Grain Flow Research Articles

Reverse Engineering to Design an Ergonomic Bio Briquette Packaging Machine

Briquettes are solids that are produced through the process of compression and pressure applicationand if burned will produce a small amount of smoke. Briquette production is carried out using ahammer mill where the raw material for briquettes is charcoal which is then crushed into charcoalgranules. The packaging process is still done manually using a shovel to fill the 50kg sack and thentake it to the sewing machine. The worker's posture when using a shovel has a Rapid Entire BodyAssessment (REBA) score of 12 so it has a high work risk of musculoskeletal disorders (MSDs) andrequires immediate improvement. The working environment at the company produces pollutants,meaning that there is no capture container for the fall of charcoal grains from the hammer mill. Basedon the existing problems, a redesign of the existing machine is needed. The proposed machine wasdesigned using the Reverse Engineering method because the existing condition already uses themachine then the existing machine is decomposed to find out the components and functions of theexisting machine to find alternative concepts. The ergonomic approach uses REBA and LBA todetermine changes in worker posture and the forces acting in the human spine. The DEM approachwas chosen to find out if the charcoal grains dropped from the hammer mill were successfully capturedand to find out the flow of the charcoal grains. The results of the proposed machine design have agood impact on workers in the packaging process.

Reduction of clogging of vibrated grains passing through a narrow aperture by the addition of low-friction particles.

We study the flow of grains under vibration passing through a small aperture in two dimensions using discrete element method simulations. Such systems are prone to clogging and strategies to ease the flow are desirable in multiple applications. We show that the addition of low-friction particles to the system can reduce clogging and lead to an enhancement of the net flux of the original species. Along with the role of the particle friction, we analyze the influence of both the size of the added particles and the mixing ratio. We consider systems with constant height of the granular column (using particle reinjection) as well as processes of fully emptying the containing hopper.

Clogging transition of granular flow in porous structures

The clogging transition of granular flow through a disordered porous structure is investigated by three-dimensional discrete element simulations. Results reveal the existence of an intermittent flow state, which has been already observed for active particles or agitated grains, but is absent in single-pore flows of passive particles. Interestingly, the analysis of the intermittent dynamics shows similar attributes to the bottleneck flow of active grains, i.e., exponential distribution of flowing intervals and power-law tails for the clogging times. Precisely, based on the exponent of the power-law tail, a clogging phase diagram for porous structures is proposed in the plane of the scaled pore size D/dp and the friction coefficient μs. Then, we demonstrate that the intermittency arises from a delay in the dissipation of particles' kinetic energy after clogging imposed by the porous structure. Finally, the maximum achievable particle flow rate driven by gravity is predicted from the Froude number Frm, which linearly scales with the pore size and the friction coefficient. Published by the American Physical Society 2024

Investigation of the Effect of Duct Geometry on Drying Air Flow in Conventional Grain Dryers by Porous Media Approach

It is a traditional practice to store many agricultural products after drying, ensuring that they are used all year round. Mixed counter flow air drying is one of the most common and traditional methods in the bulk drying process. In this application, the air flow produced by the air channels placed in the dryer bed is forced to flow through the grains in the opposite direction to the grain flow. The moisture contained in the grains is thrown out of the dryer through forced convection. However, it is expected that the air ducts installed in the dryers should not obstruct the flow of grain and provide the best possible drying performance. In this study, computational fluid dynamics (CFD) modeling for a counter-flow grain dryer was performed and the effect of the geometry of the drying channels on the process was investigated. Fluent 2020 R2 commercial software was used for 2-D flow modeling through the dryer. The airflow in the grain zone, modeled as porous media, was included in the calculation for three different geometries of the dryer air ducts (circular, angular, and straight). A constant temperature boundary condition (37°C) was applied for the air ducts in which the drying air circulated without mixing with the grain. As an output of the analysis, the dryer outlet temperature and differential pressure variation along the flow were calculated for 5 different inlet velocities (between 0.005-0.25) to determine the behavior of different air flow rates in the drying process. The increase in the inlet velocity increased the pressure difference and consequently the stability of the flow for all models. The outlet temperature decreased by about 2.5 °C with a 5-fold increase in velocity. The results showed that the sufficient outlet air for moisture removal depends on the structure of the porous medium and the flow geometry. For this analysis, the best flow was found to be for the circular cross-section model and the outlet temperature could be at acceptable levels.

ТРАНСПОРТНЕ ЗАБЕЗПЕЧЕННЯ УКРАЇНСЬКОГО ЗЕРНОВОГО ЕКСПОРТУ

The article provides an overview of the current state of the domestic marine transport infrastructure as such, which provides transport services for cargo flows of export grain products. The provided analysis covers both the pre-war period and the wartime. The main mode of transport, which implements foreign trade deliveries of grain products, is maritime, which currently works with adjacent modes of transport that provide transportation of grain to sea ports – rail and road, their participation in grain transportation is analyzed. The volumes and dynamics of handling of export grain by sea ports of Ukraine are presented. The main "grain" ports of Ukraine were identified, which in pre-war times loaded up to 90 % of the total sea grain export to sea vessels. The most powerful grain terminals are located in Mykolaiv, Chornomorsk, Pivdenny and Odesa ports, which contributes to the acquisition and maintenance of leading positions by these ports in the market of handling of grain export. Changes in the transportation of grain export caused by the war, which were the result of the blockade of Ukrainian seaports, were emphasized. Partial restoration of the work of some ports became possible in June 2022 with the signing of the Black Sea Grain Initiative. Currently, from the very beginning of the fullscale invasion, the ports of Ukraine located on the Danube, remained unblocked – the main cargo flows of export grain fell to the port of Reni, Ust-Dunaisk and Izmail during the period when the ports of Big Odesa were not working, and their cargo turnover tripled. Today, grain is exported through the ports of Big Odesa (outside the Black Sea Grain Initiative); carriages through the Danube ports remains an alternative route – it is interesting and attractive for grain exporters who invest in technical and technological development and improvement of these ports. Publicly available statistics allow you to operate with indicators for the period until 2022; official statistical data were not made public during the war years.

The Sandglass as Allegory for Ethical Evolution

As a child we all admired the sparkling desert crystal sand grains of the sandglass, and while they slowly, silently rolled down, occasionally, we started dreaming, after having turned it very carefully, watching the grains taking different directions, as the sand was suddenly starting to dance! While the sunlight reflected on the even flow of crystal grains, imagination soared far, into the actual deserts, desert ships, camels, into the fantasy worlds… It was good to dream, freely, realistically, or with a free imagination. As in the sandglass time moments are overlapping, never simply a passing of time as bidirectional succession of points. The duration of the present suggests a radical experience of the hic et Nunc. The sandglass gives us also about five minutes to figure out the right order of our experience. It is both short as an aphorism, both long enough to captures some real perfection and harmony in the world. In our dialogue we tried to crystallize a few central ethical notions, such as an ethical evolution in time, captured by the allegory of the sandglass, which opens not only the imagination but also challenges the decision-maker: “Now quick, take the right decision, I give you five minutes!”

Toward a 3D physical model of diffusive polymer chains.

Recent studies in polymer physics have created macro-scale analogs to solute microscopic polymer chains like DNA by inducing diffusive motion on a chain of beads. These bead chains have persistence lengths of O(10) links and undergo diffusive motion under random fluctuations like vibration. We present a bead chain model within a new stochastic forcing system: an air fluidizing bed of granular media. A chain of spherical 6 mm resin beads crimped onto silk thread are buffeted randomly by the multiphase flow of grains and low density rising air "bubbles". We "thermalize" bead chains of various lengths at different fluidizing airflow rates, while X-ray imaging captures a projection of the chains' dynamics within the media. With modern 3D printing techniques, we can better represent complex polymers by geometrically varying bead connections and their relative strength, e.g., mimicking the variable stiffness between adjacent nucleotide pairs of DNA. We also develop Discrete Element Method (DEM) simulations to study the 3D motion of the bead chain, where the bead chain is represented by simulated spherical particles connected by linear and angular spring-like bonds. In experiment, we find that the velocity distributions of the beads follow exponential distributions rather than the Gaussian distributions expected from polymers in solution. Through use of the DEM simulation, we find that this difference can likely be attributed to the distributions of the forces imparted onto the chain from the fluidized bed environment. We anticipate expanding this study in the future to explore a wide range of chain composition and confinement geometry, which will provide insights into the physics of large biopolymers.

Additive manufacturing of fine-grain fully lamellar titanium aluminide alloys

Additive manufacturing (AM), or 3D printing, has attracted increased attention in producing metallic parts with complex geometries, but it has proved difficult to prepare equiaxed fine-grain parts because the high thermal gradient in solidification commonly conduces the formation of coarse columnar grains. This work shows a solution to fine-grain titanium aluminide (TiAl) alloys by designing a high-frequency thermal cycling to control the solid-state phase transformations in layer-by-layer AM. After solidification, the specially-designed high-frequency thermal cycling can significantly refine the microstructure by repeatedly inducing the nucleation of new grains and suppressing the growth of these newborn fine grains. Therefore, even if solidification leads to coarse columnar grains, equiaxed fine-grain microstructure can still be obtained by solid-state phase transformations. The resulting TiAl alloys have fine heteromorphic grains (∼50 μm) and a fully lamellar microstructure. These fine grains contribute to good strength-ductility balance at room temperature, and their irregular shape and fully lamellar microstructure restrict the flow and distortion of grains at high temperatures, which stands a chance to significantly increase the operating temperature of TiAl parts.

How dirt cones form on glaciers: Field observation, laboratory experiments, and modeling.

Dirt cones are meter-scale structures encountered at the surface of glaciers, which consist of ice cones covered by a thin layer of ashes, sand, or gravel, and which form naturally from an initial patch of debris. In this article, we report field observations of cone formation in the French Alps, laboratory-scale experiments reproducing these structures in a controlled environment, and two-dimensional discrete-element-method-finite-element-method numerical simulations coupling the grain mechanics and thermal effects. We show that cone formation originates from the insulating properties of the granular layer, which reduces ice melting underneath as compared to bare ice melting. This differential ablation deforms the ice surface and induces a quasistatic flow of grains that leads to a conic shape, as the thermal length become small compared to the structure size. The cone grows until it reaches a steady state in which the insulation provided by the dirt layer exactly compensates for the heat flux coming from the increased external surface of the structure. These results allowed us to identify the key physical mechanisms at play and to develop a model able to quantitatively reproduce the various field observations and experimental findings.

Amplitude-dependent rheological responses of axisymmetric grains

Oscillatory shear flows of axisymmetric grains exhibit amplitude-dependent rheological responses, which is related to the evolution of the microstructure. In this work, it is shown that the highly ordered configuration of grains at steady-state shear flow undergoes microstructural rearrangement when subjected to shear oscillations. This rearrangement may lead to reduced ordering configurations which give rise to macroscale shear hardening, which can result in shear jamming if the applied shear traction is below the critical shear resistance. On the other hand, it was observed that applying oscillatory shear to the primary condensed shear flow enhances flowability due to microstructure rearrangement. In this study, we investigate the amplitude-dependent rheological responses of axisymmetric grains subjected oscillatory shear flows. First, we look into the evolution of grains alignment subjected to a range of oscillation amplitudes, where we show that the lower oscillation amplitudes have the potential to change the orientation from the ordered steady state to a completely disordered (isotropic) orientation. Next, we study the dependency of the shear flow resistance on the microstructure configuration, and show that the strain hardening and potential jamming have strong dependency on the oscillations amplitude. We also show that, in the case of jamming, the shear strain and the corresponding number of oscillation cycles depend not only on the grains aspect ratio but also on the oscillation amplitude.

Discrete element method simulation of rice grain motion during discharge with an auger operated at various inclinations

This paper aims to effectively evaluate the efficiency and conveying characteristics of different unloading angles. The movement characteristics of rice grains in the unloading auger were studied from the perspective of particle dynamic behaviour. A discrete element model was constructed, and numerical simulation carried out. The results showed that the voids ratio between particles with an inclination of −30° decreased gradually with increasing axial distance of auger. The voids ratio between particles with an inclination of −15° - 30° at first remained unchanged but then increased gradually with increasing axial distance of auger. The maximum average velocity of grain flow with −30°, −15°, +15° and +30° inclinations occurred in regions close to the inlet and the outlet of the auger. The axial flow performance decreased with increasing unloading angle and moisture content of rice. The axial flow of grain with different angles and moisture contents conformed to the “super” diffusion (mean square deviation ∝ t 2 ). In addition, the conveying characteristics of particle flow in different regions from the perspective of particle force and kinetic energy were explored. • Grain voids ratio distribution with different unloading angles explored. • Grain velocity fluctuation characteristics with different unloading angles studied. • Mechanism velocity change analysed from the aspect of force and energy. • Conveying law with different angles and moisture content compared.

The Role of Dust Charging and Asymmetric Ion Flow on the Dust Lattice Mode in Complex Plasma

mechanism among dust grains immersed in plasma has been reported theoretically in presence of asymmetric ion flow and dynamical charging of dust grains. The ion flow induced particle-wake interaction in addition to repulsive Yukawa type of interaction found to play a significant role in tuning the coupling strength between charged grains and hence the vibrational mode. The transition in coupling strength is obtained as a characteristic of ion flow speed and grain size. The results show a damping in strength of interaction in presence of dynamical charging of dust. The type of interaction shows a mixed phase of Wake-Yukawa in subsonic regime and highly Yukawa dominating phase in supersonic regime of ion flow. The results are significant for understanding the thermodynamic properties and the phase behavior of colloidal systems and nano-crystals.

A Review of Enzyme-Induced Calcium Carbonate Precipitation Applicability in the Oil and Gas Industry.

Enzyme-induced calcium carbonate precipitation (EICP) techniques are used in several disciplines and for a wide range of applications. In the oil and gas industry, EICP is a relatively new technique and is actively used for enhanced oil recovery applications, removal of undesired chemicals and generating desired chemicals in situ, and plugging of fractures, lost circulation, and sand consolidation. Many oil- and gas-bearing formations encounter the problem of the flow of sand grains into the wellbore along with the reservoir fluids. This study offers a detailed review of sand consolidation using EICP to solve and prevent sand production issues in oil and gas wells. Interest in bio-cementation techniques has gained a sharp increase recently due to their sustainable and environmentally friendly nature. An overview of the factors affecting the EICP technique is discussed with an emphasis on the in situ reactions, leading to sand consolidation. Furthermore, this study provides a guideline to assess sand consolidation performance and the applicability of EICP to mitigate sand production issues in oil and gas wells.

Physical characteristics of maize grain as influenced by varietal and moisture differences

ABSTRACT The objective of the study was to determine the geometric, gravimetric, aerodynamic, and frictional properties of maize grain as affected by varietal differences and moisture content. Honampa, Omankwa, Abontem, Timtim, and Obatanpa were the five maize grain varieties studied. Moisture content, geometric properties, gravimetric properties, aerodynamic properties, and frictional properties were studied. The geometric mean diameters ranged between 6.65 and 7.55 mm, while projected areas ranged between 52.98 and 73.12 m2. The surface area was between 139.69 and 180.29 mm2, and sphericity was from 0.71 to 0.80. The following ranges were obtained as thousand grain weight (213.74 and 292.89 g), and bulk density (709.50 and 746.00 kg/m3). The volume of a single seed was between 1.71 × 10−7 and 2.34 × 10−7 m3 while true density was 1250.0 kg/m3. Porosity ranged from 40.32% to 43.24% and terminal velocity ranged between 2.12 and 2.98 m/s. Drag coefficient of 7.18 to 14.60, drag force of 0.002 to 0.003, and Reynolds number between 992.71 and 1579.20 were similarly obtained. The static angle of repose varied with material surfaces while the dynamic angle of repose varied with grain variety. The grain demonstrated 19° static angle of repose, which portrays a very free flow. All the geometric properties increased with moisture besides sphericity although insignificant. The thousand grain weight, volume of single grain, and porosity increased with moisture content. Nonetheless, bulk density decreased and true density remained the same as moisture content increased. Terminal velocity, Reynolds number, and drag force increased as drag coefficient decreased with moisture content. The frictional properties increased with moisture content, and the Reynolds number was <2100, hence, the linear flow of grain. Geometric, gravimetric, aerodynamic, and frictional properties of maize grain were dependent on both grain variety and moisture content.

General linear stability properties of monoclinal shallow waves

Shallow layer equations are variously employed to describe flows of turbulent water, grains, mixed suspensions, mud and other media by selecting an appropriate model for basal drag. In each case, the equations admit steady `monoclinal' traveling wave solutions that connect uniform flows of different depths. We conduct a `model-agnostic' linear stability analysis of these solutions and their associated modes. By adopting a generalized perspective, the fundamental reasons for differences in properties between particular systems may be teased out.

How vertical oscillatory motion above a saturated sand bed leads to heap formation.

We show how oscillations in fluid flow over a fluid-saturated and porous sediment bed leads to the development of a bedform. To understand the role of pressure fluctuations on the bed associated with flow oscillations, we analyze how the flow penetrates into and through the bed. We then calculate the corresponding vertical pressure gradients within the bed that tend to expand the bed along the vertical direction. When these pressure gradients are large enough, they facilitate small irreversible rearrangements of the grains within the bed, and so cause granular creep. We conjecture that this granular creep alternates with jamming to produce a granular ratchet that slowly lifts the surface of the bed locally where pressure gradients dominate, and depresses the surface where shear stresses dominate. We observe that the shape of the resulting heap exhibits a constant characteristic width. The height of this heap evolves approximately as the square root of time, in agreement with dimensional arguments predicated on a coarse-grained viscous deformation of the bed. The surface of the heap contracts initially with the square root of time, consistent with an incompressible analysis of the flow of grains within the heap. Near its peak the heap grows due to a dilatation of the bed, to inward radial flux, or to a combination of the two.

Influence of grain bidispersity on dense granular flow in a two-dimensional hopper

This work uses the discrete-element method to investigate bidisperse dense granular flow with large and small grains in a two-dimensional hopper. A half-circular dynamical force arch forms above the outlet, and the robustness of Beverloo's law is verified to describe the relationship between flow rate and outlet size. The bidisperse flow peaks when monodisperse flow of small grains is supplemented with a small fraction of large grains. The dense flow rate relates closely to the local flow characteristics of a key area. However, the interior packing structures (i.e., an ordered arrangement for monodisperse flow and a disordered arrangement for bidisperse flow) dominate the flow-pattern transition from mass flow to funnel flow. The earlier occurrence of the transition increases the grain velocity and therefore the flow rate. This discovery of interior flow rheology provides a plausible basis for constructing a general constitutive framework for dense granular flow.

On the use of magnetic particles to enhance the flow of vibrated grains through narrow apertures

The flow of grains through narrow apertures possess an extraordinary challenge: clogging. Strategies to alleviate the effect of clogging, such as the use of external vibration or addition of smaller grains, are always part of the design of machinery for the handling of bulk materials. In this work, we study with numerical simulations the effect of adding self-repelling magnetic particles to a sample of grains. We consider a vibrated two-dimensional hopper with a small orifice through which disks flow and clog intermittently. We find that the magnetic repulsion has a second order effect in comparison with the effect of the size of the added grains. Small added grains ease the flow of the original species. However, when the magnetic repulsion is switched on for the added small grains their “lubricating” effect is usually lessened. Only for a narrow range of sizes of the added particles we observe a subtle improvement of flow rate of the original particles with magnetic repulsion.

A generalized model for dense axisymmetric grains flow with orientational diffusion

The flow of non-spherical grains is strongly affected by the orientation of the grains, as observed in experiments and simulations. An existing model that predicts the orientation of grains as a function of the flow field and shape of the grains, is limited to homogenous orientational fields where the interaction of the grains with their surroundings is negligible. To address this limitation, we generalized the model to account for inhomogeneous orientational fields in the form of spatial non-convective orientational flux. The orientational flux accounts for the interactions of grains with their surroundings and the boundaries. The proposed model is used to study the influence of orientational diffusion and boundary conditions on the flow of dense granular material down an incline. It is shown that the boundary conditions can play a significant role in the orientation of grains in such flows.

Теоретичне обґрунтування типу променевих перетворювачів при ідентифікації зернового потоку

The article is devoted to the theoretical substantiation of the type of beam converters in the identification of grain flow in planters. The working conditions of beam transducers in the process of sowing grain crops, types and characteristics of such transducers are considered. It is shown that the best characteristics are possessed by optocouples created on the basis of independent sources and receivers of infrared radiation in the form of silicon diodes operating in the range of 0.75...1.1 μm. This publication is aimed at the implementation of means of control during the sowing of grain crops, its topic is relevant. It is directed to the implementation of the program "Technical means of the new generation for agricultural production", included in the list of State targeted scientific and scientific and technical programs, defined by the law of Ukraine "On priority areas of development of science and technology". The publication examines the theoretical justification of the type of beam transducers in devices for identifying the grain flow formed by seeding devices of seed drills, in order to increase their resolution and quality of registration of discrete objects in the flow. As a result of the analysis of the conditions for identifying the grain flow when sowing grain crops, we come to the conclusion that it is advisable to use optocouplers from separate elements "radiation source"-"radiation receiver" of the infrared spectrum that work in the range of as beam converters. Based on the fact that the registration device includes dozens of discrete optocouplers, silicon light and photodiodes should be used as IR emitters and receivers, as they are the cheapest, simpler in circuit connection than photo transistors and sufficient to obtain the necessary resolution when registering and recognizing the flow of grains.