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Experimental investigation of a novel polymeric heat exchanger using modified polypropylene hollow fibers / Yuchun Qin in Industrial & engineering chemistry research, Vol. 51 N° 2 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 2 (Janvier 2012) . - pp. 882-890 Titre : Experimental investigation of a novel polymeric heat exchanger using modified polypropylene hollow fibers Type de document : texte imprimé Auteurs : Yuchun Qin, Auteur ; Baoan Li, Auteur ; Shichang Wang, Auteur Année de publication : 2012 Article en page(s) : pp. 882-890 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Hollow  fiber  Heat  exchanger Résumé : Plastic heat exchangers have attracted more and more attention because of their superior resistance to chemicals and fouling. However, the thermal conductivity of plastic materials is much lower than that of metal, which limits the wider application of plastic heat exchangers. In this study, polypropylene-based hollow fibers as a heat-conducting medium for heat exchangers was developed by melt-mixing polypropylene with graphite particles and maleated polypropylene (PP-g-MA). Results show that the addition of graphite fairly improved the crystalline, thermal stability and conductivity of the polypropylene resin and further improved the heat transfer efficienry of polypropylene-based hollow fiber heat exchangers. The overall heat transfer coefficient of 15.0 wt % graphite modified polypropylene hollow fiber heat exchangers reached 1228.7 W/(m2·K), which is 5 times higher than that of pure PP-based hollow fiber heat exchangers, and the overall conductance per unit volume reached 1.1 × 106 W/(m3·K). Further, the heat transfer efficiency increases fairly with the increase of the fluid flow rate, especially with the flow rate of the tube- side. The optimized operation mode is that the hot water flows on the tube-side and the cold water flows on the shell-side. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476421 [article] Experimental investigation of a novel polymeric heat exchanger using modified polypropylene hollow fibers [texte imprimé] / Yuchun Qin, Auteur ; Baoan Li, Auteur ; Shichang Wang, Auteur . - 2012 . - pp. 882-890. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 2 (Janvier 2012) . - pp. 882-890 Mots-clés : Hollow  fiber  Heat  exchanger Résumé : Plastic heat exchangers have attracted more and more attention because of their superior resistance to chemicals and fouling. However, the thermal conductivity of plastic materials is much lower than that of metal, which limits the wider application of plastic heat exchangers. In this study, polypropylene-based hollow fibers as a heat-conducting medium for heat exchangers was developed by melt-mixing polypropylene with graphite particles and maleated polypropylene (PP-g-MA). Results show that the addition of graphite fairly improved the crystalline, thermal stability and conductivity of the polypropylene resin and further improved the heat transfer efficienry of polypropylene-based hollow fiber heat exchangers. The overall heat transfer coefficient of 15.0 wt % graphite modified polypropylene hollow fiber heat exchangers reached 1228.7 W/(m2·K), which is 5 times higher than that of pure PP-based hollow fiber heat exchangers, and the overall conductance per unit volume reached 1.1 × 106 W/(m3·K). Further, the heat transfer efficiency increases fairly with the increase of the fluid flow rate, especially with the flow rate of the tube- side. The optimized operation mode is that the hot water flows on the tube-side and the cold water flows on the shell-side. DEWEY : 660 ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=25476421

Investigation of shell side heat transfer in cross - flow designed vacuum membrane distillation module / Bingwei Qi in Industrial & engineering chemistry research, Vol. 51 N° 35 (Septembre 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 35 (Septembre 2012) . - pp. 11463-11472 Titre : Investigation of shell side heat transfer in cross - flow designed vacuum membrane distillation module Type de document : texte imprimé Auteurs : Bingwei Qi, Auteur ; Baoan Li, Auteur ; Shichang Wang, Auteur Année de publication : 2012 Article en page(s) : pp. 11463-11472 Note générale : Industrial chemistry Langues : Anglais (eng) Mots-clés : Membrane  separation  Membrane  distillation  Design  Crossflow  Heat  transfer Résumé : This paper focuses on the investigation of heat transfer in a cross-flow designed vacuum membrane distillation (VMD) module. The employment of cross-flow membrane module could ensure significant reduction of temperature polarization effect at a relatively low range of Reynolds numbers. According to most literature on VMD, the heat transfer coefficients are usually estimated by the commonly used correlations for nonporous and rigid heat exchangers. However, due to the complex flow regime in module channel, the applicability of these formulas is questioned. In this work, the heat transfer in the shell side of VMD module was studied numerically and experimentally in the Reynolds range from 7.12 to 52.18. The experimental Nusselt numbers obtained in this work are relatively higher than those predicted in the literature for given conditions. The possible reasons leading to the considerable enhancement of heat transfer are analyzed and discussed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26324795 [article] Investigation of shell side heat transfer in cross - flow designed vacuum membrane distillation module [texte imprimé] / Bingwei Qi, Auteur ; Baoan Li, Auteur ; Shichang Wang, Auteur . - 2012 . - pp. 11463-11472. Industrial chemistry Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 35 (Septembre 2012) . - pp. 11463-11472 Mots-clés : Membrane  separation  Membrane  distillation  Design  Crossflow  Heat  transfer Résumé : This paper focuses on the investigation of heat transfer in a cross-flow designed vacuum membrane distillation (VMD) module. The employment of cross-flow membrane module could ensure significant reduction of temperature polarization effect at a relatively low range of Reynolds numbers. According to most literature on VMD, the heat transfer coefficients are usually estimated by the commonly used correlations for nonporous and rigid heat exchangers. However, due to the complex flow regime in module channel, the applicability of these formulas is questioned. In this work, the heat transfer in the shell side of VMD module was studied numerically and experimentally in the Reynolds range from 7.12 to 52.18. The experimental Nusselt numbers obtained in this work are relatively higher than those predicted in the literature for given conditions. The possible reasons leading to the considerable enhancement of heat transfer are analyzed and discussed. ISSN : 0888-5885 En ligne : http://cat.inist.fr/?aModele=afficheN&cpsidt=26324795

Permeate flux curve characteristics analysis of cross - flow vacuum membrane distillation / Hongtao Wang in Industrial & engineering chemistry research, Vol. 51 N° 1 (Janvier 2012) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 487–494 Titre : Permeate flux curve characteristics analysis of cross - flow vacuum membrane distillation Type de document : texte imprimé Auteurs : Hongtao Wang, Auteur ; Baoan Li, Auteur ; Wang, Li, Auteur Année de publication : 2012 Article en page(s) : pp. 487–494 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Distillation  Cross  flow Résumé : In this Article, the heat and mass transfer processes were analyzed to build a mathematic model of cross-flow vacuum membrane distillation (VMD) for deriving the theoretical relationship of permeate flux with operation conditions and better understanding of the novel VMD performance. The common characteristics of permeate flux curves were studied experimentally under different operation conditions in cross-flow VMD. Three main operation conditions (feed inlet temperature, vacuum level, and feed velocity) affect the permeate flux curves with different mechanisms, which form different types of permeate flux curves. Feed inlet temperature mainly affects saturated vapor pressure of feed at membrane surface, and the characteristic of the curves of permeate flux versus feed inlet temperature is opening up incremental parabola. Vacuum level mainly affects the vapor pressure of permeate side, and the characteristic of the curves of permeate flux versus vacuum level of permeate side is the linear growth line. Feed velocity mainly affects residence time of feed in membrane module and convective heat transfer coefficient of boundary layer in feed side, and the characteristic of the curves of permeate flux versus feed velocity is right opening growth parabola. Temperature polarization on the feed side intensifies with the increase of permeate flux under any operation condition, and even with the increases of feed inlet temperature, vacuum level of permeate side, and feed velocity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201961v [article] Permeate flux curve characteristics analysis of cross - flow vacuum membrane distillation [texte imprimé] / Hongtao Wang, Auteur ; Baoan Li, Auteur ; Wang, Li, Auteur . - 2012 . - pp. 487–494. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 51 N° 1 (Janvier 2012) . - pp. 487–494 Mots-clés : Distillation  Cross  flow Résumé : In this Article, the heat and mass transfer processes were analyzed to build a mathematic model of cross-flow vacuum membrane distillation (VMD) for deriving the theoretical relationship of permeate flux with operation conditions and better understanding of the novel VMD performance. The common characteristics of permeate flux curves were studied experimentally under different operation conditions in cross-flow VMD. Three main operation conditions (feed inlet temperature, vacuum level, and feed velocity) affect the permeate flux curves with different mechanisms, which form different types of permeate flux curves. Feed inlet temperature mainly affects saturated vapor pressure of feed at membrane surface, and the characteristic of the curves of permeate flux versus feed inlet temperature is opening up incremental parabola. Vacuum level mainly affects the vapor pressure of permeate side, and the characteristic of the curves of permeate flux versus vacuum level of permeate side is the linear growth line. Feed velocity mainly affects residence time of feed in membrane module and convective heat transfer coefficient of boundary layer in feed side, and the characteristic of the curves of permeate flux versus feed velocity is right opening growth parabola. Temperature polarization on the feed side intensifies with the increase of permeate flux under any operation condition, and even with the increases of feed inlet temperature, vacuum level of permeate side, and feed velocity. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie201961v

Polymeric Hollow-Fiber Heat Exchangers for Thermal Desalination Processes / Liming Song in Industrial & engineering chemistry research, Vol. 49 N° 23 (Décembre 2010) 

Public ISBD [article]  in Industrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 11961–11977 Titre : Polymeric Hollow-Fiber Heat Exchangers for Thermal Desalination Processes Type de document : texte imprimé Auteurs : Liming Song, Auteur ; Baoan Li, Auteur ; Dimitrios Zarkadas, Auteur Année de publication : 2011 Article en page(s) : pp. 11961–11977 Note générale : Chimie industrielle Langues : Anglais (eng) Mots-clés : Heat  Exchangers  Thermal  desalination Résumé : Metallic shell-and-tube heat exchangers used in thermal desalination require huge capital investments, suffer from corrosion/erosion, create heavy metal pollution, and display a large footprint. This paper has explored their potential replacement by polymeric solid hollow fiber-based heat exchangers. Using solid hollow-fibers of polypropylene (PP) (wall thickness 75 μm, outside diameter 575 μm) a number of heat exchangers were fabricated in the laboratory (heat exchange area, 195−960 cm2) and at a commercial manufacturing facility (heat exchange area, 0.15−0.44 m2). The heat transfer performances of these devices were studied for a hot brine (4% NaCl, ca. 80−98 °C)−cold water (8−25 °C) system as well as for a steam (101−113 °C)−cold water (8−25 °C) system; these systems are typically encountered in thermal desalination plants. Overall heat transfer coefficient values of as much as 2000 W/(m2 K) were achieved. This is close to the limiting value imposed by the PP wall thickness, namely, 2660 W/(m2 K). Heat exchangers built out of solid poly(ether ether ketone) (PEEK) fibers performed almost as well. Higher heat transfer coefficients were obtained by using porous asymmetric polyethersulfone hollow fibers whose internal diameter was coated by two consecutive layers of polyamide and silicone to make them impervious to moisture. A mathematical model has been developed to describe the solid hollow fiber heat exchanger performance and was proven a good predictor of heat transfer performance in such devices. Compared to metallic exchangers, these heat exchangers weigh much less, have an order of magnitude larger surface area per unit volume, and are likely to be considerably cheaper. Small polymeric heat exchange devices having an effective length less than 30.5 cm (1 ft.) achieve efficiencies close to 1, provide NTU values close to 4, and have HTU values as low as 5 cm. Further their conductance/volume values are as much as 2−15 times larger than metal heat exchangers. In addition, these devices have low flow pressure drops as low as 1 kPa/NTU compared to 30 kPa/NTU in conventional metal heat exchangers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100375b [article] Polymeric Hollow-Fiber Heat Exchangers for Thermal Desalination Processes [texte imprimé] / Liming Song, Auteur ; Baoan Li, Auteur ; Dimitrios Zarkadas, Auteur . - 2011 . - pp. 11961–11977. Chimie industrielle Langues : Anglais (eng) in Industrial & engineering chemistry research > Vol. 49 N° 23 (Décembre 2010) . - pp. 11961–11977 Mots-clés : Heat  Exchangers  Thermal  desalination Résumé : Metallic shell-and-tube heat exchangers used in thermal desalination require huge capital investments, suffer from corrosion/erosion, create heavy metal pollution, and display a large footprint. This paper has explored their potential replacement by polymeric solid hollow fiber-based heat exchangers. Using solid hollow-fibers of polypropylene (PP) (wall thickness 75 μm, outside diameter 575 μm) a number of heat exchangers were fabricated in the laboratory (heat exchange area, 195−960 cm2) and at a commercial manufacturing facility (heat exchange area, 0.15−0.44 m2). The heat transfer performances of these devices were studied for a hot brine (4% NaCl, ca. 80−98 °C)−cold water (8−25 °C) system as well as for a steam (101−113 °C)−cold water (8−25 °C) system; these systems are typically encountered in thermal desalination plants. Overall heat transfer coefficient values of as much as 2000 W/(m2 K) were achieved. This is close to the limiting value imposed by the PP wall thickness, namely, 2660 W/(m2 K). Heat exchangers built out of solid poly(ether ether ketone) (PEEK) fibers performed almost as well. Higher heat transfer coefficients were obtained by using porous asymmetric polyethersulfone hollow fibers whose internal diameter was coated by two consecutive layers of polyamide and silicone to make them impervious to moisture. A mathematical model has been developed to describe the solid hollow fiber heat exchanger performance and was proven a good predictor of heat transfer performance in such devices. Compared to metallic exchangers, these heat exchangers weigh much less, have an order of magnitude larger surface area per unit volume, and are likely to be considerably cheaper. Small polymeric heat exchange devices having an effective length less than 30.5 cm (1 ft.) achieve efficiencies close to 1, provide NTU values close to 4, and have HTU values as low as 5 cm. Further their conductance/volume values are as much as 2−15 times larger than metal heat exchangers. In addition, these devices have low flow pressure drops as low as 1 kPa/NTU compared to 30 kPa/NTU in conventional metal heat exchangers. DEWEY : 660 ISSN : 0888-5885 En ligne : http://pubs.acs.org/doi/abs/10.1021/ie100375b