The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
W. Beyer - One of the best experts on this subject based on the ideXlab platform.
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Inert Gas Diffusion in DLC-Si films
Diamond and Related Materials, 2002Co-Authors: Sérgio S. Camargo, Julio C. Damasceno, W. BeyerAbstract:Abstract Inert-Gas Diffusion in DLC–Si films was studied by thermal effusion experiments. It is shown that the motion of inert Gases in the films is controlled by Diffusion, greatly depending on the size of the diffusing species. The results provide qualitative information on the microstructure size in agreement with the doorway Diffusion model, in which the mechanical stiffness of the material and the doorway radius are the important parameters that govern the Diffusion process. Maximum effusion temperature is found to increase as the silicon content of the samples is increased, indicating smaller openings and/or increasing rigidity of the network. Analysis of inert-Gas Diffusion in annealed films suggests that the Diffusion process cannot be directly related to carbon bonding and hydrogen content in the films. Network reconstruction effects are found to play an important role in the case of DLC–Si films.
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Inert Gas Diffusion in DLC-Si films
Diamond and Related Materials, 2002Co-Authors: S.s. Camargo Jr., Julio C. Damasceno, W. BeyerAbstract:Inert-Gas Diffusion in DLC-Si films was studied by thermal effusion experiments. It is shown that the motion of inert Gases in the films is controlled by Diffusion, greatly depending on the size of the diffusing species. The results provide qualitative information on the microstructure size in agreement with the doorway Diffusion model, in which the mechanical stiffness of the material and the doorway radius are the important parameters that govern the Diffusion process. Maximum effusion temperature is found to increase as the silicon content of the samples is increased, indicating smaller openings and/or increasing rigidity of the network. Analysis of inert-Gas Diffusion in annealed films suggests that the Diffusion process cannot be directly related to carbon bonding and hydrogen content in the films. Network reconstruction effects are found to play an important role in the case of DLC-Si films. © 2002 Elsevier Science B.V. All rights reserved.
Runzhang Yuan - One of the best experts on this subject based on the ideXlab platform.
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Gas Diffusion through differently structured Gas Diffusion layers of PEM fuel cells
International Journal of Hydrogen Energy, 2007Co-Authors: Zhigang Zhan, Jinsheng Xiao, Yongsheng Zhang, Runzhang YuanAbstract:Abstract Proton exchange membrane fuel cell (PEMFC) Gas Diffusion layers (GDLs) play important parts in diffusing Gas, discharging liquid water, and conducting electricity, etc. When liquid water is discharged through GDL to Gas channel, there will be some pores of GDLs occupied by liquid water. In this study, based on a one-dimensional model, the distribution of liquid water phase saturation is analyzed for different GDL structures including GDL with uniform porosity, GDL with sudden change porosity (GDL with microporous layer (MPL)) and GDL with gradient porosity distribution. The effect on Gas Diffusion of the changes of porosity and liquid saturation due to water remaining in GDL pores is calculated. The conclusions are that for uniform porosity GDL, the Gas Diffusion increases with the increase of porosity and contact angle and increases with the decrease of the thickness of GDL; for GDL with MPL, the larger the MPL porosity and the thinner the MPL thickness are, the stronger the Gas Diffusion is; for gradient change porosity GDL with the same average equivalent porosity, the larger the porosity gradient is, the more easily the Gas diffuses. The optimization for GDL gradient structure shows that the GDL with a linear porosity distribution of 0.4 x + 0.4 is the best of the computed cases.
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Gas Diffusion through differently structured Gas Diffusion layers of PEM fuel cells
International Journal of Hydrogen Energy, 2007Co-Authors: Zhigang Zhan, Jinsheng Xiao, Mu Pan, Yongsheng Zhang, Runzhang YuanAbstract:Proton exchange membrane fuel cell (PEMFC) Gas Diffusion layers (GDLs) play important parts in diffusing Gas, discharging liquid water, and conducting electricity, etc. When liquid water is discharged through GDL to Gas channel, there will be some pores of GDLs occupied by liquid water. In this study, based on a one-dimensional model, the distribution of liquid water phase saturation is analyzed for different GDL structures including GDL with uniform porosity, GDL with sudden change porosity (GDL with microporous layer (MPL)) and GDL with gradient porosity distribution. The effect on Gas Diffusion of the changes of porosity and liquid saturation due to water remaining in GDL pores is calculated. The conclusions are that for uniform porosity GDL, the Gas Diffusion increases with the increase of porosity and contact angle and increases with the decrease of the thickness of GDL; for GDL with MPL, the larger the MPL porosity and the thinner the MPL thickness are, the stronger the Gas Diffusion is; for gradient change porosity GDL with the same average equivalent porosity, the larger the porosity gradient is, the more easily the Gas diffuses. The optimization for GDL gradient structure shows that the GDL with a linear porosity distribution of 0.4 x + 0.4 is the best of the computed cases. © 2007 International Association for Hydrogen Energy.
F. Adenot - One of the best experts on this subject based on the ideXlab platform.
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Experimental Study of Gas Diffusion in Cement Paste
Cement and Concrete Research, 2007Co-Authors: J. Sercombe, R. Vidal, C. Galle, F. AdenotAbstract:This paper presents an experimental study of Gas Diffusion in binary mixtures of hydrogen–nitrogen and xenon–nitrogen through cement pastes (CEM I and CEM V) of different water/cement ratios (0.35 and 0.45). First, the impact of water saturation on Gas Diffusion is studied by performing tests on samples pre-conditioned in specific atmospheric conditions (dry, 55, 70, 82, 93, and 100% RH) by means of saline solutions. The comparison of the results obtained for the CEM I and the CEM V samples (w/c ratio of 0.45) demonstrate the importance of pore size distribution/connectivity on Gas Diffusion. Second, Diffusion tests at different total pressures and using 2 different mixtures (hydrogen–nitrogen, xenon–nitrogen) are performed to study the nature of Gas Diffusion in cement paste. Results demonstrate that Gas Diffusion in cement paste is controlled by Knudsen and ordinary Diffusion at pressures greater than 100 kPa and mainly by Knudsen Diffusion at pressures less than 100 kPa.
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Experimental study of Gas Diffusion in cement paste
Cement and Concrete Research, 2006Co-Authors: J. Sercombe, R. Vidal, C. Galle, F. AdenotAbstract:This paper presents an experimental study of Gas Diffusion in binary mixtures of hydrogen–nitrogen and xenon–nitrogen through cement pastes (CEM I and CEM V) of different water/cement ratios (0.35 and 0.45). First, the impact of water saturation on Gas Diffusion is investigated by performing tests on samples pre-conditioned in specific atmospheric conditions (dry, 55, 70, 82, 93 and 100% RH) by means of saline solutions. The comparison of the results obtained for the CEM I and the CEM V samples ($w/c$ ratio of 0.45) demonstrate the importance of pore size distribution/connectivity on Gas Diffusion. Second, Diffusion tests at different total pressures and using two different mixtures (hydrogen–nitrogen, xenon–nitrogen) are performed to study the nature of Gas Diffusion in cement paste. Results demonstrate that Gas Diffusion in cement paste is controlled by Knudsen and ordinary Diffusion at pressures greater than 100 kPa and mainly by Knudsen Diffusion at pressures less than 100 kPa.
S.s. Camargo Jr. - One of the best experts on this subject based on the ideXlab platform.
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Inert Gas Diffusion in DLC-Si films
Diamond and Related Materials, 2002Co-Authors: S.s. Camargo Jr., Julio C. Damasceno, W. BeyerAbstract:Inert-Gas Diffusion in DLC-Si films was studied by thermal effusion experiments. It is shown that the motion of inert Gases in the films is controlled by Diffusion, greatly depending on the size of the diffusing species. The results provide qualitative information on the microstructure size in agreement with the doorway Diffusion model, in which the mechanical stiffness of the material and the doorway radius are the important parameters that govern the Diffusion process. Maximum effusion temperature is found to increase as the silicon content of the samples is increased, indicating smaller openings and/or increasing rigidity of the network. Analysis of inert-Gas Diffusion in annealed films suggests that the Diffusion process cannot be directly related to carbon bonding and hydrogen content in the films. Network reconstruction effects are found to play an important role in the case of DLC-Si films. © 2002 Elsevier Science B.V. All rights reserved.
Zhigang Zhan - One of the best experts on this subject based on the ideXlab platform.
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Gas Diffusion through differently structured Gas Diffusion layers of PEM fuel cells
International Journal of Hydrogen Energy, 2007Co-Authors: Zhigang Zhan, Jinsheng Xiao, Yongsheng Zhang, Runzhang YuanAbstract:Abstract Proton exchange membrane fuel cell (PEMFC) Gas Diffusion layers (GDLs) play important parts in diffusing Gas, discharging liquid water, and conducting electricity, etc. When liquid water is discharged through GDL to Gas channel, there will be some pores of GDLs occupied by liquid water. In this study, based on a one-dimensional model, the distribution of liquid water phase saturation is analyzed for different GDL structures including GDL with uniform porosity, GDL with sudden change porosity (GDL with microporous layer (MPL)) and GDL with gradient porosity distribution. The effect on Gas Diffusion of the changes of porosity and liquid saturation due to water remaining in GDL pores is calculated. The conclusions are that for uniform porosity GDL, the Gas Diffusion increases with the increase of porosity and contact angle and increases with the decrease of the thickness of GDL; for GDL with MPL, the larger the MPL porosity and the thinner the MPL thickness are, the stronger the Gas Diffusion is; for gradient change porosity GDL with the same average equivalent porosity, the larger the porosity gradient is, the more easily the Gas diffuses. The optimization for GDL gradient structure shows that the GDL with a linear porosity distribution of 0.4 x + 0.4 is the best of the computed cases.
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Gas Diffusion through differently structured Gas Diffusion layers of PEM fuel cells
International Journal of Hydrogen Energy, 2007Co-Authors: Zhigang Zhan, Jinsheng Xiao, Mu Pan, Yongsheng Zhang, Runzhang YuanAbstract:Proton exchange membrane fuel cell (PEMFC) Gas Diffusion layers (GDLs) play important parts in diffusing Gas, discharging liquid water, and conducting electricity, etc. When liquid water is discharged through GDL to Gas channel, there will be some pores of GDLs occupied by liquid water. In this study, based on a one-dimensional model, the distribution of liquid water phase saturation is analyzed for different GDL structures including GDL with uniform porosity, GDL with sudden change porosity (GDL with microporous layer (MPL)) and GDL with gradient porosity distribution. The effect on Gas Diffusion of the changes of porosity and liquid saturation due to water remaining in GDL pores is calculated. The conclusions are that for uniform porosity GDL, the Gas Diffusion increases with the increase of porosity and contact angle and increases with the decrease of the thickness of GDL; for GDL with MPL, the larger the MPL porosity and the thinner the MPL thickness are, the stronger the Gas Diffusion is; for gradient change porosity GDL with the same average equivalent porosity, the larger the porosity gradient is, the more easily the Gas diffuses. The optimization for GDL gradient structure shows that the GDL with a linear porosity distribution of 0.4 x + 0.4 is the best of the computed cases. © 2007 International Association for Hydrogen Energy.
