The Experts below are selected from a list of 3138 Experts worldwide ranked by ideXlab platform
Haim Kalman - One of the best experts on this subject based on the ideXlab platform.
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Bend pressure drop in horizontal and vertical Dilute Phase pneumatic conveying systems
Chemical Engineering Science, 2019Co-Authors: Naveen Mani Tripathi, Dmitry Portnikov, Avi Levy, Haim KalmanAbstract:Abstract This paper presents a detailed investigation into the modeling of the total bend pressure drop (TBPD) for all three orientations: horizontal-horizontal (H-H), horizontal-vertical (H-V), and vertical-horizontal (V-H) in Dilute Phase flow. Different types of materials were fed with a screw feeder and conveyed through two different sets of galvanized steel pipeline. The TBPD (all orientations) is the summation of the pressure drop due to the momentum change (reacceleration), the air only flow along the bend, and a function of the pressure drop due to the particles, which contributes to the bend only. A qualitative comparison was performed for blind-T and a radius bend (R/D = 10) using a particular material property. This comparison helped in obtaining a comprehensive understanding of TBPD.
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Particle velocity reduction in horizontal-horizontal bends of Dilute Phase pneumatic conveying
Powder Technology, 2019Co-Authors: Haim Kalman, Nir Santo, Naveen Mani TripathiAbstract:Abstract The significance of the acceleration zone is expressed in designing a straight pipeline that follows the feeding point or a bend of a pneumatic conveying system. Although there are various publications that suggest a mean for evaluating the primary acceleration length, no correlation has been presented for evaluating the re-acceleration length following a bend. The current paper presents a thorough experimental investigation of the particles velocity reduction due to the flow in bends and the re-acceleration velocity profile that follows various bends. The experimental results have been obtained from a 2″ Dilute Phase pneumatic conveying systems with a wide range of operating conditions, conveyed materials and six different bend geometries. The research resulted in a new correlation for the particle velocity reduction due to the flow in the bends, and accordingly we derived an expression for calculating the re-acceleration length following a bend, and the energy loss in the bend.
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Experimental analysis of velocity reduction in bends related to vertical pipes in Dilute Phase pneumatic conveying
Powder Technology, 2019Co-Authors: Naveen Mani Tripathi, Nir Santo, Avi Levy, Haim KalmanAbstract:Abstract The behavior of particles in Dilute Phase pneumatic conveying is a rather complex phenomenon. For example, particle velocities and their trajectories owing to particle-particle and particle-wall collisions are unpredictable. In this study, we focus on particle velocity reduction in horizontal-vertical (H-V) and vertical-horizontal (V-H) bends. A new terminology, ‘bend point’, is introduced to compare different bends on common measures. A broad range of materials (Archimedes numbers = 102 to 106) was investigated using six different bends (blind-T, R/D = 1.5, 4.5, 6.6, 10, and 20) and wide range of conveying velocities (10 m/s
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Experimental study on the particle velocity development profile and acceleration length in horizontal Dilute Phase pneumatic conveying systems
Powder Technology, 2018Co-Authors: Nir Santo, Naveen Mani Tripathi, Dmitry Portnikov, Haim KalmanAbstract:Abstract The significance of the acceleration zone is expressed when designing a straight pipeline that follows either the feeding point or a bend in a pneumatic conveying system. It is an effective and reliable system that takes into account the acceleration zone in the design process. The current paper presents a thorough experimental investigation of particle velocity profile at the acceleration region obtained from 3-in, 2-in and 1-in horizontal Dilute Phase pneumatic conveying systems with various operating conditions and conveyed materials. The velocity was obtained by using a high speed camera combined with image processing. Investigation of the statistical velocity distribution resulted in a new correlation for the particle velocity profile throughout the acceleration zone and the acceleration length in the range of the tested operating conditions.
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experimental study on particle steady state velocity distribution in horizontal Dilute Phase pneumatic conveying
Chemical Engineering Science, 2018Co-Authors: Nir Santo, Dmitry Portnikov, Itamar Eshel, Raviv Taranto, Haim KalmanAbstract:Abstract Particle and slip velocity evaluations are essential for the design of Dilute Phase pneumatic conveying systems in which the particles are fully suspended in the pipe, transportet at high velocities and low pressures with solid loading ratios that do not exceed 15. Although the subject was widely researched, it lacks a consistent correlation over various operating conditions and wide range of particle properties. Moreover, investigating the three dimensional velocity distribution in a cross section of a pipe may further contribute to the understanding of the phenomenon. In this study, we present a thorough experimental investigation of particle velocity obtained from 3“, 2“ and 1“ horizontal, Dilute Phase pneumatic conveying systems with various operating conditions and conveyed material with the following property ranges: 0.06 mm 940 kg m 3 ρ p 5800 kg m 3 ; 14 m s U g 28 m s ; 2.4 . · 10 4 Re g 1.4 · 10 5 ; 26 mm D 76 mm; 0.3 η 3 . The velocity was obtained using a high speed video camera combined with image processing. Data was obtained in all three dimensions for each particle allowing an investigation of the velocity distribution and the effect each component has on the equivalent velocity. The velocities of the non-axial directions were found to be considerably low in relative to the axial velocity. Therefore, in terms of the kinetic energy (e.g.), the non-axial velocities have negligible contribution; however, they have a major effect on the flow and acceleration mechanism. A correlation is presented for the axial particle velocity evaluation in the range of the tested operating conditions, which is mainly affected by the Archimedes number of the particle, with a good fit of our data and various data points from previous publications.
Naveen Mani Tripathi - One of the best experts on this subject based on the ideXlab platform.
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Bend pressure drop in horizontal and vertical Dilute Phase pneumatic conveying systems
Chemical Engineering Science, 2019Co-Authors: Naveen Mani Tripathi, Dmitry Portnikov, Avi Levy, Haim KalmanAbstract:Abstract This paper presents a detailed investigation into the modeling of the total bend pressure drop (TBPD) for all three orientations: horizontal-horizontal (H-H), horizontal-vertical (H-V), and vertical-horizontal (V-H) in Dilute Phase flow. Different types of materials were fed with a screw feeder and conveyed through two different sets of galvanized steel pipeline. The TBPD (all orientations) is the summation of the pressure drop due to the momentum change (reacceleration), the air only flow along the bend, and a function of the pressure drop due to the particles, which contributes to the bend only. A qualitative comparison was performed for blind-T and a radius bend (R/D = 10) using a particular material property. This comparison helped in obtaining a comprehensive understanding of TBPD.
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Particle velocity reduction in horizontal-horizontal bends of Dilute Phase pneumatic conveying
Powder Technology, 2019Co-Authors: Haim Kalman, Nir Santo, Naveen Mani TripathiAbstract:Abstract The significance of the acceleration zone is expressed in designing a straight pipeline that follows the feeding point or a bend of a pneumatic conveying system. Although there are various publications that suggest a mean for evaluating the primary acceleration length, no correlation has been presented for evaluating the re-acceleration length following a bend. The current paper presents a thorough experimental investigation of the particles velocity reduction due to the flow in bends and the re-acceleration velocity profile that follows various bends. The experimental results have been obtained from a 2″ Dilute Phase pneumatic conveying systems with a wide range of operating conditions, conveyed materials and six different bend geometries. The research resulted in a new correlation for the particle velocity reduction due to the flow in the bends, and accordingly we derived an expression for calculating the re-acceleration length following a bend, and the energy loss in the bend.
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Experimental analysis of velocity reduction in bends related to vertical pipes in Dilute Phase pneumatic conveying
Powder Technology, 2019Co-Authors: Naveen Mani Tripathi, Nir Santo, Avi Levy, Haim KalmanAbstract:Abstract The behavior of particles in Dilute Phase pneumatic conveying is a rather complex phenomenon. For example, particle velocities and their trajectories owing to particle-particle and particle-wall collisions are unpredictable. In this study, we focus on particle velocity reduction in horizontal-vertical (H-V) and vertical-horizontal (V-H) bends. A new terminology, ‘bend point’, is introduced to compare different bends on common measures. A broad range of materials (Archimedes numbers = 102 to 106) was investigated using six different bends (blind-T, R/D = 1.5, 4.5, 6.6, 10, and 20) and wide range of conveying velocities (10 m/s
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Experimental study on the particle velocity development profile and acceleration length in horizontal Dilute Phase pneumatic conveying systems
Powder Technology, 2018Co-Authors: Nir Santo, Naveen Mani Tripathi, Dmitry Portnikov, Haim KalmanAbstract:Abstract The significance of the acceleration zone is expressed when designing a straight pipeline that follows either the feeding point or a bend in a pneumatic conveying system. It is an effective and reliable system that takes into account the acceleration zone in the design process. The current paper presents a thorough experimental investigation of particle velocity profile at the acceleration region obtained from 3-in, 2-in and 1-in horizontal Dilute Phase pneumatic conveying systems with various operating conditions and conveyed materials. The velocity was obtained by using a high speed camera combined with image processing. Investigation of the statistical velocity distribution resulted in a new correlation for the particle velocity profile throughout the acceleration zone and the acceleration length in the range of the tested operating conditions.
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acceleration pressure drop analysis in horizontal Dilute Phase pneumatic conveying system
Powder Technology, 2018Co-Authors: Naveen Mani Tripathi, A. Levy, Haim KalmanAbstract:Abstract In pneumatic conveying pipelines, there are specific periods and distances where particles start to accelerate or deaccelerate from specific velocity to steady state. This phenomenon attributes an additional loss of energy also invoke as acceleration pressure drop. The total acceleration pressure drop is defined by measuring the pressure difference between two points at the acceleration zone. The pressure drop of steady state flow for the same length is then reduced from the previous measurement to find acceleration only energy loss. Theoretical equation of momentum change, a material physics, has used to explain the acceleration pressure drop in horizontal pipe. Experimental results have compared with the values of theoretical equation. Results indicated that predicted pressure drop is deviating from the experimental results. Hence, the problem was realized that there was need to precisely predict steady state (collision and friction) pressure drop in this zone, which in classical way of prediction would be used to do just by extrapolation up to the acceleration zone. Hence, a novel factor α has derived by the authors to accurately predict steady state loss in this zone. Experiments have conducted by using different kinds of materials (Bottom ash, Glass beads, Semolina etc.) at different conveying conditions. To view point of design engineers, contribution of acceleration pressure drop in total pipeline has demonstrated by comparing 10 m and 100 m long horizontal pipe. To a simplest case of conveying criteria, acceleration loss contribute 25% of total pipeline pressure drop for 10 m pipe and it reduced to 4% for 100 m pipeline. It has concluded that acceleration pressure drop, between any two velocities, would be predicted with momentum change equation and there is need to accurately predict the steady state pressure drop by factor alpha (α) to predict total pressure drop in acceleration zone.
George E. Klinzing - One of the best experts on this subject based on the ideXlab platform.
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comparison of flow characteristics for Dilute Phase pneumatic conveying for two different plastic pellets
Journal of The Chinese Institute of Chemical Engineers, 2008Co-Authors: Jae Bum Pahk, George E. KlinzingAbstract:Abstract A series of Dilute Phase pneumatic conveying experiments using two different types of plastic pellets has led to the determination and development of distinguishing flow characteristics. Separate experiments on polystyrene and polyolefin pellets captured pressure-drop fluctuations and values at two different measuring points—one at the lower horizontal section of the transporting pipe and another at the upper section and at two different solid-loading ratios for each material. Also, comparison and analysis of the pressure-drop fluctuations and values obtained from the experiments were carried out under the same solid-loading ratio and blower rotational speed for both materials. Basic pressure drop calculations were made to find pressure drop due to pure gas, and that due to the presence of solids using a solid friction factor. In addition, the power spectral density analysis, and the wavelet analysis were conducted for both materials to evaluate the flow characteristics.
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Comparison of flow characteristics for Dilute Phase pneumatic conveying for two different plastic pellets
Journal of the Chinese Institute of Chemical Engineers, 2008Co-Authors: Jae Bum Pahk, George E. KlinzingAbstract:A series of Dilute Phase pneumatic conveying experiments using two different types of plastic pellets has led to the determination and development of distinguishing flow characteristics. Separate experiments on polystyrene and polyolefin pellets captured pressure-drop fluctuations and values at two different measuring points - one at the lower horizontal section of the transporting pipe and another at the upper section and at two different solid-loading ratios for each material. Also, comparison and analysis of the pressure-drop fluctuations and values obtained from the experiments were carried out under the same solid-loading ratio and blower rotational speed for both materials. Basic pressure drop calculations were made to find pressure drop due to pure gas, and that due to the presence of solids using a solid friction factor. In addition, the power spectral density analysis, and the wavelet analysis were conducted for both materials to evaluate the flow characteristics. © 2008 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
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Visual analysis of particle bouncing and its effect on pressure drop in Dilute Phase pneumatic conveying
Powder Technology, 2007Co-Authors: Néstor Vásquez, Karl V. Jacob, Ray Cocco, Shrikant Dhodapkar, George E. KlinzingAbstract:Abstract During the pneumatic conveying of plastic pellets, it has been observed that materials with similar physical characteristics may develop substantial difference in pressure drop, whose cause is not fully understood. This experimental study focused on the dynamic behavior of the particles during conveying and its influence on pressure drop. The bouncing of the particles during pneumatic conveying in Dilute Phase was visually analyzed by means of a high speed video camera. The experiments included two different plastic pellets of similar size and density but different modulus of elasticity. The conveying trials were carried out in a 0.052 m I.D. aluminum pipe conveying system approximately 35 m long. The loading was controlled by an airflow control valve and a variable speed drive rotary valve. For each material, a series of tests were performed creating a matrix of six solids rates for five different air velocities. During the conveying trials a high speed video camera was used to record the actual particle motion in a horizontal section with fully accelerated flow. The videos showed significant difference in bouncing between the soft and the hard pellets. The soft pellets showed very random and intense bouncing with strong rotation, which affected the rebound considerably. In fact, some particles bounced even backwards. On the other side, the hard pellets showed significantly less bouncing and rotation. In addition to the high speed videos, in each test the pressure drop was measured in the horizontal and vertical directions. As expected, a significant difference in pressure drop was recorded for the same conveying settings when using the different materials. The pressure drop showed a close relation to the bouncing of the particles, being much higher for the soft pellets. It can be concluded that the increased pressure drop, developed by the soft polyethylene pellets, is in part due to the multiple times the particles must be reaccelerated during their transit through the conveying system. Additionally, the reduction in the average particle velocity increases the drag force. All of this resulted in up to 3-fold increase in pressure drop across the conveying line compared to the hard polyethylene pellets that showed significantly less bouncing.
Jeffrey M. Bergthorson - One of the best experts on this subject based on the ideXlab platform.
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The effect of biomass particles on the gas distribution and Dilute Phase characteristics of sand-biomass mixtures fluidized in the bubbling regime
Chemical Engineering Science, 2013Co-Authors: Farzam Fotovat, Jamal Chaouki, Jeffrey M. BergthorsonAbstract:The gas distribution between the Dilute (bubble) and dense (emulsion) Phases of a fluidized bed is studied locally and globally in the bubbling regime for mixtures composed of sand and different weight fractions of biomass (2–16%). The Dilute Phase has been characterized by analyzing the pressure and voidage signals. A suite of pressure transducers was used to measure pressure fluctuations at different locations along the bed. A reflective optical probe measured local voidage signals and was placed at different radii (0
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the effect of biomass particles on the gas distribution and Dilute Phase characteristics of sand biomass mixtures fluidized in the bubbling regime
Chemical Engineering Science, 2013Co-Authors: Farzam Fotovat, Jamal Chaouki, Jeffrey M. BergthorsonAbstract:The gas distribution between the Dilute (bubble) and dense (emulsion) Phases of a fluidized bed is studied locally and globally in the bubbling regime for mixtures composed of sand and different weight fractions of biomass (2–16%). The Dilute Phase has been characterized by analyzing the pressure and voidage signals. A suite of pressure transducers was used to measure pressure fluctuations at different locations along the bed. A reflective optical probe measured local voidage signals and was placed at different radii (0
voidage of the bed is increased with higher biomass loading, primarily because of dilution of the emulsion Phase. Changing the quantity of biomass in the bed does not significantly affect the voidage of the bubble and emulsion Phases. The void (bubble) fraction increases at the center of the bed, whereas it decreases and then increases at the wall region with increasing weight fraction of biomass. Higher quantities of biomass reduce the mean bubble size and boost the bubble frequency at the center of the bed. The core-annulus structure of the bed is intensified for mixtures with relatively low quantities of biomass, while increasing the biomass load leads to a more uniform distribution of small bubbles across the bed improving the fluidization quality.
Ulrich Heinzmann - One of the best experts on this subject based on the ideXlab platform.
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Structure investigations of Xe-adsorbate layers by spin-polarized low-energy electron diffraction II. (√3 × √3) R30°-Xe/Pd (111) and the ‘Dilute’ Phase of Xe/Pd(111)
Surface Science, 2002Co-Authors: G. Hilgers, Norbert Müller, Michael Potthoff, Ulrich HeinzmannAbstract:The adsorbate systems (√3 × √3) R30°-Xe/Pd(111) and the ‘Dilute’ Phase of Xe/Pd (111) were investigated with spin-polarized low-energy electron diffraction (SPLEED) . Spin-polarized electrons from a GaAs source were scattered and the spin-dependent intensities were measured. Comparative calculations were carried out by means of a relativistic LEED program. The structure determination of (√3 × √3)R30°-Xe/Pd(111) yields a layer distance of 3.5 ± 0.1 A, the Xe atoms being adsorbed in hollow sites. In the ‘Dilute’ Phase of Xe/Pd(111) the adsorbed Xe atoms occupy on-top sites with a Xe-Pd distance of 4.0 ± 0.1 A without two-dimensional periodicity.
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Spin-resolved photoemission from Xe on Pd(111) in the Dilute Phase: The model case of singly adsorbed atoms
Physical Review Letters, 1991Co-Authors: Bodo Vogt, B. Kessler, Norbert Müller, Gerd Schönhense, B. Schmiedeskamp, Ulrich HeinzmannAbstract:Xe absorbed on Pd(111) in the Dilute Phase, in the (\ensuremath{\surd}3 \ifmmode\times\else\texttimes\fi{} \ensuremath{\surd}3 )R30\ifmmode^\circ\else\textdegree\fi{}, and in the (\ensuremath{\surd}7 \ifmmode\times\else\texttimes\fi{}7R19.2\ifmmode^\circ\else\textdegree\fi{} structure has been studied by spin-resolved photoemission with normally incident circularly polarized light and for normal electron emission. Similar to the free atomic case, no splitting was observed for the Dilute Phase in the peak corresponding to the ${\mathit{p}}_{3/2}$ hole state. Subthreshold electronic resonances were found for the two ordered layers, but could not be detected for the Dilute Phase. Consequences regarding the splitting mechanism and the excitation and emission processes for the resonances are discussed.