Neila Mhiri - Academia.edu (original) (raw)
Uploads
Papers by Neila Mhiri
Cette these porte sur le developpement d’un procede industriel propre constitue par un couplage a... more Cette these porte sur le developpement d’un procede industriel propre constitue par un couplage absorption-distillation, destine aux traitements d’effluents gazeux charges par un Compose Organique Volatil (COV). L’absorption est effectuee dans un microabsorbeur a film tombant. La premiere etape de ce travail consiste a caracteriser le transfert de matiere dans cet appareil, lors de l’absorption gaz/liquide du Perchloroethylene (PCE) par le Di(2-EthylHexyl)Adipate (DEHA). Les experiences ont montre la faisabilite et l’interet de cette operation dans un micro-contacteur. En effet, les efficacites d’epuration obtenues sont comparables a celles des procedes classiques (jusqu’a 97%) et les quantites de solvant d’absorption utilisees sont tres faibles. Une etude parametrique a revele une intensification significative du transfert de matiere, cote gaz, et un gain en compacite, a la suite de la minimisation de l’epaisseur de la veine de gaz (2mm) et du debit de la phase gazeuse. Cette etude...
Chemical Engineering Science, 2011
The falling film microabsorber developed by the Institut für Mikrotechnik Mainz is used to study ... more The falling film microabsorber developed by the Institut für Mikrotechnik Mainz is used to study its performance for the treatment of VOC-containing gases. The technique used is the gas/liquid absorption. The gas (mixture of air and tetrachloroethylene) and the solvent (Di(ethyl-2-hexyl) adipate, DEHA) flow counter-currently in the microabsorber. The solvent streams by gravity on a plate structured by microchannels. This technique makes it possible to miniaturize the process by increasing the mass transfer flow per volume unit as explained in Part I. Experiments are presented and a model is developed from equations of mass and momentum transfers. Results show a competition between two transport phenomena: diffusion and convection. The mass transfer rate is also studied with respect to the structure of microabsorber. It is also shown that it is possible ''to optimize'' the geometry of the apparatus in order to intensify the transfer so as to miniaturize the process. In the case of physical absorption, mass transfer intensification (Murphree Efficiency) increases when the number of transfer unit NTU G (¼ t/t transfer) increases too. It is mainly due to the small volume of the apparatus where the gas phase residence time must be taken into account in the study of the mass transport towards the gas/liquid interface: the radial and the axial distances for the mass transfer and the mass transport have the same order of magnitude.
Chemical Engineering and Processing: Process Intensification, 2010
Increasing mass transfer efficiencies is reached in G/L absorption contactors thanks to stabiliza... more Increasing mass transfer efficiencies is reached in G/L absorption contactors thanks to stabilization of the liquid flow. Hydrodynamic studies about the stability of a liquid film thickness are carried out to explain variations of mass transfer efficiencies during absorption experiments. These studies are based on the analytical expression developed by Hobler (1964) [1] which enables to predict the minimum wetting
Cette these porte sur le developpement d’un procede industriel propre constitue par un couplage a... more Cette these porte sur le developpement d’un procede industriel propre constitue par un couplage absorption-distillation, destine aux traitements d’effluents gazeux charges par un Compose Organique Volatil (COV). L’absorption est effectuee dans un microabsorbeur a film tombant. La premiere etape de ce travail consiste a caracteriser le transfert de matiere dans cet appareil, lors de l’absorption gaz/liquide du Perchloroethylene (PCE) par le Di(2-EthylHexyl)Adipate (DEHA). Les experiences ont montre la faisabilite et l’interet de cette operation dans un micro-contacteur. En effet, les efficacites d’epuration obtenues sont comparables a celles des procedes classiques (jusqu’a 97%) et les quantites de solvant d’absorption utilisees sont tres faibles. Une etude parametrique a revele une intensification significative du transfert de matiere, cote gaz, et un gain en compacite, a la suite de la minimisation de l’epaisseur de la veine de gaz (2mm) et du debit de la phase gazeuse. Cette etude...
Chemical Engineering Science, 2011
The falling film microabsorber developed by the Institut für Mikrotechnik Mainz is used to study ... more The falling film microabsorber developed by the Institut für Mikrotechnik Mainz is used to study its performance for the treatment of VOC-containing gases. The technique used is the gas/liquid absorption. The gas (mixture of air and tetrachloroethylene) and the solvent (Di(ethyl-2-hexyl) adipate, DEHA) flow counter-currently in the microabsorber. The solvent streams by gravity on a plate structured by microchannels. This technique makes it possible to miniaturize the process by increasing the mass transfer flow per volume unit as explained in Part I. Experiments are presented and a model is developed from equations of mass and momentum transfers. Results show a competition between two transport phenomena: diffusion and convection. The mass transfer rate is also studied with respect to the structure of microabsorber. It is also shown that it is possible ''to optimize'' the geometry of the apparatus in order to intensify the transfer so as to miniaturize the process. In the case of physical absorption, mass transfer intensification (Murphree Efficiency) increases when the number of transfer unit NTU G (¼ t/t transfer) increases too. It is mainly due to the small volume of the apparatus where the gas phase residence time must be taken into account in the study of the mass transport towards the gas/liquid interface: the radial and the axial distances for the mass transfer and the mass transport have the same order of magnitude.
Chemical Engineering and Processing: Process Intensification, 2010
Increasing mass transfer efficiencies is reached in G/L absorption contactors thanks to stabiliza... more Increasing mass transfer efficiencies is reached in G/L absorption contactors thanks to stabilization of the liquid flow. Hydrodynamic studies about the stability of a liquid film thickness are carried out to explain variations of mass transfer efficiencies during absorption experiments. These studies are based on the analytical expression developed by Hobler (1964) [1] which enables to predict the minimum wetting