The Experts below are selected from a list of 1092 Experts worldwide ranked by ideXlab platform
Dendy E Sloan - One of the best experts on this subject based on the ideXlab platform.
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lowering of clathrate hydrate cohesive Forces by surface active carboxylic acids
Energy & Fuels, 2012Co-Authors: Zachary M. Aman, Dendy E SloanAbstract:The present work uses a micromechanical Force apparatus to directly measure hydrate particle–particle Cohesion Forces in hydrocarbon systems containing various carboxylic acids. Measured cohesive Forces provide fundamental insight to the balance between surfactant adsorption kinetics and interfacial thermodynamics in hydrate systems. These results are essential to the accurate prediction of hydrate aggregation in multiphase flow, as encountered in oil/gas production. The present data support the existence of the water capillary bridge between hydrate particles as an essential mechanism for hydrate Cohesion in oil continuous systems. The results indicate that, while all surface active compounds tested decreased the water–oil interfacial tension, only some chemicals were effective at reducing the interparticle Cohesion Force. Through systematic measurements, the data yield new insight into how some acids may alter hydrate surface wettability. Polynuclear aromatic carboxylic acids were found to be highly eff...
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micromechanical Cohesion Force measurements to determine cyclopentane hydrate interfacial properties
Journal of Colloid and Interface Science, 2012Co-Authors: Zachary M. Aman, Sanjeev Joshi, Dendy E SloanAbstract:Abstract Hydrate aggregation and deposition are critical factors in determining where and when hydrates may plug a deepwater flowline. We present the first direct measurement of structure II (cyclopentane) hydrate cohesive Forces in the water, liquid hydrocarbon and gas bulk phases. For fully annealed hydrate particles, gas phase cohesive Forces were approximately twice that obtained in a liquid hydrocarbon phase, and approximately six times that obtained in the water phase. Direct measurements show that hydrate Cohesion Force in a water-continuous bulk may be only the product of solid–solid Cohesion. When excess water was present on the hydrate surface, gas phase cohesive Forces increased by a factor of three, suggesting the importance of the liquid or quasi-liquid layer (QLL) in determining cohesive Force. Hydrate-steel adhesion Force measurements show that, when the steel surface is coated with hydrophobic wax, Forces decrease up to 96%. As the micromechanical Force technique is uniquely capable of measuring hydrate-surface Forces with variable contact time, the present work contains significant implications for hydrate applications in flow assurance.
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interfacial mechanisms governing cyclopentane clathrate hydrate adhesion Cohesion
Physical Chemistry Chemical Physics, 2011Co-Authors: Zachary M. Aman, Erika P Brown, Dendy E SloanAbstract:The present work uses a micromechanical Force apparatus to directly measure cyclopentane clathrate hydrate cohesive Force and hydrate-steel adhesive Force, as a function of contact time, contact Force and temperature. We present a hydrate interparticle Force model, which includes capillary and sintering contributions and is based on fundamental interparticle Force theories. In this process, we estimate the cyclopentane hydrate tensile strength to be approximately 0.91 MPa. This hydrate interparticle Force model also predicts the effect of temperature on hydrate particle Cohesion Force. Finally, we present the first direct measurements of hydrate cohesive Force in the gas phase to be 9.1 ± 2.1 mN/m at approximately 3 °C (as opposed to 4.3 ± 0.4 mN/m in liquid cyclopentane).
Zachary M. Aman - One of the best experts on this subject based on the ideXlab platform.
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effect of kinetic hydrate inhibitor polyvinylcaprolactam on cyclopentane hydrate Cohesion Forces and growth
Energy & Fuels, 2014Co-Authors: Reuben Wu, Karen A Kozielski, Zachary M. Aman, Patrick G. Hartley, Nobuo MaedaAbstract:The effect of Polyvinylcaprolactam (PVCap), a commonly used kinetic hydrate inhibitor (KHI), on the Cohesion Force between cyclopentane hydrate particles was measured using a micromechanical Force apparatus. The presence of PVCap in the aqueous bulk phase reduced the average hydrate cohesive Force by 54% (from 1.49 to 0.69 mN/m). However, the Cohesion Forces did not vary significantly as a function of either the PVCap concentration (0.005–0.5 wt %) or the temperature (from 1.1 to 7.2 °C). When a layer of PVCap solution was applied to the surface of a pure cyclopentane hydrate particle in a bulk liquid cyclopentane phase, the interparticle cohesive Force was reduced by 45% (from 4.3 to 2.4 mN/m). Hydrate growth on droplets of PVCap solutions was also studied by contacting a water droplet with a cyclopentane hydrate particle in a bulk cyclopentane phase. In cases where PVCap was absent, complete conversion of the water droplet to hydrate occurred within 30 s. However, when a water droplet of PVCap solution ...
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lowering of clathrate hydrate cohesive Forces by surface active carboxylic acids
Energy & Fuels, 2012Co-Authors: Zachary M. Aman, Dendy E SloanAbstract:The present work uses a micromechanical Force apparatus to directly measure hydrate particle–particle Cohesion Forces in hydrocarbon systems containing various carboxylic acids. Measured cohesive Forces provide fundamental insight to the balance between surfactant adsorption kinetics and interfacial thermodynamics in hydrate systems. These results are essential to the accurate prediction of hydrate aggregation in multiphase flow, as encountered in oil/gas production. The present data support the existence of the water capillary bridge between hydrate particles as an essential mechanism for hydrate Cohesion in oil continuous systems. The results indicate that, while all surface active compounds tested decreased the water–oil interfacial tension, only some chemicals were effective at reducing the interparticle Cohesion Force. Through systematic measurements, the data yield new insight into how some acids may alter hydrate surface wettability. Polynuclear aromatic carboxylic acids were found to be highly eff...
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micromechanical Cohesion Force measurements to determine cyclopentane hydrate interfacial properties
Journal of Colloid and Interface Science, 2012Co-Authors: Zachary M. Aman, Sanjeev Joshi, Dendy E SloanAbstract:Abstract Hydrate aggregation and deposition are critical factors in determining where and when hydrates may plug a deepwater flowline. We present the first direct measurement of structure II (cyclopentane) hydrate cohesive Forces in the water, liquid hydrocarbon and gas bulk phases. For fully annealed hydrate particles, gas phase cohesive Forces were approximately twice that obtained in a liquid hydrocarbon phase, and approximately six times that obtained in the water phase. Direct measurements show that hydrate Cohesion Force in a water-continuous bulk may be only the product of solid–solid Cohesion. When excess water was present on the hydrate surface, gas phase cohesive Forces increased by a factor of three, suggesting the importance of the liquid or quasi-liquid layer (QLL) in determining cohesive Force. Hydrate-steel adhesion Force measurements show that, when the steel surface is coated with hydrophobic wax, Forces decrease up to 96%. As the micromechanical Force technique is uniquely capable of measuring hydrate-surface Forces with variable contact time, the present work contains significant implications for hydrate applications in flow assurance.
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interfacial mechanisms governing cyclopentane clathrate hydrate adhesion Cohesion
Physical Chemistry Chemical Physics, 2011Co-Authors: Zachary M. Aman, Erika P Brown, Dendy E SloanAbstract:The present work uses a micromechanical Force apparatus to directly measure cyclopentane clathrate hydrate cohesive Force and hydrate-steel adhesive Force, as a function of contact time, contact Force and temperature. We present a hydrate interparticle Force model, which includes capillary and sintering contributions and is based on fundamental interparticle Force theories. In this process, we estimate the cyclopentane hydrate tensile strength to be approximately 0.91 MPa. This hydrate interparticle Force model also predicts the effect of temperature on hydrate particle Cohesion Force. Finally, we present the first direct measurements of hydrate cohesive Force in the gas phase to be 9.1 ± 2.1 mN/m at approximately 3 °C (as opposed to 4.3 ± 0.4 mN/m in liquid cyclopentane).
Shigui Du - One of the best experts on this subject based on the ideXlab platform.
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strength parameters of rock considering area and stress correction during shearing
Geotechnical and Geological Engineering, 2020Co-Authors: Rui Yong, Wanzhong Xu, Shigui DuAbstract:Rock shear strength parameters are the basis for rock mechanics research and rock engineering applications, generally obtained by triaxial test and compression shear test method. In the current compression-shear test method, the initial shear area of the specimen is used for calculation, and the change of the shear area during the shearing process is not considered. In the actual shearing process, as the shear displacement increases, the shearing area decreases, and the compression-shearing mold has support for the shearing part of the specimen, causing the calculation error of shear stress and normal stress, so that the cohesive Force error obtained by the compression shear test and the triaxial test is large. The area correction coefficient β and the support Force σmj of the shearing mold for the sheared specimen were introduced, and the shear stress and normal stress on the shear surface were corrected under the conditions of rock compression shear test. According to the Mohr–Coulomb criterion, the Cohesion Force is obtained, and the correction formula of rock Cohesion is proposed. Verification and error analysis of the proposed formula through experiments, the correction value is closer to the true value of rock Cohesion and improves the reliability of the compression-shear test method. Based on the formula of the Cohesion correction formula, the influence of the test factors such as the size of the specimen was discussed. It was found that the increase of the size of the specimen helps to weaken the influence of the change of the shear area on the stress.
Aibing Yu - One of the best experts on this subject based on the ideXlab platform.
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prediction of porosity from particle scale interactions surface modification of fine cohesive powders
Powder Technology, 2014Co-Authors: Maxx Capece, Rajesh N Dave, Zhonghui Huang, Daniel To, Marie Aloia, Charles Muchira, Aibing YuAbstract:Abstract Packing or powder bed porosity is a fundamental property of solid particulate systems and is of prime importance to many industries which handle or process such material. Inter-particle Forces, which may couple with particle size and shape, can significantly affect porosity. For fine dry particles, the attractive van der Waals Force is dominant and can prevent the packing of particles resulting in high porosity. This study investigates the effect of the van der Waals Force on porosity of powder beds consisting of fine cohesive particles. Dry coating is utilized to modify the surface roughness of particles in order to further elucidate this effect. The results indicate that dry coating nano-sized particles onto coarser particles ranging in size from 5 μm to 223 μm can significantly reduce the van der Waals Force resulting in reduced porosity. The granular Bond number, defined as the ratio of the Cohesion Force to particle weight was shown to accurately predict porosity, provided a multiple asperity particle contact model is employed. A subsequent theoretical investigation determined the effect of surface modification, specifically the size, surface energy, and surface area coverage of asperities on porosity. It showed that the surface roughness of non-surface modified particles may be poorly defined and may lead to erroneous calculation of inter-particle Forces. Therefore, in addition to dry coating being a useful process to improve powder properties such as porosity, dry coating can be used to define surface properties to accurately predict bulk level powder properties from multi-asperity particle scale interaction models.
Rajesh N Dave - One of the best experts on this subject based on the ideXlab platform.
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prediction of porosity from particle scale interactions surface modification of fine cohesive powders
Powder Technology, 2014Co-Authors: Maxx Capece, Rajesh N Dave, Zhonghui Huang, Daniel To, Marie Aloia, Charles Muchira, Aibing YuAbstract:Abstract Packing or powder bed porosity is a fundamental property of solid particulate systems and is of prime importance to many industries which handle or process such material. Inter-particle Forces, which may couple with particle size and shape, can significantly affect porosity. For fine dry particles, the attractive van der Waals Force is dominant and can prevent the packing of particles resulting in high porosity. This study investigates the effect of the van der Waals Force on porosity of powder beds consisting of fine cohesive particles. Dry coating is utilized to modify the surface roughness of particles in order to further elucidate this effect. The results indicate that dry coating nano-sized particles onto coarser particles ranging in size from 5 μm to 223 μm can significantly reduce the van der Waals Force resulting in reduced porosity. The granular Bond number, defined as the ratio of the Cohesion Force to particle weight was shown to accurately predict porosity, provided a multiple asperity particle contact model is employed. A subsequent theoretical investigation determined the effect of surface modification, specifically the size, surface energy, and surface area coverage of asperities on porosity. It showed that the surface roughness of non-surface modified particles may be poorly defined and may lead to erroneous calculation of inter-particle Forces. Therefore, in addition to dry coating being a useful process to improve powder properties such as porosity, dry coating can be used to define surface properties to accurately predict bulk level powder properties from multi-asperity particle scale interaction models.
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discrete element method simulation of cohesive particles mixing under magnetically assisted impaction
Powder Technology, 2013Co-Authors: Xiaoliang Deng, James V Scicolone, Rajesh N DaveAbstract:Abstract Mixing of cohesive micro and nano-powders is difficult because they form large agglomerates due to the high interparticle Forces. In order to better understand the mixing of cohesive particles, discrete element method (DEM) based modeling was performed for the magnetic assisted impaction mixing (MAIM), which is a high shear mixer previously shown to be capable of mixing at the nanoparticle scale. The JKR Cohesion Force model was used to represent interparticle Cohesion. Agglomerates were formed based on the surface energy of individual particles, thus better capturing the effect of Cohesion on the initial state. The effects of magnet-to-sample mass ratio, magnet size and surface energy of non-magnet particles on the homogeneity of mixing (HoM) were investigated. Simulation results show that the mixing will be faster with smaller magnet sizes at fixed mass ratio, by increasing the mass ratio, or by decreasing the surface energy; the latter had a significant effect on the process of mixing. When non-magnetic particles had higher surface energy, homogeneous mixing required longer processing times since higher collision numbers and collision energies were necessary to deagglomerate the particles. Results show that when the collision energy between magnets and non-magnets exceeds the cohesive energy, the mixing would reach a steady state at shorter processing intervals. The results qualitatively agree with previously published results, suggesting that this system model, which involves the formation and utilization of agglomerates in simulations, is applicable to cohesive powder mixing.