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International Conference on Fluid Mechanics and Industrial Applications (FMIA)

作者： Cheng, Jiarui Cao, Yinping Dou, Yihua Li, Zhen Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Shaanxi Peoples R China Xian Shiyou Univ Dept Mech Engn Xian Shaanxi Peoples R China

A lab experiment was carried out to study the effects of pipe flow rate, particle concentration and pipe inner diameter ratio on proppant erosion of the reducing wall in hydraulic fracturing. The results show that the erosion rate and erosion distribution are different not only in radial direction but also in circumferential direction of the sample. The upper part of sample always has a minimum erosion rate and erosion area. Besides, the erosion rate of reducing wall is most affected by fluid flow velocity, and the erosion area is most sensitive to the change in the diameter ratio. Meanwhile, the erosion rate of reducing wall in crosslinked fracturing fluid is mainly determined by the fluid flowing state due to the high viscosity of the liquid. In general, the increase in flow velocity and diameter ratio not only cause the expansion of erosion-affected flow region in sudden contraction section, but also lead to more particles impact the wall.

关键词： Erosion

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Numerical investigation on heat transfer characteristics of helium-xenon gas mixture

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INTERNATIONAL JOURNAL OF ENERGY RESEARCH 2021年第8期45卷 11745-11758页

作者： Qin, Hao Fang, Yuliang Wang, Chenglong Tian, Wenxi Qiu, Suizheng Su, Guanghui Deng, Jian Xi An Jiao Tong Univ Dept Nucl Sci & Technol Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ Shaanxi Key Lab Adv Nucl Energy & Technol Xian Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Peoples R China Nucl Power Inst China Sci & Technol Reactor Syst Design Technol Lab Chengdu Peoples R China

Helium-Xenon (He-Xe) gas mixture featured with low Prandtl number is increasingly used in various energy devices as heat-carrying agent. To figure out the heat transfer characteristics of He-Xe gas mixture in uniformly heated circular and tri-lobe channels, numerical investigations are conducted and presented in the article. The adopted calculation models are validated by comparison between simulation results and experimental data. The local and total heat transfer characteristics are obtained, and new temperature correction factors for the circular and tri-lobe channels are proposed and recommended. The simulation results obtained by using the SSTk - omega turbulent model agree well with the experimental data, this kind of turbulent model matched with appropriate turbulent Prandtl number model could provide satisfactory temperature predictions for He-Xe gas mixture in a wide range of temperature ratioT(w)/T-b. The simplified Petukhov correlation with temperature correction can give conservative predictions with relative error less than 10%. For the tri-lobe channel, due to the local restricted flow, the gas temperature at the corners is much higher than that at the concavities. The local wall temperature and localNunumber vary azimuthally, showing a large temperature gradient. The tri-lobe channel has better heat transfer performance than that of the circular tube when the temperature ratioT(w)/T(b)is no more than 1.5, but it deteriorates significantly with the increasing temperature ratio. This article may contribute to the numerical simulation and thermal design of heat transfer components concerning He-Xe gas mixture.

关键词： circular tube heat transfer characteristics helium-xenon gas mixture numerical simulation tri-lobe channel

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Synergy of nitrogen dopants and cobalt single atoms in calcium niobate nanosheets for photocatalytic oxygen evolution

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JOURNAL OF PHYSICS-ENERGY 2024年第4期6卷 045002页

作者： ul Haq, Sajjad Dong, Chung-Li Huang, Yu-Cheng Rehman, Rana Moiz Ur Djatoubai, Essossimna Lin, Zhi Khan, Muhammad Shuaib Shen, Shaohua Xi An Jiao Tong Univ Int Res Ctr Renewable Energy IRCRE State Key Lab Multiphase Flow Power Engn MPFE 28 Xianning West St Xian 710049 Peoples R China Tamkang Univ Dept Phys 151 Yingzhuan Rd New Taipei 25137 Taiwan

The successful separation of photoexcited charge carriers and their effective utilization are crucial for overcoming the slow kinetics of the four-electron process for photocatalytic oxygen evolution. Herein, a novel strategy utilizing urea as a source of N-doping on Ca2Nb3O10 nanosheets is adopted, followed by the successful deposition of Co single atoms (Co-SAs) to achieve a synergistic effect. The presence of N-dopants and Co-SAs is validated via various experimental techniques. It is also observed that the presence of N-doping contributed towards the deposition of higher content of Co-SAs (0.21 wt%) in Ca2Nb3O10-xNx-CoSA nanosheets compared to 0.15 wt% for non-doped Ca2Nb3O10-CoSA. The optimized Ca2Nb3O10-xNx-CoSA nanosheets exhibited an impressive photocatalytic O2 evolution of similar to 727.22 mu mol g-1 h-1 via the synergy of N-dopants and Co-SAs. As a result, the O2 evolution response of Ca2Nb3O10-xNx-CoSA is 3.6 times higher than that of pristine Ca2Nb3O10 nanosheets (201.26 mu mol g-1 h-1), 2.24 times better than Ca2Nb3O10-xNx nanosheets (323.42 mu mol g-1 h-1), and 1.77 times higher compared to Ca2Nb3O10-CoSA, (409.33 mu mol g-1 h-1), which clearly demonstrated the synergistic effect of N-dopants and Co-SAs in Ca2Nb3O10-xNx-CoSA nanosheets. Based on the findings of various characterization techniques, the co-presence of N-dopants and Co-SAs is observed to contribute towards better charge carrier separation, and utilization to achieve superior photocatalytic response. Thus, this study presents a novel approach for incorporating N-dopants and Co-SAs on Ca2Nb3O10 nanosheets, which can be extended to a wide range of nanosheets produced by the soft chemical exfoliation method.

关键词： cobalt single atoms nitrogen doping 2D perovskite oxide photocatalysis O-2 evolution

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NiS modified CdS pyramids with stacking fault structures: Highly efficient and stable photocatalysts for hydrogen production from water

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2017年第38期42卷 23995-24005页

作者： He, Kai Guo, Liejin North Univ Sch Energy & Power Engn Xian 030051 Shanxi Peoples R China Xi An Jiao Tong Univ Int Res Ctr Renewable Energy Xian 710049 Shaanxi Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China

NiS modified three-dimensional pyramidic CdS with stacking fault structures were successfully synthesized by using the one-step method and an ammonia aqueous solvent as the hydrothermal solvent. Thus, CdS showed superior photocatalytic activities for hydrogen evolution from water under visible light irradiation (lambda >= 420 nm), which could achieve a hydrogen evolution rate of 49.2 mmol g(-1) h(-1), with an extremely high apparent quantum yield (AQY = 74.6%) at 420 nm. To our knowledge, this value is the highest reported efficiency value for NiSx modified CdS photocatalysts. CdS exhibited a three-dimensional pyramid structure with large specific surface areas, which may provide more active sites for the photocatalytic reaction. Stacking fault structures were observed in CdS by transmission electron microscopy (TEM). P-type NiS nanoparticles were highly dispersed on the surface of n-type CdS pyramids, forming p-n junctions at the interface. The stacking fault structures and junctions strengthened the separation of photo-carriers near the interface, which may greatly enhance the activity of photocatalytic hydrogen production for CdS. The catalyst also showed perfect stability, and the photoactivity showed no significant degradation during continuous hydrogen production over nearly 120 h, which has not been reported in the literature. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

关键词： The p-n junctions The stacking fault structures Photocatalytic hydrogen production Stability

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EXPERIMENTAL INVESTIGATION ON THE FRICTIONAL PRESSURE DROP OF HIGH PRESSURE STEAM-WATER TWO-PHASE flowS IN AN OPTIMIZED INTERNALLY-RIBBED TUBE 9

EXPERIMENTAL INVESTIGATION ON THE FRICTIONAL PRESSURE DROP O...

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9th International Conference on power engineering (ICOPE-09)

作者： Wang, Jianguo Li, Huixiong Guo, Bin Yu, Shuiqing Zhang, Yuqian Chen, Tingkuan Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Xian Univ Sci & Technol Coll Energy Xian 710054 Peoples R China

ISBN: (纸本)9784906601073

Experimental investigation on the frictional pressure drop of high pressure steam-water two-phase flows in an optimized six-head internally-ribbed tube has been carried out in Xi'an Jiaotong University, China. Two adiabatic test sections were utilized, with one installed horizontally and another installed vertically. The frictional pressure drops of an adiabatic horizontal smooth tube were also measured to provide a data base for comparison. According to experimental data, the two-phase friction multiplier was calculated and its variations with the pressure, the mass flux and the steam quality were obtained. By comparison, it was found that the two-phase friction multiplier of the horizontal internally-ribbed tube had an obvious peak value, which was much larger than that of the horizontal smooth tube, in the region with high steam qualities. It was also found that the two-phase friction multiplier of the horizontal internally-ribbed tube was always greater than that of the vertically-upward internally-ribbed tube.

关键词： Optimized internally-ribbed tube Steam-water two-phase flow Frictional pressure drop Two-phase friction multiplier

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Numerical study on a single char particle gasification considering Stefan flow effects in a hot CO2/O2/H2O atmosphere

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FUEL 2022年第PartC期324卷

作者： Shang, Fei Ge, Zhiwei Wang, Yu Zhou, Chenchen Guo, Shenghui Ren, Changyifan Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

CO2 gasification of biomass provides a new approach to the resourceful solidification and utilization of CO2. The level of char conversion is critical to the overall efficiency of the gasification process. The aim of this numerical study was to investigate the external multifactorial effect of char conversion in a hot CO2/O-2/H2O atmosphere at the particle scale with considering the effects of particle size and ash layer. The results demonstrated that increasing inlet temperature promotes gasification mainly by convective heat transfer between the gas stream and the particle surface. This effect diminishes as the inlet temperature increases. The promotion by enhanced convection is mainly due to the thinner boundary layer at the head of the particle, which allows for enhanced heat and mass transfer processes. The gasification process is susceptible to changes in O(2 )concentration. Despite the fivefold increase in H2O mole fraction (0.1 % ~ 0.5 %), the gasification process was not significantly accelerated. The influence of Stefan flow on the gasification process is mainly reflected in the rate distribution of the homogeneous reactions. When considering the ash layer cover, the temperature of the particle surface is affected by multiple effects of the increased specific surface area of the char core and convective heat transfer.

关键词： CO(2)gasification Biomass Singleparticle Stefanflow Ashlayer

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Study on Liquid Turbulence Modulation by Microbubbles in Different Turbulence Layers

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ADVANCES IN MECHANICAL engineering 2014年第Pt.7期000卷

作者： Pang, Mingjun Wei, Jinjia Yu, Bo Changzhou Univ Sch Mech Engn Changzhou 213016 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China China Univ Petr Beijing Key Lab Urban Oil & Gas Distribut Technol Beijing 102249 Peoples R China

Bubbly flows exist extensively in industrial processes. To enhance efficiencies of industrial processes, it is very necessary and important to understand detailedly mechanisms of liquid turbulence modulation by bubbles. To understand mechanisms of the liquid turbulence modulation by microbubbles, an Euler-Lagrange two-way model was used to investigate and analyze deeply the liquid turbulence modulation by microbubbles in the subviscous, buffer, and outer layers, respectively. The present results show that the liquid turbulence modulation by microbubbles is related to microbubble locations;the liquid turbulence is intensified when microbubbles are in the outer layers, whereas the liquid turbulence is suppressed when microbubbles are in the subviscous and buffer layer;and the drag reduction occurs only when microbubbles are in the buffer layer.

关键词： liquids drag reduction Buffer layers Microbubbles Turbulent flow Industrial processes

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Experimental study of single-phase flow and heat transfer in rectangular channels under uniform and non-uniform heating

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EXPERIMENTAL THERMAL AND FLUID SCIENCE 2020年第0期114卷 110055-000页

作者： Sun, Rulei Song, Gongle Zhang, Dalin Deng, Jian Su, G. H. Kulacki, F. A. Tian, Wenxi Qiu, Suizheng Xi An Jiao Tong Univ Sch Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Shaanxi Key Lab Adv Nucl Energy & Technol 28 Xianning West Rd Xian Peoples R China Nucl Power Inst China Sci & Technol Reactor Syst Design Technol Lab Chengdu Peoples R China Univ Minnesota Dept Mech Engn 111 Church St SE Minneapolis MN 55455 USA

Characteristics of single-phase convective heat transfer in a rectangular channel are reported for heated and non-heated conditions. Results indicated that the friction factors were basically the same in the laminar region. However, in the transition and quasi-turbulent region, the heated friction factor was slightly lower than the non-heated values, and the value of non-uniform heating was slightly higher than that of uniform heating. The transition started critical Reynolds number increased from 2700 without heating to about 3000 with heating only due to the viscosity decreased with increasing temperatures. Due to the transition started and ended Reynolds number increased simultaneously under heating, the width of flow transition was almost the same as that without heating. The transverse power distribution influenced the average Nusselt number of the channel, although measured differences were small for uniform and non-uniform heating conditions. For the heat transfer data under uniform heating conditions obtained in this study, 15 correlations were evaluated. It is found that the existing correlations underestimated the experimental data for Re < 3000 and overestimated the data for 3000 < Re < 6000. A large database of heat transfer in rectangular channels including the experimental data obtained from this study and other researchers' work was established, and new heat transfer correlations for laminar (Re < 3000) and transition (3000 < Re < 10000) flows were developed. The Dittus-Boelter correlation was confirmed to provide a good prediction for the heat transfer for Re > 10000, with almost all data being within 20% errors.

关键词： Rectangular channel Single-phase water Friction factor Heat transfer correlation power distribution

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Low-Cost Oriented Hierarchical Growth of BiVO₄/rGO/NiFe Nanoarrays Photoanode for Photoelectrochemical Water Splitting

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ACS SUSTAINABLE CHEMISTRY & engineering 2018年第11期6卷 14695-+页

作者： Han, Xiao Wei, Yankuan Su, Jinzhan Zhao, Yan Beihang Univ Sch Mat Sci & Engn 37 Xueyuan Rd Beijing 100191 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Int Res Ctr Renewable Energy Sch Energy & Power Engn 28 Xianning West Rd Xian 710049 Shaanxi Peoples R China

A unique BiVO4/reduced graphene oxide (rGO)/NiFe hydroxide photoanode with oriented hierarchical nanostructure was fabricated via a facile and scalable solution route. Microstructure analysis shows that the ternary nanocomposite system presented a nanopyramid configuration with BiVO4 nanoarrays coated by sheetlike graphene interlayer and amorphous NiFe hydroxides. A maximum photocurrent density of 1.30 mA/cm(2) at scan rate of 20 mV/s at 1.23 V vs reversible hydrogen electrode was obtained for the BiVO4/rGO/NiFe photoelectrode, which was almost three times as high as that of pristine BiVO4. A boost of photocurrent density was achieved as a result of the synergistic effects between graphene "shuttle" interlayer and NiFe-based nanoarrays cocatalyst outer layer. Herein, rGO acts as an intermediate layer facilitating transfer of the photogenerated charge carriers, improving the adhesion of NiFe nanoarrays cocatalyst layer on the substrate and enhancing the stability and photoelectrochemical response of photoanode. This work demonstrates that tunable multicomponent design and rational hierarchical structure control are efficient approaches to enhance the photoelectrochemical water splitting performance of photoelectrode.

关键词： Photoelectrochemical water splitting Bismuth vanadate Reduced graphene oxide NiFe hydroxide Electrodeposition

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A polarization model for solid oxide fuel cells with a Bi-layer electrolyte

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INTERNATIONAL JOURNAL OF HYDROGEN ENERGY 2016年第5期41卷 3646-3654页

作者： Shen, Shuanglin Guo, Liejin Liu, Hongtan China Univ Min & Technol Sch Elect Power Engn Xuzhou 221116 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Shaanxi Peoples R China Univ Miami Clean Energy Res Inst Dept Mech & Aerosp Engn Coral Gables FL 33124 USA

A polarization model for a solid oxide fuel cell (SOFC) with a bi-layer electrolyte is developed and a set of explicit expressions for output current, maximum power and thickness ratio of bi-layer electrolyte are obtained. In the model, two dominating polarizations, activation polarization and ohmic polarization, are considered and the concentration polarization is neglected. The activation polarization at the electrodes is described by the Butler-Volmer equation. The ohmic polarization is represented by the charge transport equation, and this equation is solved with the assumption of constant ionic conductivity. To close the model equations, a supplemental relation is introduced by the energy conservation analysis. The modeling results compare well with the experimental data. The model is further used to study the effect of cathode exchange current density on the working characteristics of a solid oxide fuel cell with a bi-layer electrolyte. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

关键词： Polarization model Solid oxide fuel cell (SOFC) Bi-layer electrolyte Leakage current

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