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Chinese Journal of Chemical Engineering 2021年第12期34卷 65-77页

作者： Qihui Hu Xiaoyu Wang Wuchang Wang Yuxing Li Shuai Liu Shandong Key Laboratory of Oil-gas Storage and Transportation Safety College of Pipeline and Civil EngineeringChina University of PetroleumQingdao 266580China State Key Laboratory of Natural gas Hydrates Beijing 100028China Research Institute of Experiment and Detection Petro China Xinjiang Oilfield CompanyKaramay 834000China

To investigate the morphological evolution of the whole growth and aggregation processes of hydrate crystals near the gas–liquid interface,we used a high-pressure visual reactor with high-speed camera to capture the micromorphology of hydrate particles in a natural gas+pure water system with pressure from 2.6 to 3.6 MPa and sub-cooling from 4.7 to 6.23C.The results showed that under low sub-cooling conditions,the amount and size of particles increased first and then decreased in the range of 0–330 lm,and the small particles always dominated.These particles can be roughly classified into two categories:planar flake particles and polyhedral solid particles.Then,the concept of maximum growth dominant particle size was proposed to distinguish the morphological boundary of growth and aggregation.In addition,the micro model was established to better reflect the effects of particle formation process and evolution mechanism near the gas–liquid interface under stirring condition.The results of this study can provide a guidance for flow assurance in multiphase pipeline.

关键词： Natural gas hydrate Growth Aggregation gas-liquid interface Micromorphology Physical model

One droplet reaction for synthesis of multi-sized nanoparticles

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Nano Research 2023年第4期16卷 5850-5856页

作者： Bingda Chen Feifei Qin Meng Su Daixi Xie Zeying Zhang Qi Pan Huadong Wang Xu Yang Sisi Chen Jingwei Huang Dominique Derome Jan Carmeliet Yanlin Song Key Laboratory of Green Printing Institute of ChemistryChinese Academy of SciencesBeijing Engineering Research Center of Nanomaterials for Green Printing TechnologyBeijing National Laboratory for Molecular Sciences(BNLMS)Beijing 100190China University of Chinese Academy of Sciences Beijing 100049China Chair of Building Physics Department of Mechanical and Process EngineeringETH Zürich(Swiss Federal Institute of Technology in Zürich)Zürich 8092Switzerland Department of Civil and Building Engineering Universitéde SherbrookeSherbrooke QC J1K 2R1Canada

Reaction kinetics of nanoparticles can be controlled by tuning the Peclet number(Pe)as it is an essential parameter in synthesis of multi-sized nanoparticles.Herein,we propose to implement a self-driven multi-dimension microchannels reactor(MMR)for the one droplet synthesis of multi-sized nanoparticles.By carefully controlling the Pe at the gas-liquid interface,the newly formed seed crystals selectively accumulate and grow to a specific size.By the combination of microchannels of different widths and lengths,one droplet reaction in the same apparatus achieves the synchronous synthesis of diverse nanoparticles.MMR enables precise control of nanoparticle diameter at 5 nm precision in the range of 10-110 nm.The use of MMR can be extended to the synthesis of uniform Ag,Au,Pt,and Pd nanoparticles,opening towards the production and engineering of nanostructured materials.This approach gives the chance to regulate the accumulation probability for precise synthesis of nanoparticles with different diameters.

关键词： gas-liquid interface accumulation effect one droplet reaction multi-sized nanoparticles

Numerical investigation of mass transfer behavior of a gas-liquid two‐phase Taylor flow in a microchannel by a volume‐of‐fluid multiphase flow system

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International Journal of Mechanical System Dynamics 2022年第3期2卷 253-264页

作者： Qiuwen Zhong Zhen Jiao Wenhui Nie Yan Li Ning Gu Jiangsu Key Laboratory for Biomaterials and Devices Southeast UniversityNanjingChina Joint Research Institute of Southeast University and Monash University SuzhouChina School of Chemistry and Chemical Engineering Southeast UniversityNanjingChina School of Biological Science and Medical Engineering Southeast UniversityNanjingChina

The microchannel reactor is the most commonly used microreaction technology,an innovative reaction system developed in recent years.This study investigates the mass transfer behavior of a gas-liquid two‐phase Taylor flow in a microchannel by coupling the volume‐of‐fluid model and the species transport model.The concentration distribution and the volumetric mass transfer coefficient of the gas solute are determined and discussed in detail.The simulation results reveal that the double‐circulation flow influences the concentration distribution in the liquid slug.The highest value is observed at the bubble's surface and decreases rapidly along the vertical direction of the bubble.The increase of bubble velocity leads to a more apparent decreasing trend.The gas-liquid interface renewal rate of the bubble is accelerated with increasing bubble velocity,resulting in an increase in the average mass transfer rate in all regions of the bubble surface with an increase in bubble velocity.The results also indicate that the liquid film area contributes the most to the mass transfer behavior due to the most significant proportion and average mass transfer rate of the liquid film among the bubble.

关键词： Taylor flow microchannel hydrodynamics mass transfer behavior CFD simulation gas-liquid interface

Temperature-regulated self-assembly of lipids at free bubbles interface:A green and simple method to prepare micro/nano bubbles

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Nano Research 2020年第4期13卷 999-1007页

作者： Juan Jin Fang Yang Bin Li Dong Liu Lihong Wu Yan Li Ning Gu State Key Laboratory of Bioelectronics Jiangsu Key Laboratory for Biomaterials and DevicesSchool of Biological Sciences and Medical EngineeringSoutheast UniversityNanjing 210096China West Anhui University Luan 237012China Anhui Engineering Laboratory for Conservation and Sustainable Utilization of Traditional Chinese Medicine Resources Luan 237012China CSPC Zhongqi Pharmaceutical Technology(SJZ)Co. Ltd.Shijiazhuang 050035China

Micro/nanobubbles play an essential role in ultrasound-based biomedical applications.Here,a green and simple method to fabricate micro/nanobubbles was developed by the temperature-regulated self-assembly of lipids in the presence of free bubbles.The self-assembly mechanism of lipids interacting with gas-water interfaces was investigated,and the ultrasound imaging of the obtained lipid-encapsulated bubbles(LBs)was further confirmed.Above the phase transition temperature(Tm),fluid lipids transform from vesicles to micelles,and further assemble to the free bubbles interface to be a compressed monolayer,resulting in lipid shelled microbubbles.Cooling below 7m induces the lipid shell to glassy state and stables the LBs.Moreover,increasing the 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000](DSPE-PEG2K)content in lipids formulation can further manipulate the shell curvature and reduce the LBs size into nanobubbles.LBs with diameters of 1.68±0.11 pm,704±7 nm and 208±6 nm were successfully prepared.The in vitro and in vivo ultrasound imaging results showed that all of the LBs had excellent echogenicity.The nanosized LBs revealed elongated imaging duration time and greater microvascular details for the liver tissue.Avoiding the organic solvent and complicated multiple preparation process,this method has great potential in construction of various multifunctional micro/nanobubbles with size control for theranostic applications.

关键词： lipid self-assembly gas-liquid interface microbubbles nanobubbles ultrasound imaging

Physicochemical properties of the AC- excited helium discharges using a water electrode

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Plasma Science and Technology 2018年第7期20卷 112-120页

作者： Hafiz Imran Ahmad QAZI 辛怡颖 Muhammad Ajmal KHAN 李和平周律包成玉 Department of Engineering Physics Tsinghua University Beijing 100084 People's Republic of China School of Environment Tsinghua University Beijing 100084 People's Republic of China

In this paper, the AC-excited helium discharges generated between the powered needle electrode enclosed in a conical quartz tube and the grounded de-ionized water electrode are investigated. The current and voltage waveforms exhibit a transition from the glow-like to streamer-like mode discharges, which forms a stable cone-shaped structure at the gas-liquid interface. In this region, the air and water vapor diffusion initiate various physical-chemical processes leading to substantial changes of the primary species emission intensities （e.g., OH, N2, NO, and O） and the rotational temperatures. The experimentally measured rotational temperature at the gas-liquid interface is 870 K from the Nz（C-B） band with a power input of 26 W. With the prolongation of the discharge time, significant changes in the discharge voltage and current, discharge emission patterns, instantaneous concentrations of the secondary species （e.g., H202, NO2, and NO3） in the liquid phase, pH values and electrical conductivities of the liquids are observed experimentally. The present study is helpful for deepening the understandings to the basic physical-chemical processes in the discharges in contact with liquids, especially to those occurring in the vicinity of the gas-liquid interface, and also for promoting existing and potential applications of such type of discharges in the fields of environmental protection, biomedicine, agriculture, and so on.

关键词： solution plasma gas-liquid interface wastewater treatment biomedical science and agriculture applications

Numerical simulation of gas-liquid two-phase flow impacting fixed structure by CLSVOF/IB method based on OpenFOAM

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Journal of Hydrodynamics 2021年第6期33卷 1176-1189页

作者： Wen-kang Meng Ching-hao Yu Jia Li Rui-dong An State Key Laboratory of Hydraulics and Mountain River Engineering College of Water Resource and HydropowerSichuan UniversityChengdu 610065China

In this paper,a coupled level set and volume of fluid,immersed boundary(CLSVOF/IB)method is proposed and implemented into the interFoam solver of the OpenFOAM to simulate the gas-liquid two-phase flows,involving the gas-liquid and fluid-structure interfaces.In the volume of fluid(VOF)method,the multidimensional universal limiter with explicit solution(MULES)approach is used to restrain the volume fraction.An approach for calculating the grid characteristic size for the level set(LS)initial function and the re-initialization equation is proposed in order to make it more applicable to non-uniform grids in the finite volume method.In the proposed CLSVOF method,the continuous LS function is used to calculate the gas-liquid interface curvature so that the surface tension term can be calculated accurately.In the immersed boundary(IB)method proposed in this paper,a virtual forcing term is introduced in the momentum equation to deal with the fluid-structure interface by defining a solid volume fraction,which is convenient for the three-dimensional numerical simulation.For the present flow field solver,an improved scheme of the velocity predictor loop of the PIMPLE framework is also introduced.Two benchmark cases:the Zalesak’s notched disk and a circular bubble at equilibrium,are simulated first to examine the accuracy of the present CLSVOF method.Then,the effects of several gas-liquid two-phase flows on different fixed structures are investigated.The simulation results are in good agreement with the published numerical and experimental results.

关键词： Volume of fluid(VOF)method level set(LS)method immersed boundary method gas-liquid interface fluid-structure interface

Principle of heat transfer augmentation by interfacial vaporization heat sink

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Progress in Natural Science:Materials International 1999年第10期 11-20页

作者：沈自求 China Dalian 116012 Dalian University of Technology Research Institute of Chemical Engineering

The mechanism of the cooling process enhanced by an inert gas impinging on a heated wall in liquid coolant bath is described. The principle of heat transfer augmentation by interfaeial vaporization heat sink is proposed, in which a method applying limiting diffusion current technique (LDCT) simultaneously with heat transfer measurementis used to separate the "effect of interfacial vaporization heat sink" from the convective heat transfer, and a novel process of gas carrying evaporation is developed. Several aspects of this principle used in research and development are also discussed.

关键词： gas-liquid interface vaporization heat sink heat transfer augmentation.

Experiment of Cooling-film Flows in a Hot-fire Environment

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Experiment of Cooling-film Flows in a Hot-fire Environment