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Experimental Investigation on Critical Heat Flux for Water flowing in a Vertical Uniformly Heated Rifled Tube under Near-critical Pressures

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Journal of Thermal Science 2018年第6期27卷 527-540页

作者： XIE Haiyan YANG Dong ZHAO Yunjie JIANG Huiqing QU Mofeng State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

This study experimentally investigated the critical heat flux(CHF) of departure from nucleate boiling(DNB) of water flowing under near-critical pressures in a 2 m-long vertical upward rifled tube with the size of Φ35 × 5.67 mm. Operating conditions included pressures of 18–21 MPa, mass fluxes of 475–1000 kg·m^(-2)·s^(-1), inlet subcooling temperatures of 3–5°C, and wall heat fluxes of 40–960 kW·m^(-2). Tube wall temperature distribution and heat transfer performance in different test conditions were obtained. The effects of the operating parameters on CHF were analyzed. Four heat transfer coefficient correlations were evaluated against our experimental data for further investigation of the two-phase heat transfer characteristics. A heat transfer correlation based on Martinelli number utilized in two-phase region and two empirical correlations used to predict the CHF in rifled tube at near-critical pressures were proposed. Meanwhile, experimental CHF data in rifled tube were compared with six widely used correlations and a CHF look-up table. The CHF enhancement effect in rifled tube is obvious as compared with the CHF data in smooth tube. Results show that DNB occurs at low vapor quality and subcooled region in the rifled tube at near-critical pressures. The increase in pressure leads to the early occurrence of DNB and the decrease in CHF, whereas the increase in mass flux delays the occurrence of DNB and results in the increase in CHF. DNB presents a tendency to move toward the inlet of the rifled tube. At individual operating conditions, DNB and dryout coexist at different sections of the rifled tube.

关键词： critical heat flux near-critical pressure rifled tube DNB heat transfer

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General analytical equation of state for nanoconfined gases derived from statistical physics

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Physical Review E 2025年第2期111卷 025413-025413页

作者： Chengzhen Sun Haoxuan Li Zhixiang Zhao Mehdi Neek-Amal Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi 710049 China School of Urban Planning and Municipal Engineering Xi'an Polytechnic University Xi'an Shaanxi 710048 China Department of Physics Faculty of Sciences Shahid Rajaee Teacher Training University 16875-163 Lavizan Tehran Islamic Republic of Iran Department of Physics University of Antwerp Groenenborgerlaan 171 2020 Antwerp Belgium

The pressure prediction of nanoconfined gases is crucial for various industrial applications, yet existing equations of state (EOS) often compromise between accuracy and usability. This study derives a theoretical EOS in analytical form, combining precision and practicality through statistical physics. It begins by examining the pressure drop mechanism due to adsorbed molecules and refines molecular pairing and potential energy interactions. The resulting EOS accurately predicts the pressure of gases in nanoconfined spaces, especially with an average prediction error of about 5% for strongly adsorbing gases like nitrogen, oxygen, and argon. Additionally, it aligns with the Van der Waals EOS under macroscopic conditions, offering a unified framework across scales. This model enhances both engineering applications and the understanding of nanoconfined EOS.

关键词： Van der Waals forces

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Atomization of highly reactive simulant with Hydrogen Peroxide by a liquid–liquid pintle injector

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Acta Astronautica 2025年 233卷 266-276页

作者： Dias, Gabriel Silva da Silva Mota, Fábio Antônio Yao, Xiaoxin Fei, Lihan Tang, Chenglong de Souza Costa, Fernando State Key Laboratory of Multiphase Flows in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China São Paulo Cachoeira Paulista12630-970 Brazil São Paulo Santo André09210-580 Brazil

As interest in green hypergolic propulsion systems grows, the need for further development and a deeper understanding of promising new propellants with versatile injectors becomes crucial. This experimental work employed a pintle injector to investigate the different atomization behaviors of a reactive fuel surrogate. The surrogate was designed to partially mimic the heat release and vapor formation, captured by a time-resolved infrared camera, as well as the recently reported foamy-like structure in hypergolics using hydrogen peroxide solutions as a green oxidizer, captured by a high-speed camera. The dominant foamy-like structure significantly affects the breakup length and spray cone angle behavior of the reactive surrogate/hydrogen peroxide pair compared to a water–water non-reactive case. The average representative diameter of reactive particles was substantially larger and showed different responses to breakup and capillary deformation mechanisms, as detected by inspecting two distinct regions downstream of the injector exit. The particle size distribution exhibited a bimodal pattern for the non-reactive cases and unclear behavior for the non-reactive cases. The calculated particle velocity profile, extracted from a Particle Image Velocimetry analysis tracking droplets and reacting particles, revealed similar behavior for both non-reactive and reactive cases. The breakup process of reacting ligaments in the current study was similar in non-combustion conditions compared to that of ligaments under combustion environments from previous work. Particles smaller than 2 mm remained approximately constant in size until exiting the field of view in the non-combustion case or until extinction due to evaporation in the combustion case. Larger particles changed shape until plateauing in non-combustion, while their equivalent diameter decreased almost linearly due to evaporation in combustion. The D2-law overestimates the evaporation process until the extinction of a liga

关键词： High speed cameras

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Thermodynamic and environmental analysis of the hydrogen and combustible gas production in supercritical water partial oxidation system of coal

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Energy 2025年 326卷

作者： Li, Yifeng Xing, Guowei Liu, Shi Guo, Shenghui Ge, Zhiwei Guo, Liejin State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Supercritical water partial oxidation (SCWPO) is an eco-friendly coal treatment technology that lowers the temperature needed for complete coal gasification, promotes hydrogen output, enables targeted regulation of gaseous product composition, and eliminates gaseous pollutants. Current researches mainly focus on experiments and numerical simulations, with limited exploration in thermodynamics. The present study establishes an auto-thermal SCWPO cogeneration system for Hongliulin coal, employs sensitivity analysis to refine system parameters, and utilizes Life Cycle Assessment to evaluate the environmental impact of the hydrogen production system. When the outlet temperature of the SCWPO reactor increases, the preheating water flow and equivalence ratio (ER) enhance, the fraction of H2 in the gas product rises;conversely, the fraction of the combustible gas (CH4+CO + H2) rises. The SCWPO system can be precisely tailored to yield high-purity hydrogen or combustible gas by modulating the amount of oxygen input. The system of combustible gas production is capable of generating 241.67 GJ h−1 of energy and attaining a cold gas efficiency of 81.62 % when the ER is 0.25. The hydrogen production system can generate 1004.38 kg h−1 of H2 and 206 t h−1 of steam at 0.5 MPa and 150 °C for an ER of 0.6. The optimized hydrogen production system achieved 90.97 % energy efficiency and 59.33 % exergy efficiency. The standard Global Warming Potential through carbon capture technology is 0.087 (kg H2)−1. The system developed in this paper benefits the industrial application of SCWPO and the optimization of subsequent processes. © 2025 Elsevier Ltd

关键词： River pollution

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Thermal management performance and optimization of a hybrid system integrating liquid cooling and fin-enhanced phase change material for large-capacity energy storage battery pack

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Energy Conversion and Management 2025年 336卷

作者： Xiang-Wei Lin Zhi-Fu Zhou Maochang Liu Bin Chen You-Jun Lu Deng-Wei Jing Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Battery energy storage systems become increasingly important to address the intermittency of renewable energies, but their widespread adoption is still hindered by thermal concerns. However, a single thermal management strategy cannot ensure the overall performance of energy storage battery systems. In this study, a hybrid strategy combining topological fin structure, phase change material, and active liquid cooling is established for 280 Ah lithium-ion battery pack. A fluidic-thermal-phase change coupled model is built and verified experimentally. Meanwhile, a novel comprehensive evaluation parameter is defined to feature the overall performance of thermal management system. Based on this, comparative investigations are conducted to assess the efficiency of three cooling strategies. Despite additional weight caused by hybrid design, topological fin structure not only constructs the thermal conduction in phase change material but also dissipates the accumulated heat by connecting cold plate. Additionally, the impacts of fin fraction, thickness of phase change material, and inlet velocity are systematically explored using single-factor analysis. Furthermore, a surrogate-based model is utilized to reveal the interactions between design parameters and system performance, while accomplishing a global optimization. In contrast to original design, comprehensive evaluation parameter is reduced by 0.218, 0.273, 0.256, and 0.2 for discharge rates of 0.25, 0.5, 0.75, and 1C, respectively.

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Thermophysical property prediction of supercritical multiple mixtures fluid by molecular dynamics simulation

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Journal of Molecular Liquids 2025年 432卷

作者： Tete Gui Jiasunle Li Zhiwei Ge Liejin Guo State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an 710049 China

Supercritical multiple mixtures (H 2 O/CO 2 ) fluids are produced in the poly-generation system based on supercritical water gasification (SCWG). Understanding the thermophysical property of supercritical multiple mixtures fluid is rather essential to design and industrialize the poly-generation system. At present, the selection of force field models for H 2 O/CO 2 mixtures are rather complicated, chaotic and inconsistent, the calculation of each parameter necessitates the use of one force field model. There is no universal force field model to calculate and conduct thermophysical property of H 2 O/CO 2 at one time in a wide range of temperature within SCW. In this paper, heat capacity, viscosity and thermal conductivity of multiple mixtures in supercritical and near-critical water (575 K–1075 k) are first investigated via a novel common force field model with molecular dynamics (MD) simulations. The effects of different factors including the pressure, temperature and CO 2 mass fraction on thermophysical properties of H 2 O/CO 2 at a wide range of temperature were first analyzed and conducted in detail. The calculated results indicate that the phenomenon “critical point drift” for viscosity and thermal conductivity of H 2 O/CO 2 mixtures migrating toward the low temperature region occurs. The drift values of viscosity and thermal conductivity are about 10 K and 28 K. The variation of heat capacity and viscosity of H 2 O/CO 2 mixtures increases with increasing pressures only in low temperatures region (700 K-–800 K), while the thermal conductivity always increases with increasing pressures. When the mass fractions of CO 2 increases from 20 % to 40 % and 60 %, the drift values for thermal conductivity and viscosity of H 2 O/CO 2 mixtures decreases from 628 K to 624 K and 620 K, and from 627 K to 618 K and 610 K, respectively, and the peak heat capacity decreases from 64.9 J/mol·K to 52.4 J/mol·K and 45.1 J/mol·K. The fitting polynomial to determine conductivity, visco

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Recent advances in nanoporous graphene membrane for gas separation and water purification

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Science Bulletin 2015年第21期60卷 1807-1823页

作者： Chengzhen Sun Boyao Wen Bofeng Bai State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University

Graphene is a one-atom-thick sheet of graphite comprising sp2-hybridized carbon atoms arranged in the hexagonal honeycomb lattices. By removing the honeycomb lattices and forming nanopores with specific geometry and size, nanoporous graphene has been demonstrated as a very high-efficiency separation membrane, due to the ultrafast molecular permeation rate for its one-atom thickness. This review focuses on the recent advances in nanoporous graphene membrane for the applications of gas separation and water purification, with a major emphasis on the molecular permeation mechanisms and the advanced fabrication methods of this state-of-the-art membrane. We highlight the advanced theoretical and experimental works and discuss the gas/water molecular transport mechanisms through the graphene nanopores accompanied with theoretical models. In addition, we summarize some representative membrane fabrication methods, covering the graphene transfer to porous substrates and the pore generation. We anticipate that this review can provide a platform for understanding the current challenges to make the conceptual membrane a reality and attracting more and more attentions from scientists and engineers.

关键词： Nanoporous graphene Gas separationWater purification Molecular permeationmechanism Membrane fabrication

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A multi-physics model-based approach for macro-structured surface design to enhance heat transfer in R410A flash spray cooling systems

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International Journal of Heat and Mass Transfer 2025年 247卷

作者： Ye, Ying-Dong Lin, Xiang-Wei Zhou, Zhi-Fu Liu, Maochang Chen, Bin Lu, Youjun Jing, Dengwei State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China

Refrigerant flash spray cooling, which offers high heat flux dissipation at low temperatures, holds significant potential for thermal management of high-power electronic devices. While surface structure design can further amplify heat transfer performance, the lack of systematic methodologies to address the complexities of spray cooling has hindered progress. This study establishes a multi-physics computational framework that couples two-phase flash spray dynamics, liquid film heat transfer, and solid heat conduction to systematically optimize macro-structured surfaces. After validating the model against experimental data, the effects of surface geometry (flat, square, straight and pyramid fins) and dimensional parameters on cooling performance were analyzed. The pyramid structure demonstrated superior performance, achieving a 9 K reduction in surface temperature and a 70 % increase in effective heat transfer coefficient compared to the flat surface. Quantitative analysis revealed that optimal macro-structured design hinges on maximizing effective heat transfer area while ensuring uniform liquid film distribution via controlled droplet dynamics. Further parametric studies on nine pyramid geometries identified a base length of 1 mm and height-to-edge ratio of 0.7 as the optimal configuration, balancing heat transfer enhancement and manufacturing costs through a newly proposed Composite Heat Transfer Factor (CHTF). This work provides a mechanistic framework for designing enhanced surfaces in spray cooling systems, bridging critical gaps in both theoretical understanding and engineering application. © 2025 Elsevier Ltd

关键词： Film cooling

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Teardrop-like micro pin fin coated nanotube arrays chip for enhancement of flow boiling electronics cooling

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International Journal of Thermal Sciences 2025年 214卷

作者： Chen, Hongqiang Gao, Quan Ma, Xiang Li, Kai Du, Wangfang Li, Caifeng Zhang, Yonghai Wei, Jinjia School of Chemical Engineering and Technology Xi'an Jiaotong University 28 Xianning West Road Shaanxi Xi'an710049 China Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an710049 China National Microgravity Laboratory Institute of Mechanics Chinese Academy of Sciences Beijing100190 China School of Engineering Science University of Chinese Academy of Sciences Beijing100149 China Xi'an Shaangu Power Co. Ltd. Xi'an710075 China

Phase change flow boiling heat transfer in microchannel is a very efficient thermal management mode for high-power electronics/devices cooling. However, achieving comprehensive enhancement of flow boiling heat transfer performance at low power consumption is still challenging. Herein, we devised and manufactured a teardrop-like micro-pin-fin coated stable copper hydroxide nanotubes array chip surfaces (S-Nanotube), demonstrating their exceptional enhancement in flow boiling heat transfer efficiency. A series of experiments were conducted using HFE-7100 as a working fluid within a semi-open microchannel. Compared to the smooth surface, the critical heat flux (CHF) and the maximum boiling heat transfer coefficient (HTC) of the S-Nanotube is increased by 82.1 % (from 45.1 to 72.9 and then to 82.1 W/cm2) and 140.5 % (from 5955 to 11,325 and then to 14,316 W/m2·K) at extremely low-pressure drop (≤4 kPa), showing a high coefficient of performance (COP). The temperature of the onset of nucleate boiling on the S-Nanotube surface is reduced by 26.4 %, and the heat flux is greatly increased in a small wall temperature variations (ΔT ≤ 10 °C). In situ observation and analysis of the surface properties and the bubble dynamics, the S-Nanotube chip promotes the phase change heat transfer process by providing massive nucleation sites, reducing bubbles size and residence time, and enhancing the wicking wetting capacity. These findings provide guidance for the rational design of boiling heat transfer-enhanced surfaces and heat sinks and point the way to achieving efficient thermal management of power devices. © 2025 Elsevier Masson SAS

关键词： Electronic cooling

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A review of engine application and fundamental study on turbulent premixed combustion of hydrogen enriched natural gas

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Science China(Technological Sciences) 2014年第3期57卷 445-451页

作者： WANG JinHua WEI ZhiLong ZHANG Meng HUANG ZuoHua State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University

The application and fundamental study on turbulent premixed combustion of hydrogen enriched natural gas is reviewed in this *** include the combustion characteristics of direct injection engine fueled with hydrogen enriched natural gas,visualization study of direct injection combustion of hydrogen enriched natural gas using a constant volume vessel,and the fundamental study of turbulent premixed combustion of hydrogen enriched natural *** effect of additional hydrogen on the combustion process of natural gas engine is investigated from the fundamental view of the interaction between combustion reaction and turbulent flow.

关键词： natural gas hydrogen direct injection combustion turbulent premixed combustion OH-PLIF engine

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