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Numerical Study of Percolation and Seepage Behaviors in Ion-Adsorption-Type Rare Earth Ore Leaching Process

Mathematical Problems in engineering 2023年第1期2023卷

作者： Dianyu, E. Su, Zhongfang Zeng, Jia Yang, Liuyimei Li, Jing Xu, Qiang Wang, Lin Cui, Jiaxin Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and Technology Nanchang330013 China International Institute for Innovation Jiangxi University of Science and Technology Nanchang330013 China Ganjiang Innovation Academy Chinese Academy of Sciences Ganzhou341000 China ARC Research Hub for Computational Particle Technology Department of Chemical and Biological Engineering Monash University ClaytonVIC3800 Australia State Key Laboratory of Multiphase Flow in Power Engineering Xi'An Jiaotong University Xi'an710049 China Delft University of Technology Delft Netherlands

Ionic rare earth ore is a type of featured rare earth ore in China. Its mining process suffers from a long leaching cycle and considerable consumption of leaching agents. Improving mining efficiency requires a sound physical understanding of the leaching process. In this study, the CFD-based numerical model is used to analyze the physical process of leaching through porous media formed by particles. The simulation results indicate that a lower packing porosity and smaller particles packed granular porous medium result in much larger energy dissipation during seepage, and the energy dissipation increases with seepage velocity. It is found that when the seepage velocity increases to a certain high value, the energy dissipation exceeds the value predicted by Darcy's law, which is mainly caused by liquid turbulence. Additionally, the effect of particle shape is examined. The results show that the granular medium composed of prolate particles causes larger energy dissipation than oblate particles, and spherical particles play the least role. This phenomenon may result from the particle shape affecting the area of the frontal contact surface between particles and liquid. The results provide new insights into the fundamental understanding of percolation and seepage behaviors in the ion-adsorption-type rare earth ore leaching process. © 2023 E. Dianyu et al.

关键词： Energy dissipation

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Spatial Heterogeneity of Point Defect Properties in Refractory Multi-Principal Element Alloy with Short-Range Order: A First-Principles Study

SSRN

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SSRN 2022年

作者： Shi, Tan Lyu, Sixin Su, Zhengxiong Wang, Yunpeng Qiu, Xi Sun, Dan Xin, Yong Li, Wenjie Cao, Jiang Peng, Qing Li, Yuanming Lu, Chenyang School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China School of Electronic and Optical Engineering Nanjing University of Science and Technology Nanjing210094 China State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

The short-range order is inherently present in the multi-principal element alloys and has a profound impact on the defect behaviour. The effect of short-range order on vacancy and interstitial formation and migration was studied in body-centered cubic multi-principal element alloy NbZrTi by first-principles calculations. Two short-range order structures created by density functional theory and Monte Carlo method at 500 K and 800 K were compared with the random solid solution structure. Both vacancy and interstitial formation energies increase with the degree of short-range order. Point defect formation energies tend to be higher in region enriched in Nb and lower in region enriched in Zr and Ti. Both vacancies and interstitials prefer to migrate towards Zr,Ti-rich regions and away from Nb-rich regions, suggesting that Zr,Ti-rich region can act as recombination center for point defect annihilation. Compared to the random solid solution, the short-range order increases the spatial heterogeneity of point defect energy landscape. Tuning the degree of short-range order can be a viable strategy to optimize the point defect behaviour to achieve enhanced radiation resistance in multi-principal element alloys. © 2022, The Authors. All rights reserved.

关键词： Monte Carlo methods

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Chemical looping based ammonia production--A promising pathway for production of the noncarbon fuel

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Science Bulletin 2022年第20期67卷 2124-2138,M0004页

作者： Qinghua Lai Tianyi Cai Shik Chi Edman Tsang Xia Chen Runping Ye Zhenghe Xu Morris D.Argyle Dong Ding Yongmei Chen Jianji Wang Armistead G.Russell Ye Wu Jian Liu Maohong Fan College of Engineering and Applied Science University of WyomingLaramie WY 82071USA School of Energy and Power Engineering Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power EngineeringUniversity of Shanghai for Science and TechnologyShanghai 200093China Wolfson Catalysis Department of ChemistryUniversity of OxfordOxford Ox13QRUK College of Chemistry and Chemical Engineering Ocean University of ChinaQingdao 266100China State Key Laboratory of Catalysis Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalian 116023China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Department of Chemical and Materials Engineering University of AlbertaEdmonton Alberta T6G1H9Canada Department of Chemical Engineering Brigham Young UniversityProvo UT 84602USA Idaho National Laboratory Idaho Falls ID83415USA College of Chemistry Beijing University of Chemical TechnologyBejing 100029China School of Chemistry and Environmental Science Henan Normal UniversityXinxiang 453007China School of Civil and Environmental Engineering Georgia Institute of TechnologyAtlanta GA 30332USA MIIT Key Laboratory of Thermal Control of Electronic Equipment School of Power EngineeringNanjing University of Science&TechnologyNanjing 210094China DICP-Surrey Joint Centre for Future Materials Department of Chemical and Process Engineeringand Advanced Technology InstituteUniversity of SurreyGuilford Surrey GU27XH UK

Ammonia, primarily made with Haber-Bosch process developed in 1909 and winning two Nobel prizes, is a promising noncarbon fuel for preventing global warming of 1.5 °C above pre-industrial levels. However,the undesired characteristics of the process, including high carbon footprint, necessitate alternative ammonia synthesis methods, and among them is chemical looping ammonia production(CLAP) that uses nitrogen carrier materials and operates at atmospheric pressure with high product selectivity and energy efficiency. To date, neither a systematic review nor a perspective in nitrogen carriers and CLAP has been reported in the critical area. Thus, this work not only assesses the previous results of CLAP but also provides perspectives towards the future of CLAP. It classifies, characterizes, and holistically analyzes the fundamentally different CLAP pathways and discusses the ways of further improving the CLAP performance with the assistance of plasma technology and artificial intelligence(AI).

关键词： Ammonia synthesis Chemical looping Nitrogen carrier Renewable fuels Energy carrier

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Phenomenon of fog formation and flow characteristics of droplet-vapor-gas mixture in a cooler-condenser

Phenomenon of fog formation and flow characteristics of drop...

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ASME 2019 International Mechanical engineering Congress and Exposition, IMECE 2019

作者： Gu, Hongfang Guo, Qiwei Li, Changsong Zhou, Qing State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an Shaanxi China

ISBN: (纸本)9780791859452

Fog formation occurs in the process of condensation in the presence of non-condensable gas if the bulk temperature is lower than its saturation temperature (supersaturated). The phenomena of fogging is the formation of small condensate particles mixing with the vapor/gas stream, which creates potential problems of the vapor/gas/condensate separation and environmental pollution. Therefore, understanding of fogging mechanism and prevention of fog droplet entrainment are one of technical concerns for design and operation of cooler-condensers in the process industry. This paper presents the experimental study and numerical simulation of shell-side condensation with fog formation using a mixture of steam/non-condensable gas. The experimental data were collected on the two tube bundles (modified plastic tubes and stainless steel tubes). Using a high-speed photograph technique, the phenomenon of fog formation and flow characteristics of vapor/droplet transport were recorded over a wide range of test conditions. The numerical analysis of film and dropwise condensation, fog formation and droplet particle transport were simulated using different tube geometry and material, and flow velocity of air/droplet mixture. Based on simulation results, a new droplet trapping parameter is proposed to assess the optimal parameters of heat exchanger structural and operation conditions. Comparisons show that the numerical analysis results have a good agreement with experimental data and observations. These findings provide fundamental approach to account for the effect of fog formation, film and dropwise condensation, and droplet transport crossflow in cooler-condensers. Copyright © 2019 ASME.

关键词： Drops

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Numerical Investigation of the Thermal Response to Skin Tissue during Laser Lipolysis

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Journal of Thermal Science 2018年第5期27卷 470-478页

作者： CHEN Bin ZHANG Yue LI Dong State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

Laser lipolysis can effectively treat obesity and its associated diseases, such as hypertension, fatty liver, and hyperlipidemia. However, currently available invasive laser lipolysis, which transmits laser to a fiber-optic catheter inserted into the subcutaneous tissue for irradiation through an incision, may cause hematomas, infections, and empyrosis. The current study presents a novel, noninvasive approach for laser lipolysis, which directly irradiates the intact skin surface without an incision and preferentially targets adipose tissue at the near-infrared band. High laser energy is necessary to damage adipocytes; however, this may carbonate and burn the dermis. Therefore, the introduction of skin cooling is essential to avoid unwanted hyperthermal injury and improve the threshold of radiant exposure. In the current study, we investigated a novel noninvasive approach assisted with skin cooling by establishing a homogeneous multi-layer skin model. In this method, light propagation in the skin was simulated by using the Monte Carlo method. Skin cooling was employed before laser irradiation to protect the epidermis from thermal damage, which was treated as a boundary condition based on Newton's law. The numerical results showed that the photons were deposited in the adipose layer more than in the other layers. Laser can effectively destroy adipose tissue at an energy density of >200 J/cm^2 at 1210 nm wavelength, whereas at least 300 J/cm^2 is required at 1064 nm to achieve the same effect. In this experiment, at >5 s pulse width, the selectivity of adipose was not obvious. Moreover, the results indicated that 60 ms R134a or R404a spray can effectively reduce the temperature of the epidermis. R404a exhibited a stronger cooling effect than R134a. Cold air cooling at -10 °C for 10 s could effectively decrease the skin temperature, and deeper cooling could be achieved by cold air cooling compared with cryogen spray cooling.

关键词： laser lipolysis Nd：YAG laser multi-layer skin model skin cooling

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Melt droplet fragmentation behavior during fuel-coolant interaction 18

Melt droplet fragmentation behavior during fuel-coolant inte...

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18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019

作者： Li, Gen Feng, Haobo Wen, Panpan Zhang, Jun Wang, Jinshi Yan, Junjie State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

During a severe accident of nuclear reactor, the fuel-coolant interaction occurs at the relocation stage of corium melt. Such a mode of contact can result in vigorous thermal interactions, intense steam generation and, potentially, steam explosions. The thermal processes, in their turn, largely depend on hydrodynamic behavior. When melt is pouring into coolant pool, the melt jet fragments into large droplets or blobs, named the primary breakup. The droplets or blobs will experience secondary breakup as a result of shock wave at steam explosion. Either the primary or secondary breakup is governed by interface hydrodynamic instabilities. The droplet size distribution, which affects fuel-coolant areas, is important for evaluating heat transfer and debris coolability. In this study, we modelled melt drops deformation and fragmentation using a meshless Lagrangian MPS method. Fragments amount and size distribution were compared under different Weber numbers, and fragments drag coefficient were also analyzed. The results indicate that the melt drops breakup process could be divided into two phases: initial deformation and fragmentation phase governed by flow inertial force and the subsequent fragments coalescence phase under the impact of fluid surface tension. Fragments amount increased in fragmentation phase but decreased in coalescence phase. A large amount of fragments has a normalized diameter of 0.01 - 0.03, but a small amount of large size fragments (d/d0 > 0.04) also appeared as the crescent-shaped melt broke up and small fragments coalesced. The drag coefficient decreased with time during drop deformation period, and then reached a stable value. It has no significant difference among cases with different Weber numbers. © 2019 American Nuclear Society. All rights reserved.

关键词： Hydrodynamics

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Experimental study of auto-ignition of dimethyl ether at low-temperatures and low-pressures 12

Experimental study of auto-ignition of dimethyl ether at low...

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12th Asia-Pacific Conference on Combustion, ASPACC 2019

作者： Huang, Wenlin Sun, Wuchuan Wu, Honghuan Qin, Xiaokang Jiang, Xue Zhang, Yingjia Huang, Zuohua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Dimethyl ether (DME) is a property of alternative fuels to attract due to the special molecular structure in terms of either scientific study or engine application. However, the lack of fundamental data at low pressures and low temperatures impedes to understand thoroughly the chemistry of DME. Ignition delay times of DME/"air" mixtures with various equivalence ratios of 0.5 - 5.0 were measured in a shock tube at pressure of 3.0 atm over temperatures of 625 - 1200 K. Aramco Mech 2.0 was selected to reproduce the experimental observation. In general, the kinetic model remains an uncertainty in predicting the reactivity of DME at equivalence ratios below 2.0 but it tends much better at equivalence ratios over 3.0. Unlike the model predictions, the experimental data did not show obvious NTC behavior for the mixtures with equivalence ratios of 0.5 and 1.0. The selected model almost fails to capture the four-stage ignition feature for the mixtures with equivalence of 2.0 even considering the hot spot caused by pre-ignition energy release. © Asia-Pacific Conference on Combustion, ASPACC *** right reserved.

关键词： Ethers

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Effects of Flue Gas Recirculation on Combustion and Heat Flux Distribution in 660 Mw Double-Reheat Tower-Type Boiler

SSRN

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SSRN 2022年

作者： Deng, Lei Dong, Lingxiao Bai, Yang Wu, Yuhao Liu, Hu Belošević, Srdjan Tomanović, Ivan Che, Defu State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi’an Jiaotong University Xi’an710049 China Guoshen Institute of Technology CHN ENERGY Xi'An710065 China Department of Thermal Engineering and Energy "VINČA" Institute of Nuclear Sciences National Institute of thе Republic of Serbia University of Belgrade Mike Petrovića Alasa 12-14 11351 Vinča PO Box 522 Belgrade11001 Serbia

The ultra-supercritical double-reheat boiler has attracted more attention because of high parameters, low pollution and large capacity. However, there are some difficulties in the development of this technology, such as adjusting the reheat steam temperature. In this study, computational fluid dynamics simulation is used to analyze a 660 MW double-reheat tower-type pulverized coal-fired boiler. The influence of flue gas recirculation (FGR) on heat transfer characteristics and combustion process in the furnace (including heating surfaces in the upper parts of the furnace) are evaluated. The user-defined function approach predicates CO reduction effect on NO x . The results show that the flow at the horizontal section through the centerline of recirculating flus gas nozzles is rotating. The velocity distribution changes into an elliptical rotating flow when FGR ratio is 20%. At higher FGR ratios, the high-temperature area (1565-1700 K) shrinks and both the NO x concentration at the low-temperature superheater outlet and oxygen concentration in the furnace descend. Oxygen concentration at low-temperature superheater outlet first increases and then decreases. In the main combustion zone, the heat flux peak of water-cooled wall is about 330 kW m -2 . As FGR ratio increases from 0% to 20%, the rate of water-cooled wall heat absorption to total boiler decreases by 3.50%. This rate for reheater and superheater increases by 2.53% and 2.13%, respectively. © 2022, The Authors. All rights reserved.

关键词： Temperature

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Study on the heat and mass transfer characteristics of wet air in metal foam in the space station environment

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Applied Thermal engineering 2025年 277卷

作者： Zhu, Guowei Zhang, Liang Xia, Yujuan Zhou, Hantao School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai200093 China Key Laboratory of Multiphase Flow and Heat Transfer in Shanghai Power Engineering University of Shanghai for Science and Technology Shanghai200093 China China National Institute of Standardization Beijing100191 China

This paper has developed a novel dehumidification device for space station environment, which uses foam copper as the core, with a Stirling refrigerator providing cooling, heat pipes assisting in heat conduction and a siphon water guidance system employed to remove condensate. Experiments on dehumidifying wet air within the foam copper were then carried out under simulated microgravity dehumidification conditions. The experimental conditions included different inlet air temperatures, humidities, air velocities, and cold end temperatures of the Stirling refrigerator. The experimental research indicates that as the inlet air temperature rises from 20 °C to 30 °C, the mass transfer coefficient increases by 57.06 %, and the sensible heat coefficient rises by 10.62 %. When the air velocity increases from 0.4 m·s−1 to 1.4 m·s−1, these two coefficients increase by 111.79 % and 170.83 %, respectively. In contrast, increasing the relative humidity from 50 % to 80 % results in a 34.09 % decrease in the sensible heat coefficient, while the mass transfer coefficient increases by 11.4 %. When the cold-end temperature rises from 8 °C to 13 °C, the sensible heat transfer and mass transfer coefficients increase by 9.63 % and 4.06 %, respectively. Based on this, a sensitivity analysis was conducted using the experimental data, and heat and mass transfer correlations were fitted. The mean standard deviations of the heat and mass transfer correlations are 3.74 % and 6.30 %, respectively, indicating a high degree of fitting accuracy. This work provides a new humidity control solution for future space station thermal management systems. © 2025

关键词： Osmosis

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Activated Overall Water Splitting Over a Ni-Fe Layered Double Hydroxide Electrocatalyst by V Doping and Sulfuration

SSRN

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SSRN 2023年

作者： Wu, Wentong Peng, Lei Min, Boya Huang, Jie Liu, Saiya Lu, Kejian Lu, Shijian Jing, Dengwei Zheng, Mingsheng 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 No. 8 Oil Production Plant of PetroChina Changqing Oilfield Company Shaanxi Xi’an710016 China Carbon Neutrality Institute Jiangsu Key Laboratory of Coal-based Greenhouse Gas Control and Utilization China University of Mining and Technology Jiangsu Xuzhou221008 China Gree Altairnano New Energy Inc Zhuhai519040 China School of Chemistry and Biological Engineering University of Science and Technology Beijing Beijing100083 China

Ni-Fe layered double hydroxide (NiFe-LDH) is regarded as one of the promising non-noble electrocatalyst. However, the limited number of active sites and poor electrical conductivity impede its further development. Herein, we report the synthesis of a Ni foam supported NiFe-LDH electrocatalyst modified by V doping and vulcanization (NiFeV-S/NF). This modification endows the catalyst excellent property toward hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and overall water splitting. Only 211 mV and 127 mV of the overpotentials are required to achieve the current density of 10 mA cm-2 for OER and HER in 1 M KOH electrolyte, respectively. Particularly, the prepared NiFeV-S/NF could serve as a bifunctional electrocatalyst for overall water splitting, with a cell voltage of 1.573 V to reach a current density of 10 mA cm-2. In principle, the success relies on the intrinsically improved conductivity, increased specific surface area and the number of active sites, as well as the heterojunction structure of the catalyst. Therefore, this work provides a new idea for the design and preparation of more efficient noble-metal-free bifunctional electrocatalysts. © 2023, The Authors. All rights reserved.

关键词： Electrocatalysts

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