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Bouncing and coalescence dynamics during the impact of a falling drop with a sessile drop on different solid surfaces

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PHYSICS OF FLUIDS 2021年第6期33卷 063309-063309页

作者： Abouelsoud, Mostafa Bai, Bofeng Xi An Jiao Tong Univ Int Ctr Appl Mech Sch Aerosp State Key Lab Strength & Vibrat Mech Struct Xian 710049 Peoples R China South Valley Univ Fac Engn Mech Engn Dept Qena 83511 Egypt Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

The dynamic of an impacting drop with a sessile drop of the same liquid on different solid surfaces is investigated experimentally and theoretically. By controlling the surface wettability and the impact velocity, different regimes were observed, such as complete rebounding, direct coalescence, and coalescence during the retraction phase or the spreading phase. It is observed that the complete rebounding phenomenon has widely occurred during the impact on hydrophilic surfaces. In addition, both the maximum and minimum limits of coalescence/complete rebounding thresholds were determined. During the complete rebounding phenomena, and based on the energy balance, the maximum spreading diameter of the falling drop diameter on the sessile drop was proposed. In addition, the restitution coefficient and the contact time between the falling and sessile drops were studied experimentally, and theoretically, the models show a good agreement with the experimental work.

关键词： Coalescence

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A Parametric Sensitivity Study and Comparison Analysis on Multiple Air Separation Processes

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INDUSTRIAL & engineering CHEMISTRY RESEARCH 2019年第21期58卷 9087-9098页

作者： Zheng, Jieyu Ye, Hengyang Li, Yanzhong Yang, Yongbin Si, Biao Xi An Jiao Tong Univ Sch Energy & Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China

flowsheet grassroots-design optimization is one of the promising debottlenecking operations for energy conservation of large cryogenic air separation units. In this paper several air separation schemes including single-column, double-column, and triple-column cycles were theoretically compared and discussed to meet the diverse purity demands of industrial gases in different areas. All the proposed processes were rigorously verified via HYSYS platform processing the same amount of feed air of 10 000 N m(3)/h. Both single and triple column processes presented considerable energy saving potentials compared with conventional double-column process with an average specific energy consumption decrease of 12.3 similar to 25.9%. And triple column distillation scheme was more sensitive to oxygen product purity changes. A parametric sensitivity study was conducted using principal component analysis (PCA) method to investigate the influence of some important systematic parameters on novel triple-column cycle design. PCA method is fast enough to process large amounts of data, and is able to reflect more data essence compared with the sensitivity analysis method. The obtained results implied that the HP split ratio and oxygen purity have a greater impact on selection range of design parameter, whereas optimal MP split ratio existed under certain F-LP conditions. Subsystem contribution on the overall plant operation performance could be evaluated based on variance contribution. Heat-exchanger, distillation, and refrigeration subsystem accounted for 41%, 30%, and 24%, respectively. The obtained result has great engineering significance for air separation engineering conceptual design.

关键词： Oxygen Atmospheric chemistry Separation science Nitrogen Energy

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Multi-fluid Eulerian simulation of fluidization characteristics of mildly-cohesive particles: Cohesive parameter determination and granular flow kinetic model evaluation

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POWDER TECHNOLOGY 2020年 364卷 264-275页

作者： Wei, Liping Gu, Yukuan Wang, Yibin Lu, Youjun Northwest Univ Sch Chem Engn Xian 710069 Shaanxi Peoples R China Minist Educ Adv Use Technol Shaan Bei Energy Chem Engn Res Ctr Xian 710069 Shaanxi Peoples R China Mississippi State Univ Dept Ind & Syst Engn Mississippi State MS 39762 USA Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn SKLMF Xian 710049 Shaanxi Peoples R China

The typical granular kinetic model, the cohesive granular kinetic model based on the contact bonding energy (Kim-Arastoopour-Huilin model) and the cohesive granular kinetic model based on the excess compressibility (Ye et al.'s model) were comprehensively compared in terms of kinetic parameters, bed expansion, and bubble behavior. The calculation methods of the contact bonding energy loss and the excess compressibility were presented, and the inter-relationship between the two cohesive parameters was revealed. The three kinetic models predict consistent kinetic parameters in dilute gas-solid flow region, while Ye et al.'s model always predicts a lower value when the solid fraction is above 0.15. The Kim-Arastoopour-Huilin model and Ye et al.'s model predicts opposite variations of solid pressure with increasing cohesion. Increasing cohesion interaction reduces the granular shear viscosity and bulk viscosity. Kim-Arastoopour-Huilin model and Ye et al.'s model outperform the typical kinetic model in terms of the bubble diameter and rising velocity. (C) 2020 Elsevier B.V. All rights reserved.

关键词： Cohesive particle Granular kinetic model Two fluid model Fluidized bed Bubbling

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Layered perovskite oxides and their derivative nanosheets adopting different modification strategies towards better photocatalytic performance of water splitting

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RENEWABLE & SUSTAINABLE ENERGY REVIEWS 2020年 119卷 109527-109527页

作者： Hu, Yuchao Mao, Liuhao Guan, Xiangjiu Tucker, Kevin Andrew Xie, Huling Wu, Xuesong Shi, Jinwen Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Int Res Ctr Renewable Energy Xian 710049 Shaanxi Peoples R China Univ Elect Sci & Technol China Ctr Appl Chem Chengdu 610000 Sichuan Peoples R China Tsinghua Univ Sichuan Energy Internet Res Inst Chengdu 610000 Sichuan Peoples R China

Photocatalytic water splitting has been extensively studied in the past decades and numerous semiconductors have been proved to be effective photocatalysts. Among them, layered perovskites, which comprise of a large family of layered oxides with different chemical components, are promising materials because of their stable perovskite slabs consisting of multiple metal cations and flexible interlayer galleries that facilitate modification. In this paper, we systematically review a series of modified layered perovskites with enhanced performance of water splitting. A variety of methods have been extensively applied in the modification of layered perovskites. And derivate photocatalysts with higher activity, better stability and lower cost were obtained. For bulk layered perovskites, this article introduces those that have been modified via photocatalyst design (ion doping and pillaring) as well as synthesis procedure and cocatalyst loading improvement. They show optimized chemical composition, crystal structure, specific area, band energy and morphology, which have been extensively proved to be key factors that decide the performance of photocatalysts. Compared with bulk layered perovskites, layered perovskite nanosheets, normally prepared by exfoliation of corresponding bulk parent materials, show largely increased surface area, which is beneficial for charge transfer. Further modification using these nanosheets as building blocks to construct restacked layered photocatalysts with mono-component or multi-components fully utilizes their ultrathin and charged nature. The modified nanosheets display enhanced charge separation and light absorption due to designed band structure and micro-nano structure, offering a promising future direction of photocatalyst design.

关键词： Layered perovskite Modification strategy Photocatalysis Water splitting Exfoliation Self-assembly

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Particle-scale study of coke combustion in the raceway of an ironmaking blast furnace

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FUEL 2022年 311卷 122490-122490页

作者： E, Dianyu Zhou, Peng Guo, Suya Zeng, Jia Xu, Qiang Guo, Liejin Hou, Qinfu Yu, Aibing Jiangxi Univ Sci & Technol Jiangxi Prov Key Lab Simulat & Modelling Particul Ganzhou 341000 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Monash Univ Dept Chem Engn ARC Res Hub Computat Particle Technol Clayton Vic 3800 Australia Southeast Univ Monash Univ Joint Res Inst Ctr Simulat & Modelling Particulate Syst Suzhou 215123 Peoples R China

The raceway is a zone of considerable significance in a blast furnace (BF) because it supplies energy and reducing agents that ensure successful and stable BF operation. Recently, experimental and numerical studies of BF have been widely conducted to examine the inner multiphase flow transport phenomena;however, the study of reacting flows at the particle level in BF is limited. In this study, a multiscale method that couples computational fluid dynamics (CFD) with discrete element method (DEM) is employed to examine the dynamic evolution of the raceway and inner thermo-chemical behaviours in a BF. Raceway evolution and formation, microscale characteristics, and coke temperature and combustion are comprehensively explored and analysed under various operating conditions. The predicted results show that the distributions of coke temperature, carbon loss, and diameter variation are consistent. More burning coke particles occurs in the vicinity of the region next to the tuyere, where there is a stronger high-temperature circular gas flow than in other regions. The increase in oxygen concentration indirectly increased the carbon monoxide concentration, but changes in the inlet gas temperature and flow rate yielded no effect on the carbon monoxide level in the studied ranges. These new perceptions of the complicated reacting flows inside the raceway area are beneficial for the fundamental understanding of energy utilisation and process optimisation.

关键词： Raceway zone Coke combustion CFD-DEM Numerical simulation Blast furnace

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A self-doping strategy to improve the photoelectrochemical performance of Cu2ZnSnS4 nanocrystal films for water splitting

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CHEMICAL COMMUNICATIONS 2019年第82期55卷 12396-12399页

作者： Feng, Xiaoyang Hou, Lulu Huang, Zhenxiong Li, Rui Shi, Jinwen Chen, Yubin Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Int Res Ctr Renewable Energy Xian Shaanxi Peoples R China

A series of self-doped Cu2ZnSnS4 (CZTS) nanocrystal films with Sn ions partially replaced by Zn ions were prepared from their colloidal solutions by electrophoretic deposition. The self-doped CZTS photocathodes yielded higher photocurrents than the pristine one, which was ascribed to the upper shift in the conduction band and the formation of a shallow defect level.

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Experimental investigations on single-phase convection and two-phase flow boiling heat transfer in an inclined rod bundle

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APPLIED THERMAL engineering 2019年 148卷 340-351页

作者： Zhang, K. Hou, Y. D. Tian, W. X. Zhang, Y. P. Su, G. H. Qiu, S. Z. Xi An Jiao Tong Univ Sch Nucl Sci & Technol State Key Lab Multiphase Flow Power Engn Shanxi Key Lab Adv Nucl Technol 28 Xianning West Rd Xian 710049 Shaanxi Peoples R China

Single-phase convection and steam-water two-phase flow boiling heat transfer experiments in an electrically heated 4 x 25 staggered inclined rod bundle were carried out for the following range: 15 kg m(-2) s(-1) <= G <= 50 kg m(-2) s(-1), 20.0 kW m(-2) <= q <= 55.0 kw m(-2), 0.05 <= x(out) <= 0.79 and 117 kPa <= P-in <= 260 kPa. Single-phase convective results show that the independence principle can be applied to the case that all tubes were heated in inclined rod bundles. With respect to two-phase results, the local flow boiling heat transfer coefficient increases from the bottom row to the eleventh row and then can be considered as a constant value from the eleventh row to the top row. An increasing heat flux results in a decrease of the flow boiling heat transfer coefficient. However, no significant effects of mass velocity and quality were observed. The inclination angle has a small effect on the flow boiling heat transfer coefficient at low heat fluxes. However, when heat flux is high, the flow boiling heat transfer coefficient in the inclined rod bundle is the minimum while that in the vertical rod bundle is the maximum compared with that in the horizontal rod bundle. In a general, a Chen-type correlation was developed to predict 98.5 percent of local flow boiling heat transfer coefficient data in the inclined rod bundle with a maximum deviation of +/- 20%.

关键词： Heat transfer experiments Single-phase convection flow boiling Inclined rod bundle

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Strong Metal-Support Interaction-Induced Hydrogen Spillover Boosts Thermocatalytic Ammonia Decomposition

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Small 2025年 e2500830页

作者： Chen, Zechang Jiang, Biao Lu, Zijie Huang, Jie Shi, Jinwen Liu, Maochang International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Suzhou Academy of Xi'an Jiaotong University Jiangsu Suzhou215123 China

Efficient non-noble-metal catalysts are essential for the industrial application of ammonia decomposition reaction (ADR). This work reports a Ni-Co bimetallic thermocatalyst supported by BaCe0.8Y0.2O3-δ (BCY), a proton-conducting cermet, demonstrating state-of-the-art ADR performance. This catalyst achieves 100% NH3 conversion at 550 °C with a gas hourly space velocity of 9000 mL h−1 gcat−1 and 95.1% conversion at 520 °C, notably lowering ADR temperature requirements. It also demonstrates outstanding stability under diverse conditions. The superior ADR activity arises from Ni-Co synergies, Ce's strong basicity, as well as extensive hydrogen spillover facilitated by Y doping-induced high oxygen vacancies. Specifically, BCY's strong adsorption of H* promotes the migration of H* from the active Ni/Co surface to oxygen sites of the support and subsequent rapid diffusion as OH* in oxygen vacancy channels. This metal-support-interaction-induced hydrogen spillover effect further liberates the original active sites and boosts ammonia activation. © 2025 Wiley-VCH GmbH.

关键词： Cermets

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A sensitivity analysis of bubble departure behavior in vertical channel nucleate boiling

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INTERNATIONAL JOURNAL OF THERMAL SCIENCES 2020年 157卷 106497-106497页

作者： Li, Liangxing Xu, Zhihao Xie, Wei Zhang, Zhengzheng Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian Ning West Rd 28 Xian 710049 Peoples R China

Boiling is a very efficient heat transfer mechanism and had been exploited in numerous industrial and engineering sectors. However, limited by the experimental techniques and measuring tools, the experimental data related to the bubble dynamics especially in high heat fluxes on the wall surface is still rare and random. To contribute to this knowledge gap, the present paper proposes a statistical analysis method, attempting to identify the effect of input variables to bubble departure diameter on superheated wall by sensitivity analysis. More than 400 experimental data are collected by literature reviewing and a group of simulation data generated by selected correlation are included to supplementary and enlarge the database. Finite Mixture Model (FMM) is employed to conduct the sensitivity analysis study, where the hydraulic diameter of channel, water flow rate, flow subcooling and wall superheat are selected as input variables and the bubble departure diameter is output variable. With adopting two definitions of general distance (Kullback-Leibler divergence and chi(2) distance), the sensitivity degree order of the input variables is evaluated. Those two definitions of general distance have almost the same results concerning the order. The innovative sensitivity analysis approach is compared with the standard variance decomposition method (Sobol). The result indicates that FMM is more accurate than Sobol based on present database. The preliminary results of sensitivity analysis approach show that the flow condition has a more significant influence on bubble departure behavior than temperature does.

关键词： Sensitivity analysis Bubble departure behaviors Boiling Finite mixture model Sobol model

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A comprehensive experimental and kinetic modeling study of dimethoxymethane combustion

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COMBUSTION AND FLAME 2021年 233卷 111583-111583页

作者： Li, Ning Sun, Wuchuan Liu, Shenghua Qin, Xiaokang Zhao, Yuwei Wei, Yanju Zhang, Yingjia Xi An Jiao Tong Univ Sch Energy & Power Engn Xian 710049 Peoples R China Xi An Jiao Tong Univ State Key Lab Multiphase Flow Power Engn Xian 710049 Peoples R China Air Force Engn Univ Air & Missile Def Coll Xian 710049 Peoples R China

Dimethoxymethane (DMM, CH3OCH2OCH3), the simplest member in the class of polyoxymethylene dimethyl ethers (PODE), is regarded as a promising fuel substitute for compression ignition engines. To better understand its combustion characteristics, a comprehensive experimental and kinetic modeling study on the combustion of DMM was conducted. Ignition delay times (IDTs) of DMM/O-2/Ar mixtures were measured in a shock tube at pressures from 1.0 to 10 atm, for temperatures from 1050 to 1450 K, and equivalence ratios of 0.5, 1.0 and 2.0. A predominantly ab initio derived detailed kinetic model of DMM with 121 species and 646 reactions was developed based on AramcoMech2.0 with an updated sub-mechanism of methyl formate (MF, CH3OCHO). C-O bond fissions occurred in CH2-O and CH3-O moieties were demonstrated to be the dominating reaction pathways in DMM high temperature chemistry rather than the competing non-radical decomposition channels. Flux and sensitivity analyses indicated that the two C-O bond fissions have a comparatively promoting effect on reactivity, while the DMM = CH3OCH2O + CH3 reaction was the dominating channel at high temperatures. The proposed model was also validated against literature experimental data, including ignition delay times, jet stirred reactor species concentrations, laminar pre-mixed flame speciation, laminar burning velocities and plug-flow reactor speciation. The good performance of the proposed model for reproducing these data revealed its ability to predict DMM combustion over a wide range of conditions. Major reaction pathways of DMM could also apply to larger PODE compounds. (C) 2021 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

关键词： Dimethoxymethane Chemical kinetics Shock tube Reaction mechanism

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