Simulation of Heat Transfer in a Counterflow Porous Bed Reactor With a Thermal Non-Equilibrium Model

2011 ◽  
Author(s):  
Marcelo J. S. deLemos ◽  
Ana C. Pivem
Keyword(s):  
Heat Transfer ◽  
Control Volume ◽  
Fluid Velocity ◽  
Velocity Ratio ◽  
Thermal Capacity ◽  
Equation Model ◽  
Porous Bed ◽  
Geometrical Properties ◽  
Porosity Ratio ◽  
Volume Method

The objective of this work is to study the influence of physical and geometrical properties on heat transfer between solid and fluid phases in a counter-flow porous bed, for cases where the fluid moves in opposite direction with respect to the permeable matrix. For simulating the flow and heat transfer, a two-energy equation model is applied in addition to a mechanical model. Transport equations are discretized using the control-volume method. The effects of solid-to-fluid velocity ratio, permeability, porosity, ratio of solid-to-fluid thermal capacity and ratio of solid-to-fluid thermal conductivity on flow and heat transport are analyzed. Results for a counterflow, that is similar to the heat exchangers in a countercurrent, indicate that there is more heat exchange for the smaller values of the parameters analyzed resulting in more uniform heat transfer between phases along the channel.

A Thermo-Mechanical Model for a Counterflow Biomass Gasifier

2014 ◽  
Vol 354 ◽  
pp. 227-235
Author(s):  
Marcelo J.S. de Lemos
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Control Volume ◽  
Simple Algorithm ◽  
Thermal Capacity ◽  
Macroscopic Model ◽  
Algebraic Equations ◽  
Medium Permeability ◽  
Mechanical Approach ◽  
Volume Method

This article presents a thermo-mechanical approach to investigate heat transfer between solid and fluid phases in a model gasifier. A two-temperature equation approach is applied in addition to a macroscopic model for laminar flow through a porous moving bed. Transport equations are discretized using the control-volume method and the system of algebraic equations is relaxed via the SIMPLE algorithm. The effects on inter-phase heat transfer due to variation of medium permeability, thermal conductivity and thermal capacity are analyzed. Results indicate that for smaller medium permeabilities, as well as for higher solid-to-fluid thermal capacity and thermal conductivity ratios, enhancement of heat transfer between phases is observed.

Effect of Periodic Imposed Heat Flux on Three-Dimensional Natural Convection in a Partially Heated Cubical Enclosure

2016 ◽  
Vol 831 ◽  
pp. 83-91
Author(s):  
Lahoucine Belarche ◽  
Btissam Abourida
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Study ◽  
Control Volume ◽  
Vertical Wall ◽  
Three Dimensional ◽  
Maximum Temperature ◽  
Cubical Enclosure ◽  
Simplec Algorithm ◽  
Volume Method

The three-dimensional numerical study of natural convection in a cubical enclosure, discretely heated, was carried out in this study. Two heating square sections, similar to the integrated electronic components, are placed on the vertical wall of the enclosure. The imposed heating fluxes vary sinusoidally with time, in phase and in opposition of phase. The temperature of the opposite vertical wall is maintained at a cold uniform temperature and the other walls are adiabatic. The governing equations are solved using Control volume method by SIMPLEC algorithm. The sections dimension ε = D / H and the Rayleigh number Ra were fixed respectively at 0,35 and 106. The average heat transfer and the maximum temperature on the active portions will be examined for a given set of the governing parameters, namely the amplitude of the variable temperatures a and their period τp. The obtained results show significant changes in terms of heat transfer, by proper choice of the heating mode and the governing parameters.

Passive Heat Transfer in Porous Enclosures Using a Two-Energy Equation Model

2012 ◽  
Author(s):  
Marcelo J. S. deLemos ◽  
Paulo H. S. Carvalho
Keyword(s):  
Heat Transfer ◽  
Energy Equation ◽  
Equation Model ◽  
Thermal Conductivity Ratio ◽  
Governing Equations ◽  
Flow And Heat Transfer ◽  
Energy Models ◽  
Different Temperatures ◽  
Volume Method ◽  
Generalized Coordinate

This paper presents computations for natural convection within a porous cavity filled with a fluid saturated permeable medium. The finite volume method in a generalized coordinate system is applied. The walls are maintained at constant but different temperatures, while the horizontal walls are kept insulated. Governing equations are written in terms of primitive variables and are recast into a general form. Flow and heat transfer characteristics are investigated for two energy models and distinct solid-to-fluid thermal conductivity ratio.

Numerical Simulation of Fluid Flow and Heat Transfer in the Micro-Nozzle

2005 ◽  
Author(s):  
Longjian Li ◽  
Yihua Zhang ◽  
Wenzhi Cui ◽  
Tien-Chien Jen ◽  
Qinghua Chen ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Control Volume ◽  
Slip Model ◽  
Control Volume Method ◽  
Propulsion Performance ◽  
Micro Nozzle ◽  
Flow And Heat Transfer ◽  
Finite Control ◽  
Mems Technology ◽  
Volume Method

Micro-nozzle, based on the MEMS technology, has played an important role in orbit positioning, attitude adjusting and other applications of micro-satellites. The continuous no-slip model of two-dimensional compressible laminar flow in the micro-nozzle was proposed and solved numerically by finite control volume method. The flow and heat transfer in the micro-nozzle were computed under different conditions, including different inlet pressures, different inlet temperatures and different divergent angles. Flow field and effects of these conditions on the propulsion performance were analyzed. Finally, simulated solutions were compared and validated with the experimental results.

Buoyancy Effect on Developing Turbulent Flow and Heat Transfer in a Helical Pipe With Finite Pitch

2000 ◽  
Author(s):  
B. Zheng ◽  
C. X. Lin ◽  
M. A. Ebadian
Keyword(s):  
Heat Transfer ◽  
Turbulent Flow ◽  
Control Volume ◽  
Three Dimensional ◽  
Boussinesq Approximation ◽  
Buoyancy Effect ◽  
Constant Wall Temperature ◽  
Flow And Heat Transfer ◽  
Helical Pipe ◽  
Volume Method

Abstract Numerical modeling was performed to investigate the buoyancy effect on developing turbulent flow and the heat transfer characteristics of saturated water in a helical pipe with finite pitch. The renormalization group (RNG) κ–ε model was used to account for the turbulent flow and heat transfer in the helical pipe at a constant wall temperature with or without buoyancy force effect. A control volume method with second-order accuracy was used to numerically solve the three-dimensional full elliptic governing equations for this problem. The O-type nonuniform structured grid system was adopted to discretize the computation domain. The Boussinesq approximation was applied to deal with the buoyancy. This study explored the influence of buoyancy on the developing heat transfer along the helical pipe. Based on the results of this research, the velocity, temperature, and Nusselt number are presented graphically and analyzed.

A Reduced Dimension Finite Volume Method for Radiative Heat Transfer in Axisymmetrical Cylinders

Volume 4 ◽  
2004 ◽  
Author(s):  
Weixue Tian ◽  
Wilson K. S. Chiu
Keyword(s):  
Heat Transfer ◽  
Finite Volume Method ◽  
Finite Volume ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Control Volume ◽  
Heat Transfer Analysis ◽  
Radiative Energy ◽  
Conductive Heat ◽  
Volume Method

This paper presents a modified scheme to analyze the radiative heat transfer in axisymmetrical enclosures using the finite volume method. The modified scheme is derived from the conservation of radiative energy in an infinitely thin slice of an axisymmetrical cylinder. Therefore, the final discretized equations are based on a two-dimensional mesh in the spatial domain, and similar to meshes used for convective and conductive heat transfer analysis. The control angle overlap problem caused by misalignment of solid angles with control volume faces in the angular direction is eliminated. Error caused by the control volume face curvature is also eliminated. Comparison of results for several demonstration cases with literature yields satisfactory results.

scholarly journals Heat Transfer Enhancement of Forced Convection in Horizontal Channel with Heated Block due to Oscillation of Incoming Flow

2018 ◽  
Vol 7 (1) ◽  
Author(s):  
Abdelouahab Bouttout
Keyword(s):  
Heat Transfer ◽  
Forced Convection ◽  
Control Volume ◽  
Numerical Procedure ◽  
Horizontal Channel ◽  
Air Cooling ◽  
Electronic Components ◽  
Enhancement Of Heat Transfer ◽  
New Feature ◽  
Volume Method

The study in question consists to amplify the hydrodynamic and thermal instabilities by imposed pulsation during forced convection of air cooling of nine identical heated blocks simulate electronic components mounted on horizontal channel. The finite volume method has been used to solve the governing equations of unsteady forced convection. This approach uses control volume for velocities that are staggered with respect to those for temperature and pressure. The numerical procedure called SIMPLER is used to handle the pressure-velocity coupling. The results show that the time averaged Nusselt number for each heated block depends on the pulsation frequencies and is always larger than in the steady-state case. The new feature in this work is that we obtained a short band of frequencies which the enhancement of heat transfer of all electronic components is greater than 20 % compared with steady non pulsation flow. In addition, the gain in heat transfer Emax attainted the maximum value for the central blocks. Our numerical results were compared with other investigations and found to agree well with experimental data.

Sign in / Sign up

Export Citation Format

Share Document