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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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Eco-friendly calcium alginate microspheres enable enhanced profile control and oil displacement

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Petroleum Science 2024年第3期21卷 1928-1943页

作者： Xiao-Han Zhang Chang-Jing Zhou Yuan-Xiang Xiao Bo Hui Yong-Gang Xie Yu-Bin Su Xin-Ru Li Jie Huang Mao-Chang Liu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi'an Jiaotong UniversityXi'an710049ShaanxiPR.China Shaanxi Key Laboratory of Advanced Stimulation Technology for Oil&Gas Reservoirs School of Petroleum EngineeringXi'an Shiyou UniversityXi'an 710065ShaanxiPR.China Oil&Gas Technology Research Institute Changqing Oilfield Branch CompanyPetroChinaXi'an710021ShaanxiPR China Suzhou Academy of Xi'an Jiaotong University Suzhou215123JiangsuPR China

Polymer microspheres(PMs),such as polyacrylamide,have been widely applied for enhanced oil recovery(EOR),yet with environmental ***,we report a microfluid displacement technology containing a bio-based eco-friendly material,i.e.,calcium alginate(CaAlg)microspheres for *** dominant mechanisms responsible for EOR over Ca Alg fluid have been verified,including the microscopic oil displacement efficacy augmented by regulating capillary force(determined by the joint action of interfacial tension and wettability between different phases)and macroscopic sweep volume increment through profile control and mobility ratio *** comprehensive effectiveness can be further impacted when the CaAlg microsphere is embellished ulteriorly by using appropriate amount of sodium dodecyl sulfonate(SDS).The core flooding and nuclear magnetic resonance(NMR)tests demonstrate that CaAlg-SDS microsphere can balance the interphase property regulation(wettability alteration and IFT reduction)and rheology properties,enabling simultaneous profile control and oil *** introduction of SDS will have a negative impact on rheological properties,which is not favored for *** results show that the involvement of 4-m M SDS will provide the best behavior,with an EOR rate of 34.38%.This cost-effective and environmentally-friendly bio-microspherebased microfluidic displacement technology is expected to achieve“green”oil recovery in future oilfield exploitation.

关键词： Calcium alginate microspheres Wettability Interfacial tension Rheology Viscoelasticity Enhanced oil recovery(EOR)

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High Concentration of CO and CO2 Inhibits Coal Gasification in Supercritical Water

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SSRN 2024年

作者： Zhang, Rui Zhao, Shuaiqi Huang, Han Zhao, Kunpeng Bai, Bofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Supercritical water gasification technology achieves efficient resource utilization of lignite and produces H2, CO and CO2. In this study, we experimentally investigated the impact of gas product generated from high concentration (>30 wt%) formic acid decomposition on the gasification of Tiebei lignite in the supercritical water. H2 promotes the pyrolysis of carbon structures, the increase in CO promotes CO2 generation through the water-gas shift reactions, and the enrichment of CO2 hinders gas diffusion. We found that high concentration of formic acid(H2, CO and CO2) inhibits the gasification of Tiebei lignite in the supercritical water. Compared with coal gasification in the supercritical water without formic acid, 30wt% formic acid reduces the carbon efficiency of lignite by 7.66%, and the mass conversion of coal by 3.97%. When the concentration of formic acid is 30wt% to 70wt%, the higher concentration of formic acid(H2, CO and CO2), the worse gasification performance of Tiebei lignite. © 2024, The Authors. All rights reserved.

关键词： Water gas shift

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Experimental Study on flow Boiling and Circumferential Non-Uniform Heat Transfer Characteristics in Helically-Coiled Tube Under Coupled Heat Transfer Conditions

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SSRN 2024年

作者： Wang, Hengyuan Xuan, Qiyu Lei, Hailin Li, Xi Li, Zhibin Li, Huixiong State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

Because of its compact structure and high energy conversion efficiency, helically-coiled tube steam generator has been widely used in nuclear reactor, energy power, petrochemical and other systems. In the liquid metal reactor, the liquid metal on the primary side of the helically-coiled tube steam generator washes the helically-coiled tube bundles, and exchanges heat with the water on the secondary side. Due to the coupled heat transfer between liquid metal and water, the distribution of the wall temperature or heat transfer coefficient of helically-coiled tube are significant different in the circumference direction of the tube cross-section. An experimental system of helically-coiled tube steam generator was set up in this paper. The non-uniform heat transfer characteristics of secondary side fluid of helically-coiled tube steam generator were studied under the coupled heat transfer conditions between the heat transfer of primary side and secondary sides fluid. It was found the local wall temperature or local heat transfer coefficient in the circumferential direction of the tube cross-section was significantly different, and they showed different change trends with the change of the parameters such as subcooling degree, mass flux of the secondary side fluid, system pressure of secondary side fluid, heating temperature of primary side fluid, etc. Secondly, ηt and ηh were defined to represent the degree of local non-uniformity of local wall temperature or local heat transfer coefficient in the circumferential distribution of the tube cross-section, respectively. δt and δh were defined to characterize the degree of overall non-uniformity of wall temperature or heat transfer coefficient in the circumferential distribution of the tube cross-section, respectively. The variation rules of ηt and ηh, δt and δh with subcooling degree、system pressure、mass flux of primary side fluid、mass flux of secondary side fluid and heating temperature of primary side fluid were obtained.

关键词： Steam generators

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Liutex identification on hairpin vortex structures in a channel based on msfle and moving-PIV

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Journal of Hydrodynamics 2021年第6期33卷 1119-1128页

作者： Xin-ran Tang 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 University of Shanghai for Science and TechnologyShanghai 200093China

The spatiotemporal evolution of hairpin vortex structures in a fully developed turbulent boundary layer is investigated qualitatively and quantitatively by using two image *** this paper,the moving single-frame and long-exposure(MSFLE)image method is used to intuitively track the evolution process of a hairpin vortex,while the moving particle image velocimetry(moving-PIV)method is applied for obtaining a moving velocity field for quantitative *** to the structural characteristics of the hairpin vortex,an inclined light sheet with an appropriate inclination of 53°is arranged to capture the complete hairpin vortex structure at Re_(θ)=97–*** addition,the core size and the rotational strength of a hairpin vortex are further defined and quantified by the Liutex vector *** evolution process of a complete hairpin vortex structure observed by MSFLE shows that the shear along the normal direction leads to an increasing strength of the hairpin vortex,accompanied by a lifting vortex head and a distance decrease between two vortex legs during the dissipation *** combining moving-PIV with the Liutex identification,the spatiotemporal evolution of four typical regions of a hairpin vortex projecting into a 53°cross-section is *** results show that the process from the generation to the dissipation of a single hairpin vortex can be well characterized and recorded by the Liutex based on the core size and rotational intensity,and the evolution process is consistent with the MSFLE *** to the statistics of vortex core size and rotation intensity along time,the evolution of the hairpin vortex necks and legs can be described as a process of enhancement followed by *** the vortex head,its evolution maintains longer attributed to its far-from-wall position,which consists of an absolute enhancement process(stage 1)with an increasing rotation strength and a constant core size,and an absolute dissipation(stage 2)with a dec

关键词： Turbulent boundary layer hairpin vortex moving single-frame and long-exposure moving particle image velocimetry(PIV) Liutex vortex identification method

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Experimental Investigation on Product and Temperature Distribution in a Continuous flow Packed-Bed Reactor for Dodecahydro-N-Ethylcarbazole Dehydrogenation

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SSRN 2024年

作者： Xue, Jingwen Li, Pengzhao Yu, Pengfei Yi, Jinhao Ma, Tao Liu, Hu Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'An710049 China

The dehydrogenation of dodecahydro-N-ethylcarbazole (H12-NEC) generates enormous gas accompanied by intense heat absorption, affecting heat and mass transfer in porous catalysts. A packed-bed reactor equipped with a temperature measurement device was designed to investigate the continuous flow dehydrogenation of H12-NEC. The effects of weight hourly space velocity (WHSV), reaction temperature, catalyst particle size, and pressure were evaluated. The results reveal that the volume flow rate of hydrogen will increase with the increase of WHSV. And the generation of hydrogen enhances heat transfer by strengthening the perturbation of flow. As the temperature rises, the hydrogen yield increases along with more by-products. The decrease of catalyst particle size improves the hydrogen yield and a more uniform temperature distribution can be created within the reactor due to the weakened wall effect. 456 K and 2 mm of catalyst particle size are determined to be the optimal reaction conditions in the study, achieving the hydrogen production rate of 9.61 [[EQUATION]]. With pressure increasing, the hydrogen yield gradually decreases, but the decreased evaporation of H12-NEC results in a smaller temperature difference between the reactor and heating wall. A comparison with the thermodynamic equilibrium model reveals that the effect of pressure on chemical equilibrium may be more significant than the temperature. © 2024, The Authors. All rights reserved.

关键词： Temperature distribution

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Experimental Study on Yield and Quality of Tar from Tar-Rich Coal Under the Simulated In-Situ Conditions

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SSRN 2024年

作者： Ning, Xing Huang, Xiaole Xue, Xiangyu Wang, Chang'an Deng, Lei Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

Tar-rich coal is considered to have a great potential to extract a large body of liquid fuels through thermal treatment. In this study, an experimental system in which the in-situ conditions can be simulated was built to investigate the yield and the quality of the tar from tar-rich coal. The simulated conditions include in-situ stress, pyrolysis temperature, heating rate, and moisture content. The results indicate that the tar yield increases from 0.83 % to 10.13 % in the temperature range of 200-500 ℃, but a considerable drop of the yield occurs around 600 ℃ due to the cracking of the tar. The heating rate is decreased from 16 °C/min to 2 °C/min, the tar yield is increased from 4.63 % to 10.3 % during the simulated in-situ pyrolysis of tar-rich coal. At low heating rates, the tar yield can be boosted owing to the difference in coal size and underground environment, in contrast to the high heating rate required in traditional coal pyrolysis. Moreover, the ether bonds connected with the oxygenated compounds in the tar under in-situ stress are cleaved, increasing the light components. For other simulated conditions, the low ratio of chain hydrocarbons to aromatic hydrocarbons leads to a decrease in the heavy components. Component variation in the tar under pyrolysis condition promotes the formation of light oil while preventing the synthesis of heavy oil, improving the quality of the tar from the simulated in-situ pyrolysis of tar-rich coal. © 2024, The Authors. All rights reserved.

关键词： Pyrolysis

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Modification of Anatase TiO2with Amorphous Cu Nanoparticles: An Efficient Photocatalyst for the Reduction of CO2to CO/CH4

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The Journal of Physical Chemistry C 2025年第22期129卷 10083-10093页

作者： Xiong Liu Qulan Zhou Xiaole Chen Shicheng Liu Na Li Zhong Huang Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an 710049 China Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Energy and Power Engineering Tsinghua University Beijing 100084 China

Titanium dioxide-based photocatalysts have garnered significant attention for CO2reduction reactions (CO2RR) toward fuel production, with noble metal incorporation markedly enhancing photocatalytic efficiency. However, the development of cost-effective alternatives to expensive metals (e.g., Au, Ag) remains a critical challenge. Herein, amorphous copper nanoparticles (a-Cu NPs) were successfully anchored onto anatase TiO2via a chemical reduction method using Cu(NO3)2·3H2O as the precursor. The optimized 4 wt % a-Cu/TiO2catalyst (4CT) demonstrated remarkable activity, achieving methane and CO production rates of 3.0 and 18.4 μmol·g–1·h–1, respectively, corresponding to 10.0-fold and 7.3-fold enhancements over pristine TiO2. CO2-TPD revealed that the high surface disorder of a-Cu NPs significantly strengthened CO2chemisorption. In situ Fourier transform infrared spectroscopy (FTIR) further indicated that a-Cu loading enabled preferential CO2adsorption over H2O on TiO2surfaces while accelerating the formation of the key intermediate *COOH. This work proposes a synergistic strategy integrating nonprecious metal modification with interfacial engineering, offering a cost-effective pathway to develop high-performance photocatalysts for sustainable CO2conversion.

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Effects of Residual Carbon on Slag flow Characteristics of Zhundong High-Alkali Coal Under Oxy-Fuel Condition

SSRN

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SSRN 2024年

作者： Wang, Chang'an Chen, Yuanmao Luo, Maoyun Zhao, Lin Zhao, Pengbo Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China

The implementation of oxy-fuel combustion technology in slag-tapping cyclone furnace holds significant promise for addressing the challenges associated with the combustion of Zhundong high-alkali coal. However, the flow characteristics of the Zhundong high-alkali coal slag under oxy-fuel condition remain unclear, while the influences of residual carbon have yet to be fully understood. In the present study, a high-temperature flow experimental system was designed to investigate the effects of residual carbon content, degree of graphitization of residual carbon, and atmosphere on the high-temperature flow behaviors of the high-alkali coal slag. The scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) was utilized to further analyze the microscopic characteristics and elemental distribution within the slag samples. The results reveal that under oxy-fuel condition, the flow length of slag diminishes as the content of residual carbon increases. The slag samples blended with residual carbon exhibit rougher and looser surfaces, with numerous particles adhering to them. In addition, the higher the degree of graphitization in the residual carbon, the lesser its impact on the flowability of the slag. The slag samples in oxy-fuel atmosphere display relatively smooth surfaces with dense structures and extensive liquid-phase areas. On the contrary, slag samples under inert condition feature fewer smooth surfaces, with adherent particles visible along the edges of the structure. The present research provides valuable insights into the high-temperature flow behaviors of slag in oxy-fuel combustion for Zhundong high-alkali coal in slag-tapping boilers, which can contribute to clean and efficient energy production. © 2024, The Authors. All rights reserved.

关键词： Coal

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Excellent Energy Storage Performance Achieved in Sr(Sc0.5Nb0.5)O3-Doped Bi0.5Na0.5TiO3-Based Lead-Free Relaxor Ferroelectric Ceramics

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ACS Applied Energy Materials 2024年第5期7卷 2030-2038页

作者： Liu, Jinnan Li, Da Zhao, Weichen Xu, Diming Shi, Zhongqi Liu, Wenfeng Su, Jinzhan Zhou, Tao Chen, Guohua Zhou, Di Electronic Materials Research Laboratory & Multifunctional Materials and Structures Key Laboratory of the Ministry of Education International Center for Dielectric Research School of Electronic Science and Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China State Key Laboratory for Mechanical Behaviour of Materials Xi’an Jiaotong University Xi’an710049 China State Key Laboratory of Electrical Insulation and Power Equipment Xi’an Jiaotong University Shaanxi Xi’an710049 China International Research Centre for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China School of Electronic and Information Engineering Hangzhou Dianzi University Hangzhou310018 China Electronical Information Materials Devices Engineering Research Center of Ministry of Education Guangxi Key Laboratory of Information Materials School of Material Science and Engineering Guilin University of Electronic Technology Guilin541004 China

Dielectric energy storage ceramics have received significant attention as the primary component for high-pulse power capacitors. Currently, their development is limited by poor energy storage performance, which affects the miniaturization and lightweighting of electronic devices. In this study, a comprehensive optimization approach was adopted to enhance the storage performance (recoverable energy density Wrec and conversion efficiency η) of 0.8Bi0.5Na0.5TiO3-0.2NaNbO3 (BNT-NN) through component optimization design and repeated rolling process (RRP). A series of Sr(Sc0.5Nb0.5)O3 (SSN) was introduced into BNT-NN to modulate the phase structure and improve the relaxation properties. The repeated rolling process was applied to refine the grain and enhance the dense property to boost the breakdown of the electric field. Following the mentioned strategy, we have succeeded in simultaneously obtaining ultrahigh Wrec (∼7.22 J·cm-3) and outstanding η (∼95.32%) under 515 kV·cm-1 for 0.8(BNT-NN)-0.2SSN (RRP) ceramic. More importantly, the ceramic sample possesses outstanding stability over a wide range of temperatures (25-60 °C) and frequencies (1-100 Hz). This study proposes a viable route to better performance of dielectric ceramics for energy storage, and the outstanding performance of the 0.8(BNT-NN)-0.2SSN (RRP) ceramic indicates its promising applicability in high- and high-pulse-power electronic devices. © 2024 American Chemical Society.

关键词： Energy storage

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