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Thermal and film dynamics of multi-nozzle flash spray cooling towards large area and non-uniform heat source

Thermal Science and engineering Progress 2025年 63卷

作者： Xiang-Wei Lin Xu-Dong Wang Zhi-Fu Zhou Dong-Qing Zhu Wen-Wei Xu Hai Zhu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China Huawei Technologies Co. Ltd. Shenzhen China

Thermal management poses a crucial challenge to the operational reliability of high-power devices which characterized by large area and uneven heat sources. Flash spray, as one of the start-of-the-art technologies, satisfies the requirements of rapid heat removal and superior droplet breakup effects. This study aims to investigate the liquid dynamics and heat transfer characteristics of multi-nozzle flash spray on a non-uniform heat flux surface. Here, the Euler-Lagrangian method is coupled to account for the gas-droplet interactions, and the Lagrangian wall-film is applied to describe the liquid film evolution. The effects of spray height and nozzle number are systematically discussed in terms of velocity, liquid film thickness, average surface temperature, and temperature non-uniformity. Results reveal that the enhanced spray-to-spray interaction can greatly alter liquid film distribution, which in turn affects the heat transfer efficiency. Notably, while increasing spray coverage improves thermal contact area, it exhibits a non-linear relationship with temperature reduction, showing an optimal spray height and nozzle number for minimizing average temperature and temperature non-uniformity. The main contribution of present work lies in its in-depth analysis of multi-nozzle flash spray on large area and uneven heating surface, which is prevalent in industrial applications buy underexplored in prior works. These findings are expected to offer actionable guidelines for understanding complex spray cooling mechanisms and designing efficient thermal management systems.

关键词： Film cooling

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Experimental and modeling investigation of zero net liquid flow in hilly terrain pipeline

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Petroleum Science 2025年

作者： Huang, Bo Xu, Qiang Chang, Ying-Jie Cao, Ye-Qi Yu, Hai-Yang Li, Yu-Wen Guo, Lie-Jin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an 710049 China College of Petroleum Engineering Xi'an Shiyou University Shaanxi 710065 China

Hilly terrain pipeline is a common form of pipeline in oil and gas storage and transportation industry. Due to the hilly terrain influence, the liquid at the elbow of the gathering pipeline is easy to flow back and accumulate to form slug flow, so it is necessary to remove the accumulated liquid by gas purging. In this paper, experiment is carried out in hilly terrain pipelines. Three flow patterns of stratified flow, slug flow and stratified entrained flow are observed. The process of gas purging accumulated liquid is divided into four stages, namely liquid accumulation, liquid rising;continuous outflow and tail outflow. At the same time, the flow pattern maps of each stage are drawn. The pressure drop signal is analyzed in time domain and frequency domain, and the contour map of pressure drop distribution is drawn. It is found that the ratio of range to average value can well distinguish the occurrence range of each flow pattern. Based on visualization, the transition process of slug flow to stratified flow and stratified entrained flow is studied, and the transition boundary prediction model is established. An image processing method is proposed to convert the image signal into a similarity curve, and PSD analysis is performed to calculate the slug frequency. The normal distribution is used to fit the slug frequency, and the predicted correlation is in good agreement with the experimental data. © 2025 The Authors

关键词： flow pattern transition Hilly terrain pipeline Quantitative image processing Slug flow Zero net liquid flow

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Numerical Investigation of Developing Turbulent flow in a Helical Square Ductwith Large Curvature

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Journal of Thermal Science 2001年第1期10卷 1-6页

作者： Gao Hui,Guo Liejin (state key laboratory of multiphase flow in Power engineering, Xi’an Jiaotong University, Xi’an 710049, China ) State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an China

A fully elliptic numerical study has been carried out to investigate the three-dimensional turbulent developing flow in a helical square duct with large curvature. A two-layer zonal model is proposed and used, in which the whole region is divided into a viscosity-affected near wall layer and a fully turbulent region. A DSM closure is applied in the former, and a one-equation model is solved in the latter. The results presented in this paper cover a Reynolds number range of (l- 10) x 104. The development of flow is found to be dominated by radial pressure gradient and Dean-type secondary motion. The distribution of Reynolds stresses in fully developed flow exhibit a complex pattern of turbulence anisotropy The development of peripherally averaged friction factor and the distribution of local friction factor in fully developed flow are given and discussed.

关键词： curved pipe developing flow turbulence model numerical simulation.

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Recent advances in nonmetallic atom-doped metal nanocrystals:Synthesis and catalytic applications

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Chinese Chemical Letters 2021年第9期32卷 2679-2692页

作者： Ruiyun Guo Ke Zhang Shangdong Ji Yangzi Zheng Mingshang Jin Frontier Institute of Science and Technology and State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

Metal nanocrystals have been recognized as the main catalytic materials in many fields,but insufficient activity and stability,as well as high prices,have limited their large-scale potential *** one of the extremely promising alternatives toward metal in boosting their catalytic performance,nonmetallic atoms-doped metal nanocrystals have recently received extensive attention because of their high efficiency,chemical and structural durability,abundant reserve,and low *** this review,we highlight the most recent progress in this field and provide insights into their catalytic *** metalnonmetal nanocrystals prepared by doping metal nanocrystals with nonmetallic atoms are introduced and classified based on the types of nonmetallic atoms,including metal hydrides,borides,carbides,nitrides,oxides,phosphides,and ***,their applications in catalysis,especially in electrocatalysis and organic catalysis,have been summarized and ***,the conclusions and perspectives are given for the catalysis-driven rational design of metal-nonmetal nanocrystals in this minireview.

关键词： Nonmetallic atom-doping Metal-nonmetal nanocrystals Organic catalysis Electrocatalysis Catalyst design

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Improving sampling depth of laser speckle imaging by topical optical clearing:A theoretical and in vivo study

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Journal of Innovative Optical Health Sciences 2020年第2期13卷 33-43页

作者： D.Li Y.Zhang B.Chen State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049P.R.China

The effect of optical cleaning method combined with laser speckle imaging(LSI)was discussed to improve the detection depth of LSI due to high scattering characteristics of skin,which limit its clinical application.A double-layer skin tissue model embedded with a single blood vessel was established,and the Monte Carlo method was used to simulate photon propagation under the action of light-permeating agent.808 nm semiconductor and 632.8 nm He–Ne lasers were selected to study the e®ect of optical clearing agents(OCAs)on photon deposition in *** show that the photon energy deposition density in the epidermis increases with the amount of tissue°uid replaced by *** with glucose solution,polyethylene glycol 400(PEG 400)and glycerol can considerably increase the average penetration depth of photons in the skin tissue,thereby raising the sampling depth of the *** the action of glycerol,PEG 400,and glucose,the average photon penetration depth is increased by 51.78%,51.06%,and 21.51%for 808nm,68.93%,67.94%,and 26.67%for 632.8 nm lasers,*** vivo experiment by dorsal skin chamber proves that glycerol can cause a substantial decrease in blood°ow rate,whereas PEG 400 can signicantly improve the capability of light penetration without a®ecting blood velocity,which exhibits considerable potential in the monitoring of blood°ow in skin tissues.

关键词： Laser speckle image topical optical clearing imaging depth Monte-Carlo simulation dorsal skin experiment

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Simulation study on mineral transformation behaviors and ash fusion characteristics during high-alkali coal combustion under deep peaking conditions

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Fuel 2025年 399卷

作者： Liu, Jiamiao Ma, Guowei Du, Yongbo Wang, Chang'an Zhao, Yonggang Wu, Wanzhu Shi, Longping Zhao, Lin Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an710049 China National Energy Group Science and Technology Research Institute Co. Ltd. Nanjing210046 China Company Xi'an710076 China Huayuan Power Plant National Energy Group Hami Coal Power Co. Ltd. Hami839000 China

The safe and efficient combustion of high-alkali coal under deep peaking conditions remains a critical research focus. Boiler operating parameters under such conditions frequently fluctuate, markedly though incompletely understood in their influence on fouling and slagging, necessitating further investigation. Here, mineral transformation and ash fusion characteristics during high-alkali coal combustion in the main combustion zone were simulated through thermodynamic equilibrium calculations, addressing its fouling issues under deep peaking conditions. Variable loads were decomposed into distinct factors for analysis due to challenges of direct simulation. Additionally, the plasma ashing method was employed to prepare ash samples. High-alkali coals with distinct properties exhibit significant variations in mineral distribution, elemental evolution, ash fusion temperature, and viscosity. Abundant fayalite (Fe2SiO4) was observed in Hongshaquan (HSQ) coal, forming stable mineral phases with other components. In Shaerhu (SEH) coal, sodium primarily exists in the gaseous phase at high temperatures, significantly contributing to fouling. Meanwhile, Jiangjunmiao (JJM) and Wucaiwan (WCW) coals demonstrate limited mineral phases but higher ash fusion temperatures, with over 30 % of iron in the gaseous phase. The mineral transformation and ash fusion behaviors in various local combustion atmospheres follow consistent trends. The formations of gaseous sodium hydroxide (NaOH(g)) and sodium oxide in the slag phase (Na2O(slag)) are promoted with weakening reducing atmospheres, while total gaseous sodium content decreases. The slag phases of calcium, magnesium, and iron increase, accompanied by a decline in ash viscosity. However, unburned carbon inversely influences mineral transformation and ash fusion characteristics compared to excess air coefficients. This research provides theoretical support for overcoming the key technical challenges associated with high-alkali coal combus

关键词： Iron analysis

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Experimental and kinetic study on laminar flame speeds of ammonia/syngas/air at a high temperature and elevated pressure

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Frontiers in Energy 2022年第2期16卷 263-276页

作者： Geyuan YIN Chaojun WANG Meng ZHOU Yajie ZHOU Erjiang HU Zuohua HUANG State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Key Laboratory for Thermal Science and Power Engineering of the Ministry of Education Department of Thermal EngineeringTsinghua UniversityBeijing 100084China

The laminar flame speeds of ammonia mixed with syngas at a high pressure, temperature, and different syngas ratios were measured. The data obtained were fitted at different pressures, temperatures, syngas ratios, and equivalence ratios. Four kinetic models (the Glarborg model, Shrestha model, Mei model, and Han model) were compared and validated with experimental data. Pathway, sensitivity and radical pool analysis are conducted to find out the deep kinetic insight on ammonia oxidation and NO formation. The pathway analysis shows that H abstraction reactions and NHi combination reactions play important roles in ammonia oxidation. NO formation is closely related to H, OH, the O radical produced, and formation reactions. NO is mainly formed from reaction, HNO+ H= NO+ H2. Furthermore, both ammonia oxidation and NO formation are sensitive to small radical reactions and ammonia related reactions.

关键词： ammonia mixed with syngas laminar flame speed kinetic model sensitivity analysis pathway analysis

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A volume of fluid simulation of the steady deformation and the drag of a single droplet in a flowing gas

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Journal of Hydrodynamics 2021年第2期33卷 334-346页

作者： Zhi-bin Wang Zhong-wei Yang Lie-jin Guo Ren-jie Zhao State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChendu 610500China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

A method is proposed to investigate the steady deformation and the drag of a single droplet in a flowing gas at a high Reynolds *** volume of fluid(VOF)method is used to model the droplet surface *** direct numerical simulation(DNS)method is used to model the gas flow *** order to avoid the effect of the droplet acceleration on the drag and reduce the computation cost,a body force is added to the droplet to make it fixed at a constant *** body force is determined by using the Newton iteration *** simulated droplet aspect ratio and the drag coefficient agree well with the published experimental ***,the sources of the drag are analyzed and the effect of the Reynolds number and the Weber numbers on the droplet deformation and the drag are *** drag mainly comes from the pressure difference between the droplet-leading zone and the trailing zone,and the turbulence wake would increase the drag.

关键词： Droplet deformation steady drag volume of fluid(VOF) turbulent flow drag force

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Double Z-scheme in SnO_(2)/SnS_(2)/Cu_(2)SnS_(3)heterojunction for photocatalytic reduction of CO_(2)to ethanol

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Journal of Materials Science & Technology 2024年第22期189卷 146-154页

作者： Feng Wang Shunxin Zhang Wenhao Jing Haoran Qiu Ya Liu Liejin Guo International Research Center for Renewable Energy State Key Laboratory of Multiphase FlowXi’an Jiaotong UniversityXi’an 710049China

Photocatalytic reduction of CO_(2)to chemical fuels enables a sustainable way of reducing carbon emissions but faces a high reduction potential due to the high stability of CO_(2)***,we prepared a SnO_(2)/SnS_(2)/Cu_(2)SnS_(3)double Z-scheme heterojunction photocatalyst,in which SnO_(2),SnS_(2),and Cu_(2)SnS_(3)absorb ultraviolet,visible,and near-infrared light,*** on the comprehensive analysis of in-situ X-ray photoelectron spectroscopy and photo(chemical)characterizations,we find that the photogenerated electrons would transfer from SnO_(2)to SnS_(2)to Cu_(2)SnS_(3).The optimized SnO_(2)/SnS_(2)/Cu_(2)SnS_(3)–0.3 double Z-scheme heterojunction could achieve 28.44μmol g^(–1)h^(–1)ethanol yield and 92%selectivity,which is roughly 3 folds higher than SnO_(2)/SnS_(2)single Z-scheme *** using in-situ diffuse reflectance infrared Fourier-transform spectroscopy,we observe that ethanol is produced through a∗COCOH pathway,in which Cu_(2)SnS_(3)would decrease the activation energy barrier from^(∗)COOH to^(∗)CO.

关键词： CO_(2)reduction Photocatalysis Z-scheme Ethanol

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Investigation of the transfer ionization process in collisions of partially stripped ions on He

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Chinese Physics B 2010年第6期19卷 277-282页

作者：刘会平陈熙萌欧阳晓平席发元苏光辉 State Key Laboratory of Multiphase Flow in Power Engineering Department of Nuclear Science and TechnologyXi'an Jiaotong University School of Nuclear Science and Technology Lanzhou University

In this paper a projectile ion-recoil ion coincidence technique is used to investigate the transfer ionization processes in collisions of 0.22-6.30 MeV Cq＋ ions and 0.25-6.35 MeV 0q＋ ions （q=1, 2, 3, 4） with the He atom separately. The cross section ratio f of transfer ionization to single electron transfer is measured, and the dependence of f on both charge state q and energy E of the projectiles is investigated. The electron-structure and the mechanisms leading to transfer ionization affect the dependence of f on q and E. Our measurements, along with other data published previously, suggest a similar dependence of f on charge state and energy of projectile for partially stripped ions over a large energy range. The maximum value of f is approximately 0.17q^0.60; the energy corresponding to maximum f is about 160q^0.60 keV/u.

关键词： ion atom collision transfer ionization single electron transfer

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