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Improved filtered mesoscale interphase heat transfer model

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

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MHD Simulations Preliminarily Predict The Habitability and Radio Emission of TRAPPIST-1e

arXiv

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arXiv 2025年

作者： Wang, BoRui Ye, ShengYi Varela, J. Luo, XinYi Department of Earth and Space Sciences Southern University of Science and Technology Shenzhen518055 China Institute for Fusion Studies University of Texas AustinTX78712 United States State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China

Context. As the closest Earth-like exoplanet within the habitable zone of the M-dwarf star TRAPPIST-1, TRAPPIST-1e exhibits a magnetic field topology that is dependent on space weather conditions. Variations in these conditions influence its habitability and contribute to its radio emissions. Aims. Our objective is to analyze the response of different terrestrial magnetosphere structures of TRAPPIST-1e to various space weather conditions, including events analogous to coronal mass ejections (CMEs). We assess its habitability by computing the magnetopause standoff distance and predict the resulting radio emissions using scaling laws. This study provides some priors for future radio observations. Methods. We perform three-dimensional magnetohydrodynamic (MHD) simulations of the TRAPPIST-1e system using the PLUTO code in spherical coordinates. Assuming TRAPPIST-1e possesses various Earth-like magnetospheres, we analyze the impact of four distinct space weather conditions on its magnetospheric topology. The space weather parameters range from sub-Alfvénic conditions to CMEs. Results. Our analysis indicates that the predicted habitability and radio emission of TRAPPIST-1e strongly depend on the planet’s magnetic field intensity and magnetic axis inclination. Within sub-Alfvénic, super-Alfvénic, and transitional stellar wind regimes, the radio emission intensity positively correlates with both planetary magnetic field strength and axial tilt, while planetary habitability, quantified by the magnetopause standoff distance, shows a positive correlation with magnetic field strength and a negative correlation with magnetic axis tilt. If TRAPPIST-1e possesses a magnetic field strength and axial tilt comparable to Earth’s (∼ 0.32G and ∼ 23.5◦). its magnetosphere can effectively shield the planetary surface from stellar wind erosion even under severe space weather conditions (e.g., CME events). However, for larger axial tilts (∼ 45◦), a stronger planetary magnetic field would be

关键词： Plasma magnetohydrodynamic waves

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Modeling study on anisotropic heat conduction of PEMFC GDLs facilitated by Micro-CT

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International Journal of Heat and Mass Transfer 2025年 250卷

作者： Hang Liu Xuecheng Lv Heng Huang Yang Li Deqi Li Zhifu Zhou Wei-Tao Wu Lei Wei Yubai Li Yongchen Song Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education Dalian University of Technology Dalian 116024 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 China School of Mechanical Engineering Nanjing University of Science and Technology Nanjing 210094 China Department of Mechanical and Energy Engineering Southern University of Science and Technology Shenzhen 518055 China

The gas diffusion layer (GDL) serves as a pivotal component governing heat transfer in proton exchange membrane fuel cells (PEMFCs). Excessive heat accumulation within the catalyst layer may lead to irreversible degradation of electrochemical activity due to accelerated catalyst sintering and carbon support corrosion. Building upon multi-modal characterization integrating micro-computed tomography (Micro-CT) and scanning electron microscopy (SEM) of GDLs, this investigation systematically deciphers the interdependent relationships between fiber architecture, sphere network topology, and compression-mediated morphological evolution through advanced computational analytics and finite element modeling. The quantified synergy elucidates microstructure-property linkages governing anisotropic thermal and gas transport phenomena. The computational findings reveal pronounced anisotropic thermal conduction characteristics within GDLs, demonstrating significantly inferior thermal transport capabilities in the through-plane (TP) direction compared to the in-plane (IP) direction. Reduced fiber length diminishes multi-directional heat dissipation, whereas GDL thickening enhances multi-directional thermal transport efficiency. Quantitative analysis demonstrates a 23-fold higher susceptibility of effective thermal conductivity (ETC) to compression ratio compared to thickness variation, conclusively establishing microstructural heterogeneity as the primary determinant of anisotropic thermal transport. Spatially resolved thermal flux mapping reveals strong geometric coupling with porosity gradients. These multiscale findings provide new design paradigms for optimizing GDL architectures through targeted manipulation of fiber-sphere coupling mechanics.

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Evaluation of R513A as an environmentally friendly alternative to R134a in spray cooling for laser surgery: Heat transfer performance and optimization

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International Journal of Thermal Sciences 2025年 215卷

作者： Zhi-Zhong He Xiang-Wei Lin Chen-Xi Li Chen Kong Lin-Xin Shen Zhi-Fu Zhou State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi China School of Future Technology Xi'an Jiaotong University Xi'an 710049 Shaanxi China Xi'an Jiaotong University Health Science Center Xi'an 710049 Shaanxi China

Spray cooling plays a pivotal role in mitigating thermal injuries to the epidermis during laser surgery. However, the widespread use of R134a, a refrigerant with a high global warming potential (GWP) of 1300, poses significant environmental concerns. In this study, R513A, a more environmental-friendly cryogen with a GWP of 573, is used to investigate the feasibility of replacing R134a and the effects of spray height, spurt duration, nozzle orifice diameter, and spray pressure on R513A spray cooling through a self-built open-loop spray system. Experimental results demonstrate that R513A exhibits superior cooling performance, achieving a minimum surface temperature ( T min ) 12 °C lower and a maximum heat flux ( q max ) 27.5 % higher than R134a. Additionally, R513A offers a broader optimal spray height range (30–50 mm) in which T min is 4 °C and 13 °C lower than those at 20 mm and 10 mm, respectively. q max in this range is 10 % and 16 % higher than those at 20 mm and 10 mm, respectively. While extending the spurt duration consumes more cryogen and prolongs the liquid film lifetime, the differences in T min and q max are less than 4 °C and 10 kW/m 2 . With the nozzle orifice increasing from 0.6 mm to 1.0 mm, T min remains approximately −42 °C but q max gradually increases by 6 kW/m 2 . Macroscopic analysis reveals that higher spray pressure induces a more dispersive spray, though this does not significantly improve cooling efficiency. To advance the understanding of R513A spray cooling dynamics, a dimensionless correlation was developed to predict the dynamic heat transfer coefficient across diverse conditions. This study not only highlights the potential of R513A as a sustainable alternative but also provides critical insights into optimizing spray cooling parameters for enhanced thermal management in laser surgery.

关键词： Chilling

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Tow steps biohydrogen production: biomass pretreatment and fermentation

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AIP Conference Proceedings 2010年第1期1207卷 1060-1065页

作者： C. Ma H. H. Yang L. J. Guo aState Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University China bState Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University China cState Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University China

This paper investigated the pretreatment of cornstalk and integrated dark‐photo fermentation for hydrogen production. Five parameters of the pretreatment experiments, including NaOH concentration, temperature, residence time, and dosage of cellulase and xylanase, were optimized through the L25 (5≙5) orthogonal test. The optimal NaOH concentration, temperature, residence time, and dosage of cellulase and xylanase were 0.5wt%, 115 °C, 3 h, 0.08g/g cornstalk, 0.08g/g cornstalk, respectively. Under the optimal conditions, 0.31g glucose/g cornstalk was obtained. The two‐step fermentation consisted of dark fermentation and photo fermentation. The pretreated cornstalk was used as the substrate for dark fermentation, with cow dung as the inoculum. Then the effluents of dark fermentation were employed as the substrate for photo fermentation by photosynthetic bacteria. H2 yield of dark fermentation was 116.7 mL/g cornstalk, with H2 concentration of 41%. After photo fermentation, the total H2 yield increased to 294 mL/g cornstalk.

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Impacts of different diameter combinations on the temperature of a crude oil pipeline when colocating with a products pipeline

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中国高等学校学术文摘·能源与动力工程 2010年第2期4卷 192-197页

作者： Bo YU Yue SHI Xin LIU Jinjun ZHANG Jinjia WEI Beijing Key Laboratory of Urban Oil and Gas Distribution Technology China University of Petroleum BeijingBeijing 102249China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong UniversityXi'an 710049China

In order to show the effects of different diameter combinations on crude oil temperature when a crude oil pipeline and a products pipeline are laid in one trench, four typical diameter combinations are selected to conduct numerical simulation. After a series of calculations, the minimum mean temperature difference and the maximum temperature difference of the crude oil along the pipelines are obtained. In real pipeline constructions, the effects of other diameter combinations on crude oil temperature can be predicted by the method of linear interpolation to calculate results of the four diameter combinations obtained in this study.

关键词： technology of laying two pipelines in one trench diameter combinations crude oil temperature pipeline interval

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Research and development of helium-xenon Brayton cycle technology:A review

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National Science Open 2024年第6期3卷 188-218页

作者： Weixiong Chen Meihui Song Yiran Qian Hongxing Yu Junjie Yan State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710049China Key Laboratory of Nuclear Reactor System Design Technology Nuclear Power Institute of ChinaChengdu 610200China

Helium-xenon Brayton cycle systems have significant potential as the energy conversion system for small-scale reactors in remote land,deep-sea,and space applications due to a range of advantages,including high cycle efficiency,compact system structures,and chemical *** objective of this review is to provide a comprehensive understanding of the helium-xenon Brayton cycle system based on the projects and ***,the basic information and development history are introduced,and a series of typical designs are ***,the system configurations,cycle parameter analysis and optimization are ***,the key components are classified,such as turbine,compressor,and heat ***,the dynamic processes and control strategies are introduced in different ***,the deficiency and prospect of current research are *** review covers the representative helium-xenon Brayton cycle systems,which could provide a reference for promoting the development of energy conversion systems.

关键词： helium-xenon Brayton cycle cycle analysis heat exchanger dynamic research

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Study of Unforced Unsteadiness in Centrifugal Pump at Partial flow Rates

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Journal of Thermal Science 2021年第1期30卷 88-99页

作者： YANG Jun XIE Tian LIU Xiaohua SI Qiaorui LIU Jun School of Energy and Power Engineering University of Shanghai for Science and TechnologyShanghai 200093China Key Laboratory of Fluid and Power Machinery(Xihua University) Ministry of EducationChengdu 610039China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering Shanghai 200093China School of Aeronautics and Astronautics Shanghai Jiao Tong UniversityShanghai 200240China Research Center of Fluid Machinery Engineering and Technology Jiangsu UniversityZhenjiang 212013China

In order to explore the unforced unsteadiness of centrifugal pumps,a 2-D frequency domain imaging display technology was used to study the development of these unsteady flow structures at partial flow *** results showed that,the unsteady flow field was not only affected by rotor and stator interaction,but also appeared an unforced unsteadiness with fundamental frequency of St≈0.23 around the impeller throat ***,as the flow rates decreased,this unsteady flow structure gradually weakened and *** the flow rate was reduced to 0.6 times of design flow rate,another two unforced unsteady flow structures with characteristic frequencies of St≈0.0714 and St≈0.12 began to appear in the same ***,with the operating condition smaller than design flow rate,the internal flow became more and more *** addition to the forced unsteadiness,the unforced unsteadiness which is not connected with the blade passage frequency became more and more obvious.

关键词： centrifugal pumps partial flow conditions pressure pulsations unforced unsteadiness 2-D frequency domain visualization method

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Phase identification by a novel needle-contact capacitance probe in gas-liquid two-phase flows

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Nuclear Science and Techniques 2010年第5期21卷 316-320页

作者： HUANG Shanfang LU Jun ZHANG Bingdong WANG Dong Department of Engineering Physics Tsinghua University Beijing 100084 China State Key Laboratory of Multiphase Flow in Power Engineering Xi 'an Jiaotong University Xi'an 710049 China Beijing Aerospace Institute for Metrology and Measurement Technology Beijing 100076 China

In this paper,we propose a novel probe to identify phases in any two-phase flows where one phase is conductive and the other *** can further obtain many parameters such as void fraction,bubble velocity,and interfacial area *** with the traditional probe,the novel probe has unique advantages that it is less dependent on water conductance or distance between the electrodes,and that the amplitude is bigger between high and low *** analyses showed that the measurement error became higher when water conductance decreases or distance increases,which is consistent with the theoretical *** results showed that the output signal kept constant with salt content of 0-5% and electrode distance of 0-30 mm in tap *** level difference was up to 6.4 V,resulting in identifying two phases *** traces of phase identification were completely consistent with the flow structures.

关键词：气液两相流探头接触式鉴定一阶电导电极水电导率气泡速度

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CO_2 Leakage Identification in Geosequestration Based on Real Time Correlation Analysis Between Atmospheric O_2 and CO_2

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Chinese Journal of Chemical engineering 2014年第6期22卷 634-642页

作者：马登龙邓建强张早校 State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University School of Chemical Engineering and Technology Xi’an Jiaotong University

The paper describes a method for monitoring CO2 leakage in geological carbon dioxide sequestration. A real time monitoring parameter, apparent leakage flux(ALF), is presented to monitor abnormal CO2 leakage, which can be calculated by atmospheric CO2 and O2 data. The computation shows that all ALF values are close to zero-line without the leakage. With a step change or linear perturbation of concentration to the initial CO2 concentration data with no leakage, ALF will deviate from background line. Perturbation tests prove that ALF method is sensitive to linear perturbation but insensitive to step change of concentration. An improved method is proposed based on real time analysis of surplus CO2 concentration in least square regression process, called apparent leakage flux from surplus analysis(ALFs), which is sensitive to both step perturbation and linear perturbations of concentration. ALF is capable of detecting concentration increase when the leakage occurs while ALFs is useful in all periods of leakage. Both ALF and ALFs are potential approaches to monitor CO2 leakage in geosequestration project.

关键词： CO2 monitor carbon storage gas leakage O2/CO2 exchange correlation analyysis

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