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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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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： He, Zhi-Zhong Lin, Xiang-Wei Li, Chen-Xi Kong, Chen Shen, Lin-Xin Zhou, Zhi-Fu State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China School of Future Technology Xi'an Jiaotong University Shaanxi Xi'an710049 China Xi'an Jiaotong University Health Science Center Shaanxi Xi'an710049 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 (Tmin) 12 °C lower and a maximum heat flux (qmax) 27.5 % higher than R134a. Additionally, R513A offers a broader optimal spray height range (30–50 mm) in which Tmin is 4 °C and 13 °C lower than those at 20 mm and 10 mm, respectively. qmax 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 Tmin and qmax are less than 4 °C and 10 kW/m2. With the nozzle orifice increasing from 0.6 mm to 1.0 mm, Tmin remains approximately −42 °C but qmax gradually increases by 6 kW/m2. 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. © 2025 Elsevier Masson SAS

关键词： Chilling

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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

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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

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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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Study on startup characteristic of a supercritical carbon dioxide Brayton cycle coupled with heat pipe cooled reactor 20

Study on startup characteristic of a supercritical carbon di...

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20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023

作者： Wang, Zheng Zhang, Minghui Xu, Shihao Gou, Junli Shan, Jianqiang State Key Laboratory of Multiphase Flow in Power Engineering School of Nuclear Science and Technology Xi'an Jiaotong University Shaanxi Xi'an China

ISBN: (纸本)9780894487934

Nuclear energy is a viable choice for Unmanned Undersea Vehicles (UUVs) due to its high density and long operation life. However, traditional PWRs aren't suited to underwater working environments. To provide a safe and reliable power source for UUV, a new nuclear power plant coupled with the supercritical CO2 Brayton cycle and heat pipe cooled reactor is proposed. This provides the advantages of high reliability, high safety and high expansion ability. In this work, a simulation code for the new nuclear power plant is developed, which includes a reactor kinetics model, a core heat conduction model, a two-dimensional heat pipe network model, and a closeCO2 Brayton cycle model. In order to verify the accuracy of the model, the date of the experiment is compared with the model. And the design value of the new nuclear power plant has been modeled by this code. Meanwhile, the control strategies for start-up of the new nuclear power plant are proposed, including core startup, heat pipe startup and supercritical carbon dioxide Brayton loop startup. By utilizing the control strategies, the code has researched the operational characteristics of the start-up of heat pipe-cooled reactors. The development of this code provides a reference for the new nuclear power plant. © 2023 Proceedings of the 20th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2023. All rights reserved.

关键词： Brayton cycle

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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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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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Study on the heat transfer of cross flow in vertical upward tubes

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Journal of Zhejiang University-Science A(Applied Physics & engineering) 2005年第10期6卷 1128-1131页

作者：胡志华杨燕华周芳德 School of Mechanical Engineering Shanghai Jiao Tong University Shanghai 200030 China State Key Laboratory of Multiphase Flow Xi’an Jiaotong Univeristy Xi’an 710049 China

A special device was designed to measure temperature difference in this study of heat transfer of water and oil cross flow inside vertical upward tubes. A new heat transfer correlation was obtained for cross flow. The experimental results showed that the dependence of heat transfer on Reynolds is much smaller in a narrow space than that in a wide space. It was found that the heat transfer correlation of cross flow in a narrow space is obviously different from that in a wide space, and that the heat transfer correlation obtained in a wide space may not be applicable to the cross-flow heat transfer in a narrow space. Further, the single-phase heat transfer capability of water cross flow was compared with that of oil cross flow. The experimental results showed that the average heat transfer coefficient of water is about 2～3 times that ofoil when they have the same superficial velocity.

关键词： Heat transfer Cross flow Upward

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Novel Matching Strategy for the Coupling of Heat Flux in Furnace Side and CO_(2)Temperature in Tube Side to Control the Cooling Wall Temperatures

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Journal of Thermal Science 2021年第4期30卷 1251-1267页

作者： LIU Chao MIAO Zheng XU Jinliang XU Zeyu LI Mingjia Beijing Key Laboratory of Multiphase Flow and Heat Transfer for Low Grade Energy Utilization North China Electric Power UniversityBeijing 102206China Key Laboratory of Power Station Energy Transfer Conversion and System North China Electric Power UniversityMinistry of EducationBeijing 102206China Key Laboratory of Thermo-Fluid Science and Engineering of Ministry of Education School of Energy&Power EngineeringXi’an Jiaotong UniversityXi’an 710049China

Required by the supercritical carbon dioxide(s CO_(2))coal-fired power cycle,s CO_(2)entering a boiler has a high temperature and can cause overheating of *** eliminate the pressure drop penalty effect,the s CO_(2)boiler consists of several modules,each having different heat flux received from the furnace side(q)and different CO_(2)temperature in the cooling wall tube(T_f).We aim to search for the best matching strategy coupling furnace side and tube side to obtain the lowest temperature of *** theoretically analyzing the wall temperature influenced by q,T_f and a comprehensive thermal resistance C,two matching methods are introduced:the heat flux-temperature matching(HTM)which matches higher q with lower T_f,and the heat flux-heat flux matching(HHM)that matches higher q with higher allowable-heat-flux at the temperature limit of *** is a conventional method but HHM is newly proposed *** show that,if C is identical for different modules,the two methods coincide;otherwise,HHM is *** a s CO_(2)boiler driving 1000 MWe power plant,smaller cooling wall temperatures are obtained by HHM than *** on HHM,the mid-partition wall,heat transfer enhancement,and downward flow are comprehensively used,decreasing the wall temperature significantly.

关键词： sCO_(2)power cycle sCO_(2)modular boiler cooling wall temperature allowable heat flux matching strategy

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