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X-ray computed tomography (XCT) study of jetting in a fluidized bed: Effects of two-component fluidization

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Particuology 2025年 102卷 264-274页

作者： Xiang, Zhong Chen, Xi Liu, Shuguang Heindel, Theodore J. School of Energy and Environment Southeast University Nanjing210096 China State Key Laboratory of Low-carbon Smart Coal-fired Power Generation and Ultra-clean Emission Southeast University Nanjing210096 China Center for Multiphase Flow Research and Education and Department of Mechanical Engineering Iowa State University AmesIA50011 United States

Fluidization of non-spherical particles is commonly found in the biomass and solid waste processing industry, and the jetting characteristic above the aeration plate is critical to the fluidization performance of these particles. In this study, cylindrical particles are used as typical non-spherical particles and co-fluidized with small bed material particles. X-ray computed tomography (XCT) is used to reconstruct the 3D structure of the aeration plate region, allowing for the identification of individual aeration jets. The effects of jet velocity (Uj), cylindrical particle mass fraction (ω), cylindrical particle density (ρi), and the cylindrical particle sphericity () on jet shape and volume are investigated. The experimental results indicate that decreasing the cylindrical particle mass fraction (ω) and particle density (ρi) increases the jet length (L), maximum jet diameter (D), and maximum jet volume (V), but have little effect on the jet half angle (θ). The cylindrical particle density (ρi) is the most sensitive factor for jet shape, while the effect of cylinder particle sphericity () on jet shape is insignificant. A correlation of jet length (L) in a two-component fluidized bed with cylindrical particles and bed material is proposed based on all the experimental results. © 2025 Chinese Society of Particuology and Institute of Process engineering, Chinese Academy of Sciences

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Experimental Study on the Performance Difference of Pulsating Heat Pipe Using R170 and R134a as Working Fluids

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SSRN 2023年

作者： Song, Yuxin Chen, Xi Zhan, Jingru Zhang, Hua School of Energy and Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China Shanghai Key Laboratory of Multiphase Flow and Heat Transfer in Power Engineering University of Shanghai for Science and Technology 516 Jungong Road Shanghai200093 China

The pulsating heat pipe (PHP), as a type of heat pipes, is a flexible heat transport device with highly efficient conduction, which is widely used in many fields including aerospace, waste heat recovery, cryogenic refrigerator and so on. The working fluids have an important effect on the thermal performance of PHPs. This study experimentally compares a PHP with R170 and R134a as the working fluids, respectively, examining temperature fluctuations, thermal resistance, and temperature differentials. Findings indicate that R170 PHP exhibits sensitivity to heat input (HI), with temperature fluctuations stagnating at 70 W. Increasing the filling ratio (FR) from 30% to 60% results in a steady rise in R170 PHP thermal resistance. While R170 PHP thermal resistance increases with higher inclination angles (IAs), it does so to a lesser extent compared to R134a PHPs. In the temperature region of -20 ℃ to 0 ℃, both R170 and R134a perform similarly. However, as the working temperature (WT) decreases, R170 PHP outperforms R134a PHP. Overall, the thermal performance of R170 PHP is superior to R134a PHP. This study provides reference value for the future research of PHPs in the temperature region of -60 ℃ to 0 ℃. © 2023, The Authors. All rights reserved.

关键词： Heat resistance

Unveiling micro- and nanoscale bubble dynamics for enhanced electrochemical water splitting

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Advances in Colloid and Interface Science 2025年 343卷 103544页

作者： Lu, Xinlong Yadav, Devendra He, Baichuan Zhou, Yu Zhou, Liwu Zeng, Zilong Ma, Lijing Jing, Dengwei International Research Center for Renewable Energy & State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Shaanxi Xi'an710049 China Department of Chemical Engineering Technion - Israel Institute of Technology Haifa3200003 Israel College of Mechanical Engineering Xi'an Shiyou University Shaanxi Xi'an710065 China

Bubbles generated during electrochemical and photoelectrochemical water splitting critically influence efficiency through complex factors, including chemical reactions, species transport, mass transfer at the three-phase interface, and bubble coverage. A detailed understanding of the nucleation, growth, coalescence, and detachment of micro- and nanoscale bubbles is vital for advancing water splitting technologies. Surface-attached bubbles significantly reduce the electrocatalytically active area of electrodes, leading to increased surface overpotential at a given current density. Consequently, their effective removal is pivotal for optimizing the electrolysis process. However, the intricate interplay among single bubble evolution, mass transport, bubble coverage, and overpotential remain inadequately understood. This review explores the fundamental mechanisms underpinning bubble evolution, with an emphasis on the Marangoni effect and its influence on bubble dynamics. Furthermore, recent advancements in understanding individual bubbles on micro and nano-electrodes are highlighted, offering valuable insights into scale-dependent bubble behavior. These findings enrich our knowledge of gas-liquid interfacial phenomena and underscore their industrial significance, presenting opportunities to enhance water splitting performance through optimized bubble dynamics. © 2025

关键词： Electrolysis

Development, Validation and Application of Sub-Channel Thermal-Hydraulic Analysis Code for Liquid Metal Cooled Reactor

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SSRN 2024年

作者： Wang, Jinshun Chen, Ronghua Liang, Yu Gui, Minyang Zhu, Xinyang Tian, Wenxi Qiu, Suizheng Su, Guanghui School of Nuclear Science and Technology Shaanxi Key Laboratory of Advanced Nuclear Energy and Technology State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Nuclear Power Institute of China 328 Changshun Avenue Chengdu610213 China Science and Technology on Reactor System Design Technology Laboratory Nuclear Power Institute of China Chengdu610213 China College of Nuclear Science and Technology Harbin Engineering University Harbin150001 China

The liquid metal reactor, specifically the lead-based fast reactor and the sodium-cooled fast reactor, are generally recognized as the most significant representatives of the Gen IV reactors due to their sustainability, economy, security and reliability. In order to conduct thermal-hydraulic safety analysis for liquid metal cooled fast reactors, adaptive improvements are made to the model and solution algorithms based on the sub-channel analysis method, and a Sub-channel Analysis Code Of Safety for Liquid Metal cooled Reactor (SACOS-LMR) is developed. The validation of SACOS-LMR is conducted using classic experimental data of liquid metal. The results show that the dimensionless temperature deviations of ORNL 19-pin test and Toshiba 37-pin test are within 10%, and the relative temperature deviations of KIT-KALLA 19-pin test are within 25%. These findings confirm the accuracy and reliability of SACOS-LMR in predicting the temperature distribution of liquid metal reactors. Ultimately, calculations conducted on the ALFRED lead-cooled fast reactor demonstrated the practical utility of the code and have certain guiding significance for its subsequent design and development. © 2024, The Authors. All rights reserved.

关键词： Liquid metals

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

Gold/oxide heterostructured nanoparticles for enhanced SERS sensitivity and reproducibility

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Rare Metals 2020年第7期39卷 834-840页

作者： Qi-Kui Fan Ting-Zhuo Liu Hou-Shen Li Shu-Meng Zhang Kai Liu Chuan-Bo Gao Frontier Institute of Science and Technology and State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong UniversityXi’an 710054China College of Chemistry and Material Science Shandong Agricultural UniversityTaian 271018China

In surface-enhanced Raman scattering(SERS),it is highly desirable to obtain Raman signals with high sensitivity and reproducibility from noble metal nanoparticle substrates,which remains a great challenge due to the inhomogeneity of the plasmonic coupling that is sensitive to the interparticle *** this work,we report that the interparticle plasmonic coupling could be circumvented by first synthesizing Au/metal or nonmetal oxide heterostructured nanoparticles and then depositing them uniformly onto the substrates,leading to high reproducibility of the Raman *** plasmonic coupling has been found at the Au/oxide interface,which enables high sensitivity of the SERS analysis that accompanies the excellent signal *** different oxides investigated(SiO2,TiO2 and Fe2O3),the Au/Fe2O3 heterostructured nanoparticles demonstrate the highest Raman enhancement *** believe our strategy opens a promising route to fabricate SERS substrates that are capable of sensitively and quantitatively detecting molecules of interest in a much reliable manner.

关键词： Gold nanoparticles Au/oxide heterostructures Hot spots Surface-enhanced Raman scattering Reproducibility

Interfacial Mass Transfer Enhancement for Photoelectrochemical Water Splitting Using 3d flow Field Structure

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SSRN 2022年

作者： Wang, Baoyuan Yang, Suyi Lai, Yongquan Su, Jinzhan International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Shaanxi Xi’an710049 China

Hydrogen production using solar energy water splitting is an economical and feasible clean energy solution. It is recognized that the efficiency of photoelectrochemical water splitting is not only related to the electrode material, but also influenced by the mass transport at the electrode surface. To investigate that relationship, we design a novel photoelectrochemical water splitting reactor, which generates a turbulent flow at the electrode/electrolyte interface, and change the temperature of the electrolyte. It was found that the flow rate and temperature of the electrolyte mainly affect the mass transport and charge transfer at the photoelectrode/electrolyte interface. Based on the results of LSV, EIS, and the calculation of mass transfer coefficient, the photoelectrochemical performance of the system at flow rate ranging from 0 to 145 ml/min and temperature between 20-90 °C is analyzed. The influence of the flow rate on the photocurrent density is more significant during the transition of the flow state and at the high flow rate. The best performance is achieved at the flow rate of 127 ml/min, and the temperature of 90 °C. The electrochemical impedance spectroscopy results show that in the test range, ion transport impedance decreases with increasing electrolyte temperature, as a result, the photocurrent density at 90 °C is increased about 2.2 times compared to that at 20 °C. It is also shown that the design of the 3D step-like structure has a more significant effect on the electrolyte flow than the planar structure, and the photocurrent density is increased about 1.3 times. © 2022, The Authors. All rights reserved.

关键词： Mass transfer

Occurrence and flow Characteristics of Methane in High-Temperature and High-Pressure Nanopores of Deep Shale

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Kung Cheng Je Wu Li Hsueh Pao/Journal of engineering Thermophysics 2025年第4期46卷 1200-1204页

作者： Wang, Rui Sun, Chengzhen Yang, Xu State Key Laboratory of Multiphase Flow in Power Engineering Xi’an Jiaotong University Xi’an710049 China Petroleum Engineering School Southwest Petroleum University Chengdu610500 China

The understanding of gas transport in deep shale nanopores is still not clear. In this study, molecular simulations of methane occurrence and flow in illite slits of deep shales under the condition of high-temperature and high-pressure was carried out. The occurrence, diffusion and flow characteristics of methane molecules were analyzed. The effects of temperature and pressure on methane occurrence and flow were elucidated. The results show that the distribution of methane density in illite slits is nonuniform, and there are density peaks near the wall. Compared with Middle and Shallow shales, more methane molecules can exist in the pores of deep shale, and the diffusion ability is limited. The methane flow flux decreases with the decrease of pressure (5∼80 MPa) and increases with the decrease of temperature (60∼120◦C). Pressure is the main dominating factor of flow flux, and the flow flux decreases gradually during depressurization. © 2025 Science Press. All rights reserved.

关键词： Nanopores

flow and Thermal Analysis of the Transition Scheme between Micro-Channel and Micro-Jet Cooling Solution

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SSRN 2022年

作者： Guo, Yuming Fan, Liang-Liang Zhao, Liang State Key Laboratory of Multiphase Flow in Power Engineering Xi'an Jiaotong University Xi'An710049 China School of Mechanical Engineering Xi'an Jiaotong University Xi'An China

With the rapid development of high-power electronics, the thermal management of these emerging devices is challenging due to the danger of ultra high heat flux and uneven temperature distribution. In this perspective, as promising cooling technologies, micro-channel and micro-jet cooling designs have been extensively investigated. In the past decade, certain heat-dissipation technologies based on micro-channel and micro-jet cooling have utilized geometrically identical heat sinks;however, their corresponding flow and thermal characteristics are dissimilar including micro-channel cooling technologies often have large temperature gradients as well as high heat transfer coefficients, while microjet technologies are more advantageous in terms of temperature distribution uniformity but larger pressure drop penalty. To characterize the enhanced heat-transfer mechanism driving this dissimilitude, a transition scheme between micro-channel and micro-jet was designed, featuring a gap on the channel fins top to provide extra flow area, and investigated experimentally and numerically. By controlling the volumetric flow ratio of the channel and jet, the flow and thermal characteristics of the transition scheme could be interchangeably transformed between the micro-channel and micro-jet. Moreover, we investigated the effect of the vortex generated by the jet impingement on channel bottom and fins top, an important factor causing the distinctions between the two schemes. The results revealed that the vortex in the stagnation zone enhanced the local heat-transfer coefficient corresponding to the channel bottom and promoted temperature uniformity;however, it caused the thermal boundary layer on the fins top to thicken. Although the vortex was favorable for the forced convection in the acceleration zone, the vortex intersections formed by adjacent jets introduced a greater pressure-drop penalty and flow blockage, which were not conducive to enhancing the heat transfer. Subsequently,

关键词： Vortex flow