Calculation of moisture distribution in early-age concrete / Jun Zhang in Journal of engineering mechanics, Vol. 135 N° 8 (Août 2009)  

Public ISBD [article]  inJournal of engineering mechanics > Vol. 135 N° 8 (Août 2009) . - pp. 871-880 Titre : Calculation of moisture distribution in early-age concrete Type de document : texte imprimé Auteurs : Jun Zhang, Auteur ; Qi, Kun, Auteur ; Yu Huang, Auteur Article en page(s) : pp. 871-880 Note générale : Mécanique appliquée Langues : Anglais (eng) Mots-clés : Concrete Aging Moisture Humidity. Résumé : The moisture content in concrete pores is a critical parameter for most of the degradation processes suffered by concrete, such as concrete shrinkage and related cracking. The objective of this paper is to present the formulation of a general moisture distribution model for young-age concrete. In the modeling, both cement hydration and moisture diffusion resulted humidity variations are taken into account synchronously. The effect of initial water distribution (after concrete casting) on the development of moisture distribution is considered by introducing a critical time parameter. The simulation of humidity reduction produced from self-desiccation is based on cement hydration degree that taking the effect of temperature into account by using the equilibrant age concept. During modeling the moisture diffusion, a multilinear model was adopted to simulate the moisture dependent diffusivity. The developed model and finite deferential method can well predict the moisture distribution as well as its variations with time. Good agreement between model predictions and experimental results is found. These results can subsequently be used in shrinkage induced stress field analyses, and further be used for cracking control of concrete structures. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...] [article] Calculation of moisture distribution in early-age concrete [texte imprimé] / Jun Zhang, Auteur ; Qi, Kun, Auteur ; Yu Huang, Auteur . - pp. 871-880. Mécanique appliquée Langues : Anglais (eng) in Journal of engineering mechanics > Vol. 135 N° 8 (Août 2009) . - pp. 871-880 Mots-clés : Concrete Aging Moisture Humidity. Résumé : The moisture content in concrete pores is a critical parameter for most of the degradation processes suffered by concrete, such as concrete shrinkage and related cracking. The objective of this paper is to present the formulation of a general moisture distribution model for young-age concrete. In the modeling, both cement hydration and moisture diffusion resulted humidity variations are taken into account synchronously. The effect of initial water distribution (after concrete casting) on the development of moisture distribution is considered by introducing a critical time parameter. The simulation of humidity reduction produced from self-desiccation is based on cement hydration degree that taking the effect of temperature into account by using the equilibrant age concept. During modeling the moisture diffusion, a multilinear model was adopted to simulate the moisture dependent diffusivity. The developed model and finite deferential method can well predict the moisture distribution as well as its variations with time. Good agreement between model predictions and experimental results is found. These results can subsequently be used in shrinkage induced stress field analyses, and further be used for cracking control of concrete structures. DEWEY : 620.1 ISSN : 0733-9399 En ligne : http://ascelibrary.aip.org/vsearch/servlet/VerityServlet?KEY=JENMDT&smode=strres [...]

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Ethanol dehydration using hydrophobic and hydrophilic polymer membranes / Yu Huang in Industrial & engineering chemistry research, Vol. 49 N° 23 (Décembre 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 12067–12073 Titre : Ethanol dehydration using hydrophobic and hydrophilic polymer membranes Type de document : texte imprimé Auteurs : Yu Huang, Auteur ; Jennifer Ly, Auteur ; Dung Nguyen, Auteur Année de publication : 2011 Article en page(s) : pp. 12067–12073 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Ethanol Hydrophobic Polymer Résumé : This paper describes the development of membranes based on perfluoro polymers for the separation of aqueous ethanol mixtures in pervaporation or vapor permeation mode. Hydrophobic perfluoro polymers were selected because their chemical and thermal stability allows them to be used at temperatures up to 130 °C in hot ethanol/water vapors. The permeance and selectivity of membranes made from these polymers are quite different from the properties of the cross-linked hydrophilic membranes that are commonly used to separate water/ethanol mixtures. Perfluoro polymers absorb less than 1% liquid in mixtures ranging from pure water to pure ethanol. As a result, the water permeance and water/ethanol selectivity of the membranes are essentially independent of feed water/ethanol composition. However, the water permeances of perfluoro membranes are low for commercial applications. Multilayer composite membranes, consisting of a perfluoro protective layer and a selective hydrophilic polymer underlayer, have the stability of hydrophobic perfluoro membranes combined with the high permeances and good selectivities of hydrophilic membranes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100608s [article] Ethanol dehydration using hydrophobic and hydrophilic polymer membranes [texte imprimé] / Yu Huang, Auteur ; Jennifer Ly, Auteur ; Dung Nguyen, Auteur . - 2011 . - pp. 12067–12073. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 12067–12073 Mots-clés : Ethanol Hydrophobic Polymer Résumé : This paper describes the development of membranes based on perfluoro polymers for the separation of aqueous ethanol mixtures in pervaporation or vapor permeation mode. Hydrophobic perfluoro polymers were selected because their chemical and thermal stability allows them to be used at temperatures up to 130 °C in hot ethanol/water vapors. The permeance and selectivity of membranes made from these polymers are quite different from the properties of the cross-linked hydrophilic membranes that are commonly used to separate water/ethanol mixtures. Perfluoro polymers absorb less than 1% liquid in mixtures ranging from pure water to pure ethanol. As a result, the water permeance and water/ethanol selectivity of the membranes are essentially independent of feed water/ethanol composition. However, the water permeances of perfluoro membranes are low for commercial applications. Multilayer composite membranes, consisting of a perfluoro protective layer and a selective hydrophilic polymer underlayer, have the stability of hydrophobic perfluoro membranes combined with the high permeances and good selectivities of hydrophilic membranes. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100608s

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Low-energy distillation-membrane separation process / Yu Huang in Industrial & engineering chemistry research, Vol. 49 N° 8 (Avril 2010)  

Public ISBD [article]  inIndustrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3760–3768 Titre : Low-energy distillation-membrane separation process Type de document : texte imprimé Auteurs : Yu Huang, Auteur ; Richard W. Baker, Auteur ; Leland M. Vane, Auteur Année de publication : 2010 Article en page(s) : pp. 3760–3768 Langues : Anglais (eng) Mots-clés : Energy Distillation-membrane Separation process Résumé : A low-energy separation process combining distillation and membrane vapor permeation is introduced as an alternative to conventional distillation. The process can be applied to any liquid mixture for which appropriate selective membranes are available. However, in this paper, the discussion is limited to water/organic solvent mixtures using membranes that preferentially permeate water. Such membranes are available. The process is illustrated with two mixtures: ethanol (light component)/water (heavy component) and acetic acid (heavy component)/water (light component) mixtures. In both cases, the combination process reduces the energy consumption of the separation to half that of simple distillation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901545r [article] Low-energy distillation-membrane separation process [texte imprimé] / Yu Huang, Auteur ; Richard W. Baker, Auteur ; Leland M. Vane, Auteur . - 2010 . - pp. 3760–3768. Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 8 (Avril 2010) . - pp. 3760–3768 Mots-clés : Energy Distillation-membrane Separation process Résumé : A low-energy separation process combining distillation and membrane vapor permeation is introduced as an alternative to conventional distillation. The process can be applied to any liquid mixture for which appropriate selective membranes are available. However, in this paper, the discussion is limited to water/organic solvent mixtures using membranes that preferentially permeate water. Such membranes are available. The process is illustrated with two mixtures: ethanol (light component)/water (heavy component) and acetic acid (heavy component)/water (light component) mixtures. In both cases, the combination process reduces the energy consumption of the separation to half that of simple distillation. ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie901545r

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