The Experts below are selected from a list of 222 Experts worldwide ranked by ideXlab platform
V. L. Polyakov - One of the best experts on this subject based on the ideXlab platform.
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Filtration of suspensions at the descending rate at Linear Kinetics of mass exchange
Journal of Water Chemistry and Technology, 2012Co-Authors: V. L. PolyakovAbstract:We have presented an effective approximated solution of the problem of filtration of a suspension at the set pressure heads at the boundaries of the medium and Linear Kinetics of mass transfer. We have developed the procedure of determining the time of a filtration cycle based on two criteria controlling the quality of the filtrate and filter capacity. A detailed analysis of an impact of various factors of the indicated time has been conducted on numerous examples with typical initial data.
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The engineering calculation of filtering a suspension through a two-layer medium in Linear Kinetics of mass exchange
Journal of Water Chemistry and Technology, 2011Co-Authors: V. L. PolyakovAbstract:We have obtained a simple approximated solution of the problem of filtrating of little concentrated suspension through a two-layer porous medium in Linear Kinetics of mass exchange. Its comparison was carried out with the known strict solution on numerous examples of calculating physicochemical characteristics and technological parameters, which demonstrated high accuracy of formulas proposed for the practice of water treatment.
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Filtration of suspensions through a multilayer medium in nonLinear Kinetics of mass exchange. 2. Quantitative analysis
Journal of Water Chemistry and Technology, 2011Co-Authors: V. L. PolyakovAbstract:The paper sets out the results of the quantitative analysis of the filtration of suspensions through a double layer medium in nonLinear and Linear Kinetics of mass exchange, the constant filtration rate carried out based on strict theoretical relationships from the first part of the general paper. Using numerous examples with typical initial data, regularities of the variations of the output concentration of the suspension were set, just as the time of losses of the pressure head and characteristic times and especially the duration of a filtration cycle depending on the important model parameters.
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Filtration of suspensions through a multilayer medium in nonLinear Kinetics of mass transfer. 1. Theoretical part
Journal of Water Chemistry and Technology, 2011Co-Authors: V. L. PolyakovAbstract:The paper has presented strict theoretical relationships for calculating volumetric concentrations of a sediment and suspension, head losses and characteristic times (medium protection action and the achievement of maximum allowable head losses) in the multilayer medium in nonLinear Kinetics of mass transfer and constant filtration rate. In addition, in the particular case of the two-layer medium similar formulas have been given as applied to Linear Kinetics.
Guillermo F Barreto - One of the best experts on this subject based on the ideXlab platform.
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evaluating the effectiveness factor from a 1d approximation fitted at high thiele modulus spanning commercial pellet shapes with Linear Kinetics
Chemical Engineering Science, 2009Co-Authors: Nestor J Mariani, Clarisa Mocciaro, Sergio D Keegan, Osvaldo M Martinez, Guillermo F BarretoAbstract:Abstract In the present contribution a one-dimensional model (1D model) is employed to account for the effect of pellet shape in the solution of diffusion–catalytic reaction problems. The 1D model free parameter (σ) is fitted so as to match the second term of the series for the effective reaction rate at fast kinetic conditions. The performance of the model was evaluated for a large collection of pellets available commercially, covering almost all the main shapes offered by catalyst manufacturers. For isothermal Linear Kinetics the effectiveness factors calculated by the 1D model differ at most by 3% from those of the actual 3D pellets.
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Estimation of Effectiveness Factor for Arbitrary Particle Shape and Non-Linear Kinetics
Industrial & Engineering Chemistry Research, 2009Co-Authors: Nestor J Mariani, Clarisa Mocciaro, Osvaldo M Martinez, Guillermo F BarretoAbstract:A one-dimensional model, called generalized cylinder (GC), is employed to analyze the diffusion−reaction problem in catalytic pellets of different shapes and nonLinear Kinetics. The fitting parameter (σ) of the GC model was adjusted by matching the behavior of the actual pellet at high reaction rates. The errors of the GC model, considering five different kinetic expressions (isothermal zero and second order, isothermal Langmuir−Hinshelwood−Hougen−Watson type, first order exothermic, and first order endothermic) and four different catalytic pellet shapes turned out to be less than 3.5%.
Robert P Lowell - One of the best experts on this subject based on the ideXlab platform.
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precipitation of quartz during high temperature fracture controlled hydrothermal upflow at ocean ridges equilibrium versus Linear Kinetics
Journal of Geophysical Research, 2000Co-Authors: Jeffrey T Martin, Robert P LowellAbstract:We have addressed quartz precipitation resulting from cooling of silica-saturated, high-temperature hydrothermal solutions ascending through crack-controlled permeable regions beneath an ocean ridge crest. The results of this work indicate that for systems with high initial permeabilities, such as black-smoker-like systems, fluid channels can exist for several decades without serious sealing as a result of quartz precipitation, provided the Kinetics of silica precipitation are considered. In lower-permeability systems, even though Kinetics of precipitation remain important, reduction of permeability as a result of quartz precipitation can occur on a time-scale of a decade, leading to a decline in heat output and temperature of fluid as it encounters lower-temperature regions. In addition, we show that Kinetics considerations result in the preferential sealing of thin cracks. This result is consistent with seismic velocity data, which suggest that the increase in seismic velocity with depth and age in the oceanic crust may result from the preferential closing of thinner cracks. These results also suggest that precipitation of quartz should occur near the dike/lava transition zone or in mineralized zones where large temperature gradients may exist as a result of mixing between cool seawater and hot hydrothermal fluids. The results of this model are thus consistent with the observed increase in quartz veins in such regions beneath the TAG mound and in ophiolites.
A Lombès - One of the best experts on this subject based on the ideXlab platform.
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Development and implementation of standardized respiratory chain spectrophotometric assays for clinical diagnosis
Mitochondrion, 2009Co-Authors: F. Medja, C Jardel, STEPHANE ALLOUCHE, P. Frachon, M. Malgat, B. Mousson De Camaret, J. Lunardi, Jean-pierre Mazat, A. Slama, A LombèsAbstract:Diversity of respiratory chain spectrophotometric assays may lead to difficult comparison of results between centers. The French network of mitochondrial diseases diagnostic centers undertook comparison of the results obtained with different protocols in the French diagnostic centers. The diversity of protocols was shown to have striking consequences, which prompted the network to undertake standardization and optimization of the protocols with respect to clinical diagnosis, i.e. high velocity while maintaining Linear Kinetics relative to time and enzyme concentration. Assays were set up on animal tissues and verified on control human muscle and fibroblasts. Influence of homogenization buffer and narrow range of optimal concentration of phosphate, substrate and tissue were shown. Experimental data and proposed protocols have been posted on a free access website. Their subsequent use in several diagnostic centers has improved consistency for all assays. © 2009 Mitochondria Research Society.
Nestor J Mariani - One of the best experts on this subject based on the ideXlab platform.
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evaluating the effectiveness factor from a 1d approximation fitted at high thiele modulus spanning commercial pellet shapes with Linear Kinetics
Chemical Engineering Science, 2009Co-Authors: Nestor J Mariani, Clarisa Mocciaro, Sergio D Keegan, Osvaldo M Martinez, Guillermo F BarretoAbstract:Abstract In the present contribution a one-dimensional model (1D model) is employed to account for the effect of pellet shape in the solution of diffusion–catalytic reaction problems. The 1D model free parameter (σ) is fitted so as to match the second term of the series for the effective reaction rate at fast kinetic conditions. The performance of the model was evaluated for a large collection of pellets available commercially, covering almost all the main shapes offered by catalyst manufacturers. For isothermal Linear Kinetics the effectiveness factors calculated by the 1D model differ at most by 3% from those of the actual 3D pellets.
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Estimation of Effectiveness Factor for Arbitrary Particle Shape and Non-Linear Kinetics
Industrial & Engineering Chemistry Research, 2009Co-Authors: Nestor J Mariani, Clarisa Mocciaro, Osvaldo M Martinez, Guillermo F BarretoAbstract:A one-dimensional model, called generalized cylinder (GC), is employed to analyze the diffusion−reaction problem in catalytic pellets of different shapes and nonLinear Kinetics. The fitting parameter (σ) of the GC model was adjusted by matching the behavior of the actual pellet at high reaction rates. The errors of the GC model, considering five different kinetic expressions (isothermal zero and second order, isothermal Langmuir−Hinshelwood−Hougen−Watson type, first order exothermic, and first order endothermic) and four different catalytic pellet shapes turned out to be less than 3.5%.