scholarly journals Equilibrium acoustic velocity in vapor-liquid mixture in layer of spherical particles

2014 ◽  
Vol 18 (2) ◽  
pp. 591-602 ◽  
Author(s):  
Boris Pokusaev ◽  
Emir Tairov ◽  
Alexey Safarov ◽  
Dmitry Nekrasov
Keyword(s):  
Heat Transfer ◽  
Liquid Mixture ◽  
Vertical Channel ◽  
Acoustic Velocity ◽  
Spherical Particles ◽  
Nonstationary Heat Transfer ◽  
Packed Layer ◽  
Half Wave ◽  
Close Packed Layer ◽  
Vapor Liquid

Theoretical and experimental study of acoustic velocity in vapor-liquid mixture that contained close-packed layer of spherical particles was performed with respect to nonstationary heat transfer between mixture and particles in compression half-wave. Theoretical model allows to explain the decay of equilibrium acoustic velocity compared to its adiabatic value in case of increasing of void fraction in the mixture. Calculated results are in agreement with experimental data, obtained in vertical channel with vapor-liquid filtration with close-packed layer of spherical particles of borosilicate glass, steel and lead.

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.

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