scholarly journals INCORPORATION OF A TWO-FLUX MODEL FOR RADIATIVE HEAT TRANSFER IN A COMPREHENSIVE FLUIDIZED BED SIMULATOR PART I: PRELIMINARY THEORETICAL INVESTIGATIONS

2003 ◽  
Vol 2 (1) ◽  
Author(s):  
J. A. Rabi ◽  
M. L. De Souza Santos
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Thermal Radiation ◽  
Fluidized Bed ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Basic Structure ◽  
Solid Particles ◽  
Particulate Media ◽  
Bubbling Fluidized Bed

Over the last two decades, a comprehensive mathematical model and its corresponding computational program, aimed to simulate steady-state operations of bubbling fluidized bed equipments, has been continuously improved and tested. Despite its success, the simulator has employed a simple approach for radiative heat transfers. In cases of high temperatures, thermal radiation becomes an important energy transfer mode and the original model could lead to deviations above acceptable levels. The purpose of the present work was to improve the model for thermal radiation heat transfer between all solid particles in the bed section by applying a two-flux method to a non-homogeneous polydispersed particulate media in radiative equilibrium. Gases in the emulsion and in the bubbles were assumed transparent to thermal radiation. This first part of the paper presents and discusses the basic structure of the former mathematical model and of the new one.

scholarly journals INCORPORATION OF A TWO-FLUX MODEL FOR RADIATIVE HEAT TRANSFER IN A COMPREHENSIVE FLUIDIZED BED SIMULATOR PART I: PRELIMINARY THEORETICAL INVESTIGATIONS

2003 ◽  
Vol 2 (1) ◽  
pp. 64 ◽  
Author(s):  
J. A. Rabi ◽  
M. L. De Souza Santos
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Thermal Radiation ◽  
Fluidized Bed ◽  
Radiative Heat ◽  
Radiation Heat Transfer ◽  
Basic Structure ◽  
Solid Particles ◽  
Particulate Media ◽  
Bubbling Fluidized Bed

Over the last two decades, a comprehensive mathematical model and its corresponding computational program, aimed to simulate steady-state operations of bubbling fluidized bed equipments, has been continuously improved and tested. Despite its success, the simulator has employed a simple approach for radiative heat transfers. In cases of high temperatures, thermal radiation becomes an important energy transfer mode and the original model could lead to deviations above acceptable levels. The purpose of the present work was to improve the model for thermal radiation heat transfer between all solid particles in the bed section by applying a two-flux method to a non-homogeneous polydispersed particulate media in radiative equilibrium. Gases in the emulsion and in the bubbles were assumed transparent to thermal radiation. This first part of the paper presents and discusses the basic structure of the former mathematical model and of the new one.

scholarly journals Mathematical model of unsteady gas to solid particles heat transfer in fluidized bed

2009 ◽  
Vol 13 (1) ◽  
pp. 55-68 ◽  
Author(s):  
Mladen Stojiljkovic ◽  
Branislav Stojanovic ◽  
Jelena Janevski ◽  
Gradimir Ilic
Keyword(s):  
Heat Transfer ◽  
Mathematical Model ◽  
Computer Program ◽  
Fluidized Bed ◽  
Particle Temperature ◽  
Prediction Method ◽  
Solid Particles ◽  
Gas Temperature ◽  
One Dimensional ◽  
The Mathematical Model

The mathematical model of unsteady one-dimensional gas to particles heat transfer for non-isothermal fluidized bed with periodic heating of solid particles has been described. The method of numerical solution of governing differential equations, the algorithm and the computer program, have been presented. By using mathematical model and computer program, the temperature profiles for interstitial gas, gas in bubbles, and solid particles along the height of fluidized bed in function of time, have been determined. The results obtained on the basis of prediction method are compared to the experimental results of the authors; the satisfactory agreement has been found for interstitial gas temperature and solid particle temperature. On the basis of this comparison, the mathematical model has been verified.

The imaginary plane mothod of radiation heat transfer in the freeboard of atmospheric bubbling fluidized bed boiler

1993 ◽  
Vol 2 (1) ◽  
pp. 18-24 ◽  
Author(s):  
Huilin Lu ◽  
Yiling Bao ◽  
Zidong Zhang ◽  
Lidan Yang ◽  
Yukun Qin
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Radiation Heat Transfer ◽  
Radiation Heat ◽  
Bubbling Fluidized Bed ◽  
Imaginary Plane

Effect of Recycle on Radiative Heat Transfer in the Freeboard of a Fluidized Bed Combustor

2005 ◽  
Author(s):  
Nevin Selc¸uk ◽  
Isil Ayranci ◽  
Yusuf Gogebakan
Keyword(s):  
Heat Transfer ◽  
Fluidized Bed ◽  
Radiative Heat Transfer ◽  
Radiative Heat ◽  
Method Of Lines ◽  
Heat Fluxes ◽  
Radiative Properties ◽  
Discrete Ordinates ◽  
Bubbling Fluidized Bed ◽  
Fluidized Bed Combustor

Effect of recycle on radiative heat transfer in the freeboard of a fluidized bed combustor is investigated by applying a previously developed 3-D radiation model to the prediction of incident radiative heat fluxes along the freeboard walls of lignite-fired 0.3 MWt Middle East Technical University (METU) Atmospheric Bubbling Fluidized Bed Combustor (ABFBC) Test Rig and comparing its predictions with measurements. Freeboard is treated as a rectangular enclosure containing gray, absorbing, emitting and isotropically scattering medium bounded by gray and diffuse walls. Radiative properties of the medium are calculated by using Leckner’s correlations for gas and Mie theory for polydisperse particle cloud. Radiative transfer equation for this system is solved by using Method of Lines (MOL) solution of Discrete Ordinates Method (DOM). Experimental data required for application and validation are generated from two runs in which parameters other than recycle ratio was held as nearly constant as possible. Comparisons between predicted incident radiative heat fluxes and measurements with and without recycle reveal that the agreement is excellent and that the effect of recycle on incident radiative heat fluxes is significant. A parametric study is also carried out to investigate the effect of particle load on fluxes. Predictions are found to be relatively insensitive to the particle load but strongly affected by the temperature profile.

scholarly journals Effects of radiative heat transfer on the structure of turbulent supersonic channel flow

2011 ◽  
Vol 677 ◽  
pp. 417-444 ◽  
Author(s):  
S. GHOSH ◽  
R. FRIEDRICH ◽  
M. PFITZNER ◽  
CHR. STEMMER ◽  
B. CUENOT ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Radiation ◽  
Radiative Heat Transfer ◽  
Radiation Effects ◽  
Radiative Heat ◽  
Pure Water ◽  
Molecular Transport ◽  
Working Fluid ◽  
Mean Flow ◽  
Total Energy Balance

The interaction between turbulence in a minimal supersonic channel and radiative heat transfer is studied using large-eddy simulation. The working fluid is pure water vapour with temperature-dependent specific heats and molecular transport coefficients. Its line spectra properties are represented with a statistical narrow-band correlated-k model. A grey gas model is also tested. The parallel no-slip channel walls are treated as black surfaces concerning thermal radiation and are kept at a constant temperature of 1000 K. Simulations have been performed for different optical thicknesses (based on the Planck mean absorption coefficient) and different Mach numbers. Results for the mean flow variables, Reynolds stresses and certain terms of their transport equations indicate that thermal radiation effects counteract compressibility (Mach number) effects. An analysis of the total energy balance reveals the importance of radiative heat transfer, compared to the turbulent and mean molecular heat transport.

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