The Experts below are selected from a list of 4173 Experts worldwide ranked by ideXlab platform
K. Hooman - One of the best experts on this subject based on the ideXlab platform.
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entropy generation for microscale forced convection effects of different thermal boundary conditions velocity slip temperature jump viscous dissipation and Duct Geometry
International Communications in Heat and Mass Transfer, 2007Co-Authors: K. HoomanAbstract:This work presents closed form solutions for fully developed temperature distribution and entropy generation due to forced convection in microelectromechanical systems (MEMS) in the Slip-flow regime, for which the Knudsen number lies within the range 0.001
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K. Hooman International Communications in Heat and Mass Transfer 34 (2007) 945-957 1 Entropy generation for microscale forced convection: effects of different thermal boundary conditions, velocity slip, temperature jump, viscou s dissipation, and duc
2007Co-Authors: K. HoomanAbstract:Entropy generation for microscale forced convection: effects of different thermal boundary conditions, velocity slip, temperature jump, viscous dissipation, and Duct Geometry K. Hooman School of Engineering, The University of Queensland, Brisbane, Australia Abstract This work presents closed form solutions for fully developed temperature distribution and entropy generation due to forced convection in microelectromechanical systems (MEMS) in the Slip-flow regime, for which the Knudsen number lies within the range 0.001< Kn
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k hooman international communications in heat and mass transfer 34 2007 945 957 1 entropy generation for microscale forced convection effects of different thermal boundary conditions velocity slip temperature jump viscou s dissipation and Duct geomet
2007Co-Authors: K. HoomanAbstract:Entropy generation for microscale forced convection: effects of different thermal boundary conditions, velocity slip, temperature jump, viscous dissipation, and Duct Geometry K. Hooman School of Engineering, The University of Queensland, Brisbane, Australia Abstract This work presents closed form solutions for fully developed temperature distribution and entropy generation due to forced convection in microelectromechanical systems (MEMS) in the Slip-flow regime, for which the Knudsen number lies within the range 0.001< Kn <0.1. Two different cross-sections are analyzed, being microDucts (composed of two parallel plates) and micropipes, with the effects of viscous dissipation being included. Invoking the temperature jump equation, two different thermal boundary conditions are investigated, being isothermal and isoflux walls. Expressions are presented for the local and bulk temperature profiles, the Nusselt number, the Bejan number, and the entropy generation rate in terms of the key parameters. Though the results are obtained for the microscale problems, they can be generalized to the macroscale counterparts by letting Kn =0. Keywords: Microscale, MEMS, Entropy generation, Velocity slip, Temperature jump Nomenclature A cross-section area Br Brinkman number, Br= µU
Noam Lior - One of the best experts on this subject based on the ideXlab platform.
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Effect of Flow-Duct Geometry on Solid Desiccant Dehumidification
Industrial & Engineering Chemistry Research, 2008Co-Authors: Hassan S. Al-sharqawi, Noam LiorAbstract:This study presents a comparative numerical solution of a conjugate-transient three-dimensional heat and mass transfer problem between a solid desiccant (silica gel) and a humid transient-laminar air stream in Ducts with different cross-sectional geometries: square, circular, and triangular. The problem is solved by using a finite control-volume method and validated relative to available experimental data. The effects of the u velocity gradient normal to the wall (∂u/∂y) and the pressure drop (Ap) on the heat and mass transport for the three Ducts are investigated. In Duct flows, the results show that the average (∂u/∂y) for the triangular Duct is 6.6% and 19.6% larger than that in the circular and square Ducts, respectively; therefore, the triangular Duct provides the largest convective heat and mass transport and absorbs 11% and 42% more water than the circular and square Ducts, respectively. At the same time, the average pressure drop for the triangular Duct is 69% and 73.5% larger than that for the square and circular Ducts, respectively, which would result in higher fan power consumption. Using a figure of merit (W r ) that is a ratio of the required fan work to the dehumidification attained, the circular Duct was found to be the best and the triangular Duct was found to be the worst among the three geometries compared. The results obtained from this study can also be useful for designing desiccant Ducts, as they give guidance about Duct length optimization and Duct cross-sectional shape considering both dehumidification effectiveness and flow pressure drop.
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The Effect of Flow-Duct Geometry on Solid Desiccant Dehumidification
ASME JSME 2007 Thermal Engineering Heat Transfer Summer Conference Volume 3, 2007Co-Authors: Hassan S. Al-sharqawi, Noam LiorAbstract:This study presents a comparative numerical solution of a conjugate-transient three-dimensional heat and mass transfer problem between a solid desiccant (silica gel) and a humid transient-laminar air stream in Ducts with different cross-sectional geometries: square, circular, and triangular. The problem is solved by using a finite control-volume method and validated relative to available experimental data. The effects of the u velocity gradient normal to the wall (∂u/∂y) and the pressure drop (Δp) on the heat and mass transport for the three Ducts are investigated. In Duct flows, the results show that the average (∂u/∂y) for the triangular Duct is 6.6% and 19.6% larger than that in the circular and square Ducts, respectively; therefore, the triangular Duct provides the largest convective heat and mass transport and absorbs 11% and 42% more water than the circular and square Ducts, respectively. At the same time, the average pressure drop for the triangular Duct is 69% and 73.5% larger than that for the s...
M. Q. Tran - One of the best experts on this subject based on the ideXlab platform.
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Parasitic Oscillations in Smooth-Wall Circular Symmetric Gyrotron Beam Ducts
Journal of Infrared Millimeter and Terahertz Waves, 2019Co-Authors: J. Genoud, G. Le Bars, Stefano Alberti, P. Kaminski, Trach-minh Tran, J.-ph. Hogge, K. A. Avramidis, M. Q. TranAbstract:In order to study parasitic oscillation that may occur in a realistic beam Duct upstream to the gyrotron cavity, the self-consistent linear and spectral code TWANGlinspec has been modified. The large inhomogeneities in the smooth-wall beam Duct Geometry or in the magnetic field profile required the implementation of a numerical approach using a hybrid finite element method. The new model permits to characterize a large number of potentially spurious TE modes. Compared to previous studies on gyrotron beam Duct instabilities, an extended interaction space including also the gyrotron cavity has been considered. The role of the connecting part between the beam Duct and the cavity, called spacer, is highlighted and it is shown that the gyro backward-wave TE modes excited in this region generally have their minimum starting current. The sensitivity of the minimum starting current on electron beam velocity spread is also evaluated.
J. Genoud - One of the best experts on this subject based on the ideXlab platform.
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Parasitic Oscillations in Smooth-Wall Circular Symmetric Gyrotron Beam Ducts
Journal of Infrared Millimeter and Terahertz Waves, 2019Co-Authors: J. Genoud, G. Le Bars, Stefano Alberti, P. Kaminski, Trach-minh Tran, J.-ph. Hogge, K. A. Avramidis, M. Q. TranAbstract:In order to study parasitic oscillation that may occur in a realistic beam Duct upstream to the gyrotron cavity, the self-consistent linear and spectral code TWANGlinspec has been modified. The large inhomogeneities in the smooth-wall beam Duct Geometry or in the magnetic field profile required the implementation of a numerical approach using a hybrid finite element method. The new model permits to characterize a large number of potentially spurious TE modes. Compared to previous studies on gyrotron beam Duct instabilities, an extended interaction space including also the gyrotron cavity has been considered. The role of the connecting part between the beam Duct and the cavity, called spacer, is highlighted and it is shown that the gyro backward-wave TE modes excited in this region generally have their minimum starting current. The sensitivity of the minimum starting current on electron beam velocity spread is also evaluated.
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Linear and non-linear studies of spurious backward-wave instabilities in a smooth-wall gyrotron beam Duct
2017 42nd International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2017Co-Authors: J. Genoud, G. Le Bars, Stefano Alberti, P. Kaminski, Trach-minh TranAbstract:Recently developed self-consistent models for beam-wave interaction simulations of a gyrotron oscillator are used to study spurious backward-wave instabilities in smooth-wall metallic beam Ducts. Starting from a simple case with a basic Geometry, the influence of the beam Duct Geometry and the magnetic field profile on the instabilities threshold and on the quality of the electron beam are studied.
Trach-minh Tran - One of the best experts on this subject based on the ideXlab platform.
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Parasitic Oscillations in Smooth-Wall Circular Symmetric Gyrotron Beam Ducts
Journal of Infrared Millimeter and Terahertz Waves, 2019Co-Authors: J. Genoud, G. Le Bars, Stefano Alberti, P. Kaminski, Trach-minh Tran, J.-ph. Hogge, K. A. Avramidis, M. Q. TranAbstract:In order to study parasitic oscillation that may occur in a realistic beam Duct upstream to the gyrotron cavity, the self-consistent linear and spectral code TWANGlinspec has been modified. The large inhomogeneities in the smooth-wall beam Duct Geometry or in the magnetic field profile required the implementation of a numerical approach using a hybrid finite element method. The new model permits to characterize a large number of potentially spurious TE modes. Compared to previous studies on gyrotron beam Duct instabilities, an extended interaction space including also the gyrotron cavity has been considered. The role of the connecting part between the beam Duct and the cavity, called spacer, is highlighted and it is shown that the gyro backward-wave TE modes excited in this region generally have their minimum starting current. The sensitivity of the minimum starting current on electron beam velocity spread is also evaluated.
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Linear and non-linear studies of spurious backward-wave instabilities in a smooth-wall gyrotron beam Duct
2017 42nd International Conference on Infrared Millimeter and Terahertz Waves (IRMMW-THz), 2017Co-Authors: J. Genoud, G. Le Bars, Stefano Alberti, P. Kaminski, Trach-minh TranAbstract:Recently developed self-consistent models for beam-wave interaction simulations of a gyrotron oscillator are used to study spurious backward-wave instabilities in smooth-wall metallic beam Ducts. Starting from a simple case with a basic Geometry, the influence of the beam Duct Geometry and the magnetic field profile on the instabilities threshold and on the quality of the electron beam are studied.
