HEAT TRANSFER AND PRESSURE DROP OF FIXED BED REACTORS WITH SUBMERGED TUBE BUNDLES

1982 ◽  
Author(s):  
P. Hesse ◽  
D. U. Ringer
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Fixed Bed ◽  
Fixed Bed Reactors ◽  
Tube Bundles

scholarly journals Influence of Macroscopic Wall Structures on the Fluid Flow and Heat Transfer in Fixed Bed Reactors with Small Tube to Particle Diameter Ratio

Processes ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 689
Author(s):  
Thomas Eppinger ◽  
Nico Jurtz ◽  
Matthias Kraume
Keyword(s):  
Heat Transfer ◽  
Fixed Bed ◽  
Particle Diameter ◽  
Diameter Ratio ◽  
Spherical Particles ◽  
Reactor Wall ◽  
Entry Length ◽  
Fixed Bed Reactors ◽  
Wall Structures ◽  
Small Tube

Fixed bed reactors are widely used in the chemical, nuclear and process industry. Due to the solid particle arrangement and its resulting non-homogeneous radial void fraction distribution, the heat transfer of this reactor type is inhibited, especially for fixed bed reactors with a small tube to particle diameter ratio. This work shows that, based on three-dimensional particle-resolved discrete element method (DEM) computational fluid dynamics (CFD) simulations, it is possible to reduce the maldistribution of mono-dispersed spherical particles near the reactor wall by the use of macroscopic wall structures. As a result, the lateral convection is significantly increased leading to a better radial heat transfer. This is investigated for different macroscopic wall structures, different air flow rates (Reynolds number Re = 16 ...16,000) and a variation of tube to particle diameter ratios (2.8, 4.8, 6.8, 8.8). An increase of the radial velocity of up to 40%, a reduction of the thermal entry length of 66% and an overall heat transfer increase of up to 120% are found.

CFD study on particle-to-fluid heat transfer in fixed bed reactors: Convective heat transfer at low and high pressure

2006 ◽  
Vol 61 (13) ◽  
pp. 4341-4353 ◽  
Author(s):  
A. Guardo ◽  
M. Coussirat ◽  
F. Recasens ◽  
M.A. Larrayoz ◽  
X. Escaler
Keyword(s):  
Heat Transfer ◽  
High Pressure ◽  
Convective Heat Transfer ◽  
Convective Heat ◽  
Fixed Bed ◽  
Fixed Bed Reactors

Thermal Analysis of a Heat Recovery System for Externally Fired Micro Gas Turbines

2007 ◽  
Author(s):  
Mehdi Bahador ◽  
Takamasa Ito ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Thermal Efficiency ◽  
Gas Turbines ◽  
Fixed Bed ◽  
Geometrical Parameters ◽  
Transfer Model ◽  
Wood Pellets ◽  
Recovery System ◽  
Material Durability

Several serious problems such as material durability and fouling in the High Temperature Heat Exchanger (HTEH) for Externally Fired Micro Gas Turbines (EFMGT) cause the low thermal efficiency. In this study for increasing the thermal efficiency, a duct around a cylindrical fixed bed combustor which burns wood pellets is proposed and two different designs, empty and porous material filled, are investigated. A heat transfer model, based on coupling between radiative and convective modes at the combustor and duct sides is developed to evaluate the important geometrical parameters in the different designs. The predicted results for the empty duct show that although an increase of the combustion length increases the temperature of air at the duct outlet, an increase of the combustor diameter is more effective. In addition, an increase of the duct cross section is the most effective way and according to the predictions, the pressure drop in this case is still acceptable. The porous duct design shows a significant increase in the air temperature at the duct outlet. However, the pressure drop is high. The investigation shows the possibility of reduction of the pressure drop with the same amount of heat transfer by selecting suitable particle size and porosity.

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