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Chinese Journal of Aeronautics 2025年第5期 82-93页

作者： Lihan FEI Wu ZHU Yuyuan ZHANG Peng ZHANG Zuohua HUANG Chenglong TANG State Key Laboratory of Multiphase Flow and Power Engineering Xi'an Jiaotong University Department of Mechanical Engineering City University of Hong Kong

The evaporation behaviors are crucial for the flame location estimation in liquid rocketengines. This work, for the first time, experimentally reports the sub-millimeter droplet evaporationcharacteristics of the corrosive dinitrogen tetroxide（NTO, one prevailing hypergolic oxidizer） athigh ambient pressure up to 4.5 MPa. An in-house corrosion-resistant droplet generator is usedto generate isolated flying droplets of sub-millimeter size, which are then exposed in a gas environ-ment with temperatures between 1 010 K and 1 210 K and pressures in the range between 2.0 MPaand 4.5 MPa, provided by an optical rapid compression machine. Parallelly, a theoretical modelconsidering both the droplet ambient convection and the NTO dissociation is developed. Resultsindicate that firstly, the present theoretical model that considers the transient droplet-ambient con-vection as well as the temperature and pressure dependent rate of dissociation shows good agree-ment with the experimentally observed droplet lifetime. In addition, the flying droplets velocityregress gradually due to momentum exchange with the ambient, which is more prominent at higherpressure. The evaporation caused droplet size reduction is consistent with the classical D2-law pre-diction, in the present temperature and pressure range. Finally, higher temperature and pressureaccelerate the evaporation and an empirical correlation for the temperature and pressure dependentevaporation rate constant is proposed, which shows good agreement with experiment and simula-tion results.

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Experimental studies of ash film fractions based on measurement of cenospheres geometry in pulverized coal combustion

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Frontiers in Energy 2021年第1期15卷 91-98页

作者： Siqi LIU Yanqing NIU Liping WEN Yang LIANG Bokang YAN Denghui WANG Shi'en HUI State Key Laboratory of Multiphase Flow in Power Engineering Department of Thermal EngineeringSchool of Energy and Power EngineeringXi'an Jiaotong UniversityXi'an 710049China

In pulverized coal particle combustion, part of the ash forms the ash film and exerts an inhibitory influence on combustion by impeding the diffusion of oxygen to the encapsulated char core, while part of the ash diffuses toward the char core. Despite the considerable ash effects on combustion, the fraction of ash film still remains unclear. However, the research of the properties of cenospheres can be an appropriate choice for the fraction determination, being aware that the formation of cenospheres is based on the model of coal particles with the visco-plastic ash film and a solid core. The fraction of ash film X is the ratio of the measuring mass of ash film and the total ash in coal particle. In this paper, the Huangling bituminous coal with different sizes was burnt in a drop-tube furnace at 1273, 1473, and 1673 K with air as oxidizer. A scanning electron microscope (SEM) and cross-section analysis have been used to study the geometry of the collected cenospheres and the effects of combustion parameters on the fraction of ash film. The results show that the ash film fraction increases with increasing temperature and carbon conversion ratio but decreases with larger sizes of coal particles. The high fraction of ash film provides a reasonable explanation for the extinction event at the late burnout stage. The varied values of ash film fractions under different conditions during the dynamic combustion process are necessary for further development of kinetic models.

关键词： ash film fraction cenospheres coal combustion fly ash

Uncertainty Analysis of FLiNaK Thermophysical Properties on Convective Heat Transfer Characteristics in Circular Tube

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SSRN 2024年

作者： Li, Haoyang Ding, Ming Guo, Zehua Heilongjiang Provincial Key Laboratory of Nuclear Power System & Equipment Harbin Engineering University Harbin150001 China State Key Laboratory of Multiphase Flow in Power Engineering Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology School of Nuclear Science and Technology Xi’an Jiaotong University Xi’an710049 China

Molten salts have attracted a spate of quantity of interest in energy and chemistry fields due to their large volumetric capacity, and thermodynamic stability at elevated temperatures. However, on account of immature technology and measurement methods, the physical properties of molten salts, such as dynamic viscosity, thermal conductivity, specific heat capacity and density, have large uncertainties, which will be transported with CFD simulation equations and experimental processes. While present investigations normally focus on thermal-hydraulic characteristics, disregarding the impact of uncertainty on reactor safety. Thus, this paper firstly performs a numerical simulation to investigate the thermal-hydraulic performance of FLiNaK (LiF-NaF-KF, 46.5–11.5–42 mol%) in a horizontal tube using a computational fluid dynamic (CFD) tool, STAR-CCM+, and validates the applicability of classic correlations for molten salt. Based on this, an uncertainty analysis methodology, polynomial chaos expansion (PCE) is carried out to analyze the uncertainty that contributes to the heat transfer characteristic. Three primary physical properties of molten salt are considered as the input parameter, tensor product quadrature nodes are employed in this work to calculate the representative sample points to alleviate the computational expense. The contributions of each parameter to heat transfer are also analyzed by the sobol composition method. Finally, deviations in the experimental post-processing (compared with classic correlations) caused by discrepancies in the selected properties from the actual properties due to uncertainty are also taken into account. The result shows the thermal-hydraulic performance can be nicely modeled and simulated results are in good agreement with widely used correlations. Meanwhile, the consequences of uncertainty analysis suggest that the polynomial chaos expansion methodology is robust and neoteric for molten salt analysis. © 2024, The Authors. All righ

关键词： Uncertainty analysis

Improved filtered mesoscale interphase heat transfer model

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Particuology 2021年第4期19卷 176-186页

作者： Yu Li Yaxiong Yu Chi Zhang Zheqing Huang Qiang Zhou School of Chemical Engineering and Technology Xi’an Jiao Tong UniversityXi’an 710049China AVIC Xi’an Flight Automatic Control Research Institute Xi’an 710049China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiao Tong UniversityXi’an 710049China

Mesoscale structures that form in gas-solid flows considerably affect interphase heat transfer.A filtered interphase heat transfer model accounts for the effects of unresolved mesoscale structures is required in coarse-grid *** the literature,researchers obtain the filtered interphase heat transfer coefficient using a correction(Q)to the microscopic interphase heat transfer *** models are based on filtered data in the range 01 is *** percentage can reach approximately 20%when the dimensionless filter size is smaller than 1.028(66.7×the particle diameter).We proposed an improved filtered interphase heat transfer model by considering the data in the range Q<0 and Q>*** evaluated the predictive power of our model in an a priori *** model has much better performance than other models when the dimensionless filter size△<8.222.

关键词： Gas-solid flows Two-fluid model Interphase heat transfer Filtered model Mesoscale

Boosting photocatalytic water vapor splitting by the integration of porous g-C_(3)N_(4)and carbonized melamine foam

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Science China Materials 2024年第9期67卷 2957-2964页

作者： Shujian Wang Dongjie Liu Chunyang Zhang Jie Huang Shidong Zhao Kejian Lu Biao Wang Hao Peng Yitao Si Maochang Liu International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power EngineeringXi’an Jiaotong UniversityXi’an710049China School of Chemistry and Chemical Engineering Southeast UniversityNanjing211189China Suzhou Academy of Xi’an Jiaotong University Suzhou215123China Gree Altairnano New Energy Inc. Zhuhai519040China

We report a photothermally-induced liquid-solid/gas-solid-decoupling photocatalytic water-splitting system,where a carbonized melamine foam(CMF)and a porous g-C_(3)N_(4)(PCN)serve as the photothermal substrate and model photocatalyst,***,liquid water is transformed into the gaseous phase over the CMF due to the photothermal effect,and the generated vapor can be split into hydrogen by PCN via the *** unique biphasic photocatalytic system exhibits a high hydrogen production rate of 368.1µmol h^(-1),which is 2.4 and 25.6 times larger than those of the traditional triphasic PCN system(151.7µmol h^(-1))and g-C_(3)N_(4)(CN)system(14.4µmol h^(-1)),*** improved photocatalytic performance is mainly attributed to the optimized energy and mass transfer at the gas-liquid-solid reaction interface,where gas products are rapidly desorbed in the photocatalytic *** work provides a novel strategy to enhance the photocatalytic performance from the perspectives of energy and mass flow.

关键词： photocatalytic photothermal mass transfer g-C_(3)N_(4) gas-solid

Morphology Construction of Molybdenum Doped Nickel Sulfide Electrocatalyst Induced by Nh4f to Promote Hydrogen Evolution Reaction

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SSRN 2024年

作者： Zhang, Baikai Li, Xiaohui Liu, Maochang Huadian Electric Power Research Institute Co. Ltd. Zhejiang310030 China School of Eenergy and Power Engineering Xi’an Jiaotong University Shaanxi 710049 China State Key Laboratory of Multiphase Flow in Power Engineering China

Here, by varying the mass of NH4F throughout the hydrothermal process, Mo-doped nickel-based sulfide catalysts (Mo-NiS-Fx) with various morphologies (prisms, rods, flakes, and cones) were created. Among these, the flaky Mo-NiS-F1.2 exhibited exceptional performance towards electrochemical hydrogen evolution reaction, surpassing most similar catalysts with an overpotential of 79 mV at 10 mA cm-2 and a Tafel slope of 49.8 mV dec-1. Significantly, Mo-NiS-F1.2 maintained its high activity for hydrogen evolution over 60 h at 10 mA cm-2, making it suitable for widespread commercial application. This work demonstrates the potential of morphology manipulation to enhance catalytic activity. © 2024, The Authors. All rights reserved.

关键词： Hydrogen

Sub- and Supercritical Water Flooding for Enhanced Oil Recovery in High Water Cut Heavy Oil Reservoirs: An Experimental Study

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SSRN 2024年

作者： Miao, Yan Zhao, Qiuyang Huang, Zujie Zhao, keyu Zhao, Hao Guo, Liejin Wang, Yechun State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Xinjin Weihua Institute of Clean Energy Research Foshan528216 China

High water cut poses a formidable challenge for heavy oil reservoirs, necessitating a strategy to enhance oil recovery. This study introduces a green-efficient approach - Supercritical Water Flooding (SCWF), suitable for sandstone heavy oil reservoirs with high water cut, compared to conventional subcritical water flooding and steam flooding. A novel experimental system (450°C,30MPa) was established to conduct SCWF experiments for heavy oil from Shengli Oilfield. The results showed that SCWF at 400°C and 25MPa had the recovery factor of 96.27% and the viscosity reduction rate of 61.6% for GD heavy oil. The dynamic process of SCWF is divided into three stages: pressure rising drainage stage, heating and depressurization stage, and miscible flooding stage. Analysis indicates that the high diffusivity, solubility and reactivity of supercritical water make thermal fluid breakthrough, miscible flooding and aquathermolysis reactions become the key mechanisms for high oil recovery and in situ upgrading of SCWF for high water cut heavy oil reservoirs. © 2024, The Authors. All rights reserved.

关键词： Crude oil

Alkaline Pulping Catalyzed Ordered Conversion of Bark in Supercritical Water

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SSRN 2023年

作者： Ge, Hui Huang, Yong Liu, Zhaozheng Liu, Fan Chen, Yu-Nan Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University No.28 Xianning West Road Xi’an710049 China

The hydrophilicity of lignocellulosic biomass hinders the application of a high concentration slurry for supercritical water gasification, thereby reducing the efficiency of gasification and energy self-sufficiency. A pretreatment method of alkaline pulping with KOH and NaOH was proposed considering initial pressure to prepare high concentration slurry. In this study, bark as lignocellulosic biomass specimen, whose 30wt% and 40wt% slurries, with favorable rheology and stability, was prepared via alkaline pulping successfully. The most economical conditions were 180 °C and 24% KOH addition. The bark macromolecules were restructured due to the hydrolysis of cellulose and lignin by breaking down the hydrogen bond and ether bond with trivial hydrocarbon matrix loss. The scattered crystal growth being created and a reduction of hydrophilic groups facilitated the uniform premixing of bark and water, which is improved by a stable charge system furtherly. Additionally, metal ions could be deposited onto the bark surface during alkaline pulping. The chemical modification leading by alkaline pulping achieved the premixing of feedstock and water to form bark slurry. The conversion barrier was decreased to fulfill the ordered conversion. Consequently, the commendable catalytic effect of 95.66% gasification efficiency was displayed for 40wt% bark slurry with trivial coke yield. The functional groups of organic matter in the slurry were significantly converted into the gas phase, and lattice oxygen was produced in the solid product. The maximum alkali recovery of 80% was achieved at 580 °C. The successful completion of this research affirms the dominance of the pulping-alkali recovery-gasification method for expanding the application of SCWG of lignocellulosic biomass in large engineering projects. © 2023, The Authors. All rights reserved.

关键词： Chemical modification

Simulation Study on the Dynamic Characteristics of Natural Circulation Coupled Phase Change Material for Equal Height Difference Passive Containment Cooling System

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SSRN 2024年

作者： Chen, Weixiong Huang, Yufan Wang, Han Yang, Xiaohu Li, Shaodan Zhao, Quanbin Chong, Daotong State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Wuhan Second Ship Design and Research Institute Wuhan430205 China

The passive containment cooling system (PCCS) plays a significant role in ensuring the safety of nuclear power plants. To further reduce peak pressure in the containment during a loss of coolant accident (LOCA), phase change materials (PCMs) are utilized to improve the system’s cooling effectiveness. The dynamic simulation model of PCCS has been developed using Apros software. This article focuses on examining the system’s dynamic characteristics related to various tube startup methods and comparatively analyzing the impact of different PCM thicknesses on heat transfer capacity. The results indicate that post-accident, PCM significantly suppresses peak pressure in the containment. Under the full tube startup method with 4 mm PCM, the peak pressure decreases to 1.75 MPa, whereas under the empty tube startup method, it is reduced to 1.69 MPa. With natural circulation empty tube startup method, PCM can reduce pressure change intensity in the containment but negatively affects natural circulation heat transfer. Although the full tube startup method underperforms the empty tube startup method on suppressing peak pressure, PCM can positively affect natural circulation heat transfer in the early stages of the accident. Empty tube startup offers the advantages of higher heat transfer capacity and lighter weight, making it the optimal choice for ocean nuclear platforms. Additionally, the higher peak power of PCM heat transfer under the empty tube startup method indicates that system can withstand larger thermal shocks. © 2024, The Authors. All rights reserved.

关键词： Thermoelectric equipment

Pilot-Scale Photoreforming of Hydrolyzed Polylactic Acid Waste to High-Value Chemicals and H2 via Atomic Ru Integration

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Advanced Energy Materials 2025年第0期

作者： Liu, Feng Zhang, Chunyang Lu, Kejian Yan, Xueli Wang, Yi Jing, Dengwei Guo, Liejin 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

Photoreforming of polylactic acid (PLA) waste into valuable chemicals offers a promising approach for environmental protection and waste valorization, yet faces challenges of low yields and harsh conditions. Herein, a Cd0.5Zn0.5S nanotwin catalyst decorated with Ru single atoms and clusters is reported, enabling selective photoreforming of PLA into pyruvic acid (PA) and H2. It is demonstrated that Ru single atoms favor PA formation via hydroxyl dissociation, while the further incorporation of Ru clusters serve as active sites for H2 production. This synergistic effect significantly enhances photocatalytic performance, achieving 96.8% PA selectivity and efficient H2 production with a record-breaking apparent quantum efficiency of 83.7% at 400 nm. This approach is scalable for outdoor processes, utilizing direct 1 m2 sunlight irradiation to deliver ≈1191 mL h−1 of H2 and 47.27 mmol h−1 of PA from PLA waste, paving a viable pathway for large-scale simultaneous production of high-value chemicals and H2. © 2025 Wiley-VCH GmbH.

关键词： Photolysis