Simulation of Multiphase Heat Transfer in Pebble Bed Modular Reactor

2004 ◽  
Author(s):  
Andrey A. Troshko ◽  
Ajey Y. Walavalkar
Keyword(s):  
Heat Transfer ◽  
Gas Phase ◽  
Packed Bed ◽  
Multiphase Model ◽  
Test Rig ◽  
Pebble Bed ◽  
Model Predictions ◽  
Two Phases ◽  
Drag Law ◽  
Eulerian Multiphase Model

Computational Fluid Dynamics in conjunction with an Eulerian multiphase model of heat transfer in a Pebble Bed Modular Reactor (PBMR) was validated against experimental data obtained in a test rig. The cooling gas and packed fuel pebbles constituted two phases. The velocity of pebble phase was fixed to zero and a drag law accounting for a packed bed condition was used. The density of the gas phase varied with temperature. Volume averaged effective thermal conductivities accounting for radiation and packed spheres geometry were used for both phases. Model predictions compared favorably with the experiment for two gases — helium and nitrogen and two power levels. It was found that accounting for increased affective porosity close to walls results in more realistic velocity field prediction.

Packed-bed reactor for short time gas phase olefin polymerization: Heat transfer study and reactor optimization

AIChE Journal ◽  
2011 ◽  
Vol 58 (1) ◽  
pp. 256-267 ◽  
Author(s):  
Estevan Tioni ◽  
Roger Spitz ◽  
J. P. Broyer ◽  
Vincent Monteil ◽  
Timothy McKenna
Keyword(s):  
Heat Transfer ◽  
Gas Phase ◽  
Olefin Polymerization ◽  
Packed Bed ◽  
Packed Bed Reactor ◽  
Reactor Optimization ◽  
Short Time ◽  
Transfer Study

Effective numerical model for flow boiling of a nanofluid

2017 ◽  
Vol 7 ◽  
Author(s):  
Anurag Alam Shetty ◽  
Pradyumna Ghosh ◽  
S. S. Mondal ◽  
Nirupama S. Patra. ◽  
R. S. Singh
Keyword(s):  
Heat Transfer ◽  
Flow Boiling ◽  
Nucleate Boiling ◽  
Multiphase Model ◽  
Heat Transfer Characteristics ◽  
Two Phase ◽  
Ansys Fluent ◽  
Phase Mixture ◽  
Eulerian Multiphase Model ◽  
Good Agreement

Flow boiling of Al2O3-Water nanofluid has been investigated numerically using the Eulerian multiphase model in ANSYS FLUENT. The physical properties have been computed using the two phase mixture model. In the Eulerian multiphase model, Rensselaer Polytechnic Initiative (RPI) nucleate boiling model has been used for modeling boiling. Axial vapor fraction has been computed in case of flow boiling of water and heat transfer coefficient has been computed in case of flow boiling of Al2O3-Water nanofluid. The numerical results obtained were in good agreement with experimental results. The RPI model predicts the heat transfer characteristics quickly.

Numerical modeling of the influence of bubbles on flow and heat transfer in the descending gas-liquid flow in a pipe

2012 ◽  
Vol 9 (1) ◽  
pp. 131-135
Author(s):  
M.A. Pakhomov
Keyword(s):  
Heat Transfer ◽  
Gas Phase ◽  
Liquid Flow ◽  
Bubble Diameter ◽  
Gas Content ◽  
Two Phase ◽  
Eulerian Description ◽  
Flow And Heat Transfer ◽  
Gas Liquid Flow ◽  
The Mathematical Model

The paper presents the results of modeling the dynamics of flow, friction and heat transfer in a descending gas-liquid flow in the pipe. The mathematical model is based on the use of the Eulerian description for both phases. The effect of a change in the degree of dispersion of the gas phase at the input, flow rate, initial liquid temperature and its friction and heat transfer rate in a two-phase flow. Addition of the gas phase causes an increase in heat transfer and friction on the wall, and these effects become more noticeable with increasing gas content and bubble diameter.

Theoretical analysis of counter-current absorption of a poorly soluble gas based on the PDE-AD model

1986 ◽  
Vol 51 (6) ◽  
pp. 1222-1239 ◽  
Author(s):  
Pavel Moravec ◽  
Vladimír Staněk
Keyword(s):  
Experimental Data ◽  
Liquid Phase ◽  
Gas Phase ◽  
Transfer Functions ◽  
Packed Bed ◽  
Packed Bed Column ◽  
Interfacial Transport ◽  
Gaseous Component ◽  
Poorly Soluble ◽  
Counter Current

Expression have been derived in the paper for all four possible transfer functions between the inlet and the outlet gas and liquid steams under the counter-current absorption of a poorly soluble gas in a packed bed column. The transfer functions have been derived for the axially dispersed model with stagnant zone in the liquid phase and the axially dispersed model for the gas phase with interfacial transport of a gaseous component (PDE - AD). calculations with practical values of parameters suggest that only two of these transfer functions are applicable for experimental data evaluation.

An experimental study of gas phase back mixing under the counter-current gas-liquid flow on a vertical expanded metal sheet packing by static tracer technique

1980 ◽  
Vol 45 (1) ◽  
pp. 214-221
Author(s):  
Jan Červenka ◽  
Mirko Endršt ◽  
Václav Kolář
Keyword(s):  
Gas Phase ◽  
Flow Model ◽  
Plug Flow ◽  
Packed Bed ◽  
Metal Sheet ◽  
Concentration Profiles ◽  
Expanded Metal ◽  
Gas Liquid Flow ◽  
Counter Current ◽  
Back Mixing

Gas phase back mixing has been measured in a column packed with vertical expanded metal sheet under the counter-current flow of gas and liquid by the static method using a tracer. The observed experimental concentration profiles has not confirmed our earlier proposed model of back mixing, based on the concentration profiles in absorption runs. These profiles do not even conform with the axially dispersed plug flow model currently used to describe axial mixing in packed bed columns. The concentration profiles may be described by a combination of the axially dispersed plug flow model with back flow.

Near-Wall Microlayer Evaporation Analysis and Experimental Study of Nucleate Pool Boiling on Inclined Surfaces

1998 ◽  
Vol 120 (3) ◽  
pp. 641-653 ◽  
Author(s):  
G. F. Naterer ◽  
W. Hendradjit ◽  
K. J. Ahn ◽  
J. E. S. Venart
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Heating Surface ◽  
Nucleate Boiling ◽  
Inclined Surfaces ◽  
Wide Range ◽  
Model Predictions ◽  
Microlayer Evaporation ◽  
Near Wall

Boiling heat transfer from inclined surfaces is examined and an analytical model of bubble growth and nucleate boiling is presented. The model predicts the average heat flux during nucleate boiling by considering alternating near-wall liquid and vapor periods. It expresses the heat flux in terms of the bubble departure diameter, frequency and duration of contact with the heating surface. Experiments were conducted over a wide range of upward and downward-facing surface orientations and the results were compared to model predictions. More active microlayer agitation and mixing along the surface as well as more frequent bubble sweeps along the heating surface provide the key reasons for more effective heat transfer with downward facing surfaces as compared to upward facing cases. Additional aspects of the role of surface inclination on boiling dynamics are quantified and discussed.

Lateral transport in a fluidized-packed bed: Part II. Heat transfer

AIChE Journal ◽  
1965 ◽  
Vol 11 (1) ◽  
pp. 130-132 ◽  
Author(s):  
John D. Gabor ◽  
Bruce E. Stangeland ◽  
William J. Mecham
Keyword(s):  
Heat Transfer ◽  
Packed Bed ◽  
Lateral Transport
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