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Flow properties of fine powders in powder coating

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Particuology 2010年第1期8卷 19-27页

作者： jesse Zhu Particle Technology Research Centre Department of Chemical and Biochemical EngineeringThe University of Western Ontario

Three types of nanoparticles and their combinations were blended into a fine powder, which has been used in the powder coating industry. To study their effects on flow properties, the modified powder samples were characterized using a variety of techniques that tested the powder under different powder states ranging from dynamic to static. It was found that all three nanoparticles improved the flow properties of the powder to some degree, though the amounts of the nanoparticles needed were different depending on their physical properties. Secondly, inconsistency among these powder characterization techniques was also found. This is attributed to the different states of the powder samples during a measurement including dynamic, dynamic-static and static states. It was confirmed that characterization techniques which test the flow properties of a powder under all three states are needed to fully describe the flow properties of the powder. Finally, the effects of combinations of nanoparticles were explored, and it was found that combinations of nanoparticles can intensify, weaken or combine the effects of their component nanoparticles. The effects of nanoparticle combinations are not a simple summation of the effects of their comnonent nanoparticles.

关键词： Fine powders Nanoparticle Flow property Flow property characterization Powder coating

Circulating turbulent fluidization-A new fluidization regime or just a transitional phenomenon

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Particuology 2010年第6期8卷 640-644页

作者： jesse Zhu Particle Technology Research Centre and Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioN6A 5B9Canada

While circulating fluidized bed （CFB） reactor has many advantages over the more conventional turbulent fluidized bed （TFB） reactor, it does at least have one significant shortcoming-the rather dilute solids volume concentration in CFB reactor gives rise to less ideal reaction intensity. On the other hand, while having higher reaction intensity, TFB reactor has one fatal drawback of particle back-mixing, making it not suitable for certain reactions such as catalytic reaction where the catalyst requires frequent regeneration. This paper describes some key issues in the development of a circulating turbulent fluidized bed （CTFB） reactor that combines the advantages of both TFB and CFB, that is, to have the high reaction intensity as in TFB but and also to have a suppressed solids back-mixing as in CFB due to a continuous net upflow of solids flux through the bed. Experimental results show enough evidence to suggest that a new fluidization regime is formed, the characteristics of which appears to be distinct from those observed in a regular TFB and from those in either the bottom or the upper sections of regular CFB and/or high-density CFB （HDCFB）. Fundamentally, the difference is that particle-particle interaction （collision） dominates the motion of particles in CTFB and TFB, while gas-particle interaction （drag force） is the key element that determines the two phase flow in CFB including HDCFB.

关键词： Circulating-turbulent fluidized bed Flow regime Circulating-turbulent fluidizationTurbulent fluidized bed Circulating fluidized bed

Experimental study on reactor performance of gas-solids low-velocity fluidized beds

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Particuology 2022年第7期20卷 21-28页

作者： Jiangshan Liu jesse Zhu Particle Technology Research Centre Department of Chemical and Biochemical EngineeringThe University of Western OntarioLondonOntarioN6A 3K7Canada

Reactor performance of bubbling fluidized bed(BFB)and turbulent fluidized bed(TFB)was carefully examined and systematically compared using catalytic ozone decomposition as a model reaction,based on a complete mapping of local flow structures and spatial distributions of ozone conversion and solids *** clearly has a higher conversion and shows better reactor performance than BFB as a result of the vigorously turbulent flow and the relatively homogeneous gas–solids mixing in ***,the intensive interaction between gas and solids in TFB leads to greater gas–solids contact efficiency of TFB over that of *** to gas bypassing and backmixing caused by bubbling behaviours and two-phase structure,BFB deviates significantly from a plug flow reactor and sometimes from a continuously stirred tank *** flow structures essentially dictate the reactor performance in the low-velocity fluidized beds.

关键词： Bubbling fluidized bed Turbulent fluidized bed Conversion distribution Flow structure Reactor performance Gas–solids contact efficiency

Preamble for special issue honouring Professor Mooson Kwauk

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Particuology 2010年第6期8卷 491-492页

作者： jesse Zhu Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioCanada N6A 5B9

Two years after assuming a new name and format change, the year 2010 marks the 8th anniversary of Particuology. To commemorate this special occasion for the journal, the thematic editors met in Montreal at the 8th World Congress of Chemical Engineering and decided to compile a truly special issue. Instead of producing another ＂conventional＂ special issue of the more ＂regular＂ research papers on some given subjects, we have decided to take a more innovative format for this issue to present short discussion papers that provide quick overviews of the current status of selected subiects and then discuss forward thinking for the future.

关键词： Preamble for special issue honouring Professor Mooson Kwauk EMMS very

Cluster identification using image processing

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Particuology 2015年第6期13卷 16-24页

作者： Jingsi Yang jesse Zhu Particle Technology Research Centre Department of Chemical and Biochemical Engineering University of Western Ontario London Ontario N6A 5B9Canada

By closely examining hue, saturation and value （HSV） images of the solids holdup distribution in a riser, it can be seen that a ＂cluster＂ is the combination of a relatively stable core cluster of the highest solids holdups and constantly changing cluster clouds of solids holdups that are higher than the dilute phase. Based on this analysis, a threshold selection method maximizing the inter-class variance between the background and foreground classes is introduced. A systematic cluster identification process is therefore proposed that：（｜） applies the threshold selection method to obtain the critical solids holdup threshold ~c to discriminate dense and dilute phases and （2） applies the method again in the dense phase regions to obtain the cluster solids holdup threshold Ssct that identifies the core clusters. Using this systematic process, clusters of different shapes and sizes and a relatively clear boundary can be visualized clearly and identified accurately. Using ~sct, the core cluster fraction is calculated by dividing the total number of pixels in the core cluster by the total number of image pixels. The variation of the core cluster fraction according to operating conditions is also discussed.

关键词： Cluster identification Image processingCluster fractionRectangular circulating fluidized bed riser

Dry powder platform for pulmonary drug delivery

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Particuology 2008年第4期6卷 225-238页

作者： Derek Ivan Daniher jesse Zhu Graduate Program in Biomedical Engineering Department of Chemical and Biochemical EngineeringThe University of Western OntarioLondonOntarioCanada

The phenomenon of particle interaction involved in pulmonary drug delivery belongs to a wide variety of disciplines of particle technology, in particular, fluidization. This paper reviews the basic concepts of pulmonary drug delivery with references to fluidization research, in particular, studies on Geldart group C powders. Dry powder inhaler device-formulation combination has been shown to be an effective method for delivering drugs to the lung for treatment of asthma, chronic obstructive pulmonary disease and cystic fibrosis. Even with advanced designs, however, delivery efficiency is still poor mainly due to powder dispersion problems which cause poor lung deposition and high dose variability. Drug particles used in current inhalers must be 1–5 μm in diameter for effective deposition in small-diameter airways and alveoli. These powders are very cohesive, have poor flowability, and are difficult to disperse into aerosol due to cohesion arising from van der Waals attraction. These problems are well known in fluidization research, much of which is highly relevant to pulmonary drug delivery.

关键词： Dry powder inhaler Interparticle forces Aerosol Pulmonary drug delivery Carrier particle Fluidization

Numerical investigations on gas-solid flow in circulating fluidized bed risers using a new cluster-based drag model

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Particuology 2022年第4期20卷 9-23页

作者： Zeneng Sun Chao Zhang jesse Zhu Department of Chemical and Biochemical Engineering.The University of Western Ontario LondonOntarioN6A 3K7Canada Department of Mechanical and Materials Engineering The University of Western OntarioLondonOntarioN6A 3K7Canada

A cluster-based drag model is proposed for the gas-solid circulating fluidized bed(CFB)riser by including the cluster information collected from image processing and wavelet analysis into the calculation of system *** performance of the proposed drag model is compared with some commonly used drag models.A good agreement with the experimental data is achieved by the proposed cluster-based drag *** analysis of the proposed cluster-based drag model based on the local distributions of solids holdup and particle velocity is *** clustering phenomenon in the low-density and high-density CFB risers and the effect of the cluster size on the simulation accuracy are also numerically studied by the proposed drag model.

关键词： Drag model Clustering effect Gas-solid flow structures Circulating fluidized bed

Fast raycasting using a compound deep image for virtual point light range determination

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Computational Visual Media 2019年第3期5卷 257-265页

作者： jesse Archer Geoff Leach Pyarelal Knowles School of Science RMIT University

The concept of using multiple deep images,under a variety of different names, has been explored as a possible acceleration approach for finding raygeometry intersections. We leverage recent advances in deep image processing from order independent transparency for fast building of a compound deep image(CDI) using a coherent memory format well suited for raycasting. We explore the use of a CDI and raycasting for the problem of determining distance between virtual point lights(VPLs) and geometry for indirect lighting,with the key raycasting step being a small fraction of total frametime.

关键词： deep image indirect lighting raycasting

Improving flow and fluidization quality of fine and ultrafine particles via nanoparticle modulation

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Nano Research 2023年第10期16卷 12013-12025页

作者： Jiaying Wang Yuanyuan Shao jesse Zhu Department of Chemical and Biochemical Engineering The University of Western OntarioLondonOntario N6A 3K7Canada School of Chemical Engineering and Technology Tianjin UniversityTianjin 300072China Beacons of Excellence Research and Innovation Institute University of NottinghamNingbo 315100China

Fine and ultrafine particles possess great potential for industrial applications ascribed from their huge specific surface area and ability to provide good gas–solid ***,these powders are inherently cohesive,making it challenging to achieve smooth flow and *** challenge can be well-resolved by nanoparticle modulation(nano-modulation),where a small amount of nanoparticles is uniformly mixed with the cohesive fine/ultrafine *** nano-modulation,the fluidization system of cohesive powders exhibits distinguishable minimum fluidization velocity,enlarged bed expansion ratio(particularly the dense phase expansion),and scarcer,smaller,and slower moving bubbles,indicating improved flow and fluidization *** purpose of the current work is to systematically summarize the state-of-the-art progress in the fluidization and utilization of fine and ultrafine particles via the nanoparticle modulation ***,a broader audience can be enlightened regarding this promising fine/ultrafine particle fluidization technology,so as to provoke their attention and encourage interdisciplinary integration and industry-academia collaborative research.

关键词： fine particle ultrafine particle cohesive powder flowability fluidization nanoparticle modulation