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Hiroyuki Kumano - One of the best experts on this subject based on the ideXlab platform.
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Flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide hydrate slurry in the transition region
International Journal of Refrigeration-revue Internationale Du Froid, 2012Co-Authors: Hiroyuki Kumano, Tetsuo Hirata, Yuki KobayashiAbstract:Abstract The flow and heat transfer characteristics of a tetra-n-butyl ammonium bromide (TBAB) hydrate slurry were investigated experimentally. The characteristics in the transition region were examined in detail. Two types of hydrates form from TBAB solution of different concentrations. The hydrate type, Reynolds number and solid fraction were varied as experimental parameters and the coefficients of pipe Friction and heat transfer were measured. In the low solid fraction region, it was found that the coefficients of pipe Friction and heat transfer were constant and the values were the same as that for turbulent flow of the TBAB solution. However, for the high solid fraction region, a laminarization phenomenon occurs and the flow and heat transfer characteristics can be estimated from the laminar flow of the hydrate slurry. Moreover, the laminarization point for the solid fraction can be predicted using the apparent Reynolds number.
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experimental study on the flow and heat transfer characteristics of a tetra n butyl ammonium bromide hydrate slurry first report flow characteristics
International Journal of Refrigeration-revue Internationale Du Froid, 2011Co-Authors: Hiroyuki Kumano, Tetsuo Hirata, Tomoya KudohAbstract:The flow characteristics of a tetra-n-butyl ammonium bromide hydrate slurry were investigated experimentally. Reynolds number, tube diameter and solid fraction were varied as the experimental parameters. For laminar flow, it was found that the ratio of the coefficients of pipe Friction increases with solid fraction, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow, the ratio of the coefficients of pipe Friction was approximately 1 for all tube diameters at low solids fraction. It then decreased slightly at a particular solid fraction and increased again at high solid fraction. Theoretical analysis was carried out using the experimental results, and it was found that the flow characteristics of the hydrate slurry can be treated as those of a pseudoplastic fluid and clarified using the apparent Reynolds number.
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Study on Flow and Heat Transfer Characteristics of Tetra-n-Butyl Ammonium Bromide Hydrate Slurry
ASME JSME 2011 8th Thermal Engineering Joint Conference, 2011Co-Authors: Hiroyuki Kumano, Yuki Kobayashi, Tetsuo Hirata, Tomoya KudohAbstract:Flow and heat transfer characteristics of TBAB hydrate slurry were investigated experimentally. The Reynolds number, diameter of the tubes and solid fraction were varied as experimental parameters. For laminar flow condition, it was found that the ratio of the coefficients of pipe Friction and Nusselt numbers increases with solid fraction, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow condition, the ratio of the coefficients of pipe Friction and Nusselt numbers was 1 for each condition in the case of a low solid fraction. On the other hand, the ratio of the Nusselt numbers increased with the solid fraction in the high-solid fraction region. Moreover, it was found that the effects of the difference of the size and shape of hydrate particles on the coefficients of pipe Friction are large. On the other hand, the effects of the difference of the hydrate particles on the Nusselt number are small.Copyright © 2011 by ASME
C. Scandian - One of the best experts on this subject based on the ideXlab platform.
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effect of molybdenum and chromium contents in sliding wear of high chromium white cast iron the relationship between microstructure and wear
Wear, 2009Co-Authors: C. Scandian, Christine Boher, J. D. B. Mello, Farhad RezaiariaAbstract:Abstract High-chromium white cast irons are commonly used in applications requiring excellent abrasion resistance, as in the mining and mineral ore processing industry. Their excellent abrasion resistance is mainly due to their solidification microstructures. During their solidification, high levels of chromium (16–32%) lead to the formation of a high-volume fraction of eutectic M 7 C 3 -carbides, which may or may not be associated with primary carbides in a heterogeneous austenitic/martensitic dendritic structure. Generally, in common white high-chromium cast iron, the molybdenum content is less than 3 wt.% (by weight) so as to avoid a perlitic transformation. It is reported that by addition of molybdenum in quantities of more than 3 wt.%, new carbides (M 2 C, M 6 C) are formed which greatly increase the high-temperature wear resistance. In this paper, 15 high-chromium white cast alloys containing different chromium contents (16 wt.%Cr to 32 wt.%Cr) and molybdenum (Mo free to 9 wt.%Mo) are examined. For each alloy, the chemical composition and volume fraction of carbides and matrix have previously been determined. The matrix microstructure and the type of carbides depend on the relative contents of molybdenum and chromium. The wear experiments are carried out on a pin-on-disc tribometer at room temperature. The pin is made of cast iron. The wear mechanisms are observed by scanning electron microscopy (SEM). It is observed that the pin height loss, the evolution of Friction versus time curves and the mean Friction coefficient are largely dictated by the matrix microstructure. The carbides volume fraction and the macroscopic hardness both play only a minor role. The pin height loss is significant for a single-phased matrix and the mean Friction coefficient is high. When the matrix is multiphased, the pin height loss tends towards zero and the coefficient of Friction is lower. Detailed SEM observations and analysis of the evolution of the Friction versus time curves indicate the substantial contribution of the large carbides in Friction contact.
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Effect of molybdenum and chromium contents in sliding wear of high‐chromium white cast iron: The relationship between microstructure and wear
Wear, 2009Co-Authors: C. Scandian, Christine Boher, J. D. B. Mello, Farhad Rezai-ariaAbstract:High‐chromium white cast irons are commonly used in applications requiring excellent abrasion resistance, as in the mining and mineral ore processing industry. Their excellent abrasion resistance is mainly due to their solidification microstructures. During their solidification, high levels of chromium (16‐32%) lead to the formation of a high‐volume fraction of eutectic M(7)C(3)‐carbides, which may or may not be associated with primary carbides in a heterogeneous austenitic/martensitic dendritic structure. Generally, in common white high‐chromium cast iron, the molybdenum content is less than 3 wt.% (by weight) so as to avoid a perlitic transformation. It is reported that by addition of molybdenum in quantities of more than 3 wt.%, new carbides (M(2)C, M(6)C) are formed which greatly increase the high‐temperature wear resistance. In this paper, 15 high‐chromium white cast alloys containing different chromium contents (16 wt.%Cr to 32 wt.%Cr) and molybdenum (Mo free to 9 wt.%Mo) are examined. For each alloy, the chemical composition and volume fraction of carbides and matrix have previously been determined. The matrix microstructure and the type of carbides depend on the relative contents of molybdenum and chromium. The wear experiments are carried out on a pin‐on‐disc tribometer at room temperature. The pin is made of cast iron. The wear mechanisms are observed by scanning electron microscopy (SEM). It is observed that the pin height loss, the evolution of Friction versus time curves and the mean Friction coefficient are largely dictated by the matrix microstructure. The carbides volume fraction and the macroscopic hardness both play only a minor role. The pin height loss is significant for a single‐phased matrix and the mean Friction coefficient is high. When the matrix is multiphased, the pin height loss tends towards zero and the coefficient of Friction is lower. Detailed SEM observations and analysis of the evolution of the Friction versus time curves indicate the substantial contribution of the large carbides in Friction contact.
Tomoya Kudoh - One of the best experts on this subject based on the ideXlab platform.
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experimental study on the flow and heat transfer characteristics of a tetra n butyl ammonium bromide hydrate slurry first report flow characteristics
International Journal of Refrigeration-revue Internationale Du Froid, 2011Co-Authors: Hiroyuki Kumano, Tetsuo Hirata, Tomoya KudohAbstract:The flow characteristics of a tetra-n-butyl ammonium bromide hydrate slurry were investigated experimentally. Reynolds number, tube diameter and solid fraction were varied as the experimental parameters. For laminar flow, it was found that the ratio of the coefficients of pipe Friction increases with solid fraction, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow, the ratio of the coefficients of pipe Friction was approximately 1 for all tube diameters at low solids fraction. It then decreased slightly at a particular solid fraction and increased again at high solid fraction. Theoretical analysis was carried out using the experimental results, and it was found that the flow characteristics of the hydrate slurry can be treated as those of a pseudoplastic fluid and clarified using the apparent Reynolds number.
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Study on Flow and Heat Transfer Characteristics of Tetra-n-Butyl Ammonium Bromide Hydrate Slurry
ASME JSME 2011 8th Thermal Engineering Joint Conference, 2011Co-Authors: Hiroyuki Kumano, Yuki Kobayashi, Tetsuo Hirata, Tomoya KudohAbstract:Flow and heat transfer characteristics of TBAB hydrate slurry were investigated experimentally. The Reynolds number, diameter of the tubes and solid fraction were varied as experimental parameters. For laminar flow condition, it was found that the ratio of the coefficients of pipe Friction and Nusselt numbers increases with solid fraction, and the rate of increase is high in the case of a low Reynolds number. For turbulent flow condition, the ratio of the coefficients of pipe Friction and Nusselt numbers was 1 for each condition in the case of a low solid fraction. On the other hand, the ratio of the Nusselt numbers increased with the solid fraction in the high-solid fraction region. Moreover, it was found that the effects of the difference of the size and shape of hydrate particles on the coefficients of pipe Friction are large. On the other hand, the effects of the difference of the hydrate particles on the Nusselt number are small.Copyright © 2011 by ASME
Farhad Rezai-aria - One of the best experts on this subject based on the ideXlab platform.
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Effect of molybdenum and chromium contents in sliding wear of high‐chromium white cast iron: The relationship between microstructure and wear
Wear, 2009Co-Authors: C. Scandian, Christine Boher, J. D. B. Mello, Farhad Rezai-ariaAbstract:High‐chromium white cast irons are commonly used in applications requiring excellent abrasion resistance, as in the mining and mineral ore processing industry. Their excellent abrasion resistance is mainly due to their solidification microstructures. During their solidification, high levels of chromium (16‐32%) lead to the formation of a high‐volume fraction of eutectic M(7)C(3)‐carbides, which may or may not be associated with primary carbides in a heterogeneous austenitic/martensitic dendritic structure. Generally, in common white high‐chromium cast iron, the molybdenum content is less than 3 wt.% (by weight) so as to avoid a perlitic transformation. It is reported that by addition of molybdenum in quantities of more than 3 wt.%, new carbides (M(2)C, M(6)C) are formed which greatly increase the high‐temperature wear resistance. In this paper, 15 high‐chromium white cast alloys containing different chromium contents (16 wt.%Cr to 32 wt.%Cr) and molybdenum (Mo free to 9 wt.%Mo) are examined. For each alloy, the chemical composition and volume fraction of carbides and matrix have previously been determined. The matrix microstructure and the type of carbides depend on the relative contents of molybdenum and chromium. The wear experiments are carried out on a pin‐on‐disc tribometer at room temperature. The pin is made of cast iron. The wear mechanisms are observed by scanning electron microscopy (SEM). It is observed that the pin height loss, the evolution of Friction versus time curves and the mean Friction coefficient are largely dictated by the matrix microstructure. The carbides volume fraction and the macroscopic hardness both play only a minor role. The pin height loss is significant for a single‐phased matrix and the mean Friction coefficient is high. When the matrix is multiphased, the pin height loss tends towards zero and the coefficient of Friction is lower. Detailed SEM observations and analysis of the evolution of the Friction versus time curves indicate the substantial contribution of the large carbides in Friction contact.
Farhad Rezaiaria - One of the best experts on this subject based on the ideXlab platform.
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effect of molybdenum and chromium contents in sliding wear of high chromium white cast iron the relationship between microstructure and wear
Wear, 2009Co-Authors: C. Scandian, Christine Boher, J. D. B. Mello, Farhad RezaiariaAbstract:Abstract High-chromium white cast irons are commonly used in applications requiring excellent abrasion resistance, as in the mining and mineral ore processing industry. Their excellent abrasion resistance is mainly due to their solidification microstructures. During their solidification, high levels of chromium (16–32%) lead to the formation of a high-volume fraction of eutectic M 7 C 3 -carbides, which may or may not be associated with primary carbides in a heterogeneous austenitic/martensitic dendritic structure. Generally, in common white high-chromium cast iron, the molybdenum content is less than 3 wt.% (by weight) so as to avoid a perlitic transformation. It is reported that by addition of molybdenum in quantities of more than 3 wt.%, new carbides (M 2 C, M 6 C) are formed which greatly increase the high-temperature wear resistance. In this paper, 15 high-chromium white cast alloys containing different chromium contents (16 wt.%Cr to 32 wt.%Cr) and molybdenum (Mo free to 9 wt.%Mo) are examined. For each alloy, the chemical composition and volume fraction of carbides and matrix have previously been determined. The matrix microstructure and the type of carbides depend on the relative contents of molybdenum and chromium. The wear experiments are carried out on a pin-on-disc tribometer at room temperature. The pin is made of cast iron. The wear mechanisms are observed by scanning electron microscopy (SEM). It is observed that the pin height loss, the evolution of Friction versus time curves and the mean Friction coefficient are largely dictated by the matrix microstructure. The carbides volume fraction and the macroscopic hardness both play only a minor role. The pin height loss is significant for a single-phased matrix and the mean Friction coefficient is high. When the matrix is multiphased, the pin height loss tends towards zero and the coefficient of Friction is lower. Detailed SEM observations and analysis of the evolution of the Friction versus time curves indicate the substantial contribution of the large carbides in Friction contact.
