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Markus Bussmann - One of the best experts on this subject based on the ideXlab platform.
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Oil Particle separation in a falling sphere configuration effect of viscosity ratio interfacial tension
International Journal of Multiphase Flow, 2018Co-Authors: Sasan Mehrabian, Edgar Acosta, Markus BussmannAbstract:Abstract The separation of Oil from a single Oil-coated spherical Particle falling through an aqueous solution is evaluated as a function of viscosity ratio and interfacial tension. A solvent was used to modify the viscosity of the Oil and a surfactant was used to modify the interfacial tension. The separation process is characterized with respect to a capillary number (ratio of viscous shear stress to interfacial tension) and the viscosity ratio (between the Oil phase and the aqueous solution). The separation of Oil from the falling sphere can be described as a two-stage process. The first stage is the deformation of the Oil film coating the sphere, leading to the formation of a thread or “tail” downstream of the Particle. The second stage involves the breakup of that tail as the sphere falls. The initial film deformation and tail formation is best described by a capillary number based on the shear rate at the Oil-water interface; and the tail breakup by the rate of elongation experienced by the tail. More Oil is removed when thicker tails are formed, which are obtained at high viscosity ratios. However, high viscosity ratios require longer shearing time for the tail to form. Our results indicate that maximum separation takes place when the viscosity ratio is between 0.1 and 1, with capillary numbers close to 1.
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Oil Particle separation in a falling sphere configuration effect of Oil film thickness
Energy & Fuels, 2016Co-Authors: Sasan Mehrabian, Edgar Acosta, Markus BussmannAbstract:High-speed videos of Oil-coated solid spheres falling through an aqueous solution were analyzed to determine the amount of Oil separated and the velocity of the coated sphere during free fall. The Oil-coated sphere configuration is relevant to understanding the recovery of Oil from Oil sands; hence, bitumen was used as the Oil phase. A new form of a capillary number based on a low-Reynolds number solution is introduced to characterize the separation process. The proposed Particle-based capillary number takes into account the effect of the Oil film thickness and the viscosity ratio. In this study, the separation of Oil from an Oil-coated sphere is examined as a function of the Oil film thickness, while keeping the viscosity ratio constant at 0.08. From the experimental results, it was observed that there is a critical Oil film thickness beyond which Oil separation from a Particle is observed. Higher Oil removal efficiencies are obtained at higher Oil film thicknesses. The velocity of an Oil-coated sphere i...
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breakup of high solid volume fraction Oil Particle cluster in simple shear flow
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Sasan Mehrabian, Markus Bussmann, Edgar AcostaAbstract:Abstract Experiments were conducted of the low-Reynolds number breakup and separation of Oil–Particle clusters characterized by a high volume fraction of relatively large solid Particles, under simple shear in an aqueous solution. The breakup of such Oil–Particle clusters, and the separation of Particles from the clusters, are evaluated as a function of viscosity ratio of the Oil phase to the aqueous solution, interfacial tension, and shearing time. When the viscosity ratio is high, clusters are more difficult to breakup, a longer shear time is needed, and few Particles detach. At low viscosity ratios, clusters are easily deformed and break up into smaller clusters, and more clean Particles detach. Lowering the interfacial tension also facilitates the liberation of Oil droplets from Particles. The results show that the breakup of Oil–Particle clusters with a high volume fraction of large Particles can be characterized as simple droplet breakup, meaning that the viscosity of the Oil governs the dynamics of the cluster, rather than an effective viscosity that is a function of the solid volume fraction. The degree of cluster breakup and the separation of Particles from the primary cluster is related to a cluster-based capillary number and the viscosity ratio. There is a critical capillary number required to obtain clean Particles.
Sasan Mehrabian - One of the best experts on this subject based on the ideXlab platform.
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Oil Particle separation in a falling sphere configuration effect of viscosity ratio interfacial tension
International Journal of Multiphase Flow, 2018Co-Authors: Sasan Mehrabian, Edgar Acosta, Markus BussmannAbstract:Abstract The separation of Oil from a single Oil-coated spherical Particle falling through an aqueous solution is evaluated as a function of viscosity ratio and interfacial tension. A solvent was used to modify the viscosity of the Oil and a surfactant was used to modify the interfacial tension. The separation process is characterized with respect to a capillary number (ratio of viscous shear stress to interfacial tension) and the viscosity ratio (between the Oil phase and the aqueous solution). The separation of Oil from the falling sphere can be described as a two-stage process. The first stage is the deformation of the Oil film coating the sphere, leading to the formation of a thread or “tail” downstream of the Particle. The second stage involves the breakup of that tail as the sphere falls. The initial film deformation and tail formation is best described by a capillary number based on the shear rate at the Oil-water interface; and the tail breakup by the rate of elongation experienced by the tail. More Oil is removed when thicker tails are formed, which are obtained at high viscosity ratios. However, high viscosity ratios require longer shearing time for the tail to form. Our results indicate that maximum separation takes place when the viscosity ratio is between 0.1 and 1, with capillary numbers close to 1.
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Oil Particle separation in a falling sphere configuration effect of Oil film thickness
Energy & Fuels, 2016Co-Authors: Sasan Mehrabian, Edgar Acosta, Markus BussmannAbstract:High-speed videos of Oil-coated solid spheres falling through an aqueous solution were analyzed to determine the amount of Oil separated and the velocity of the coated sphere during free fall. The Oil-coated sphere configuration is relevant to understanding the recovery of Oil from Oil sands; hence, bitumen was used as the Oil phase. A new form of a capillary number based on a low-Reynolds number solution is introduced to characterize the separation process. The proposed Particle-based capillary number takes into account the effect of the Oil film thickness and the viscosity ratio. In this study, the separation of Oil from an Oil-coated sphere is examined as a function of the Oil film thickness, while keeping the viscosity ratio constant at 0.08. From the experimental results, it was observed that there is a critical Oil film thickness beyond which Oil separation from a Particle is observed. Higher Oil removal efficiencies are obtained at higher Oil film thicknesses. The velocity of an Oil-coated sphere i...
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breakup of high solid volume fraction Oil Particle cluster in simple shear flow
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Sasan Mehrabian, Markus Bussmann, Edgar AcostaAbstract:Abstract Experiments were conducted of the low-Reynolds number breakup and separation of Oil–Particle clusters characterized by a high volume fraction of relatively large solid Particles, under simple shear in an aqueous solution. The breakup of such Oil–Particle clusters, and the separation of Particles from the clusters, are evaluated as a function of viscosity ratio of the Oil phase to the aqueous solution, interfacial tension, and shearing time. When the viscosity ratio is high, clusters are more difficult to breakup, a longer shear time is needed, and few Particles detach. At low viscosity ratios, clusters are easily deformed and break up into smaller clusters, and more clean Particles detach. Lowering the interfacial tension also facilitates the liberation of Oil droplets from Particles. The results show that the breakup of Oil–Particle clusters with a high volume fraction of large Particles can be characterized as simple droplet breakup, meaning that the viscosity of the Oil governs the dynamics of the cluster, rather than an effective viscosity that is a function of the solid volume fraction. The degree of cluster breakup and the separation of Particles from the primary cluster is related to a cluster-based capillary number and the viscosity ratio. There is a critical capillary number required to obtain clean Particles.
Edgar Acosta - One of the best experts on this subject based on the ideXlab platform.
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Oil Particle separation in a falling sphere configuration effect of viscosity ratio interfacial tension
International Journal of Multiphase Flow, 2018Co-Authors: Sasan Mehrabian, Edgar Acosta, Markus BussmannAbstract:Abstract The separation of Oil from a single Oil-coated spherical Particle falling through an aqueous solution is evaluated as a function of viscosity ratio and interfacial tension. A solvent was used to modify the viscosity of the Oil and a surfactant was used to modify the interfacial tension. The separation process is characterized with respect to a capillary number (ratio of viscous shear stress to interfacial tension) and the viscosity ratio (between the Oil phase and the aqueous solution). The separation of Oil from the falling sphere can be described as a two-stage process. The first stage is the deformation of the Oil film coating the sphere, leading to the formation of a thread or “tail” downstream of the Particle. The second stage involves the breakup of that tail as the sphere falls. The initial film deformation and tail formation is best described by a capillary number based on the shear rate at the Oil-water interface; and the tail breakup by the rate of elongation experienced by the tail. More Oil is removed when thicker tails are formed, which are obtained at high viscosity ratios. However, high viscosity ratios require longer shearing time for the tail to form. Our results indicate that maximum separation takes place when the viscosity ratio is between 0.1 and 1, with capillary numbers close to 1.
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Oil Particle separation in a falling sphere configuration effect of Oil film thickness
Energy & Fuels, 2016Co-Authors: Sasan Mehrabian, Edgar Acosta, Markus BussmannAbstract:High-speed videos of Oil-coated solid spheres falling through an aqueous solution were analyzed to determine the amount of Oil separated and the velocity of the coated sphere during free fall. The Oil-coated sphere configuration is relevant to understanding the recovery of Oil from Oil sands; hence, bitumen was used as the Oil phase. A new form of a capillary number based on a low-Reynolds number solution is introduced to characterize the separation process. The proposed Particle-based capillary number takes into account the effect of the Oil film thickness and the viscosity ratio. In this study, the separation of Oil from an Oil-coated sphere is examined as a function of the Oil film thickness, while keeping the viscosity ratio constant at 0.08. From the experimental results, it was observed that there is a critical Oil film thickness beyond which Oil separation from a Particle is observed. Higher Oil removal efficiencies are obtained at higher Oil film thicknesses. The velocity of an Oil-coated sphere i...
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breakup of high solid volume fraction Oil Particle cluster in simple shear flow
Colloids and Surfaces A: Physicochemical and Engineering Aspects, 2015Co-Authors: Sasan Mehrabian, Markus Bussmann, Edgar AcostaAbstract:Abstract Experiments were conducted of the low-Reynolds number breakup and separation of Oil–Particle clusters characterized by a high volume fraction of relatively large solid Particles, under simple shear in an aqueous solution. The breakup of such Oil–Particle clusters, and the separation of Particles from the clusters, are evaluated as a function of viscosity ratio of the Oil phase to the aqueous solution, interfacial tension, and shearing time. When the viscosity ratio is high, clusters are more difficult to breakup, a longer shear time is needed, and few Particles detach. At low viscosity ratios, clusters are easily deformed and break up into smaller clusters, and more clean Particles detach. Lowering the interfacial tension also facilitates the liberation of Oil droplets from Particles. The results show that the breakup of Oil–Particle clusters with a high volume fraction of large Particles can be characterized as simple droplet breakup, meaning that the viscosity of the Oil governs the dynamics of the cluster, rather than an effective viscosity that is a function of the solid volume fraction. The degree of cluster breakup and the separation of Particles from the primary cluster is related to a cluster-based capillary number and the viscosity ratio. There is a critical capillary number required to obtain clean Particles.
Miriam Dupas Hubinger - One of the best experts on this subject based on the ideXlab platform.
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influence of different combinations of wall materials and homogenisation pressure on the microencapsulation of green coffee Oil by spray drying
Food Research International, 2014Co-Authors: Vanessa Silva, Glaucia S Vieira, Miriam Dupas HubingerAbstract:Abstract The aim of this study was to assess the influence of different combinations of modified starches (Hi-Cap, Capsul and N-Lok) or gum Arabic with maltodextrin 10 DE (MD) (75:25), on microencapsulation of green coffee Oil by spray drying and two homogenisation processes on emulsion preparation step. All emulsions were evaluated for droplet size, viscosity, zeta potential and surface tension, while microParticles were analysed for encapsulation efficiency, Oil retention, moisture content, Particle mean diameter, microstructure, in vitro sun protection factor and oxidative stability by Rancimat. Critical storage conditions based on sorption isotherms and glass transition temperature and diterpenes quantification were determined for the microParticles with the highest values of encapsulation efficiency. In general, the use of 50 MPa of homogenisation pressure allowed a reduction of droplet mean diameter for about 1 μm, with a slight decrease on emulsion viscosity. For microParticles, there was an increase on encapsulation efficiency with the use of high pressure homogenisation. Oil retention was influenced by the type of wall material. Moisture content (2.0%) and in vitro sun protection factor values (FPS = 2.1) were similar for all emulsions and in the last case were similar to pure Oil. Particle mean diameter ranged from 10.7 to 16.0 μm. Powders produced with the mixture Hi-Cap/MD presented good values of critical water activity of 0.60 and critical moisture content of 0.08 g/g of dry solids, respectively, and also the highest oxidative stability. High concentration of diterpenes of 0.21 and 0.24 mg of kahweol/g powder, 0.19 and 0.21 mg of cafestol/g powder were observed for Particles produced with Hi-Cap/MD and GA/MD, with emulsions homogenised at 50 MPa.
Petros Koutrakis - One of the best experts on this subject based on the ideXlab platform.
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a compact multistage cascade impactor for the characterization of atmospheric aerosols
Journal of Aerosol Science, 2004Co-Authors: Philip Demokritou, Stephen T Ferguson, Seungjoo Lee, Petros KoutrakisAbstract:Abstract This paper presents the development, laboratory characterization, and field evaluation of a compact multistage cascade impactor (CCI). The CCI operates at a flow rate of 30 LPM and consists of eight impaction stages equipped with rectangular slit-shaped acceleration nozzles. A 47 mm backup Teflon membrane filter is used downstream of the eighth stage to collect Particles smaller than 0.16 μm . In each stage, Particles are retained by impaction onto the inert polyurethane foam (PUF) substrate. The major feature of this novel sampler is its ability to both fractionate by size and collect relatively large amounts of Particles (mg quantities) onto an inert polyurethane foam impaction substrates. Even though the impaction substrates are not coated with adhesives such as grease or mineral Oil, Particle bounce and re-entrainment losses were found to be insignificant. Impaction characteristics (cutpoint and sharpness of collection efficiency curve) of the PUF substrates are maintained for mass loadings of at least 25 mg , which is much higher than for other commonly used rigid, flat impaction substrates. The system was calibrated in laboratory experiments using polydisperse aerosols. The 50% cutpoints of the eight stages were 9.9, 5.3, 3.3, 2.5, 1.7, 1.0, 0.47 and 0.16 μm (aerodynamic diameter), with pressure drops of 0.02, 0.02, 0.04, 0.06, 0.08, 0.27, 1.57 and 5.73 kPa . These pressure drops are considerably lower than those obtained using flat rigid impaction substrates with comparable cutpoints. Particle losses for each stage were less than 10% for Particles smaller than 7 μm and less than 20% for Particles larger than 7 μm . The CCI was also compared with the collocated micro-orifice impactor (MOI) in laboratory-controlled experiments using artificially generated polydisperse aerosol. These laboratory tests showed that the mass concentrations measured by the MOI are considerably lower than those measured by the CCI (the average ratio of total mass concentration of MOI to CCI was 0.86), with the size distribution measured by the CCI closer to that measured using the real time Particle sizing instruments (SMPS, APS). A field comparison of CCI, the Harvard impactor (HI) and the federal reference method (FRM) for fine Particles showed a good agreement between the CCI and the reference samplers for Particles smaller than 2.5 μm .
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development and laboratory performance evaluation of a personal cascade impactor
Journal of The Air & Waste Management Association, 2002Co-Authors: Philip Demokritou, Tarun Gupta, Stephen T Ferguson, Petros KoutrakisAbstract:Abstract This paper presents the design and laboratory evaluation of a personal cascade impactor. The system is compact, lightweight, and uses a single battery-operated sampling pump. It operates at a flow rate of 5 L/min and consists of four impaction stages, each equipped with slit-shaped acceleration nozzles, and a backup filter. The impactor was calibrated using polydisperse Particles. The 50% cut points of the four stages were 9.6, 2.6, 1.0, and 0.5 μm, respectively. The backup filter is placed downstream of the fourth stage and is used to collect the Particles with an aerodynamic diameter smaller than 0.5 μm (dp < 0.5 μm). The major feature of this novel sampler is its ability not only to fractionate the Particles with an aerodynamic diameter smaller than 10 μm to the various size fractions, but also to collect them onto relatively small polyurethane foam substrates without using adhesives. Although the impaction substrates are not coated with adhesives such as grease or mineral Oil, Particle bounce...
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development of a high volume cascade impactor for toxicological and chemical characterization studies
Aerosol Science and Technology, 2002Co-Authors: Philip Demokritou, Stephen T Ferguson, Ilias G Kavouras, Petros KoutrakisAbstract:This paper presents the design and development of a compact high volume cascade impactor (HVCI). The HVCI operates at a flow rate of 900 l/min and consists of 4 impaction stages equipped with circular slit-shaped acceleration nozzles and a backup filter. The backup filter is placed downstream of the fourth stage and is used to collect the ultrafine Particles ( d p < 0.1 w m). The major feature of this novel sampler is its ability to collect relatively large amounts of Particles (mg-g levels) onto relatively small polyurethane foam substrates without using adhesives. As previously reported, the capacity of the impaction substrate is 2.15 g of collected Particles per cm 2 of foam. Although the impaction substrates are not coated with adhesives such as grease or mineral Oil, Particle bounce and re-entrainment losses were found not to be significant. Particles can be easily recovered from the foam substrates using aqueous extraction. The impactor was calibrated using polydisperse Particles. The 50% cutpoints ...
