scholarly journals Assessing the wall effects of packed concentric cylinders and angular walls on granular bed porosity

2022 ◽  
Vol 24 (1) ◽  
Author(s):  
Peter Michael Bandelt Riess ◽  
Heiko Briesen ◽  
Daniel Schiochet Nasato
Keyword(s):  
Particle Size ◽  
Discrete Element Method ◽  
Wall Friction ◽  
Granular Bed ◽  
Wall Effects ◽  
Internal Wall ◽  
Filtration Process ◽  
Process Improvements ◽  
Bed Porosity ◽  
Concentric Cylinders

AbstractThe effect of added wall support on granular bed porosity is systematically studied to elucidate performance enhancements in filtration processes achieved by using inserts, as demonstrated experimentally (Bandelt Riess et al. in Chem Eng Technol 2018, 2021). Packed beds of spheres are simulated through discrete element method in cylinders with different internal wall configurations. Three containing systems are generated: concentric cylinders, angular walls, and a combination of both. Variations of particle size and wall friction and thickness are also considered, and the resulting granular bed porosities are analyzed. The porosity increase is proportional to the incorporated wall support; the combination of cylindrical and angular inserts displays the greatest effect (up to 26% increase). The sinusoidal porosity values near the walls are exhibited to clarify the effects. The presented method can change and evaluate granular bed porosity increments, which could lead to filtration process improvements, and the obtained behaviors and profiles can be used to explore additional effects and further systems. Graphical abstract

scholarly journals Effect of pebble size and bed dimension on the distribution of voidages in pebble bed reactor

2017 ◽  
Vol 10 (3) ◽  
pp. 99-108 ◽  
Author(s):  
Yin Xiong ◽  
Ge Liang ◽  
Gui Nan ◽  
Yang Xingtuan ◽  
Tu Jiyuan ◽  
...  
Keyword(s):  
Particle Size ◽  
Discrete Element Method ◽  
Economic Efficiency ◽  
Discrete Element ◽  
Inherent Safety ◽  
Wall Effects ◽  
Pebble Bed ◽  
Pebble Bed Reactor ◽  
Tsinghua University ◽  
2D And 3D

The HTR-10 built at Tsinghua University is an advanced pebble bed reactor because of its inherent safety and economic efficiency. It is fundamental to explore the voidage of the pebble bed. The existing experimental bed is limited in depth and contains mono-size pebbles. The effects of pebble size and bed dimension of voidage distribution are still not well known. In this work, the discrete element method is used to simulate the static packing of pebbles of three sizes in 2D and 3D pebble beds under the same load. The effects of bed dimension and pebble size on voidage distribution are analyzed. The results are useful for better understanding of the voidage distribution of pebble bed reactor and the effects of bed dimension and particle size as well as the wall effects.

Producing Steam by Spraying Water on a Heated Bed of Steel Spheres

2021 ◽  
pp. 1-42
Author(s):  
D. Jordan Bouchard ◽  
HengSheng Yang ◽  
Sanjeev Chandra
Keyword(s):  
Particle Size ◽  
Thermal Mass ◽  
Steam Generation ◽  
Bed Porosity ◽  
The Media ◽  
Effect Of Particle Size ◽  
The Difference ◽  
Rate Of Evaporation ◽  
A Minor ◽  
Counter Current

Abstract Steam generators used in industrial baking ovens operate by pouring or spraying water on a preheated thermal mass. This paper presents a methodology to quantify the amount of steam generated from a thermal mass along with experiments to determine the effect of particle size and porosity on steam generation. Three sizes of steel spheres, 0.6 mm, 8 mm, and 16 mm in diameter, were used to construct porous media beds that were preheated in an oven after which water was sprayed onto them from a full-cone nozzle for a fixed duration. The weight of the heated bed and the impinging water were recorded during spraying. The difference in weight change when spraying on heated and unheated beds gave the rate of evaporation. Thermocouples were used to record the internal temperature of the bed. Steam generation rate increased with particle size while bed porosity had only a minor influence. The counter-current flow of steam within the media bed disrupts the downward flow of water enough to leave pockets of hot material, reducing steam production. To maximize steam generation the media size, material, and spray time should be matched to ensure the surfaces of particles remain above the boiling point of water during spraying.

scholarly journals Validation of Particle Size Segregation of Sintered Ore during Flowing through Laboratory-scale Chute by Discrete Element Method

2008 ◽  
Vol 48 (12) ◽  
pp. 1696-1703 ◽  
Author(s):  
Hiroshi Mio ◽  
Satoshi Komatsuki ◽  
Masatoshi Akashi ◽  
Atsuko Shimosaka ◽  
Yoshiyuki Shirakawa ◽  
...  
Keyword(s):  
Particle Size ◽  
Discrete Element Method ◽  
Discrete Element ◽  
Laboratory Scale ◽  
Size Segregation ◽  
Element Method

scholarly journals SIMULATION OF FRACTURE USING A MESH-DEPENDENT FRACTURE CRITERION IN THE DISCRETE ELEMENT METHOD

2018 ◽  
Vol 16 (1) ◽  
pp. 41 ◽  
Author(s):  
Andrey Dimaki ◽  
Evgeny Shilko ◽  
Sergey Psakhie ◽  
Valentin Popov
Keyword(s):  
Particle Size ◽  
Discrete Element Method ◽  
Mechanical Behavior ◽  
Fracture Criterion ◽  
Discrete Element ◽  
Macroscopic Behavior ◽  
Detachment Criterion ◽  
Discrete Element Methods ◽  
Adhesive Contacts ◽  
Fracture Processes

Recently, Pohrt and Popov have shown that for simulation of adhesive contacts a mesh dependent detachment criterion must be used to obtain the mesh-independent macroscopic behavior of the system. The same principle should be also applicable for the simulation of fracture processes in any method using finite discretization. In particular, in the Discrete Element Methods (DEM) the detachment criterion of particles should depend on the particle size. In the present paper, we analyze how the mesh dependent detachment criterion has to be introduced to guarantee the macroscopic invariance of mechanical behavior of a material. We find that it is possible to formulate the criterion which describes fracture both in tensile and shear experiments correctly.

Permanent Compression of a Rigidly Contained Granular Bed Following Impact With a Rigid Body

1969 ◽  
Vol 36 (3) ◽  
pp. 545-550 ◽  
Author(s):  
C. C. Silverstein
Keyword(s):  
Rigid Body ◽  
Critical Velocity ◽  
Granular Bed ◽  
Particle Crushing ◽  
Rigid Plastic ◽  
Ottawa Sand ◽  
Bed Porosity ◽  
Plastic Analysis ◽  
Sand Beds

The end-on impact of a rigidly contained cylindrical granular bed against a rigid body at velocities in excess of the critical velocity for initiation of bed particle crushing is analyzed. Based on a modification of Taylor’s rigid-plastic analysis, equations are developed for predicting the length of the granular bed over which particle crushing occurs, the variation of bed porosity over the damaged length, and the total bed length following impact. These quantities are calculated for 20–40 mesh Ottawa sand beds following impact at velocities ranging from 100–450 fps.

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