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D Cantero - One of the best experts on this subject based on the ideXlab platform.
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influence of trickling Liquid Velocity low molar ratio of nitrogen sulfur and gas Liquid flow pattern in anoxic biotrickling filters for biogas desulfurization
Biochemical Engineering Journal, 2019Co-Authors: Patricio I Cano, Javier Brito, Fernando Almenglo, Martin J Ramirez, Jose Manuel Gomez, D CanteroAbstract:Abstract Hydrogen sulfide has been successfully removed from biogas using anoxic biotrickling filters but an in-depth study of the main operational variables has not yet been carried out. The effect of (i) the empty bed residence time (32–164 s) at a hydrogen sulfide concentration of 2,000 ppmv, (ii) the inlet hydrogen sulfide concentration (2,000–10,000 ppmv), (iii) the trickling Liquid Velocity (4.8–20.9 m h−1) and (iv) the feed of low nitrogen/sulfur molar ratio (0.334–0.409 mol N-NO3– mol−1 S-H2S) on the hydrogen sulfide removal efficiency have been studied. The BTF (total packed volume of 2.8 L, height/diameter ratio of 9.8) was filled with polypropylene Pall rings (5/8″) and fed continuously with nitrate and a biogas mimic operating in counter-current and co-current flow modes. The maximum elimination capacity was 282.0 gS-H2S m–3 h–1 (RE 97 ± 0.5%) for counter-current flow and 287.5 gS-H2S m–3 h–1 (RE 99 ± 0.4%) for co-current flow mode for an EBRT of 164 s. In addition, in terms of the nitrogen/sulfur molar ratio a higher elemental sulfur production was found in counter-current flow (97.6 ± 2.0%) when compared to co-current flow (87.6±2.8%) since a better depletion of nitrate occurred in co-current flow mode. Finally, three different nitrogen/sulfur molar ratios (0.4, 1.0 and 1.6 mol N-NO3– mol–1 S-H2S) were compared economically. The low and high ratios would involve a nitrate cost of 0.54 and 2.15 € per kg of treated of S-H2S and an elemental sulfur production of 21.5 metric tons and zero production, respectively.
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Influence of trickling Liquid Velocity, low molar ratio of nitrogen/sulfur and gas-Liquid flow pattern in anoxic biotrickling filters for biogas desulfurization
Biochemical Engineering Journal, 2019Co-Authors: Patricio I Cano, Javier Brito, Fernando Almenglo, Jose Manuel Gomez, Martín Ramírez, D CanteroAbstract:Abstract Hydrogen sulfide has been successfully removed from biogas using anoxic biotrickling filters but an in-depth study of the main operational variables has not yet been carried out. The effect of (i) the empty bed residence time (32–164 s) at a hydrogen sulfide concentration of 2,000 ppmv, (ii) the inlet hydrogen sulfide concentration (2,000–10,000 ppmv), (iii) the trickling Liquid Velocity (4.8–20.9 m h−1) and (iv) the feed of low nitrogen/sulfur molar ratio (0.334–0.409 mol N-NO3– mol−1 S-H2S) on the hydrogen sulfide removal efficiency have been studied. The BTF (total packed volume of 2.8 L, height/diameter ratio of 9.8) was filled with polypropylene Pall rings (5/8″) and fed continuously with nitrate and a biogas mimic operating in counter-current and co-current flow modes. The maximum elimination capacity was 282.0 gS-H2S m–3 h–1 (RE 97 ± 0.5%) for counter-current flow and 287.5 gS-H2S m–3 h–1 (RE 99 ± 0.4%) for co-current flow mode for an EBRT of 164 s. In addition, in terms of the nitrogen/sulfur molar ratio a higher elemental sulfur production was found in counter-current flow (97.6 ± 2.0%) when compared to co-current flow (87.6±2.8%) since a better depletion of nitrate occurred in co-current flow mode. Finally, three different nitrogen/sulfur molar ratios (0.4, 1.0 and 1.6 mol N-NO3– mol–1 S-H2S) were compared economically. The low and high ratios would involve a nitrate cost of 0.54 and 2.15 € per kg of treated of S-H2S and an elemental sulfur production of 21.5 metric tons and zero production, respectively.
Akio Tomiyama - One of the best experts on this subject based on the ideXlab platform.
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distributions of void fraction and Liquid Velocity in air water bubble column
International Journal of Multiphase Flow, 2014Co-Authors: Shimpei Ojima, Shigeo Hosokawa, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract Multi-fluid simulations of heterogeneous bubbly flows in an air–water bubble column were carried out to verify the speculation that a heterogeneous bubbly flow is predictable without turbulence models such as k–ɛ and LES models, provided that the Velocity fluctuation caused by large-scale vortical flow structures prevails over the bubble-induced and shear-induced turbulences. Experiments on the heterogeneous air–water bubbly flows in a rectangular bubble column were also carried out to obtain experimental data of the mean Velocity, fluctuation Velocity and void fraction for validation of the numerical method. A small LDV probe developed in our previous study was utilized to measure the Liquid Velocity in the column at high spatial and high temporal resolutions. The distribution of void fraction was measured using an electrical conductivity probe. The conclusions obtained under the present experimental conditions are as follows: (1) the small LDV probe is of great use in measuring the distributions of mean and fluctuation velocities of the Liquid phase at high spatial and high temporal resolutions, (2) the Velocity fluctuation in the heterogeneous regime in the bubble column is mainly due to large-scale vortical structures, and (3) the multi-fluid model can give good predictions of a heterogeneous bubbly flow without using the turbulence models, provided that large-scale vortical structures in the flow prevail over the bubble-induced and shear-induced turbulences.
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Distributions of void fraction and Liquid Velocity in air–water bubble column
International Journal of Multiphase Flow, 2014Co-Authors: Shimpei Ojima, Shigeo Hosokawa, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract Multi-fluid simulations of heterogeneous bubbly flows in an air–water bubble column were carried out to verify the speculation that a heterogeneous bubbly flow is predictable without turbulence models such as k–ɛ and LES models, provided that the Velocity fluctuation caused by large-scale vortical flow structures prevails over the bubble-induced and shear-induced turbulences. Experiments on the heterogeneous air–water bubbly flows in a rectangular bubble column were also carried out to obtain experimental data of the mean Velocity, fluctuation Velocity and void fraction for validation of the numerical method. A small LDV probe developed in our previous study was utilized to measure the Liquid Velocity in the column at high spatial and high temporal resolutions. The distribution of void fraction was measured using an electrical conductivity probe. The conclusions obtained under the present experimental conditions are as follows: (1) the small LDV probe is of great use in measuring the distributions of mean and fluctuation velocities of the Liquid phase at high spatial and high temporal resolutions, (2) the Velocity fluctuation in the heterogeneous regime in the bubble column is mainly due to large-scale vortical structures, and (3) the multi-fluid model can give good predictions of a heterogeneous bubbly flow without using the turbulence models, provided that large-scale vortical structures in the flow prevail over the bubble-induced and shear-induced turbulences.
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cavitation in a two dimensional nozzle and Liquid jet atomization ldv measurement of Liquid Velocity in a nozzle
Jsme International Journal Series B-fluids and Thermal Engineering, 2006Co-Authors: Akio Tomiyama, Shigeo Hosokawa, Shinji Nigorikawa, Tatsutoshi MaedaAbstract:Cavitation in nozzles of Liquid injectors is known to affect the atomization of a discharged Liquid jet. To understand how cavitating flow in a nozzle enhances the Liquid jet atomization, Liquid Velocity distribution of cavitating flow in a two-dimensional transparent nozzle was measured using a Laser Doppler Velocimetry (LDV) system. As a result, the following conclusions were obtained: (1) The inception of cavitation occurs near the outer edge of separated boundary layer (SBL), where the time-averaged local Velocity takes the highest value and the time-averaged pressure is almost equal to the vapor saturation pressure. (2) When the cavitation number σ is greater than 0.78 (in no cavitation and developing cavitation regimes), the reattachment of SBL occurs in the middle of the nozzle. A large Velocity fluctuation, which appears just downstream of SBL, decreases near the nozzle exit. Hence the wavy jet is formed in these regimes. (3) For σ < 0.65 (in super cavitation regime), the lateral flow directing from the core region toward the side walls just upstream of the nozzle exit is a major cause of the increase in the spray angle and drastic enhancement of Liquid jet atomization. The strong turbulence just upstream of the exit must play an important role in the formation of ligaments on Liquid jet interface.
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cavitation in a two dimensional nozzle and Liquid jet atomization 2nd report ldv measurement of Liquid Velocity in a nozzle
Transactions of the Japan Society of Mechanical Engineers. B, 2006Co-Authors: Akio Tomiyama, Shigeo Hosokawa, Shinji Nigorikawa, Tatsutoshi MaedaAbstract:Cavitation and internal flow in the nozzle of a Liquid injector are known to affect the atomization of a discharged Liquid jet. In order to obtain the knowledge on the mechanism how cavitating flow in a nozzle enhances the Liquid jet atomization, Liquid Velocity distributions of cavitating flows in a two-dimensional transparent nozzle were measured using a Laser Doppler Velocimetry (LDV) system. As a result, the following conclusions were obtained : (1) The inception of cavitation occurs near the outer edge of the separated boundary layer (SBL), where the mean local Velocity takes the highest value and the mean pressure is lower than the vapor saturation pressure. (2) When the cavitation number σ≥0.78 (No Cavitation or Developing Cavitation), the reattachment of SBL occurs in the middle of the nozzle. A large Velocity fluctuation, which appears in and just downstream of SBL, decreases near the nozzle exit. This may be the reason of the wavy jet. (3) Whenσ≤0.65 (Super Cavitation), the lateral flow from the core region toward the side walls just upstream of the nozzle exit may be the major cause of the increase in spray angle and a drastic promotion of Liquid jet atomization. The strong turbulence just upstream of the exit may also play a role on the formation of ligaments at Liquid jet interface.
Jyeshtharaj B. Joshi - One of the best experts on this subject based on the ideXlab platform.
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Advanced PIV/LIF and shadowgraphy system to visualize flow structure in two-phase bubbly flows
Chemical Engineering Science, 2010Co-Authors: Mayur J. Sathe, I. H. Thaker, Tyson E. Strand, Jyeshtharaj B. JoshiAbstract:Particle image velocimetry (PIV) is a promising technique to measure dispersed phase size, dispersed phase hold-up and Velocity of both the phases. The current work reports measurement of the shape, size, Velocity and acceleration of bubbles using shadowgraphy, and Liquid Velocity measurement obtained using PIV/LIF with fluorescent tracer particles. Measurements were performed in a narrow rectangular column at moderate gas hold-up (~5%) with wide variation of bubble sizes (0.1-15 mm). The Liquid Velocity field was subjected to 2D discrete wavelet transform (DWT) to visualize the flow structures in the bubbly flow. Further, the slip Velocity of individual bubbles was obtained from the DWT filtered Liquid Velocity field. The results are compared with the slip Velocity correlations reported in literature for single bubbles rising in quiescent water. The comparison shows the difference in slip Velocity of single bubbles and bubbles rising in swarm. The scale wise decomposition obtained from DWT was also used to quantify the Liquid Velocity field in terms of wavenumber spectrum. The Velocity and acceleration measurements are demonstrated on a single spherical cap bubble rising in quiescent water. The measurements show the potential of the 2D acceleration measurement to facilitate the estimation of unsteady drag on bubbles.
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advanced piv lif and shadowgraphy system to visualize flow structure in two phase bubbly flows
Chemical Engineering Science, 2010Co-Authors: Mayur J. Sathe, I. H. Thaker, Tyson E. Strand, Jyeshtharaj B. JoshiAbstract:Particle image velocimetry (PIV) is a promising technique to measure dispersed phase size, dispersed phase hold-up and Velocity of both the phases. The current work reports measurement of the shape, size, Velocity and acceleration of bubbles using shadowgraphy, and Liquid Velocity measurement obtained using PIV/LIF with fluorescent tracer particles. Measurements were performed in a narrow rectangular column at moderate gas hold-up (~5%) with wide variation of bubble sizes (0.1-15 mm). The Liquid Velocity field was subjected to 2D discrete wavelet transform (DWT) to visualize the flow structures in the bubbly flow. Further, the slip Velocity of individual bubbles was obtained from the DWT filtered Liquid Velocity field. The results are compared with the slip Velocity correlations reported in literature for single bubbles rising in quiescent water. The comparison shows the difference in slip Velocity of single bubbles and bubbles rising in swarm. The scale wise decomposition obtained from DWT was also used to quantify the Liquid Velocity field in terms of wavenumber spectrum. The Velocity and acceleration measurements are demonstrated on a single spherical cap bubble rising in quiescent water. The measurements show the potential of the 2D acceleration measurement to facilitate the estimation of unsteady drag on bubbles.
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Effect of Liquid Velocity on axial mixing in gas-Liquid dispersions: a CFD simulation
Chemical Engineering & Technology, 2006Co-Authors: Swarnendu Roy, Jyeshtharaj B. JoshiAbstract:A CFD analysis has been carried out to elucidate the characteristic features of axial mixing in gas-Liquid dispersed upflow when the flow changes between two extremes: from bubble column, with very low/no Liquid Velocity, to pipe flow with very high Liquid Velocity. The CFD model was validated by simulating flow both in multiphase and in single phase. An agreement was observed between the predictions and the experimental data available in the published literature. The validated CFD model has been extended for the simulation of the axial dispersion coefficient for both multiphase and single phase. CFD predictions of the axial dispersion coefficient show good agreement with experimental values published in the literature. A systematic numerical study was done by varying the superficial Liquid Velocity, from a very low value to a very high value, to understand its effect on axial dispersion.
Xiaodong Sun - One of the best experts on this subject based on the ideXlab platform.
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Local Liquid Velocity in Vertical Air-Water Downward Flow
Journal of Fluids Engineering, 2004Co-Authors: Xiaodong Sun, Mamoru Ishii, Sidharth Paranjape, Seungjin Kim, Hiroshi Goda, Joseph M. KellyAbstract:We present an experimental study of local Liquid Velocity measurement in downward air-water bubbly and slug flows in a 50.8 mm inner-diameter round pipe. The axial Liquid Velocity and its fluctuations were measured by a laser Doppler anemometry (LDA) system. The maximum Liquid Velocity in a downward two-phase flow could occur off the pipe centerline at relatively low Liquid flow rates and this observation is consistent with other researchers' results
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LDA measurement in air–water downward flow
Experimental Thermal and Fluid Science, 2004Co-Authors: Xiaodong Sun, Mamoru Ishii, Sidharth Paranjape, Jennifer UhleAbstract:Abstract Local characteristics of the Liquid phase in air–water downward flow were investigated in a 50.8 mm inner-diameter round pipe. A laser Doppler anemometry (LDA) system was used to measure axial Liquid Velocity and its fluctuations. To reduce the measurement uncertainty, the experiments were performed in flow conditions with low void fraction. Titanium dioxide particles with a mean diameter of 2 μm were used as seeding particles to enhance the data rate. Benchmark experiment in the single-phase Liquid flow was first carried out to ensure good performance of the LDA system in the current setup. A total of 13 flow conditions were examined in air–water two-phase experiment. By applying a special setup of the LDA system, it was found that no further signal discrimination process was required to obtain the Liquid Velocity in the present low void fraction conditions. The comparisons between the Liquid flow rates measured by the magnetic flow meter and those obtained from the local measurements showed good agreements, with differences less than 6.0%. The measurement results demonstrated that the presence of the bubbles tended to flatten the Liquid Velocity radial profile, and the maximum Liquid Velocity might occur off the pipe centerline, in particular at relatively low flow rates. Furthermore, the axial Liquid Velocity fluctuations were quite uniform in the radial direction. No significant turbulent reduction in the two-phase downward flow was observed in the current experimental flow conditions.
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Liquid Velocity in upward and downward air–water flows
Annals of Nuclear Energy, 2004Co-Authors: Xiaodong Sun, Sidharth Paranjape, Seungjin Kim, Basar Ozar, Mamoru IshiiAbstract:Abstract Local characteristics of the Liquid phase in upward and downward air–water two-phase flows were experimentally investigated in a 50.8-mm inner-diameter round pipe. An integral laser Doppler anemometry (LDA) system was used to measure the axial Liquid Velocity and its fluctuations. No effect of the flow direction on the Liquid Velocity radial profile was observed in single-phase Liquid benchmark experiments. Local multi-sensor conductivity probes were used to measure the radial profiles of the bubble Velocity and the void fraction. The measurement results in the upward and downward two-phase flows are compared and discussed. The results in the downward flow demonstrated that the presence of the bubbles tended to flatten the Liquid Velocity radial profile, and the maximum Liquid Velocity could occur off the pipe centerline, in particular at relatively low flow rates. However, the maximum Liquid Velocity always occurred at the pipe center in the upward flow. Also, noticeable turbulence enhancement due to the bubbles in the two-phase flows was observed in the current experimental flow conditions. Furthermore, the distribution parameter and the void-weighted area-averaged drift Velocity were obtained based on the definitions.
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Local Liquid Velocity in Vertical Air-Water Bubbly Downward Flow
Volume 1: Fora Parts A B C and D, 2003Co-Authors: Xiaodong Sun, Mamoru Ishii, Sidharth Paranjape, Seungjin Kim, Hiroshi Goda, Joseph M. KellyAbstract:Local characteristics of the Liquid phase in downward air-water bubbly and slug flows were investigated in a 50.8-mm inner-diameter round pipe. A laser Doppler anemometry system was used to measure axial Liquid Velocity and its fluctuations. To reduce the measurement uncertainty, the experiments were performed in flow conditions with low void fraction. The comparisons between the Liquid flow rates measured by the magnetic flow meter and those obtained from the local measurements showed good agreements. In addition, based on the LDA measurements and the data acquired by the local conductivity probes, the local relative Velocity distribution, the distribution parameter and the drift Velocity in the drift-flux model were obtained for the current downward flow.© 2003 ASME
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Local Liquid Velocity measurements in air-water bubbly flow
Experiments in Fluids, 2002Co-Authors: Xiaodong Sun, Seungjin Kim, T. R. Smith, Mamoru IshiiAbstract:Local measurements of axial Liquid Velocity were performed for vertical upward air-water bubbly flow in a 101.6-mm inner-diameter round pipe by using a laser Doppler anemometer (LDA) and a hot-film anemometer (HFA). The data reduction approaches for both the LDA and HFA are discussed in detail. A threshold scheme with the information of local void fraction and Velocity distribution in single-phase flow was applied to the LDA to approximately discriminate Liquid Velocity signals from those of the bubble interface Velocity. Furthermore, a formulation was given to account for the effect of the bubble relative Velocity on the Liquid in the front and wake regions of the bubbles. For the HFA, an amplitude threshold scheme and a slope criterion were used to extract Liquid Velocity information. To reduce the measurement uncertainty, the experiments were performed in flow conditions where the area-averaged void fraction was less than 20%. The experimental results showed satisfactory agreement between the Liquid volumetric flow rates calculated by area integration of the local Liquid Velocity and void fraction measurements, and the measured value by a magnetic flow meter. Also, the area-averaged relative Velocity between the gas and Liquid phases obtained from the current measurements agreed well with previous research.
Shimpei Ojima - One of the best experts on this subject based on the ideXlab platform.
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distributions of void fraction and Liquid Velocity in air water bubble column
International Journal of Multiphase Flow, 2014Co-Authors: Shimpei Ojima, Shigeo Hosokawa, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract Multi-fluid simulations of heterogeneous bubbly flows in an air–water bubble column were carried out to verify the speculation that a heterogeneous bubbly flow is predictable without turbulence models such as k–ɛ and LES models, provided that the Velocity fluctuation caused by large-scale vortical flow structures prevails over the bubble-induced and shear-induced turbulences. Experiments on the heterogeneous air–water bubbly flows in a rectangular bubble column were also carried out to obtain experimental data of the mean Velocity, fluctuation Velocity and void fraction for validation of the numerical method. A small LDV probe developed in our previous study was utilized to measure the Liquid Velocity in the column at high spatial and high temporal resolutions. The distribution of void fraction was measured using an electrical conductivity probe. The conclusions obtained under the present experimental conditions are as follows: (1) the small LDV probe is of great use in measuring the distributions of mean and fluctuation velocities of the Liquid phase at high spatial and high temporal resolutions, (2) the Velocity fluctuation in the heterogeneous regime in the bubble column is mainly due to large-scale vortical structures, and (3) the multi-fluid model can give good predictions of a heterogeneous bubbly flow without using the turbulence models, provided that large-scale vortical structures in the flow prevail over the bubble-induced and shear-induced turbulences.
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Distributions of void fraction and Liquid Velocity in air–water bubble column
International Journal of Multiphase Flow, 2014Co-Authors: Shimpei Ojima, Shigeo Hosokawa, Kosuke Hayashi, Akio TomiyamaAbstract:Abstract Multi-fluid simulations of heterogeneous bubbly flows in an air–water bubble column were carried out to verify the speculation that a heterogeneous bubbly flow is predictable without turbulence models such as k–ɛ and LES models, provided that the Velocity fluctuation caused by large-scale vortical flow structures prevails over the bubble-induced and shear-induced turbulences. Experiments on the heterogeneous air–water bubbly flows in a rectangular bubble column were also carried out to obtain experimental data of the mean Velocity, fluctuation Velocity and void fraction for validation of the numerical method. A small LDV probe developed in our previous study was utilized to measure the Liquid Velocity in the column at high spatial and high temporal resolutions. The distribution of void fraction was measured using an electrical conductivity probe. The conclusions obtained under the present experimental conditions are as follows: (1) the small LDV probe is of great use in measuring the distributions of mean and fluctuation velocities of the Liquid phase at high spatial and high temporal resolutions, (2) the Velocity fluctuation in the heterogeneous regime in the bubble column is mainly due to large-scale vortical structures, and (3) the multi-fluid model can give good predictions of a heterogeneous bubbly flow without using the turbulence models, provided that large-scale vortical structures in the flow prevail over the bubble-induced and shear-induced turbulences.