The Experts below are selected from a list of 255 Experts worldwide ranked by ideXlab platform

David Fletcher - One of the best experts on this subject based on the ideXlab platform.

  • Simulation of the Flow around Spacer Filaments between Channel Walls. 2. Mass-Transfer Enhancement
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David Fletcher
    Abstract:

    A computational fluid dynamics (CFD) code was used to study the effects of Reynolds number, mesh length, and Filament Diameter on mass-transfer enhancement for three spacer configurations, a cavity, a zigzag, and a submerged spacer. For the cavity and zigzag spacers, mass-transfer enhancement first increases with a decrease in the mesh length, reaches a maximum, and then decreases with a further decrease in the mesh length, while pressure loss showed a continuous increase with a decrease in the mesh length. The submerged spacer shows a continuous increase of the mass-transfer enhancement and pressure loss with a decrease in the mesh length. For all spacer types, mass transfer increases with the Filament Diameter. However, at a smaller Filament Diameter, the overall spacer performance increases, as indicated by a high mass-transfer enhancement to pressure loss ratio. Overall, the CFD simulations reveal that the zigzag spacer is the most efficient spacer type for a spiral-wound membrane module.

  • Simulation of the Flow around Spacer Filaments between Narrow Channel Walls. 1. Hydrodynamics
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David Fletcher
    Abstract:

    Insights into the effect of spacer Filaments in membrane systems on the flow pattern were obtained using a computational fluid dynamics code. The flow patterns were examined for a single Filament adjacent to the wall and centered in the channel and for three different spacer configurations, the cavity, zigzag, and submerged spacers, with variations in both the mesh length and Filament Diameter for Reynolds numbers ranging from 90 to 768. Large recirculation regions were formed behind the Filaments, and the flow around the Filament increased the shear stress on the wall. For an identical Reynolds number and Filament Diameter, a single Filament adjacent to a membrane wall produced a larger recirculation region than a single Filament in the center of the channel. For the cavity and submerged spacers, above a critical Reynolds number or mesh length, the recirculation regions between sequential Filaments influenced each other and merged to form one large recirculation region between sequential Filaments. In co...

J. Schwinge - One of the best experts on this subject based on the ideXlab platform.

  • a cfd study of unsteady flow in narrow spacer filled channels for spiral wound membrane modules
    Desalination, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David F Fletcher
    Abstract:

    In spiral-wound membrane modules, spacers are used to enhance wall shear stress and to promote eddy mixing, thereby reducing wall concentration and fouling. Insights into the effect of spacer Filaments on flow patterns in narrow channels were obtained using a computational fluid dynamics (CFD) code. The flow patterns were visualized for different Filament configurations incorporating variations in mesh length, Filament Diameter and for channel Reynolds numbers up to 1000. The simulated flow patterns revealed the dependence of the formation of recirculation regions on the Filament configuration, mesh length, Filament Diameter and the Reynolds number. When the channel Reynolds number is increased above 300, the flow becomes super-critical showing time-dependent movements for a Filament located in the center of a narrow channel; and when the channel Reynolds number is increased above 500, the flow becomes super-critical for a Filament adjacent to the membrane wall. For multiple Filament configurations, flow transition can occur at channel Reynolds numbers as low as 80 for the submerged spacer at a very small mesh length (lm/hch = 1) and at a slightly larger Reynolds number at a larger mesh length (lm/hch = 4). The transition occurs above Rech of 300 for the cavity spacer (lm/hch = 4) and above Rech of 400 for the zigzag spacer (lm/hch = 4).

  • Simulation of the Flow around Spacer Filaments between Channel Walls. 2. Mass-Transfer Enhancement
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David Fletcher
    Abstract:

    A computational fluid dynamics (CFD) code was used to study the effects of Reynolds number, mesh length, and Filament Diameter on mass-transfer enhancement for three spacer configurations, a cavity, a zigzag, and a submerged spacer. For the cavity and zigzag spacers, mass-transfer enhancement first increases with a decrease in the mesh length, reaches a maximum, and then decreases with a further decrease in the mesh length, while pressure loss showed a continuous increase with a decrease in the mesh length. The submerged spacer shows a continuous increase of the mass-transfer enhancement and pressure loss with a decrease in the mesh length. For all spacer types, mass transfer increases with the Filament Diameter. However, at a smaller Filament Diameter, the overall spacer performance increases, as indicated by a high mass-transfer enhancement to pressure loss ratio. Overall, the CFD simulations reveal that the zigzag spacer is the most efficient spacer type for a spiral-wound membrane module.

  • Simulation of the Flow around Spacer Filaments between Narrow Channel Walls. 1. Hydrodynamics
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David Fletcher
    Abstract:

    Insights into the effect of spacer Filaments in membrane systems on the flow pattern were obtained using a computational fluid dynamics code. The flow patterns were examined for a single Filament adjacent to the wall and centered in the channel and for three different spacer configurations, the cavity, zigzag, and submerged spacers, with variations in both the mesh length and Filament Diameter for Reynolds numbers ranging from 90 to 768. Large recirculation regions were formed behind the Filaments, and the flow around the Filament increased the shear stress on the wall. For an identical Reynolds number and Filament Diameter, a single Filament adjacent to a membrane wall produced a larger recirculation region than a single Filament in the center of the channel. For the cavity and submerged spacers, above a critical Reynolds number or mesh length, the recirculation regions between sequential Filaments influenced each other and merged to form one large recirculation region between sequential Filaments. In co...

Dianne E. Wiley - One of the best experts on this subject based on the ideXlab platform.

  • a cfd study of unsteady flow in narrow spacer filled channels for spiral wound membrane modules
    Desalination, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David F Fletcher
    Abstract:

    In spiral-wound membrane modules, spacers are used to enhance wall shear stress and to promote eddy mixing, thereby reducing wall concentration and fouling. Insights into the effect of spacer Filaments on flow patterns in narrow channels were obtained using a computational fluid dynamics (CFD) code. The flow patterns were visualized for different Filament configurations incorporating variations in mesh length, Filament Diameter and for channel Reynolds numbers up to 1000. The simulated flow patterns revealed the dependence of the formation of recirculation regions on the Filament configuration, mesh length, Filament Diameter and the Reynolds number. When the channel Reynolds number is increased above 300, the flow becomes super-critical showing time-dependent movements for a Filament located in the center of a narrow channel; and when the channel Reynolds number is increased above 500, the flow becomes super-critical for a Filament adjacent to the membrane wall. For multiple Filament configurations, flow transition can occur at channel Reynolds numbers as low as 80 for the submerged spacer at a very small mesh length (lm/hch = 1) and at a slightly larger Reynolds number at a larger mesh length (lm/hch = 4). The transition occurs above Rech of 300 for the cavity spacer (lm/hch = 4) and above Rech of 400 for the zigzag spacer (lm/hch = 4).

  • Simulation of the Flow around Spacer Filaments between Channel Walls. 2. Mass-Transfer Enhancement
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David Fletcher
    Abstract:

    A computational fluid dynamics (CFD) code was used to study the effects of Reynolds number, mesh length, and Filament Diameter on mass-transfer enhancement for three spacer configurations, a cavity, a zigzag, and a submerged spacer. For the cavity and zigzag spacers, mass-transfer enhancement first increases with a decrease in the mesh length, reaches a maximum, and then decreases with a further decrease in the mesh length, while pressure loss showed a continuous increase with a decrease in the mesh length. The submerged spacer shows a continuous increase of the mass-transfer enhancement and pressure loss with a decrease in the mesh length. For all spacer types, mass transfer increases with the Filament Diameter. However, at a smaller Filament Diameter, the overall spacer performance increases, as indicated by a high mass-transfer enhancement to pressure loss ratio. Overall, the CFD simulations reveal that the zigzag spacer is the most efficient spacer type for a spiral-wound membrane module.

  • Simulation of the Flow around Spacer Filaments between Narrow Channel Walls. 1. Hydrodynamics
    Industrial & Engineering Chemistry Research, 2002
    Co-Authors: J. Schwinge, Dianne E. Wiley, David Fletcher
    Abstract:

    Insights into the effect of spacer Filaments in membrane systems on the flow pattern were obtained using a computational fluid dynamics code. The flow patterns were examined for a single Filament adjacent to the wall and centered in the channel and for three different spacer configurations, the cavity, zigzag, and submerged spacers, with variations in both the mesh length and Filament Diameter for Reynolds numbers ranging from 90 to 768. Large recirculation regions were formed behind the Filaments, and the flow around the Filament increased the shear stress on the wall. For an identical Reynolds number and Filament Diameter, a single Filament adjacent to a membrane wall produced a larger recirculation region than a single Filament in the center of the channel. For the cavity and submerged spacers, above a critical Reynolds number or mesh length, the recirculation regions between sequential Filaments influenced each other and merged to form one large recirculation region between sequential Filaments. In co...

Ting Chen - One of the best experts on this subject based on the ideXlab platform.

  • Numerical study on the polymer drawing of the spunbonding process
    Thermal Science, 2015
    Co-Authors: Kang Yang, Ting Chen
    Abstract:

    A polymer drawing model is established for the spunbonding process through numerical computation of the air flow field. The results show that the model predicts the Filament Diameter effectively. The paper contributes to in-depth understanding of the spunbonding technology.

  • EFFECTS OF THE CONDUIT GEOMETRY ON THE AIR FLOW FIELD IN THE SPUNBONDING PROCESS
    Thermal Science, 2015
    Co-Authors: Hong-mei Sun, Ting Chen
    Abstract:

    In the spunbonding process, the air flow field of the drawing conduit affects the polymer drawing and therefore the Filament Diameter greatly. Effects of the conduit parameters on the air flow field are studied using the previously established air flow field model. The results show that longer narrow section, longer contracting section and larger height of narrow entry are of benefit to increasing the air velocity, thus helpful for decreasing the Filament Diameter.

  • study on the air flow field of the drawing conduit in the spunbonding process
    Thermal Science, 2015
    Co-Authors: Hong-mei Sun, Ting Chen
    Abstract:

    The air flow field of the drawing conduit in the spunbonding process has a great effect on the polymer drawing, the Filament Diameter and orientation. A numerical simulation of the process is carried out, and the results are compared with the experimental data, showing good accuracy of the numerical prediction. This research lays an important foundation for the optimal design of the drawing conduit in the spunbonding process.

  • Preliminary Study on the Fabrication Mechanism of Nanofibers in the Melt Splitting Process
    Journal of Nano Research, 2013
    Co-Authors: Yuan Ling Cheng, Ting Chen
    Abstract:

    Melt splitting is a new technique for the mass production of nanofibers. The polymer melt split radially into several hundred very fine Filaments in a specially designed nozzle. The prediction model for Filament Diameter after splitting in the melt splitting process is established based on the surface wave method. The predicted Filament Diameter compares favorably with the experimental data. Effects of the air pressure and polymer flow rate on the Filament Diameter are studied. It is found that larger air pressure and smaller polymer flow rate can all produce finer Filaments. The results provide a good foundation for the optimization of the melt splitting technique.

I. M. Ward - One of the best experts on this subject based on the ideXlab platform.

  • The relation between Filament Diameter and fracture strength for ultra-high-modulus polyethylene fibres
    Journal of Materials Science, 1993
    Co-Authors: T. Amornsakchai, D. L. M. Cansfield, S. A. Jawad, G. Pollard, I. M. Ward
    Abstract:

    The effect of Filament Diameter on the failure stress of polyethylene fibres has been studied using Weibull analysis. Both gel-spun and melt-spun fibres have been examined, so that differences might be observed for changes in draw ratio or modulus as well as molecular weight. It is concluded that the strength of high-modulus melt-spun fibres relates to the concentration of flaws and is significantly dependent on Filament Diameter. Conflicting results for gel-spun fibres are discussed in the light of the present investigation, and it is concluded that the mechanism of failure in these fibres is different from that of the melt-spun fibres.