The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform

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

  • the effect of a non woven Scrim at the surface of a flat sheet microporous membrane on gas liquid mass transfer
    Journal of Membrane Science, 2008
    Co-Authors: Jose R Alvarez, John W Shanahan, Michael J Semmens
    Abstract:

    Abstract Non-woven Scrims can be attached to membranes to provide a protective support for biofilm development and discourage complete biofilm sloughing. This work characterizes the impact of a ∼400-μm thick, non-woven Scrim at a membrane surface on gas–liquid oxygen transfer. The gas transfer characteristics of a conventional microporous membrane, with and without Scrim attached to its surface, were measured experimentally. In addition, local changes in gas transfer behavior were characterized using microelectrodes to measure dissolved oxygen profiles above each membrane. Reynolds numbers were varied from 50 to 1400 and a high gas flow rate was used to ensure a negligible drop in oxygen partial pressure across the membrane module. Higher mass transfer coefficients were generally obtained for the membrane without Scrim. Indeed, the experimental performance dramatically exceeded that expected from theory, and we believe this was attributable to the module inlet design, and a localized boundary layer disruption. Dissolved oxygen profiles along the membrane confirmed the expected boundary layer development. When a Scrim was added it created a stagnant film close to the membrane surface but it appeared to interrupt the development of an overlying boundary layer. As a result, the Scrim-covered membrane performed as well as the theoretical predictions for a flat-sheet membrane. These data suggest that the presence of the Scrim did not significantly impede gas transfer and may actually enhance gas transfer in long membrane modules.

  • The effect of a non-woven Scrim at the surface of a flat-sheet, microporous membrane on gas–liquid mass transfer
    Journal of Membrane Science, 2008
    Co-Authors: Jose R Alvarez, John W Shanahan, Michael J Semmens
    Abstract:

    Abstract Non-woven Scrims can be attached to membranes to provide a protective support for biofilm development and discourage complete biofilm sloughing. This work characterizes the impact of a ∼400-μm thick, non-woven Scrim at a membrane surface on gas–liquid oxygen transfer. The gas transfer characteristics of a conventional microporous membrane, with and without Scrim attached to its surface, were measured experimentally. In addition, local changes in gas transfer behavior were characterized using microelectrodes to measure dissolved oxygen profiles above each membrane. Reynolds numbers were varied from 50 to 1400 and a high gas flow rate was used to ensure a negligible drop in oxygen partial pressure across the membrane module. Higher mass transfer coefficients were generally obtained for the membrane without Scrim. Indeed, the experimental performance dramatically exceeded that expected from theory, and we believe this was attributable to the module inlet design, and a localized boundary layer disruption. Dissolved oxygen profiles along the membrane confirmed the expected boundary layer development. When a Scrim was added it created a stagnant film close to the membrane surface but it appeared to interrupt the development of an overlying boundary layer. As a result, the Scrim-covered membrane performed as well as the theoretical predictions for a flat-sheet membrane. These data suggest that the presence of the Scrim did not significantly impede gas transfer and may actually enhance gas transfer in long membrane modules.

Jose R Alvarez - One of the best experts on this subject based on the ideXlab platform.

  • the effect of a non woven Scrim at the surface of a flat sheet microporous membrane on gas liquid mass transfer
    Journal of Membrane Science, 2008
    Co-Authors: Jose R Alvarez, John W Shanahan, Michael J Semmens
    Abstract:

    Abstract Non-woven Scrims can be attached to membranes to provide a protective support for biofilm development and discourage complete biofilm sloughing. This work characterizes the impact of a ∼400-μm thick, non-woven Scrim at a membrane surface on gas–liquid oxygen transfer. The gas transfer characteristics of a conventional microporous membrane, with and without Scrim attached to its surface, were measured experimentally. In addition, local changes in gas transfer behavior were characterized using microelectrodes to measure dissolved oxygen profiles above each membrane. Reynolds numbers were varied from 50 to 1400 and a high gas flow rate was used to ensure a negligible drop in oxygen partial pressure across the membrane module. Higher mass transfer coefficients were generally obtained for the membrane without Scrim. Indeed, the experimental performance dramatically exceeded that expected from theory, and we believe this was attributable to the module inlet design, and a localized boundary layer disruption. Dissolved oxygen profiles along the membrane confirmed the expected boundary layer development. When a Scrim was added it created a stagnant film close to the membrane surface but it appeared to interrupt the development of an overlying boundary layer. As a result, the Scrim-covered membrane performed as well as the theoretical predictions for a flat-sheet membrane. These data suggest that the presence of the Scrim did not significantly impede gas transfer and may actually enhance gas transfer in long membrane modules.

  • The effect of a non-woven Scrim at the surface of a flat-sheet, microporous membrane on gas–liquid mass transfer
    Journal of Membrane Science, 2008
    Co-Authors: Jose R Alvarez, John W Shanahan, Michael J Semmens
    Abstract:

    Abstract Non-woven Scrims can be attached to membranes to provide a protective support for biofilm development and discourage complete biofilm sloughing. This work characterizes the impact of a ∼400-μm thick, non-woven Scrim at a membrane surface on gas–liquid oxygen transfer. The gas transfer characteristics of a conventional microporous membrane, with and without Scrim attached to its surface, were measured experimentally. In addition, local changes in gas transfer behavior were characterized using microelectrodes to measure dissolved oxygen profiles above each membrane. Reynolds numbers were varied from 50 to 1400 and a high gas flow rate was used to ensure a negligible drop in oxygen partial pressure across the membrane module. Higher mass transfer coefficients were generally obtained for the membrane without Scrim. Indeed, the experimental performance dramatically exceeded that expected from theory, and we believe this was attributable to the module inlet design, and a localized boundary layer disruption. Dissolved oxygen profiles along the membrane confirmed the expected boundary layer development. When a Scrim was added it created a stagnant film close to the membrane surface but it appeared to interrupt the development of an overlying boundary layer. As a result, the Scrim-covered membrane performed as well as the theoretical predictions for a flat-sheet membrane. These data suggest that the presence of the Scrim did not significantly impede gas transfer and may actually enhance gas transfer in long membrane modules.

Stephen K Gray - One of the best experts on this subject based on the ideXlab platform.

  • identification of material and physical features of membrane distillation membranes for high performance desalination
    Journal of Membrane Science, 2010
    Co-Authors: Jianhua Zhang, Mikel Duke, Eddy Ostarcevic, Junde Li, Stephen K Gray
    Abstract:

    In this paper, the performances of various membranes were assessed in Direct Contact Membrane Distillation (DCMD) under different feed velocities and inlet temperatures. The membranes studied included a polyvinylidenefluoride (PVDF) microfiltration membrane with a non-woven support layer, a polytetrafluoroethylene (PTFE) microfiltration membrane with a non-woven support layer, and three MD membranes made from PTFE of different pore size and all with a structured Scrim support layer. The results showed that distillation using PTFE membranes produced much higher flux than that of the PVDF microfiltration membrane at the same operational conditions, and the support layer affected not only the flux, but also the energy efficiency (0.51–0.24). The results also show that increasing the velocity of the feed and its inlet temperature increased the flux, but the rate of flux increase diminishes at high velocities. The mass transfer coefficient improved for thinner support and active layer membranes, leading to fluxes as high as 46 L m−2 h−1 at 80 °C. The heat transfer characteristics were found to be superior for the open Scrim backed membranes compared to the non-woven support membranes, resulting in significantly greater thermal efficiency for the Scrim backed membranes.

John W Shanahan - One of the best experts on this subject based on the ideXlab platform.

  • the effect of a non woven Scrim at the surface of a flat sheet microporous membrane on gas liquid mass transfer
    Journal of Membrane Science, 2008
    Co-Authors: Jose R Alvarez, John W Shanahan, Michael J Semmens
    Abstract:

    Abstract Non-woven Scrims can be attached to membranes to provide a protective support for biofilm development and discourage complete biofilm sloughing. This work characterizes the impact of a ∼400-μm thick, non-woven Scrim at a membrane surface on gas–liquid oxygen transfer. The gas transfer characteristics of a conventional microporous membrane, with and without Scrim attached to its surface, were measured experimentally. In addition, local changes in gas transfer behavior were characterized using microelectrodes to measure dissolved oxygen profiles above each membrane. Reynolds numbers were varied from 50 to 1400 and a high gas flow rate was used to ensure a negligible drop in oxygen partial pressure across the membrane module. Higher mass transfer coefficients were generally obtained for the membrane without Scrim. Indeed, the experimental performance dramatically exceeded that expected from theory, and we believe this was attributable to the module inlet design, and a localized boundary layer disruption. Dissolved oxygen profiles along the membrane confirmed the expected boundary layer development. When a Scrim was added it created a stagnant film close to the membrane surface but it appeared to interrupt the development of an overlying boundary layer. As a result, the Scrim-covered membrane performed as well as the theoretical predictions for a flat-sheet membrane. These data suggest that the presence of the Scrim did not significantly impede gas transfer and may actually enhance gas transfer in long membrane modules.

  • The effect of a non-woven Scrim at the surface of a flat-sheet, microporous membrane on gas–liquid mass transfer
    Journal of Membrane Science, 2008
    Co-Authors: Jose R Alvarez, John W Shanahan, Michael J Semmens
    Abstract:

    Abstract Non-woven Scrims can be attached to membranes to provide a protective support for biofilm development and discourage complete biofilm sloughing. This work characterizes the impact of a ∼400-μm thick, non-woven Scrim at a membrane surface on gas–liquid oxygen transfer. The gas transfer characteristics of a conventional microporous membrane, with and without Scrim attached to its surface, were measured experimentally. In addition, local changes in gas transfer behavior were characterized using microelectrodes to measure dissolved oxygen profiles above each membrane. Reynolds numbers were varied from 50 to 1400 and a high gas flow rate was used to ensure a negligible drop in oxygen partial pressure across the membrane module. Higher mass transfer coefficients were generally obtained for the membrane without Scrim. Indeed, the experimental performance dramatically exceeded that expected from theory, and we believe this was attributable to the module inlet design, and a localized boundary layer disruption. Dissolved oxygen profiles along the membrane confirmed the expected boundary layer development. When a Scrim was added it created a stagnant film close to the membrane surface but it appeared to interrupt the development of an overlying boundary layer. As a result, the Scrim-covered membrane performed as well as the theoretical predictions for a flat-sheet membrane. These data suggest that the presence of the Scrim did not significantly impede gas transfer and may actually enhance gas transfer in long membrane modules.

Jianhua Zhang - One of the best experts on this subject based on the ideXlab platform.

  • identification of material and physical features of membrane distillation membranes for high performance desalination
    Journal of Membrane Science, 2010
    Co-Authors: Jianhua Zhang, Mikel Duke, Eddy Ostarcevic, Junde Li, Stephen K Gray
    Abstract:

    In this paper, the performances of various membranes were assessed in Direct Contact Membrane Distillation (DCMD) under different feed velocities and inlet temperatures. The membranes studied included a polyvinylidenefluoride (PVDF) microfiltration membrane with a non-woven support layer, a polytetrafluoroethylene (PTFE) microfiltration membrane with a non-woven support layer, and three MD membranes made from PTFE of different pore size and all with a structured Scrim support layer. The results showed that distillation using PTFE membranes produced much higher flux than that of the PVDF microfiltration membrane at the same operational conditions, and the support layer affected not only the flux, but also the energy efficiency (0.51–0.24). The results also show that increasing the velocity of the feed and its inlet temperature increased the flux, but the rate of flux increase diminishes at high velocities. The mass transfer coefficient improved for thinner support and active layer membranes, leading to fluxes as high as 46 L m−2 h−1 at 80 °C. The heat transfer characteristics were found to be superior for the open Scrim backed membranes compared to the non-woven support membranes, resulting in significantly greater thermal efficiency for the Scrim backed membranes.

  • Identification of material and physical features of membrane distillation membranes for high performance desalination
    Journal of Membrane Science, 2010
    Co-Authors: Jianhua Zhang, Mikel Duke, Eddy Ostarcevic, Junde Li, Stephen Gray
    Abstract:

    In this paper, the performances of various membranes were assessed in Direct Contact Membrane Distillation (DCMD) under different feed velocities and inlet temperatures. The membranes studied included a polyvinylidenefluoride (PVDF) microfiltration membrane with a non-woven support layer, a polytetrafluoroethylene (PTFE) microfiltration membrane with a non-woven support layer, and threeMDmembranes made from PTFE of different pore size and all with a structured Scrim support layer. The results showed that distillation using PTFE membranes produced much higher flux than that of the PVDF microfiltration membrane at the same operational conditions, and the support layer affected not only the flux, but also the energy efficiency (0.51–0.24). The results also show that increasing the velocity of the feed and its inlet temperature increased the flux, but the rate of flux increase diminishes at high velocities. The mass\ud transfer coefficient improved for thinner support and active layer membranes, leading to fluxes as high as 46 Lm−2 h−1 at 80 degrees C. The heat transfer characteristics were found to be superior for the open Scrim backed membranes compared to the non-woven support membranes, resulting in significantly greater thermal efficiency for the Scrim backed membranes