The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Takayuki Saito - One of the best experts on this subject based on the ideXlab platform.
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discussion about the differences in mass transfer bubble motion and Surrounding Liquid motion between a contaminated system and a clean system based on consideration of three dimensional wake structure obtained from lif visualization
Chemical Engineering Science, 2017Co-Authors: Jie Huang, Takayuki SaitoAbstract:Abstract Mass transfer from a bubble to the Surrounding Liquid plays an important role in industry processes. To improve the efficiency of the industrial processes, a deep understanding of the mass transfer mechanism is essential. In the present study, the relationship between the instantaneous mass transfer and the motions of the bubble and three-dimensional bubble wakes is discussed, on the basis of precise measurement. Moreover, since some industrial applications are contaminated system, the authors consider influences of bubble-surface contamination on the above. In the present experiments, purified water, and water contaminated with a very small amount of surfactant (1-pentanol) were employed. LIF (Laser Induced Fluorescence) technique and HPTS (a pH-sensitive dye) that was calibrated through a photoelectric optical fiber probe in advance were employed to visualize the mass transfer of the bubble and the wake structure of the bubble. The authors investigated highly reproducible single bubbles (considered to be almost the same bubble) launched from a special bubble-launch device; successfully they acquired pseudo-time-series sliced bubble wakes' images from every y-z plane at an equidistant interval. By processing the pseudo-time-series images through their own new image-processing, they challengingly reconstructed three-dimensional bubble wakes. From careful observations on the three-dimensional bubble wakes’ structure, they indirectly found out that the Marangoni convection, which was induced by the non-uniform distribution of surfactants desorption on the bubble surface, raised changes in the boundary layers in the contaminated water. The authors discussed the influences of gas-Liquid interface contamination on the bubble motions, bubble wakes, and mass transfer process based on the reconstruction of three-dimensional bubble wakes in the purified water and contaminated water.
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the effects of bubble interface contamination on bubble motion bubble induced Surrounding Liquid motion and mass transfer
ASME JSME KSME 2015 Joint Fluids Engineering Conference, 2015Co-Authors: Yuki Iburi, Jie Huang, Takayuki SaitoAbstract:Mass transfer from a bubble to the Surrounding Liquid plays an important role in chemical engineering processes. To improve the efficiency and safety of the processes, a deep understanding of the mass transfer mechanism from bubbles to the Surrounding Liquid is essential. In the present study, we examined a CO2 single bubble of 2∼3 mm in equivalent diameter that ascended zigzag in purified water and contaminated water (500ppm 1-pentanol solution). We used a high speed video camera systems with high spatial and temporal resolution, for visualization of the bubble wake and bubble-induced Surrounding Liquid motion.The dissolution process of CO2 from the bubble to the Surrounding Liquid was visualized via LIF/HPTS (Laser Induced Fluorescence) method. HPTS, which is a fluorescent substance, was excited by Ar ion laser with a wavelength of 458 nm, then emitted with a wavelength of 513 nm. A pH level of CO2 solution decreased with increase in CO2 concentration; hence the emission intensity of HPTS was reduced. As a result, dark regions observed below the bubble rear accorded with the bubble wakes; from visualization of this bubble wakes through the high speed video cameras, dynamic CO2 dissolution process was obtained. In the purified water, the bubble shape was oblate ellipsoid, and horse-shoe-like vortices were formed in the rear of the bubble. On the other hand, in the contaminated water, the bubble was nearly spherical. Furthermore, behavior of the vortices changed. These different results in two conditions were caused by the decrease in the surface tension owing to the bubble surface contamination. While the bubble was rising, the non-uniform distribution of the surfactant on the bubble surface occurred. Hence, a gradient of the surface tension was formed on the bubble surface, furthermore, it caused the Marangoni convection.Meanwhile, in order to consider the relationship between dissolution process and the Surrounding Liquid motion, we measured the Liquid phase velocities via PIV.Copyright © 2015 by JSME
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effects of a bubble and the Surrounding Liquid motions on the instantaneous mass transfer across the gas Liquid interface
Chemical Engineering Journal, 2015Co-Authors: Takayuki Saito, Masahiko ToriuAbstract:Abstract To understand the mass transfer mechanism from a bubble to the Surrounding Liquid, one must consider the relation between the mass transfer, gravity-center and surface motions of the bubble. Bubbles in chemical and bio-reactors usually exhibit a zigzag motion. Simultaneously, such bubbles accompany periodic surface oscillation. Knowledge about the correlation between the mass-transfer mechanism and bubble motion is as yet incomplete. In this study, we used experimental results from highly precise measurements of bubble volume to clarify the instantaneous mass-transfer coefficients of a zigzagging CO 2 bubble. We visualized the zigzagging motion and surface oscillation 3-dimensionally and simultaneously, using two high-speed cameras and mirrors. We also visualized the CO 2 dissolution (mass transfer) process from the bubble to the Surrounding Liquid using the LIF/HPTS method. To obtain the precise instantaneous mass transfer coefficient and bubble motions, single bubbles were visualized in three sections: the linear-ascent, the first-inversion, and the second-inversion of the zigzag motion. The instantaneous mass-transfer coefficients in an interval of 6 ms in these sections were calculated from the bubble-volume shrinkage with ms time-resolution. The instantaneous mass-transfer coefficients increased in acceleration areas—i.e., in the linear-ascent and second-inversion sections. Interestingly, in the latter, the gravity-center velocity of the bubble reached terminal velocity and was constant, but the velocity of the bubble hemisphere was accelerated due to the zigzag motion. This partial acceleration of the bubble hemisphere led to a high renewal rate of the Liquid on the bubble interface. The effect of the partial acceleration on the instantaneous mass transfer was significant for bubbles categorized into zigzag motion.
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Effects of a bubble and the Surrounding Liquid motions on the instantaneous mass transfer across the gas–Liquid interface
Chemical Engineering Journal, 2015Co-Authors: Takayuki Saito, Masahiko ToriuAbstract:Abstract To understand the mass transfer mechanism from a bubble to the Surrounding Liquid, one must consider the relation between the mass transfer, gravity-center and surface motions of the bubble. Bubbles in chemical and bio-reactors usually exhibit a zigzag motion. Simultaneously, such bubbles accompany periodic surface oscillation. Knowledge about the correlation between the mass-transfer mechanism and bubble motion is as yet incomplete. In this study, we used experimental results from highly precise measurements of bubble volume to clarify the instantaneous mass-transfer coefficients of a zigzagging CO 2 bubble. We visualized the zigzagging motion and surface oscillation 3-dimensionally and simultaneously, using two high-speed cameras and mirrors. We also visualized the CO 2 dissolution (mass transfer) process from the bubble to the Surrounding Liquid using the LIF/HPTS method. To obtain the precise instantaneous mass transfer coefficient and bubble motions, single bubbles were visualized in three sections: the linear-ascent, the first-inversion, and the second-inversion of the zigzag motion. The instantaneous mass-transfer coefficients in an interval of 6 ms in these sections were calculated from the bubble-volume shrinkage with ms time-resolution. The instantaneous mass-transfer coefficients increased in acceleration areas—i.e., in the linear-ascent and second-inversion sections. Interestingly, in the latter, the gravity-center velocity of the bubble reached terminal velocity and was constant, but the velocity of the bubble hemisphere was accelerated due to the zigzag motion. This partial acceleration of the bubble hemisphere led to a high renewal rate of the Liquid on the bubble interface. The effect of the partial acceleration on the instantaneous mass transfer was significant for bubbles categorized into zigzag motion.
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a newly developed photoelectric optical fiber probe for simultaneous measurements of a co2 bubble chord length velocity and void fraction and the local co2 concentration in the Surrounding Liquid
Flow Measurement and Instrumentation, 2012Co-Authors: Masahiro Yamada, Takayuki SaitoAbstract:Abstract In a bubbly flow, the mass transfer from bubble swarms to the Surrounding Liquid and the concentration of dissolved gas transported in the Liquid are deeply related to time-spatial structures of the gas and Liquid phases. Various techniques to measure bubble characteristics or solution concentration in gas-Liquid two-phase flows have been developed. However, detailed discussions about the gas absorption process in consideration of the above relations are not found, because there was no instrument to enable simultaneous measurement of bubble characteristics and concentrations of the Surrounding Liquid. The purpose of the present study was to develop a new type of probe that enables the simultaneous measurement of these features. We have developed a platinum (Pt)-plated optical fiber probe (POFP: Photoelectric Optical Fiber Probe), which can perform the functions of an optical fiber probe and an electrical probe. The POFP is able to simultaneously measure a CO 2 -included bubble chord length, velocity, and time-series void fraction as well as the Liquid-phase local CO 2 concentration. The bubble velocities and chord lengths measured via the POFP method satisfactorily agreed with those obtained with high-speed visualization. Based on the theoretical analysis and primary experimental results, the POFP was considered to possess satisfactory accuracy and response speed for the simultaneous measurement of a bubble velocity, a bubble chord length, a void fraction and a CO 2 concentration in the Surrounding water. We demonstrated the performance of the POFP by examining it in a bubble column. The CO 2 concentration fluctuation at the bottom zone of the bubble column correlated rationally with the void fraction fluctuation. The correlation faded out toward the upper zone. The POFP is considered a useful tool for revealing the relations between flow structures of a bubbly flow and concentration transportation.
Da-wen Sun - One of the best experts on this subject based on the ideXlab platform.
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Temperature evolution and mass losses during immersion vacuum cooling of cooked beef joints - A finite difference model
Meat Science, 2008Co-Authors: Liana Drummond, Da-wen SunAbstract:A finite difference model was developed to describe and predict the temperature and mass loss evolution in reconstructed beef joints during immersion vacuum cooling. Fast cooling is obtained within beef pores and at beef surface when evaporation in the Surrounding Liquid is high. The cooling rate diminishes as the vacuum chamber pressure stabilizes and the Liquid temperature reaches its lower value. The maximum deviation between measured and calculated temperatures was within 5 ??C for the beef (core and surface) and within 7 ??C for the Surrounding Liquid (measured at the bottom of the container). Absolute differences between predicted and experimental mass losses for the Liquid and beef sample were around 2% and 1%, respectively. Mass losses are higher during the first period when evaporation is the main mode of heat transfer. Mechanical agitation in the Surrounding Liquid is suggested as a way to further reduce cooling times and to prevent uneven cooling. ?? 2008 Elsevier Ltd. All rights reserved.
Masahiko Toriu - One of the best experts on this subject based on the ideXlab platform.
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effects of a bubble and the Surrounding Liquid motions on the instantaneous mass transfer across the gas Liquid interface
Chemical Engineering Journal, 2015Co-Authors: Takayuki Saito, Masahiko ToriuAbstract:Abstract To understand the mass transfer mechanism from a bubble to the Surrounding Liquid, one must consider the relation between the mass transfer, gravity-center and surface motions of the bubble. Bubbles in chemical and bio-reactors usually exhibit a zigzag motion. Simultaneously, such bubbles accompany periodic surface oscillation. Knowledge about the correlation between the mass-transfer mechanism and bubble motion is as yet incomplete. In this study, we used experimental results from highly precise measurements of bubble volume to clarify the instantaneous mass-transfer coefficients of a zigzagging CO 2 bubble. We visualized the zigzagging motion and surface oscillation 3-dimensionally and simultaneously, using two high-speed cameras and mirrors. We also visualized the CO 2 dissolution (mass transfer) process from the bubble to the Surrounding Liquid using the LIF/HPTS method. To obtain the precise instantaneous mass transfer coefficient and bubble motions, single bubbles were visualized in three sections: the linear-ascent, the first-inversion, and the second-inversion of the zigzag motion. The instantaneous mass-transfer coefficients in an interval of 6 ms in these sections were calculated from the bubble-volume shrinkage with ms time-resolution. The instantaneous mass-transfer coefficients increased in acceleration areas—i.e., in the linear-ascent and second-inversion sections. Interestingly, in the latter, the gravity-center velocity of the bubble reached terminal velocity and was constant, but the velocity of the bubble hemisphere was accelerated due to the zigzag motion. This partial acceleration of the bubble hemisphere led to a high renewal rate of the Liquid on the bubble interface. The effect of the partial acceleration on the instantaneous mass transfer was significant for bubbles categorized into zigzag motion.
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Effects of a bubble and the Surrounding Liquid motions on the instantaneous mass transfer across the gas–Liquid interface
Chemical Engineering Journal, 2015Co-Authors: Takayuki Saito, Masahiko ToriuAbstract:Abstract To understand the mass transfer mechanism from a bubble to the Surrounding Liquid, one must consider the relation between the mass transfer, gravity-center and surface motions of the bubble. Bubbles in chemical and bio-reactors usually exhibit a zigzag motion. Simultaneously, such bubbles accompany periodic surface oscillation. Knowledge about the correlation between the mass-transfer mechanism and bubble motion is as yet incomplete. In this study, we used experimental results from highly precise measurements of bubble volume to clarify the instantaneous mass-transfer coefficients of a zigzagging CO 2 bubble. We visualized the zigzagging motion and surface oscillation 3-dimensionally and simultaneously, using two high-speed cameras and mirrors. We also visualized the CO 2 dissolution (mass transfer) process from the bubble to the Surrounding Liquid using the LIF/HPTS method. To obtain the precise instantaneous mass transfer coefficient and bubble motions, single bubbles were visualized in three sections: the linear-ascent, the first-inversion, and the second-inversion of the zigzag motion. The instantaneous mass-transfer coefficients in an interval of 6 ms in these sections were calculated from the bubble-volume shrinkage with ms time-resolution. The instantaneous mass-transfer coefficients increased in acceleration areas—i.e., in the linear-ascent and second-inversion sections. Interestingly, in the latter, the gravity-center velocity of the bubble reached terminal velocity and was constant, but the velocity of the bubble hemisphere was accelerated due to the zigzag motion. This partial acceleration of the bubble hemisphere led to a high renewal rate of the Liquid on the bubble interface. The effect of the partial acceleration on the instantaneous mass transfer was significant for bubbles categorized into zigzag motion.
Liana Drummond - One of the best experts on this subject based on the ideXlab platform.
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Temperature evolution and mass losses during immersion vacuum cooling of cooked beef joints - A finite difference model.
Meat Science, 2008Co-Authors: Liana DrummondAbstract:A finite difference model was developed to describe and predict the temperature and mass loss evolution in reconstructed beef joints during immersion vacuum cooling. Fast cooling is obtained within beef pores and at beef surface when evaporation in the Surrounding Liquid is high. The cooling rate diminishes as the vacuum chamber pressure stabilizes and the Liquid temperature reaches its lower value. The maximum deviation between measured and calculated temperatures was within 5 °C for the beef (core and surface) and within 7 °C for the Surrounding Liquid (measured at the bottom of the container). Absolute differences between predicted and experimental mass losses for the Liquid and beef sample were around 2% and 1%, respectively. Mass losses are higher during the first period when evaporation is the main mode of heat transfer. Mechanical agitation in the Surrounding Liquid is suggested as a way to further reduce cooling times and to prevent uneven cooling.
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Temperature evolution and mass losses during immersion vacuum cooling of cooked beef joints - A finite difference model
Meat Science, 2008Co-Authors: Liana Drummond, Da-wen SunAbstract:A finite difference model was developed to describe and predict the temperature and mass loss evolution in reconstructed beef joints during immersion vacuum cooling. Fast cooling is obtained within beef pores and at beef surface when evaporation in the Surrounding Liquid is high. The cooling rate diminishes as the vacuum chamber pressure stabilizes and the Liquid temperature reaches its lower value. The maximum deviation between measured and calculated temperatures was within 5 ??C for the beef (core and surface) and within 7 ??C for the Surrounding Liquid (measured at the bottom of the container). Absolute differences between predicted and experimental mass losses for the Liquid and beef sample were around 2% and 1%, respectively. Mass losses are higher during the first period when evaporation is the main mode of heat transfer. Mechanical agitation in the Surrounding Liquid is suggested as a way to further reduce cooling times and to prevent uneven cooling. ?? 2008 Elsevier Ltd. All rights reserved.
Jie Huang - One of the best experts on this subject based on the ideXlab platform.
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discussion about the differences in mass transfer bubble motion and Surrounding Liquid motion between a contaminated system and a clean system based on consideration of three dimensional wake structure obtained from lif visualization
Chemical Engineering Science, 2017Co-Authors: Jie Huang, Takayuki SaitoAbstract:Abstract Mass transfer from a bubble to the Surrounding Liquid plays an important role in industry processes. To improve the efficiency of the industrial processes, a deep understanding of the mass transfer mechanism is essential. In the present study, the relationship between the instantaneous mass transfer and the motions of the bubble and three-dimensional bubble wakes is discussed, on the basis of precise measurement. Moreover, since some industrial applications are contaminated system, the authors consider influences of bubble-surface contamination on the above. In the present experiments, purified water, and water contaminated with a very small amount of surfactant (1-pentanol) were employed. LIF (Laser Induced Fluorescence) technique and HPTS (a pH-sensitive dye) that was calibrated through a photoelectric optical fiber probe in advance were employed to visualize the mass transfer of the bubble and the wake structure of the bubble. The authors investigated highly reproducible single bubbles (considered to be almost the same bubble) launched from a special bubble-launch device; successfully they acquired pseudo-time-series sliced bubble wakes' images from every y-z plane at an equidistant interval. By processing the pseudo-time-series images through their own new image-processing, they challengingly reconstructed three-dimensional bubble wakes. From careful observations on the three-dimensional bubble wakes’ structure, they indirectly found out that the Marangoni convection, which was induced by the non-uniform distribution of surfactants desorption on the bubble surface, raised changes in the boundary layers in the contaminated water. The authors discussed the influences of gas-Liquid interface contamination on the bubble motions, bubble wakes, and mass transfer process based on the reconstruction of three-dimensional bubble wakes in the purified water and contaminated water.
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the effects of bubble interface contamination on bubble motion bubble induced Surrounding Liquid motion and mass transfer
ASME JSME KSME 2015 Joint Fluids Engineering Conference, 2015Co-Authors: Yuki Iburi, Jie Huang, Takayuki SaitoAbstract:Mass transfer from a bubble to the Surrounding Liquid plays an important role in chemical engineering processes. To improve the efficiency and safety of the processes, a deep understanding of the mass transfer mechanism from bubbles to the Surrounding Liquid is essential. In the present study, we examined a CO2 single bubble of 2∼3 mm in equivalent diameter that ascended zigzag in purified water and contaminated water (500ppm 1-pentanol solution). We used a high speed video camera systems with high spatial and temporal resolution, for visualization of the bubble wake and bubble-induced Surrounding Liquid motion.The dissolution process of CO2 from the bubble to the Surrounding Liquid was visualized via LIF/HPTS (Laser Induced Fluorescence) method. HPTS, which is a fluorescent substance, was excited by Ar ion laser with a wavelength of 458 nm, then emitted with a wavelength of 513 nm. A pH level of CO2 solution decreased with increase in CO2 concentration; hence the emission intensity of HPTS was reduced. As a result, dark regions observed below the bubble rear accorded with the bubble wakes; from visualization of this bubble wakes through the high speed video cameras, dynamic CO2 dissolution process was obtained. In the purified water, the bubble shape was oblate ellipsoid, and horse-shoe-like vortices were formed in the rear of the bubble. On the other hand, in the contaminated water, the bubble was nearly spherical. Furthermore, behavior of the vortices changed. These different results in two conditions were caused by the decrease in the surface tension owing to the bubble surface contamination. While the bubble was rising, the non-uniform distribution of the surfactant on the bubble surface occurred. Hence, a gradient of the surface tension was formed on the bubble surface, furthermore, it caused the Marangoni convection.Meanwhile, in order to consider the relationship between dissolution process and the Surrounding Liquid motion, we measured the Liquid phase velocities via PIV.Copyright © 2015 by JSME
