The Experts below are selected from a list of 240 Experts worldwide ranked by ideXlab platform
Deovaldo De Moraes Júnior - One of the best experts on this subject based on the ideXlab platform.
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External Heat Transfer Coefficient in Agitated Vessels Using a Radial Impeller and Vertical Tube Baffles
Industrial & Engineering Chemistry Research, 2014Co-Authors: Vitor Da Silva Rosa, Marlene Silva De Moraes, Juliana Tófano De Campos Leite Toneli, Deovaldo De Moraes JúniorAbstract:There are several correlations used to predict the external heat transfer coefficient in tanks equipped with vertical tube baffles in batch operations, but little information concerning the external heat transfer coefficient in steady state operations. The objective of the present article is to experimentally determine a correlation of the external heat transfer coefficient based on the model proposed by Sieder and Tate (Ind. Eng. Chem. 1936, 1429–1435) in a steady flow rate in a vessel equipped with a Radial Impeller, turbine type, with six flat blades. The study was carried out in a 50 dm3 working capacity acrylic vessel, fitted with vertical tube baffles made of copper, in which water and sucrose solutions at mass concentrations of 20% and 50% were heated. Heating temperatures varied from 28 to 45 °C, whereas the rotations varied from 90 to 330 rpm. From the Nusselt, Reynolds, and Prandtl similarity parameters, a correlation was obtained which yielded excellent results of the observed data–a maximum de...
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Experimental comparison of heat exchange in tanks equipped with helical coil using Radial and axial mechanical Impellers
2012Co-Authors: Marcilio Dias Lopes, Vitor Da Silva Rosa, Carlos Alberto Amaral Moino, Aldo Ramos Santos, Karina Tamião De Campos Roseno, Deovaldo De Moraes JúniorAbstract:Tanks with mechanical Impellers are used in all chemical and petrochemical industry segments, being the most common applications: reactors, substance homogenizing, solids solubilization and products dissolution. It is common that these processes require a heat transfer operation and, in such cases, may be used spiral or helical coils, jackets and tubular baffle. For each operation involving agitation and heat transfer, there is an overall heat transfer coefficient that depends on the physical properties of the fluid, the vessel geometry, the heat source, the Impeller type and rotation. This study aimed to determine experimentally the Sieder-Tate equation constants to calculate the outer film heat transfer coefficient of a helical coil as a function of which Impeller used and compare the thermal efficiency with two Impellers used. The experimental unit basically consisted of a 50-L tank, axial and Radial Impellers and helical coil. Water was used as the heater fluid. The water flow rate was 1,8 L/min and the inlet temperature was 62°C. The cold fluid flow was 1,0 L/min and inlet temperature between the range of 29-45°C. The rotation varied between the range of 90-330 rpm. The results allow to affirm that the greatest heat transfer was obtained using the Radial Impeller. Key word Mechanical Impeller, helical coil, Sieder Tate equation.
Takuji Tsugawa - One of the best experts on this subject based on the ideXlab platform.
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Case Study of Improved High Specific Speed Radial Impeller
Volume 2: Symposia Parts A B and C, 2003Co-Authors: Takuji TsugawaAbstract:It is usually thought that the axial Impeller is used for high specific speed Impeller and the Radial Impeller is used for low specific speed Impeller. In the previous paper, the optimum meridian profile of axial Impeller and Radial Impeller were obtained for various specific speed by means of the optimization of four shape factors using diffusion factor. The four shape factors were inlet relative flow angle β1 , turning angle Δβ, axial velocity ratio (meridian velocity ratio) kc = Cm2 /Cm1 and Impeller diameter ratio kd = D1c /D2c in mid span stream surface. In case of axial Impeller, the optimum meridian profiles agreed with meridian profiles of conventional Impellers. To develop the Radial high specific speed Impeller, the optimum four shape factors of Radial high specific speed Impellers were calculated by diffusion factor. And the optimum meridian profiles of Radial high specific speed Impellers were proposed. In case of the Radial Impeller, the hub diameter is equal to the tip diameter in Impeller outlet (the outlet hub-tip ratio is 1.0). And in axial Impeller, the outlet blade height depends on the outlet hub-tip ratio. On the other hand, in mixed flow Impeller, the outlet hub-tip ratio is various and the outlet blade height is independent of the outlet hub-tip ratio. To obtain the optimum meridian profile of mixed flow Impeller, the hub-tip ratio of Impeller outlet ν2 is adopted new additional independent shape factor for optimization in this paper. The mixed flow angle on tip meridian stream line (= 0 degree in axial Impeller, = 90 degrees in Radial Impeller) isn’t able to be decided by this optimization using diffusion factor. But, the mixed flow angle will be decided by the number of blade and solidity. And, it will be decided by meridian velocity distribution from hub to tip for each specific speed of Impeller. So, in this paper the five shape factors are used for optimization by diffusion factor. (β1 , Δβ, kc , kd , ν2 ) The optimum meridian profiles of mixed flow Impellers for various specific speed are obtained. The relative efficiency or the cavitation performance of mixed flow Impeller is better than that of Radial or axial Impeller. In this optimum method, the relative efficiency and the cavitation performance are calculated for all specified combinations of five shape factors. The number of five shape factors are expressed by Nβ1 , NΔβ , Nkc , Nkd and Nν2 . The number of calculations is expressed by Nβ1 × NΔβ × Nkc × Nkd × Nν2 . The calculation time of five shape factors method is Nν2 times the calculation time of four shape factors method. Then, the best 1000 combinations of five shape factors are plotted on β1 - Δβ, kc - kd and kd - ν2 plane. The aspect of the best 1000 optimum conditions are found by these three figures. In initial step of Impeller design, the result of the efficiency and cavitation performance of Impeller calculated in optimum principal design parameters is important. The principal design parameters are hub-tip ratio, inlet-outlet diameter ratio, axial velocity ratio, solidity, inlet flow angle, turning angle and blade number. The author proposed the optimum meridian profile design method by diffusion factor for various condition of design parameters. There is a good correlation between the optimum hub-tip ratio and the specific speed considering cavitation performance. The optimum solidity is obtained for the specific speed considering efficiency and cavitation performance. It was found that the optimum meridian profile of high specific speed Impeller with appropriate efficiency and cavitation performance had large inclination on hub and tip stream lines. The calculated data base is five dimensional using five shape factors β1 , Δβ, kc , kd and ν2 . Using the five shape factors in case of the best efficiency, the optimum meridian profile of improved Radial flow Impeller is able to be calculated. At first step of the case study, the best 1000 optimum meridian profiles and the best design parameter are selected using five dimensional optimum method. Next, the blade section shape of Impeller is decided by the blade or cascade design method. Using Impeller flow analysis, the cavitation performance decided by 3% head reduction is calculated. Finally, the relations between the many type of meridian profile and its Impeller performance by flow analysis are obtained. These relations are very useful for new type of high specific speed Impeller design. Consequently, Radial Impellers and axial Impellers are improved by the consideration of the additional shape factor, that is, outlet hub-tip ratio ν2 . This calculation shows that the improved Radial high specific speed Impeller considering outlet hub-tip ratio is used for high suction specific speed and high efficiency.Copyright © 2003 by ASME
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Case Study of High Specific Speed Radial Impeller
Volume 1: Fora Parts A and B, 2002Co-Authors: Takuji TsugawaAbstract:The optimum shape of high specific speed Impeller is usually axial flow Impeller. The Radial Impeller is often used without axial flow guidevane. Usually, the Radial Impeller is the high pressure and low specific speed Impeller. The design parameters of Radial high specific speed Impeller have not been obtained yet. In the previous papers, the optimum meridian shape of axial flow Impeller with axial flow guidevane is obtained for various specific speed. The optimum meridian shapes calculated by diffusion factor agree with meridian shapes of conventional Impellers. In this paper, the design parameters of Radial high specific speed Impellers without guidevane are calculated by diffusion factor. And the optimum meridian shapes of Radial high specific speed Impellers are proposed. In case of the Radial Impeller, the hub diameter is equal to the tip diameter in Impeller outlet. So, in Radial Impellers, the outlet hub-tip ratio is 1.0. The optimum meridian shapes of Radial Impellers for various specific speed are also obtained in this paper. The relative efficiency and cavitation performance of Impellers in various shape factors were calculated. The calculation of Radial meridian shape needs four kinds of shape factors as the previous papers. The four shape factors are inlet relative flow angle β1 , turning angle Δβ, axial velocity ratio (meridian velocity ratio) kc = Cm2 /Cm1 and Impeller diameter ratio kd = D1c /D2c inmid span streamsurface. In initial step of Impeller design, the result of the efficiency and cavitation performance of Impeller calculated in optimum principal design parameters is important. The principal design parameters are hub-tip ratio, inlet-outlet diameter ratio, axial velocity ratio, solidity, inlet flow angle, turning angle and blade number. The author proposed the optimum meridian profile design method by diffusion factor for various condition of design parameters. There is a good correlation between the optimum hub-tip ratio and the specific speed considering cavitation performance. The optimum solidity is obtained for the specific speed considering efficiency and cavitation performance. It was found that the optimum meridian profile of high specific speed Impeller with appropriate efficiency and cavitation performance has large inclination on hub and tip stream lines. The calculated data base is four dimensional using four various shape parameter β1 , Δβ, kc and kd . Using the four shape factor, the optimum meridian shape of Radial flow Impeller is able to be obtained. The best 1000 optimum design parameters are selected using four dimensional calculated data. The aspect of optimization is recognized with 1000 plotted data on 6 planes. The result of Radial flow Impeller optimization is different from that of axial flow Impeller. In case of axial flow Impellers, the shape factors are optimized for each specific speed. But, in Radial flow Impellers, if both the specific speed and the total head coefficient are given, the optimum shape factors are optimized. The calculation results between profiles and specifications were very useful for the development of new type high specific speed Radial Impellers.Copyright © 2002 by ASME
Edward M. Greitzer - One of the best experts on this subject based on the ideXlab platform.
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Surge Dynamics in a Free-Spool Centrifugal Compressor System
Journal of Turbomachinery, 1992Co-Authors: David Allan Fink, N. A. Cumpsty, Edward M. GreitzerAbstract:Turbocharger surge has been investigated in a Radial Impeller-vaneless diffuser free-spool system. Several different aspects are addressed. First, two very different compression systems, one with a large downstram volume and one with the smallest possible downstram voluem, are employed to examine stall initiation phenomena as well as the behavior of the compressor characteristics when operating in surge. The measurements show Impeller stall at the inducer tips to be a key phenomena in initiating surge. The inducer stall is stationary and asymmetric, due to the presence of the volute, and is most severe near the volute tongue angular position
Vitor Da Silva Rosa - One of the best experts on this subject based on the ideXlab platform.
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External Heat Transfer Coefficient in Agitated Vessels Using a Radial Impeller and Vertical Tube Baffles
Industrial & Engineering Chemistry Research, 2014Co-Authors: Vitor Da Silva Rosa, Marlene Silva De Moraes, Juliana Tófano De Campos Leite Toneli, Deovaldo De Moraes JúniorAbstract:There are several correlations used to predict the external heat transfer coefficient in tanks equipped with vertical tube baffles in batch operations, but little information concerning the external heat transfer coefficient in steady state operations. The objective of the present article is to experimentally determine a correlation of the external heat transfer coefficient based on the model proposed by Sieder and Tate (Ind. Eng. Chem. 1936, 1429–1435) in a steady flow rate in a vessel equipped with a Radial Impeller, turbine type, with six flat blades. The study was carried out in a 50 dm3 working capacity acrylic vessel, fitted with vertical tube baffles made of copper, in which water and sucrose solutions at mass concentrations of 20% and 50% were heated. Heating temperatures varied from 28 to 45 °C, whereas the rotations varied from 90 to 330 rpm. From the Nusselt, Reynolds, and Prandtl similarity parameters, a correlation was obtained which yielded excellent results of the observed data–a maximum de...
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Experimental comparison of heat exchange in tanks equipped with helical coil using Radial and axial mechanical Impellers
2012Co-Authors: Marcilio Dias Lopes, Vitor Da Silva Rosa, Carlos Alberto Amaral Moino, Aldo Ramos Santos, Karina Tamião De Campos Roseno, Deovaldo De Moraes JúniorAbstract:Tanks with mechanical Impellers are used in all chemical and petrochemical industry segments, being the most common applications: reactors, substance homogenizing, solids solubilization and products dissolution. It is common that these processes require a heat transfer operation and, in such cases, may be used spiral or helical coils, jackets and tubular baffle. For each operation involving agitation and heat transfer, there is an overall heat transfer coefficient that depends on the physical properties of the fluid, the vessel geometry, the heat source, the Impeller type and rotation. This study aimed to determine experimentally the Sieder-Tate equation constants to calculate the outer film heat transfer coefficient of a helical coil as a function of which Impeller used and compare the thermal efficiency with two Impellers used. The experimental unit basically consisted of a 50-L tank, axial and Radial Impellers and helical coil. Water was used as the heater fluid. The water flow rate was 1,8 L/min and the inlet temperature was 62°C. The cold fluid flow was 1,0 L/min and inlet temperature between the range of 29-45°C. The rotation varied between the range of 90-330 rpm. The results allow to affirm that the greatest heat transfer was obtained using the Radial Impeller. Key word Mechanical Impeller, helical coil, Sieder Tate equation.
David Allan Fink - One of the best experts on this subject based on the ideXlab platform.
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Surge Dynamics in a Free-Spool Centrifugal Compressor System
Journal of Turbomachinery, 1992Co-Authors: David Allan Fink, N. A. Cumpsty, Edward M. GreitzerAbstract:Turbocharger surge has been investigated in a Radial Impeller-vaneless diffuser free-spool system. Several different aspects are addressed. First, two very different compression systems, one with a large downstram volume and one with the smallest possible downstram voluem, are employed to examine stall initiation phenomena as well as the behavior of the compressor characteristics when operating in surge. The measurements show Impeller stall at the inducer tips to be a key phenomena in initiating surge. The inducer stall is stationary and asymmetric, due to the presence of the volute, and is most severe near the volute tongue angular position
