergoes a transition from quasi-two-dimensional vortex shedding to three-dimensional turbulence. © The Author(s) 2025.

关键词： Froude number Internal wave Linearly stratified flow Wake

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Ventilation and cooling of wind generator: A numerical study and experimental verification 7

Ventilation and cooling of wind generator: A numerical study...

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7th International Conference on Power engineering, ICOPE 2019

作者： Ao, Yunjin Li, Na Zhou, Qulan State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

In the wind generator, a large amount of heat is generated during the operation, which usually causes severe temperature rise and decrease of efficiency. By coupling fluid dynamics and heat transfer, a numerical method has been developed to calculate the velocity filed and temperature distribution of a common air-cooled doubly-fed wind generator. The numerical results have been verified by the experiments. The results show that the flow resistance is higher in the center in the axial direction, thus the temperature is much higher than the ends. In the height direction, there locate the most dangerous points and the temperature rise is about 110K. In the circumference direction, there are regularity of fluctuation and can assist in finding the dangerous points. The variations of heat source and cooler power as well as rotation speed all affect the temperature rise of the generator. The regularity and method of this study can be applied to similar generators or generators of other forms, thus advice can be given for the design, manufacture, operation and maintenance of wind generators. © ICOPE 2019 - 7th International Conference on Power engineering, Proceedings. All rights reserved.

关键词： Temperature distribution

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

SSRN

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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

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