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SSRN 2024年

作者： Li, Peng Gai, Zhongrui Zhang, Jinrui Rao, Qiong Tang, Sanli Shen, Yuanhui Pan, Ying Jin, Hongguang Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing100190 China State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China University of Chinese Academy of Sciences Beijing100049 China

The feasibility of a solar-driven chemical looping dry reforming of methane (DRM) process, which converts solar energy and methane into syngas via a looping material oxygen carrier is investigated experimentally. Thermogravimetric analysis (TGA) experiments were firstly carried out to verify the effect of the Rh-doped LaCeO3.5 which were synthesized via modified Pechini method and incipient wetness method and the result shows that Rh greatly improved the reaction kinetics. Photo-TGA experiments were conducted to evaluate the light effect in chemical looping DRM. Under the light condition, the Rh-doped LaCeO3.5 shows higher methane conversion, oxygen extraction rate and CO selectivity compared with the undoped one, decreasing the apparent activation energy of the reaction at the same time. Insights obtained from the UV-Vis spectroscopy verified that the surface Rh under the light could promote the activation of surface methane species and increase the light absorbance. Meanwhile, the FEM methods were used to obtain the distributions of the temperature fields of the photo-TGA reactor through the calculation of the coupling of the fluid, reaction and temperature fields. In this way, the conversion mechanism of the solar, heating and chemical energy was illustrated and furthermore, the calculated surface reaction rate and the variation tendency of the outlet-gas were consistent with the experimental results. Through the integration of solar energy, a high methane to solar fuel conversion efficiency could be achieved. The proposed process has the potential to produce solar fuels at high efficiency with reduced carbon footprint. © 2024, The Authors. All rights reserved.

关键词： Methane

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Experimental Study on Stable Jet Impact Process Under Simulated Pipeline Rupture

Experimental Study on Stable Jet Impact Process Under Simula...

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Student Conference on Research and Development (SCOReD)

作者： Zhang Tao Bi Qincheng Zhao Jinle Wang Teng Chen Jingrong Feng Fan State Key Lab Multiphase Flow Power Engn Xi’an Jiaotong University Xi’an Shaanxi China School of Energy Power and Mechanical Engineering North China Electric Power University Bao’ding Hebei China

ISBN: (数字)9798350318821

ISBN: (纸本)9798350318838

In this study, an advanced experimental system was utilized that incorporated heating, jetting, recycling, and cooling capabilities to ensure the successful execution of stable jet impact experiment that simulating a pipeline complete rupture. High-temperature resistant tempered glass was employed in the experimental system to realize the visibility. During the experiment, 8mm pipes/nozzles of varying lengths were employed as the test sections, and jetting phenomena when the import status is single-phase cold water or two-phase mixture at 0-2MPa were obtained by high-resolution photos. Additionally, the shape of the jet cone and the impact force exerted on the target plate were meticulously analyzed after the working fluid under different state parameters jetting into an atmospheric pressure environment through pipes/nozzles. The research also focused on the variation trend in the magnitude of the jet-impact force, as a function of inlet pressure and temperature, target plate distances, and length-to-diameter ratios. The research findings revealed that cold water(below 100°C), sub-cooled water(above 100°C but not reaching saturation temperature), and two-phase steam-water mixture exhibited distinct jet cone shapes during the jetting process, resulting in varying distributions of the jet force. Furthermore, the distance from the spout to the target plate and the length-to-diameter ratio significantly influenced the magnitude of the jet impact force.

关键词： Resistance Visualization Temperature distribution Fluids Shape Force Pipelines

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Study in steam-water two-phase flow heat transfer at high mass velocity of flow in vertical helical coiled tube

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2008年第3期29卷 423-428页

作者： Guo, Meng Zhao, Liang Mao, Yu-Fei Zhen, Fei-Qiang Zhang, Wen-Bin Guo, Lie-Jin Peng, Xiao-Feng State Key Lab. of Multiphase Flow in Power Engineering Xi'an 710049 China

Experiments were conducted to further understand the heat transfer in two-phase flow in vertical helically-coiled tubes. The experiments covered a wide range of pressure 8.0-15.0 MPa, mass flow rate 2500-4000 kg/(m2s), heat flux 200-800 kW/m2. The experimental segment is 2.335 meter long and made by φ14 × 2 mm steel tube. The diameter ratio D/d is 30.1. Through analyzing the influence of heat flux, mass velocity on average heat transfer coefficient, we acknowledge the activities of nucleate boiling and forced convection two mechanism on steam-water two-phase heat transfer in helical coils tubes at high mass flow rate. The average and local heat transfer coefficient correlations were obtained. At high mass flow rate conditions, the effect of heat transfer in the steam-water two-phase flow in helically coils is inclined to that of straight tube at same conditions and the results are compared.

关键词： Heat exchangers

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Microwave-assisted synthesis of bimetallic NiCo-MOF-74 with enhanced open metal site for efficient CO 2 capture

Environmental Functional Materials

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Environmental Functional Materials 2022年第3期1卷 253-266页

作者： Changwei Chen Mohammadreza Kosari Meizan Jing Chi He State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power Engineering Xi'an Jiaotong University Xi'an 710049 Shaanxi PR China Department of Chemical and Biomolecular Engineering Faculty of Engineering National University of Singapore 10 Kent Ridge Crescent 119260 Singapore Department of Chemistry Key Laboratory of Organic Optoelectronics & Molecular Engineering of Ministry of Education Tsinghua University Beijing PR China National Engineering Laboratory for VOCs Pollution Control Material & Technology University of Chinese Academy of Sciences Beijing 101408 PR China

Metal–organic frameworks (MOFs) containing two different inorganic metal nodes (known as bimetallic MOFs) could exhibit enhanced CO 2 adsorption compared to their monometallic counterparts. Herein, a series of bimetallic NiCo-MOF-74 synthesized by microwave-assisted method were investigated for CO 2 adsorption. It was revealed that narrow micropore channel with open metal site (OMS) of the bimetallic NiCo-MOF-74 influence CO 2 binding affinity and CO 2 /N 2 adsorption. The CO 2 uptake of Ni 1 Co 1 -MOF-74 at 0 °C and 1 bar (100 kPa) was 8.30 mmol g −1 which is higher than those of Ni-MOF-74 (3.99 mmol g −1 ), Ni 6 Co 1 -MOF-74 (3.62 mmol g −1 ), Ni 1 Co 6 -MOF-74 (6.40 mmol g −1 ) and Co-MOF-74 (5.03 mmol g −1 ). While this could be related to the high specific surface area of Ni 1 Co 1 -MOF-74, Ni 1 CO 2 -MOF-74 with relatively low specific surface areas still shows good CO 2 adsorption capacity up to 5.70 mmol/g, which is higher than those of adsorbents Ni-MOF-74, Ni 6 Co 1 -MOF-74 and Co-MOF-74, indicating that adsorption performance mainly relies on coordinated metals. Ni 1 Co 1 -MOF-74 showed remarkable recyclability performance, ranking selectivity of CO 2 /N 2 reach up to 34, and suitable isosteric heat (31–23 kJ mol −1 ), manifesting a great probability for industrial CO 2 capture. As revealed, incorporated Ni 2+ /Co 2+ nodes within Ni 1 Co 1 -MOF-74, which are acting as active and open sites for CO 2 capture, led to the synergetic effects comprising of micropores as well as dense dual-metal sites.

关键词： Bimetallic metal–organic frameworks NiCo-MOF-74 Microwave-assisted synthesis Open metal site CO 2 capture

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Thermal Characteristics and Structural Parameters Optimization of Apg/Cu/Pcm Integrated Architecture

SSRN

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SSRN 2024年

作者： Su, Lizheng Zhang, Tianning Li, Xiaoyang Li, Dong Jiang, Xinyu Xie, Zhongnan Xi'an Electronic Engineering Research Institute Xi’an710100 China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi’an710049 China State Key Laboratory of Nonferrous Metals and Processes GRINM Group Co. Ltd. Beijing100088 China

The challenges faced by radar seeker primarily stem from inadequate heat dissipation in chips and excessive weight. To address these issues, this study introduces a novel integrated phase-change heat sink architecture, composed of a copper alloy matrix, annealed pyrolytic graphite (APG), and phase-change materials (PCMs) serving as heat conduction reinforcements. The numerical analysis of the heat dissipation performance of this architecture is conducted using Fluent software. The study evaluates the impact of APG anisotropy, APG/Cu interface thermal resistance, APG thickness, and surface area on the heat conduction efficiency. Results demonstrate that APG facilitates a uniform in-plane temperature distribution, allowing PCMs to absorb heat more evenly. Consequently, APG proves effective in enhancing heat dissipation and safeguarding chips from high temperatures. In comparison to a pure copper component, the APG/Cu/PCM structure reduces chip temperature by a substantial 56.27%. Furthermore, increasing the surface area of APG generally contributes to an enhanced heat transfer capability of entire architecture. The paper presents a quantitative relationship between APG surface area and optimal thickness. Importantly, APG satisfies the lightweight requirement, further emphasizing its suitability for addressing the thermal challenges in radar seeker structures. © 2024, The Authors. All rights reserved.

关键词： Phase change materials

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Photocatalytic desulfurization of gasoline by TiO2 coupling with ultrasonic

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Ranliao Huaxue Xuebao/Journal of Fuel Chemistry and Technology 2010年第4期38卷 428-433页

作者： Chen, Song-Xuan Zhao, Jing-Lian Su, Ci State Key Laboratory of Multiphase Flow in Power Engineering Department of Environmental Engineering Xi'an Jiaotong University Xi'an 710049 China

The photocatalytic oxidation of dibenzothiophen (DBT) in octance (as solvent) was conducted using O2 in air as the oxidant, TiO2 prepared by sol-gelatin method as the photocatalyst and coupling with ultrasonic. The effect of light distance, photocatalyst amount, reaction time, DBT initial concentration and ultasonic power on the removal of DBT were investigated deeply. The results show that the degradation rate of DBT increases by 10% by using ultrasonic. Under the conditions of TiO2 dosage of 2 g/L, air flow rate of 800 mL/min, distance of UV light of 20 cm, initial concentration of DBT of 600 mg/L, reaction time of 150 min, ultrasound power of 500 W, the degradation rate of DBT can reach up to 72.6%.

关键词： Ultrasonics

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Optimal heat transfer criterion and inclination angle effects on non-boiling regime spray cooling

Optimal heat transfer criterion and inclination angle effect...

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IEEE Symposium on Semiconductor Thermal Measurement and Management (SEMI-THERM)

作者： Yong-xian Guo Zhi-fu Zhou Jian-yuan Jia Shao-rong Zhou School of Mechano-Electronic Engineering Xidian University Xi'an Shaanxi China State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'an Shaanxi China Intel Asia-Pacific Research and Development Limited Shanghai China

Based on the maximum CHF (critical heat flux) criterion, an optimal heat transfer criterion, which is called H criterion, was proposed. Experimental apparatuses were conducted. Distilled water was used as the working fluid. Three different DANFOSS nozzles with cone angles being 54deg, 50deg and 54deg respectively were used to cool a 30times30 mm 2 square copper surface. Experimental results indicated that the volumetric fluxes were pro-portioned to P 0.5 , where P is the pressure drop across the nozzles. The optimal distance between the nozzles and the heated surface were derived. The results indicated that the optimal heat transfer appeared while the outside of the impellent thin spray film inscribed in the square heated surface. Based on the H criterion aforementioned, two DANFOSS nozzles of the three were used to study the temperature distribution of the heated surface experimentally while there were spray inclination angles. Distilled water was also used impacting on the 30times30 mm 2 square copper surface aforementioned and a circular heated copper surface with diameters being 30 mm respectively. The heat flux of the surface was kept in constant (about 26-35 W/cm 2 ). The inclination angles were 0deg, 10deg, 20deg, 30deg, 40deg and 50deg respectively. Experimental results indicated that the grads of the temperature of the surface increases first and then decreases with the increase of the inclination angle.

关键词： Heat transfer Spraying Temperature Electronics cooling Coolants Heat engines Copper Uncertainty Water heating Space exploration

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Depth from Defocus Technique for High Number Densities and Non-spherical Particles

arXiv

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arXiv 2024年

作者： Xu, Rixin Huang, Zuojie Gong, Wenchao Zhou, Wu Tropea, Cameron School of Energy and Power Engineering University of Shanghai for Science and Technology Shanghai China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer for Power Engineering University of Shanghai for Science and Technology Shanghai China Institute for Fluid Mechanics and Aerodynamics Technical University of Darmstadt Darmstadt Germany

The Depth from Defocus (DFD) imaging technique for measuring the size and number concentration of particles in a dispersed two-phase flow has up to now been restricted to relatively sparse particle densities and to identifying only spherical particles. The present study examines two advancements to the technique, widening its range of application significantly. The first advancement introduces an image processing procedure which can identify and size particle images which are overlapping. This increases the tolerable number concentration of particles which can be identified and processed within the measurement volume. The second advancement explores the possibility of determining the size and position of non-spherical particles within an observation volume. Both advancements build on recent theoretical work, utilizing not only the gray level of the blurred, out-of-focus images, but also the gradient of the gray level normal to the nominal particle or particle ensemble contour. This gray-level gradient is used to estimate the width of the blur kernel, which is assumed to remain Gaussian. These enhancements are experimentally validated using a dedicated apparatus in which particles of known size, shape and degree of overlapping images can be systematically varied. This experimental setup provides benchmark data to quantify the accuracy and limitations of the processing algorithms. © 2024, CC BY.

关键词： Spheres

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Non-Hermitian Delocalization in a Two-Dimensional Photonic Quasicrystal

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Physical Review Letters 2024年第26期132卷 263801-263801页

作者： Zhaoyang Zhang Shun Liang Ismaël Septembre Jiawei Yu Yongping Huang Maochang Liu Yanpeng Zhang Min Xiao Guillaume Malpuech Dmitry Solnyshkov Key Laboratory for Physical Electronics and Devices of the Ministry of Education & Shaanxi Key Lab of Information Photonic Technique School of Electronic Science and Engineering Faculty of Electronics and Information PHOTON-N2 Université Clermont Auvergne CNRS Clermont INP F-63000 Clermont-Ferrand France International Research Center for Renewable Energy and State Key Laboratory of Multiphase Flow in Power Engineering Department of Physics National Laboratory of Solid State Microstructures and School of Physics 75231 Paris France

Theoretical and experimental studies suggest that both Hermitian and non-Hermitian quasicrystals show localization due to the fractal spectrum and to the transition to diffusive bands via exceptional points, respectively. Here, we present an experimental study of a dodecagonal photonic quasicrystal based on electromagnetically induced transparency in a Rb vapor cell. First, we observe the suppression of the wave packet expansion in the Hermitian case. We then discover a new regime, where increasing the non-Hermiticity leads to delocalization, demonstrating that the behavior in non-Hermitian quasicrystals is richer than previously thought.

关键词： Electromagnetically induced transparency Localization Photonics Non-Hermitian systems Quasicrystals

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Experimental study of natural convection in horizontally-positioned open-celled metal foams

Experimental study of natural convection in horizontally-pos...

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International Conference on Materials for Renewable Energy and Environment

作者： Z. G. XU Z. G. QU C. Y. ZHAO State Key Laboratory of Multiphase Flow School of Energy and Power Engineering Xi'an Jiaotong University

ISBN: (纸本)9781612847498

Experimental study of air natural convection in horizontally-positioned copper metallic foams with open cells was conducted. Temperature distributions on the heating surface were tested under different heating power for foam samples having different porosities and pore densities. The effects of porosity and pore density on the total thermal resistance of the foam sample were quantified. It is found that the porous surface can enhance the natural convection and reduce the thermal resistance by about 20% in comparison with a smooth surface. The surface area density and mass flow rate in natural convection are affected by porosity and pore density simultaneously. When the porosity is relative small (ε = 90%), there exits a critical value of the Gr number (turning point) for two pore densities (10ppi and 40ppi). When the Gr number is less than this critical value, the foam with a higher pore density has the lower total thermal resistance, whereas when the Gr number exceeds the turning point value, the opposite holds. If the porosity is increased to ε = 95%, the foam with a higher pore density has the lower thermal resistance in the whole experimental range. When the porosity and pore density is the same, the foam with smaller size has the higher thermal resistance in the whole experimental range. If the size is relatively small (100×100×50mm), for the two pore densities studied (20ppi and 80ppi), there exits a critical value of the Gr number (turning point). The foam with a lower porosity (ε = 90%) has the lower thermal resistance and the decrease is more obvious for the case of 80ppi. If the size is relatively big(100×100×80mm), there exists a critical value of the Gr number (turning point) only for the case of 10ppi. When the Gr number is less than this critical value, the foam with a higher porosity (ε = 95%) has the higher total thermal resistance, the opposite holds. While for the other two pore densities (20ppi and 40ppi), there is no turning point. The foam with

关键词： Metal foam Natural convection Porosity Pore density Thermal resistance

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