The Experts below are selected from a list of 1584 Experts worldwide ranked by ideXlab platform

Rajesh N. Dave - One of the best experts on this subject based on the ideXlab platform.

  • Influence of guest and host particle sizes on dry coating effectiveness: When not to use high mixing intensity
    Powder Technology, 2020
    Co-Authors: Kai Zheng, Kuriakose Kunnath, Zhipeng Ling, Liang Chen, Rajesh N. Dave
    Abstract:

    Abstract The effects of material stiffness, host and guest particle sizes, and mixing intensity on dry coating quality were investigated using a high-intensity vibrational mixer, using KCl, cornstarch, aluminum silicate and nano-sized silica. The coating quality deteriorated with larger guest particle size at high process intensity, and high material stiffness. Coarse guest particles detached from host particles above certain mixing intensity, indicating higher intensity is not recommended; e.g., the best coating quality for cornstarch was for medium-sized hosts below 30 Gs intensity. However, for nano-silica guests, higher processing intensity did not lead to their detachment, but decreased their agglomeration. Such behavior was explained using the energy-based stick/bounce model and two indices. The coating quality index (Kc), the ratio of total detachment energy to relative kinetic energy, assessed the guest particle attachment tendency. The Deagglomeration index (Kd), the ratio of Deagglomeration energy to relative kinetic energy, assessed the guest particle agglomeration tendency.

  • Discrete element method based analysis of mixing and collision dynamics in adhesive mixing process
    Chemical Engineering Science, 2018
    Co-Authors: Xiaoliang Deng, Kai Zheng, Rajesh N. Dave
    Abstract:

    Abstract When small amounts of fine particles are mixed with coarser particles, they tend to form ordered or adhesive mixtures. In order to understand the effect of fine particle amount and cohesion on the adhesive mixing process, discrete element method (DEM) simulations are carried out in which cohesion is represented by surface energy. High-intensity vibrational mixing was used to examine two important and related dynamic processes; fine particle Deagglomeration and their subsequent adhesion to coarse particles, by analyzing normalized fine-fine (FF) and coarse–fine (CF) particle contact numbers, respectively, along with the mixing quality. It is found that FF contacts decreases with the mixing time, indicating Deagglomeration, before reaching equilibrium; while CF contacts, an indicator of coating, as well as mixing quality increase before reaching equilibrium. A major new finding is that the number of fine particles per coarse particle at equilibrium follows lognormal distribution. The time scales to reach equilibrium FF contact number and mixing quality are comparable, indicating that Deagglomeration is the dominant factor for achieving a uniform adhesive mixture. As expected, increasing surface energy of fine particles leads to decreased mixing quality due to stronger agglomerates that cannot be broken by collisions. On the other hand, collision rate can dictate mixing quality, as long as the collision energy is greater than the corresponding detachment energy of fine particles agglomerates. Selected experimental results validate the DEM simulations and their ability to describe the adhesive mixing process.

  • Nanoparticle mixing through rapid expansion of high pressure and supercritical suspensions
    Journal of Nanoparticle Research, 2011
    Co-Authors: Sankaran Sundaresan, Rajesh N. Dave
    Abstract:

    Mixing of binary mixtures of nanopowders afforded by rapid expansion of high pressure and supercritical suspensions (REHPS) is investigated to examine the roles of two previously reported Deagglomeration mechanisms. The quality of mixing was characterized through intensity and scale of segregation using concentration data obtained through energy dispersive X-ray spectroscopy; the corresponding Deagglomeration was quantified using differential mobility and image analyses in conjunction with electron microscopy. Increasing the pressure from which expansion was carried out, and decreasing the nozzle diameter led to improved Deagglomeration. However, increased pressure alone did not influence the mixture quality, which was found to also depend on the scale of mixedness of the constituents before transport through the nozzle, establishing that the REHPS mixing is significantly improved by improving the quality of the premix. The scale of segregation correlated with the size of the most energetic eddies present during flow through the nozzle, both of which increased with nozzle diameter, corroborating the importance of previously reported shear-induced Deagglomeration mechanism. Finally, REHPS was also shown to be capable of deagglomerating carbon nanotube bundles and mix them well with alumina, silica, and titania at submicron scale.

  • Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high‐pressure suspensions
    Aiche Journal, 2009
    Co-Authors: Rajesh N. Dave, Xiaolong Yin, Sankaran Sundaresan
    Abstract:

    Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high-pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 μm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 μm. Analysis of the RESS/REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub-micron level Deagglomeration. © 2009 American Institute of Chemical Engineers AIChE J, 2009

  • Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high pressure suspensions
    Aiche Journal, 2009
    Co-Authors: Rajesh N. Dave, Xiaolong Yin, Sankaran Sundaresan
    Abstract:

    Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high-pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 μm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 μm. Analysis of the RESS/REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub-micron level Deagglomeration. © 2009 American Institute of Chemical Engineers AIChE J, 2009

Sankaran Sundaresan - One of the best experts on this subject based on the ideXlab platform.

  • Nanoparticle mixing through rapid expansion of high pressure and supercritical suspensions
    Journal of Nanoparticle Research, 2011
    Co-Authors: Sankaran Sundaresan, Rajesh N. Dave
    Abstract:

    Mixing of binary mixtures of nanopowders afforded by rapid expansion of high pressure and supercritical suspensions (REHPS) is investigated to examine the roles of two previously reported Deagglomeration mechanisms. The quality of mixing was characterized through intensity and scale of segregation using concentration data obtained through energy dispersive X-ray spectroscopy; the corresponding Deagglomeration was quantified using differential mobility and image analyses in conjunction with electron microscopy. Increasing the pressure from which expansion was carried out, and decreasing the nozzle diameter led to improved Deagglomeration. However, increased pressure alone did not influence the mixture quality, which was found to also depend on the scale of mixedness of the constituents before transport through the nozzle, establishing that the REHPS mixing is significantly improved by improving the quality of the premix. The scale of segregation correlated with the size of the most energetic eddies present during flow through the nozzle, both of which increased with nozzle diameter, corroborating the importance of previously reported shear-induced Deagglomeration mechanism. Finally, REHPS was also shown to be capable of deagglomerating carbon nanotube bundles and mix them well with alumina, silica, and titania at submicron scale.

  • Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high‐pressure suspensions
    Aiche Journal, 2009
    Co-Authors: Rajesh N. Dave, Xiaolong Yin, Sankaran Sundaresan
    Abstract:

    Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high-pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 μm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 μm. Analysis of the RESS/REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub-micron level Deagglomeration. © 2009 American Institute of Chemical Engineers AIChE J, 2009

  • Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high pressure suspensions
    Aiche Journal, 2009
    Co-Authors: Rajesh N. Dave, Xiaolong Yin, Sankaran Sundaresan
    Abstract:

    Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high-pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 μm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 μm. Analysis of the RESS/REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub-micron level Deagglomeration. © 2009 American Institute of Chemical Engineers AIChE J, 2009

Gul Ozcan-taskin - One of the best experts on this subject based on the ideXlab platform.

  • Power and flow characteristics of the in-line rotor-stator Ytron ZC
    2020
    Co-Authors: James Mitchell, James Bacon, Nabeel Umar, Chris D. Rielly, Gul Ozcan-taskin
    Abstract:

    • The suction performance of an in-line rotor-stator used for powder incorporation into a liquid, the Ytron ZC1, showed an optimum range of operation avoiding liquid flow into the powder inlet for both 1.5 and 3.0 mm gap heads• Power characteristics of the Ytron ZC1 were determined and two expressions were obtained for 1.5 and 3.0 mm gap rotor-stator heads• Results obtained will form the basis for further studies on incorporation and Deagglomeration

  • Break up of silica nanoparticle clusters using ultrasonication
    2018
    Co-Authors: James Bacon, Chris Rielly, Gul Ozcan-taskin
    Abstract:

    This study is concerned with the Deagglomeration of hydrophilic silica nanoparticle clusters (Aerosil® 200V) in water using an ultrasonicator operated in batch mode. An impeller was also present in the tank to ensure homogeneity. The effect of power input was studied in the range of 18 to 77 W (9 to 39 kW m-3) on the kinetics and mechanisms of Deagglomeration and the dispersion fineness. The effect of particle concentration was also studied in the range of 1 to 15% wt. The process was monitored through the evolution of particle size distribution (PSD), which indicated erosion as the dominant mechanism of breakup. The smallest attainable particle size was found to be independent of power input and solid concentration. Faster break up kinetics were noted as the power input was increased whereas increasing the solids concentration to 15% wt. slowed the process. It could also be shown that processing concentrated dispersions can be beneficial as the break up rate assessed on the basis of energy per unit mass of solids was faster for increased particle concentration

  • Comparative performance of in-line rotor-stators for Deagglomeration processes
    2016
    Co-Authors: Gul Ozcan-taskin, Gustavo A. Padron, Dominik Kubicki
    Abstract:

    Comparative performance of in-line rotor-stators for Deagglomeration processe

Xiaolong Yin - One of the best experts on this subject based on the ideXlab platform.

  • Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high‐pressure suspensions
    Aiche Journal, 2009
    Co-Authors: Rajesh N. Dave, Xiaolong Yin, Sankaran Sundaresan
    Abstract:

    Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high-pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 μm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 μm. Analysis of the RESS/REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub-micron level Deagglomeration. © 2009 American Institute of Chemical Engineers AIChE J, 2009

  • Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high pressure suspensions
    Aiche Journal, 2009
    Co-Authors: Rajesh N. Dave, Xiaolong Yin, Sankaran Sundaresan
    Abstract:

    Deagglomeration of suspensions of alumina and titania nanopowders (i.e., nanoparticle aggregates) via rapid expansion of supercritical suspensions (RESS) or high-pressure suspensions (REHPS) was studied. The size distribution of fragmented nanopowders was characterized by online Scanning Mobility Particle Spectrometer (SMPS) and Aerodynamic Particle Sizer (APS), and by offline Scanning Electron Microscopy (SEM). SMPS and SEM measurements indicate that the average agglomerate sizes were well below 1 μm, consistent with the length scales observed in our complementary RESS/REHPS mixing experiments using alumina and silica nanopowders. The APS measurements, on the other hand, were affected by reagglomeration during sampling and yielded an agglomerate size range of 1 to 3 μm. Analysis of the RESS/REHPS process through compressible flow models revealed that both the shear stress in the nozzle and the subsequent impact of the agglomerates with the Mach disc in the free expansion region can lead to micron or sub-micron level Deagglomeration. © 2009 American Institute of Chemical Engineers AIChE J, 2009

Christine M. Hrenya - One of the best experts on this subject based on the ideXlab platform.

  • cluster induced Deagglomeration in dilute gravity driven gas solid flows of cohesive grains
    Physical Review Letters, 2018
    Co-Authors: Peiyua Liu, Christine M. Hrenya
    Abstract:

    Clustering is often presumed to lead to enhanced agglomeration between cohesive grains due to the reduced relative velocities of particles within a cluster. Our discrete-particle simulations on gravity-driven, gas-solid flows of cohesive grains exhibit the opposite trend, revealing a new mechanism we coin "cluster-induced Deagglomeration." Specifically, we examine relatively dilute gas-solid flows and isolate agglomerates of cohesive origin from overall heterogeneities in the system, i.e., agglomerates of cohesive origin and clusters of hydrodynamic origin. We observe enhanced clustering with an increasing system size (as is the norm for noncohesive systems) as well as reduced agglomeration. The reduced agglomeration is traced to the increased collisional impact velocities of particles at the surface of a cluster; i.e., higher levels of clustering lead to larger relative velocities between the clustered and nonclustered regions, thereby serving as an additional source of granular temperature. This physical picture is further evidenced by a theoretical model based on a balance between the generation and breakage rates of agglomerates. Finally, cluster-induced Deagglomeration also provides an explanation for a surprising saturation of agglomeration levels in gravity-driven, gas-solid systems with increasing levels of cohesion, as opposed to the monotonically increasing behavior seen in free-evolving or driven granular systems in the absence of gravity. Namely, higher cohesion leads to more energy dissipation, which is associated with competing effects: enhanced agglomeration and enhanced clustering, the latter of which results in more cluster-induced Deagglomeration.

  • Cluster-induced Deagglomeration in Dilute Gas-solid Flows of Cohesive Grains
    2018
    Co-Authors: Peiyuan Liu, Christine M. Hrenya
    Abstract:

    Clustering instabilities are often presumed to lead to enhanced agglomeration between cohesive grains due to the reduced relative velocities of particles within a cluster. Our discrete-particle simulations exhibit the opposite trend, revealing a new mechanism we coin "cluster-induced Deagglomeration". We examine relatively dilute gas-solid flows, and isolate agglomerates of cohesive origin from overall heterogeneities in the system - i.e., those arising from clusters of hydrodynamic origin as well as cohesive agglomerates. We observe enhanced clustering with increasing system size (as is the norm for non-cohesive systems) as well as reduced agglomeration. The reduced agglomeration is traced to the increased collisional impact velocities of particles at the surface of a cluster - i.e., higher levels of clustering lead to larger relative velocities between the clustered and non-clustered regions, thereby serving as an additional source of granular temperature. This physical picture is further evidenced by a theoretical model based on a balance between the generation and breakage rates of agglomerates. Finally, cluster-induced Deagglomeration also provides an explanation for a surprising saturation of agglomeration levels in gas-solids systems with increasing levels of cohesion, as opposed to the monotonic behavior seen in granular flows of cohesive grains. Namely, higher cohesion leads to more energy dissipation, which is associated with competing effects: enhanced agglomeration and enhanced clustering, the latter of which results in more cluster-induced Deagglomeration.