Simulation of Flow and Heat Transfer in a Moving Bed Reactor With Cross Flow

2008 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Relative Velocity ◽  
Solid Phase ◽  
Cross Flow ◽  
Vertical Direction ◽  
Momentum Equation ◽  
Solid Matrix ◽  
Flow And Heat Transfer ◽  
Temperature Distributions ◽  
Solid Phases

Heat transfer in a porous reactor under cross flow is investigated. The reactor is modeled as a porous bed in which the solid phase is moving horizontally and the flow is forced into the bed in a vertical direction. Equations are time-and-volume averaged and the solid phase is considered to have a constant imposed velocity. Additional drag terms appearing the momentum equation are a function of the relative velocity between the fluid and solid phases. Turbulence equations are also affected by the speed of the solid matrix. Results show temperature distributions for several ratios of the solid to fluid speed.

Mathematical Modeling of Flow and Heat Transfer in a Moving Bed Reactor

2008 ◽  
Author(s):  
Marcelo J. S. de Lemos
Keyword(s):  
Mathematical Modeling ◽  
Heat Transfer ◽  
Transfer Rate ◽  
Relative Velocity ◽  
Solid Phase ◽  
Porous Matrix ◽  
Momentum Equation ◽  
Moving Bed ◽  
Flow And Heat Transfer ◽  
Solid Phases

This paper shows a proposition of a set of transport equations and their boundary conditions for solving problems involving flow and heat transfer in a moving bed equipment. The reactor is seen as a porous matrix in which the solid phase is moving. Additional drag terms appearing the momentum equation are a function of the relative velocity between the fluid and solid phases. Turbulence equations are also influenced by the speed of the solid phase. Results show the decrease for turbulent kinetic energy as the solid speed approaches the fluid speed. Heat transfer rate between phases is also damped as the solid speed increases.

Simulation of a Moving Porous Bed Reactor With a Two-Energy Equation Model

2010 ◽  
Author(s):  
Marcelo J. S. de Lemos ◽  
Ana C. Pivem
Keyword(s):  
Heat Transfer ◽  
Conduction Mechanism ◽  
Solid Phase ◽  
Porous Matrix ◽  
Momentum Equation ◽  
Equation Model ◽  
Porous Bed ◽  
Flow And Heat Transfer ◽  
Interface Heat Transfer ◽  
Interface Heat

Interface heat transfer in a moving porous bed is analyzed. This work proposes a set of transport equations for solving problems involving turbulent flow and heat transfer in a moving bed equipment. The device is modeled as a saturated porous matrix in which the solid phase moves with a steady imposed velocity. Additional drag terms appearing in the momentum equation, as well as interfacial heat transfer between phases, are assumed to be a function of the relative velocity between the fluid and solid phases. Results indicate that, as the phases attain velocities of equal order, heat transfer between solid and fluid occurs mainly by the conduction mechanism.

Effects of alternating elliptical chamber on jet impingement heat transfer in vane leading edge under different cross-flow conditions

2021 ◽  
pp. 1-17
Author(s):  
K. Xiao ◽  
J. He ◽  
Z. Feng
Keyword(s):  
Heat Transfer ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Leading Edge ◽  
Longitudinal Vortices ◽  
Impingement Jet ◽  
Flow And Heat Transfer ◽  
Impingement Heat Transfer ◽  
Cross Flow Velocity ◽  
The Cross

ABSTRACT This paper proposes an alternating elliptical impingement chamber in the leading edge of a gas turbine to restrain the cross flow and enhance the heat transfer, and investigates the detailed flow and heat transfer characteristics. The chamber consists of straight sections and transition sections. Numerical simulations are performed by solving the three-dimensional (3D) steady Reynolds-Averaged Navier–Stokes (RANS) equations with the Shear Stress Transport (SST) k– $\omega$ turbulence model. The influences of alternating the cross section on the impingement flow and heat transfer of the chamber are studied by comparison with a smooth semi-elliptical impingement chamber at a cross-flow Velocity Ratio (VR) of 0.2 and Temperature Ratio (TR) of 1.00 in the primary study. Then, the effects of the cross-flow VR and TR are further investigated. The results reveal that, in the semi-elliptical impingement chamber, the impingement jet is deflected by the cross flow and the heat transfer performance is degraded. However, in the alternating elliptical chamber, the cross flow is transformed to a pair of longitudinal vortices, and the flow direction at the centre of the cross section is parallel to the impingement jet, thus improving the jet penetration ability and enhancing the impingement heat transfer. In addition, the heat transfer in the semi-elliptical chamber degrades rapidly away from the stagnation region, while the longitudinal vortices enhance the heat transfer further, making the heat transfer coefficient distribution more uniform. The Nusselt number decreases with increase of VR and TR for both the semi-elliptical chamber and the alternating elliptical chamber. The alternating elliptical chamber enhances the heat transfer and moves the stagnation point up for all VR and TR, and the heat transfer enhancement is more obvious at high cross-flow velocity ratio.

Numerical Modeling of Velocity and Temperature Distributions in a Bipolar Plate of PEM Electrolysis Cell With Greatly Improved Flow Uniformity

2009 ◽  
Author(s):  
Jephanya Kasukurthi ◽  
K. M. Veepuri ◽  
Jianhu Nie ◽  
Yitung Chen
Keyword(s):  
Heat Transfer ◽  
Proton Exchange Membrane ◽  
Three Dimensional ◽  
Flow Distribution ◽  
Bipolar Plate ◽  
Proton Exchange ◽  
Electrolysis Cell ◽  
Flow And Heat Transfer ◽  
Temperature Distributions ◽  
Pem Electrolysis

In this present work, finite volume method was used to simulate the three-dimensional water flow and heat transfer in a flow field plate of the proton exchange membrane (PEM) electrolysis cell. The standard k-ε model together with standard wall function method was used to model three-dimensional fluid flow and heat transfer. First, numerical simulations were performed for a basic bipolar plate and it was found that the flow distribution inside the channels in not uniform. The design of the basic bipolar plate has been changed to a new model, which is featured with multiple inlets and multiple outlets. Numerical results show that the flow and temperature distributions for the new design become much homogeneous.

Numerical Prediction of Flow and Heat Transfer Past a Circular Tube With Annular Fins

2003 ◽  
Author(s):  
D. Chakraborty ◽  
G. Biswas ◽  
P. K. Panigrahi
Keyword(s):  
Heat Transfer ◽  
Circular Tube ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Local Heat Transfer ◽  
Local Heat ◽  
Stagnation Line ◽  
Flow And Heat Transfer ◽  
Annular Fin ◽  
Annular Fins

A numerical investigation was carried out to study the flow and heat transfer behavior of a vertical circular tube, which is situated between two annular fins in cross-flow. The flow structure of the limiting streamlines on the surface of the circular tube and the annular fins was analysed. A finite volume method was employed to solve the Navier-Stokes and energy equations. The numerical results pertaining to heat transfer and flow characteristics were compared with the available experimental results. The following salient features were observed in this configuration. A horseshoe vortex system was formed at the junction of the stagnation line of the circular tube and the annular fin. The separation took place at the rear of the tube. The influence of the horseshoe vortices on local heat transfer was substantial. The ratio of the axial gap between two annular fins (L) to the radial protrusion length of the annular fin (LR) was identified as an important parameter. The flow and heat transfer results were presented for different L/LR ratios for a Reynolds number of 1000.

Cross flow and heat transfer past a permeable stretching/shrinking sheet in a hybrid nanofluid

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Natalia C. Roşca ◽  
Alin V. Roşca ◽  
Amin Jafarimoghaddam ◽  
Ioan Pop
Keyword(s):  
Heat Transfer ◽  
Differential Equations ◽  
Cross Flow ◽  
Porous Wall ◽  
Shrinking Sheet ◽  
Hybrid Nanofluid ◽  
Lower Branch ◽  
Content Type ◽  
Flow And Heat Transfer ◽  
Branch Solution

Purpose The purpose of this paper is to study the laminar boundary layer cross flow and heat transfer on a rotational stagnation-point flow over either a stretching or shrinking porous wall submerged in hybrid nanofluids. The involved boundary layers are of stream-wise type with stretching/shrinking process along the surface. Design/methodology/approach Using appropriate similarity variables the partial differential equations are reduced to ordinary (similarity) differential equations. The reduced system of equations is solved analytically (by high-order perturbed field propagation for small to moderate stretching/shrinking parameter and low-order perturbation for large stretching/shrinking parameter) and numerically using the function bvp4c from MATLAB for different values of the governing parameters. Findings It was found that the basic similarity equations admit dual (upper and lower branch) solutions for both stretching/shrinking surfaces. Moreover, performing a linear stability analysis, it was confirmed that the upper branch solution is realistic (physically realizable), while the lower branch solution is not physically realizable in practice. These dual solutions will be studied in the present paper. Originality/value The authors believe that all numerical results are new and original and have not been published before for the present problem.

scholarly journals Fluid Flow and Heat Transfer around Two Circular Cylinders of Different Diameters in Cross Flow

1979 ◽  
Vol 22 (167) ◽  
pp. 715-723 ◽  
Author(s):  
Munehiko HIWADA ◽  
Tatsuhisa TAGUCHI ◽  
Ikuo MABUICHI ◽  
Masaya KUMADA
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Cross Flow ◽  
Circular Cylinders ◽  
Flow And Heat Transfer ◽  
Different Diameters
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