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Experimental and Numerical Study on Co-combustion Behaviors and NO_(x) Emission Characteristics of Semi-coke and Coal in a Tangentially Fired Utility Boiler

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Journal of Thermal Science 2021年第4期30卷 1116-1131页

作者： WANG Chang’an FENG Qinqin JIN Liyan WANG Zhichao YAO Wei WANGPengqian DU Yongbo ZHANG Xilai YANG Zhongcan CHE Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Xi’an Thermal Power Research Institute Co. LTD.Xi’an 710054China

The utilization of powdery semi-coke as a power fuel in pulverized coal-fired power plants has become a new and potential technique to consume the excess powdery *** characteristic of low volatile results in poor combustion performance and high NO_(x) emission,and to co-fire with bituminous coal is a practical strategy to address this ***,the co-combustion characteristics and the inherent interaction between semi-coke and coal remain insufficiently *** addition,the influences of secondary air arrangement,the boiler operation load,and the fuel type on co-combustion process are still unclear,which is urgent to be further *** the present study,experiments and numerical simulations were jointly utilized to inquire into the co-combustion behaviors and NO_(x) emission features of semi-coke and *** results demonstrated that the"out-furnace method"was a suitable choice for small-capacity boiler when the proportion of semi-coke was 33%,due to the limited combinations of the semi-coke injection *** was recommended that semi-coke was preferred to be injected from the middle layers of the furnace under the"in-furnace method"to improve the overall co-combustion *** critical value of the separated over fire air ratio in this study was 27.5%,over which a slight drop of carbon content in fly ash could come ***,the elevation in the proportion of separated over fire air gave rise to the significant decline of NO_(x) *** constricted secondary air arrangement was preferred to be employed due to the high boiler *** separated over fire air and the surrounding air needed to maintain a wide-open degree to prevent the increase of NO_(x) emissions and the coking of *** the load reduction regulation method adopted in this study,the NO_(x) concentration first rose and then dropped,while the burnout ratio decreased obviously as the operation load was *** combinations of coa

关键词： semi-coke numerical simulation co-combustion NOx emission blending method

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Experimental study on dynamic mechanism of vortex evolution in a turbulent boundary layer of low Reynolds number

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Journal of Hydrodynamics 2020年第5期32卷 807-819页

作者： Yan-ang Guo Xiang-rui Dong Xiao-shu Cai Wu Zhou School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering Shanghai 200093China

The dynamic mechanism of the vortex generation and evolution process in a fully developed turbulent boundary layer with Reθ=97-194 is experimentally *** this study,a moving single-frame and long-exposure(MSFLE)imaging method and a moving particle image velocimetry/particle tracing velocimetry(M-PIV/PTV)are designed and implemented for measuring the temporal and spatial evolution of vortex cores in both qualitative and quantitative ways,*** the other hand,the Liutex vector,which is a new mathematical definition and identification of the vortex core proposed by Liu’s group,is first applied in the experiment for the structural visualization and quantitative analysis of the local fluid *** results show that an intuitional process of vortex evolution can be clearly observed by tracking the vortex using MSFLE and verify that the roll-up of the shear layer induced by shear instability is the origin of vortex formation in ***,a quantitative investigation in terms of the critical vortex core boundary(size)and its accurate rotation strength is carried out based on the Liutex vector field analysis by M-PIV/*** to statistics of the relation between vortex core size and the rotation strength during the whole process,the physical mechanism of vortex generation and evolution in a turbulent boundary layer of low Reynolds number can be summarized as a four-dominant-state course consisting of the“synchronous linear segment(SL)-absolute enhancement segment(AE)-absolute diffusion segment(AD)-skewing dissipation segment(SD)”.

关键词： Turbulent boundary layer high-and low-speed fluid vortex generation moving single-frame and long-exposure moving particle image velocimetry/particle tracing velocimetry Liutex vector

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Effect of Particle Orientation on Heat Transfer in Arrays of Prolate Particles

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Computer Modeling in engineering & Sciences 2023年第8期136卷 1509-1526页

作者： Romana Basit Xinyang Li Zheqing Huang Qiang Zhou School of Chemical Engineering and Technology Xi’an Jiaotong UniversityXi’anChina State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’anChina

Direct Numerical Simulations have been carried out to study the forced convection heat transfer of flow through fixed prolate particles for a variety of aspect ratios ar={5/4,5/3,5/1}with Reynolds number(Re)up to *** variations of the solid volume fraction c={0.1,0.2,0.3}with four Hermans orientation factors S={−0.5,0,0.5,1}are *** has been found that changes in S cause prominent variations in the Nusselt *** general,Nusselt number increases with the decrease of *** all three aspect ratios,the Nusselt number remains a linear function of S at different c and ***,it is concluded that,for heat transfer from prolate muti-particle system,the effects of orientations cannot be ignored.A new correlation for Nusselt number has been developed for arrays of prolate particles using the simulation data as a function of Re,c,S and ar.

关键词： Direct Numerical Simulation heat transfer lattice Boltzmann method particle orientations prolate particles

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Resource utilization of solid waste carbide slag:a brief review of application technologies in various scenes

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Waste Disposal and Sustainable Energy 2022年第1期4卷 1-16页

作者： Hongxia Wang Wanyi Xu Maimoona Sharif Guangxu Cheng Zaoxiao Zhang State Key Laboratory of Multiphase Flow in Power Engineering School of Chemical Engineering and TechnologyXi’an Jiaotong UniversityXi’an 710049ShaanxiChina

China is the largest producer and consumer of calcium carbide in the *** calcium carbide industry is an indispensable industry to support the basic life of *** huge production capacity of calcium carbide is accompanied by a large number of solid waste carbide *** to the immature treatment technology of carbide slag,a large number of carbide slag are stacked on-site,resulting in land occupation,air-drying,easy take-off ash,and pollution of the environment and water *** China,calcium carbide is mainly used to produce acetylene and further utilized,80%of which is used to produce polyvinyl chloride(PVC).A large amount of carbide slag is not used,while only a small part is used in the traditional building materials industry,flue gas desulfurization,sewage treatment,etc.,however,the economic benefits are ***,converting the solid waste carbide slag produced by the calcium carbide industry into high value-added CaCO3,CaCl2,CaSO4 whiskers,*** become a potential way to expand the development field of the calcium carbide industry and is environmentally *** paper focuses on summarizing the traditional and emerging high value-added utiliza-tion technologies of carbide slag,and then introduces the application research of carbide slag in carbon emission ***,the defects of these technologies are summarized and further research directions are *** study provides basic guidance for the diversified development of efficient resource utilization of carbide *** abstract Diversified development of calcium carbide industry,resource utilization of solid waste carbide slag and its application of carbon emission reduction have been fully reviewed.

关键词： Calcium carbide Carbide slag Application research High added value Carbon emission reduction

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Estimation of particle depth from two defocused images using the Fourier transform

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Particuology 2020年第2期18卷 48-54页

作者： Wu Zhou Xu Luo Benting Chen Yukun Zhang Xiaoshu Cai School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Depth from defocus is one technology for depth *** estimate particle depth information from two defocused images captured simultaneously by two coaxial cameras with different imaging *** images are processed with the Fourier transform to obtain the characteristic parameter(i.e.,the standard deviation of the relative blur kernel of these two defocused images).First,we theoretically analyze the functional relationship between the object depth and the standard deviation or variation of the relative blur ***,we verify the relationship *** analyze the influence of particle size,window size and image noise on the calibration curves using both numerical simulations and *** obtain the depth range and accuracy of this measurement system *** the verification experiments,we use a sample of glass microbeads and the irregularly-shaped dust particles on a microscope *** of these experiments present a suitable depth measurement ***,we apply the measuring system to the depth estimation of drops from a small anti-fogging *** results show that our system and image processing algorithm are robust for different types of particles,facilitating the in-line three-dimensional positioning of particles.

关键词： Depth from two defocused images Fourier transform Standard deviation of relative blur kernel Drops depth measurement Sensitivity and accuracy analysis

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Particle convective heat transfer near the wall in a supercritical water fluidized bed by single particle model coupled with CFD-DEM

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Particuology 2023年第2期73卷 47-58页

作者： Tianning Zhang Zhen Wan Youjun Lu State Key Laboratory of Multiphase Flow in Power Engineering(SKLMFPE) Xi'an Jiaotong UniversityXi'an710049ShaanxiChina Xi'an Electronic Engineering Research Institute Xi'an710100ShaanxiChina

Supercritical water fluidized bed(SCWFB)is a promising reactor to gasify biomass or *** optimization design is closely related to wall-to-bed heat transfer,where particle convective heat transfer plays an important *** paper evaluates the particle convective heat transfer coefficient(h_(pc))at the wall in SCWFB using the single particle *** critical parameters in the single particle model which is difficult to get experimentally are obtained by the computational fluid dynamics-discrete element method(CFD-DEM).The contact statistics related to particle-to-wall heat transfer,such as contact number and contact distance,are also *** results show that particle residence time(τ),as the key parameter to evaluate h_(pc),is found to decrease with rising velocity,while increase with larger thermal boundary layer thickness.τfollows a gamma function initially adopted in the gas-solid fluidized bed,making it possible to evaluate h_(pc) in SCWFB by a simplified single particle *** theoretical predicted h_(pc) tends to increase with rising thermal gradient thickness at a lower velocity(1.5 U_(mf)),while first decreases and then increases at higher velocity(1.75 and 2 U_(mf)).h_(pc) occupies 30%-57%of the overall wall-to-bed heat transfer coefficient for a particle diameter of 0.25 *** results are helpful to predict the overall wall-to-bed heat transfer coefficient in SCWFB combined with a reasonable fluid convective heat transfer model from a theoretical perspective.

关键词： Supercritical water Fluidized bed Particle residence time Discrete element method Single particle model

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Numerical simulation of strongly swirling turbulent flows in a liquid-liquid hydrocyclone using the Reynolds stress transport equation model

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Science China(Technological Sciences) 2000年第1期43卷 86-96页

作者：陆耀军周力行沈熊 State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China Department of Engineering Mechanics Tsinghua University Beijing 100084 China

The Reynolds stress transport equation model (DSM) is used to predict the strongly swirling turbulent flows in a liquid-liquid hydrocyclone, and the predictions are compared with LDV measurements . Predictions properly give the flow behavior observed in experiments, such as the Rankine-vortex structure and double peaks near the inlet region in tangential velocity profile, the downward flow near the wall and upward flow near the core in axial velocity profiles. In the inlet or upstream region of the hydrocyclone, the reverse flow near the axis is well predicted, but in the region with smaller cone angle and cylindrical section, there are some discrepancies between the model predictions and the LDV measurements. Predictions show that the pressure is small in the near-axis region and increases to the maximum near the wall. Both predictions and measurements indicate that the turbulence in hydrocy-clones is inhomogeneous and anisotropic.

关键词： strongly swirling flows numerical simulation hydrocyclone

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Influence of Soil-Structure Interaction Models on the Dynamic Responses of An Offshore Wind Turbine Under Environmental Loads

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China Ocean engineering 2023年第2期37卷 218-231页

作者： TANG Hong-ming YUE Min-nan YAN Yang-tian LI Zhi-hao LI Chun NIU Kai-lun School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China

Offshore wind turbines(OWTs) suffer wind, wave and earthquake loads. The investigation of OWTs' dynamic response under environmental loads is essential for structural safety assessment. The soil-structure interaction(SSI)significantly affects the responses of OWT under environmental loads. However, there is few systematic research about the difference in the dynamic response of different SSI models under environmental loads. In order to solve the problem, the OWT is modeled by shell element, and several SSI models are built. The wind, wave and earthquake loads are taken into account. Moreover, the dynamic response, fatigue and buckling analysis are performed by ANSYS. The results indicate that SSI cannot be ignored in the dynamic response of the OWT under wind and wave loads. The SSI can decrease the displacement response of the OWT by 19% under wind and wave loads and reduce the fatigue damage of the pile. Multi-layer SSI can strongly influence the OWT's dynamic response under wind and wave loads or earthquake-only load. The vertical earthquake load increases the dynamic response in three ***, in order to simulate real environment, multi-layer SSI, soil damping and vertical SSI must be considered to evaluate the displacement response of the OWT under wind, wave and earthquake loads. The earthquake and gravity loads can cause more obvious response of the OWT than that of only wind and wave loads. The top and bottom of the tower are prone to occur buckling.

关键词： OWT soil structure interaction earthquake dynamic analysis structural damage

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Cobalt oxide and carbon modified hematite nanorod arrays for improved photoelectrochemical water splitting

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Chinese Chemical Letters 2017年第12期28卷 2207-2211页

作者： Miao Wang Meng Wang Yanming Fu Shaohua Shen International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an fiaotong UniversityXi'on 710049China

Given the proper band gap, low cost and good stability, hematite （α-Fe2O3） has been considered as a promising candidate for photoelectrochemical （PEC） water splitting, however suffers from the sluggish surface water oxidation reaction kinetics. In this study, a simple dip-coating process was used to modify the surface of α-Fe2O3 nanorod arrays with cobalt oxide （COOx） and carbon （C） for the improved PEC performance, with a photocurrent density at 1.6V （vs. reversible hydrogen electrode, RHE） increased from 0.10 mA/cm2 for the pristine α-Fe2O3 to 0.37 mA/cm2 for the CoOx/C modified α-Fe2O3 nanorods. As revealed by electrochemical analysis, thanks to the synergistic effect of CoOx and C, the PEC enhancement could be attributed to the enhanced charge transfer ability, decreased surface charge recombination, and accelerated water oxidation reaction kinetics. This study serves as a good example for improving PEC water splitting performance via a simple method.

关键词： Hematite nanorodsSurface modificationPhotoelectrochemical water splittingWater oxidationElectrochemical impedance spectroscopy

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Error Analysis of Liquid Holdup Measurement in Gas-Liquid Annular flow Through Circular Pipes Using High-Speed Camera Method

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Journal of Shanghai Jiaotong university(Science) 2018年第S1期23卷 34-40页

作者： LIU Li BAI Bofeng School of Nuclear Science and Engineering Shanghai Jiao Tong University State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Accurate measurement of gas-liquid phase fraction is essential for the proper modelling of the pressure drop, heat transfer coefficient, mass transfer rate and interfacial area in two-phase flows. In this paper, taking the issue of optical distortion into account, an analytical model was proposed to estimate and correct the liquid holdup in gas-liquid annular flow through a circular pipe using high-speed camera method. The error in the liquid holdup measurement generated from different refractive indices among transparent circular pipe, liquid film and air core was firstly theoretically analyzed based on the geometric optics. Experimental tests were then carried out to identify the difference as well as to validate the proposed model. Results indicated that the prediction of the liquid holdup has a good performance with the experimental data(i.e., mean relative error is 4.1%) and the measured liquid holdup is larger than the real one. It was found that the measured liquid holdup is larger than the real one. Generally, when the real liquid holdup gets smaller, the discrepancy between the measured liquid holdup by image and the real liquid holdup becomes more significant. Thus, after measuring the liquid holdup from the images, the value of the measured liquid holdup must be corrected by the present model in order to obtain the real liquid holdup.

关键词： gas-liquid annular flow liquid holdup optical refraction analytical correction

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