The Experts below are selected from a list of 261 Experts worldwide ranked by ideXlab platform
A C Payatakes - One of the best experts on this subject based on the ideXlab platform.
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simulation of downflow and upflow depth filtration of non brownian particles under Constant flowrate or Constant Pressure Drop conditions
Journal of The Chinese Institute of Chemical Engineers, 2004Co-Authors: E D Skouras, V N Burganos, Christakis A Paraskeva, A C PayatakesAbstract:The mechanistic simulator of depth filtration of non-Brownian particles in granular bids, which was reported in Burganos et al., 2001, is upgraded and used to investigate the effects of various filter design modes on particle capture efficiency and permeability. The simulation covers all stages of deposition, including extensive pore clogging. The design modes which are examined here are downflow and upflow, in combination with either Constant flowrate or Constant Pressure Drop. It is shown that the direction of the macroscopic flow relative to that of gravity has significant effects. Downflow filters clog slower than upflow ones. It is also shown that the modulating functions, which give the effect of the specific deposit on the filtration coefficient and the permeability, dipend on whether the flowrate or the Pressure Drop is kept Constant. During the early stages of deposition, the modulating functions are virtually the same for both modes of operation, but in advanced stages of deposition substantial differences are observed. These differences are attributed to the fact that when the flowrate is kept Constant (at the expense of a virtually monotonically increasing Pressure Drop), the flow is channeled through certain connected pathways which are composed of relatively deposit-free pores. Such pores are kept clean because the local interstitial velocity is high. This phenomenon is much weaker or even absent when the Pressure Drop is kept Constant, in which case the flowrate decreases virtually monotonically. Another interesting new result is that both of the modulating functions depend, weakly but noticeably, on depth.
John M Smid - One of the best experts on this subject based on the ideXlab platform.
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steam foam performance in oil sand cores at Constant Pressure Drop
Fuel, 1991Co-Authors: Kirk M Green, Eddy E Isaacs, John M SmidAbstract:Abstract Although a great deal of laboratory work has been done to examine steam-foam oil recovery processes in corefloods, most of the work reported has been for conditions of Constant flow rate. In the work described here, a series of steam-foam oil displacement runs were carried out with oil sand cores under conditions of Constant Pressure Drop and the results were compared with those obtained under Constant flow conditions. Under Constant Pressure Drop conditions, foam formation in a high permeability flow path resulted in a reduction in steam mobility, which in turn led to a Drop in flow rate through the core. Two surfactants were used, and in the absence of a non-condensible gas, injection of the two surfactants resulted in similar mobility reductions. However, one of the surfactants was significantly slower to foam and reach steady-state mobility. Under the conditions of this study, coinjection of non-condensible gas appeared to have little or no beneficial effect on the mobility reduction achieved. Recovery enhancements of the order of 30–50% relative to steam-only were obtained with both surfactants. When mobility reduction was very high, relatively little oil was produced, presumably because of the drastic reduction in flow rate.
E. Hugh Stitt - One of the best experts on this subject based on the ideXlab platform.
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Flow, Transport, and Reaction Interactions in Shaped Cylindrical Particles for Steam Methane Reforming
Industrial & Engineering Chemistry Research, 2012Co-Authors: Anthony G. Dixon, M. Ertan Taskin, Michiel Nijemeisland, Justin Boudreau, Anne Rocheleau, Alexandre Troupel, E. Hugh StittAbstract:Complex interactions between steam methane reforming reaction rates, conduction, and diffusion inside cylindrical catalyst particles with holes, and the external flow and temperature fields near the heated tube wall were shown in detail using computational fluid dynamics and compared to prior work on full cylinders. This work highlights the differences caused by the particle features. Simulations were done under industrial tube inlet conditions at a Constant Pressure Drop for one-, three-, four-, and six-hole cylinders. Heat and mass fluxes were within 10% for all particle surfaces; the holes provided the reactant good access to the particles. The six-hole catalyst particles offered the best temperature distribution and reaction rate. However, the four-hole particles gave a higher mass flow rate and lower tube-wall temperature for a set Pressure Drop.
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CFD Study of the Influence of Catalyst Particle Design on Steam Reforming Reaction Heat Effects in Narrow Packed Tubes
Industrial & Engineering Chemistry Research, 2008Co-Authors: M. Ertan Taskin, Anthony G. Dixon, Michiel Nijemeisland, E. Hugh StittAbstract:The heat effects of methane steam reforming reactions were simulated in a narrow packed tube using computational fluid dynamics (CFD) with heat sinks in the particles. Simulations were performed at Constant Pressure Drop for cylindrical particles with different numbers and sizes of internal voids, and at different activity levels, corresponding to 2%, 3%, and 5% of the particle radius. Fluid and solid radial temperature profiles were found to be insensitive to the distribution of activity in the tube, but solid temperatures did depend on the activity level. At the tube wall, strong temperature differences were observed across the particles. The multihole particle designs showed higher heat uptakes and lower tube wall temperatures at each activity level. The CFD simulation results allowed a quantitative assessment of the effects of changing catalyst particle design.
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Wall-to-particle heat transfer in steam reformer tubes: CFD comparison of catalyst particles
Chemical Engineering Science, 2008Co-Authors: Anthony G. Dixon, M. Ertan Taskin, Michiel Nijemeisland, E. Hugh StittAbstract:Abstract Computational fluid dynamics (CFD) was used to simulate non-reacting heat transfer in a steam reforming packed reactor tube of tube-to-particle diameter ratio ( N ) equal to 4, with cylindrical multi-hole catalyst particles. These simulations extend those of our previous study [Nijemeisland, M., Dixon, A.G., Stitt, E.H., 2004. Catalyst design by CFD for heat transfer and reaction in steam reforming. Chemical Engineering Science 59, 5185–5191] to provide accurate tube wall temperatures, runs at Constant Pressure Drop in addition to those at Constant mass flow rate and simulations of particles with different sizes of holes. At Constant Pressure Drop, particles with higher void fractions allowed higher mass flow rates, resulting in tube wall temperatures and radial temperature profiles in order: solid cylinders > one-hole particles > multi-hole particles. Little difference was seen between three-hole and four-hole particles. The particles with multiple holes gave a substantial reduction in tube wall temperature, with only a small decrease in core tube heat transfer. The effect of hole size was small, for the cases investigated in this study.
E D Skouras - One of the best experts on this subject based on the ideXlab platform.
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simulation of downflow and upflow depth filtration of non brownian particles under Constant flowrate or Constant Pressure Drop conditions
Journal of The Chinese Institute of Chemical Engineers, 2004Co-Authors: E D Skouras, V N Burganos, Christakis A Paraskeva, A C PayatakesAbstract:The mechanistic simulator of depth filtration of non-Brownian particles in granular bids, which was reported in Burganos et al., 2001, is upgraded and used to investigate the effects of various filter design modes on particle capture efficiency and permeability. The simulation covers all stages of deposition, including extensive pore clogging. The design modes which are examined here are downflow and upflow, in combination with either Constant flowrate or Constant Pressure Drop. It is shown that the direction of the macroscopic flow relative to that of gravity has significant effects. Downflow filters clog slower than upflow ones. It is also shown that the modulating functions, which give the effect of the specific deposit on the filtration coefficient and the permeability, dipend on whether the flowrate or the Pressure Drop is kept Constant. During the early stages of deposition, the modulating functions are virtually the same for both modes of operation, but in advanced stages of deposition substantial differences are observed. These differences are attributed to the fact that when the flowrate is kept Constant (at the expense of a virtually monotonically increasing Pressure Drop), the flow is channeled through certain connected pathways which are composed of relatively deposit-free pores. Such pores are kept clean because the local interstitial velocity is high. This phenomenon is much weaker or even absent when the Pressure Drop is kept Constant, in which case the flowrate decreases virtually monotonically. Another interesting new result is that both of the modulating functions depend, weakly but noticeably, on depth.
Kirk M Green - One of the best experts on this subject based on the ideXlab platform.
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steam foam performance in oil sand cores at Constant Pressure Drop
Fuel, 1991Co-Authors: Kirk M Green, Eddy E Isaacs, John M SmidAbstract:Abstract Although a great deal of laboratory work has been done to examine steam-foam oil recovery processes in corefloods, most of the work reported has been for conditions of Constant flow rate. In the work described here, a series of steam-foam oil displacement runs were carried out with oil sand cores under conditions of Constant Pressure Drop and the results were compared with those obtained under Constant flow conditions. Under Constant Pressure Drop conditions, foam formation in a high permeability flow path resulted in a reduction in steam mobility, which in turn led to a Drop in flow rate through the core. Two surfactants were used, and in the absence of a non-condensible gas, injection of the two surfactants resulted in similar mobility reductions. However, one of the surfactants was significantly slower to foam and reach steady-state mobility. Under the conditions of this study, coinjection of non-condensible gas appeared to have little or no beneficial effect on the mobility reduction achieved. Recovery enhancements of the order of 30–50% relative to steam-only were obtained with both surfactants. When mobility reduction was very high, relatively little oil was produced, presumably because of the drastic reduction in flow rate.