Impact of Moisture Content and Composition on Flow Properties of Dairy Powders

Milk protein concentrate (MPC) and isolate (MPI), and milk permeate powder (MPP) are functional dairy powder products that are used in food applications worldwide. It is critical that environmental factors and physical powder characteristics during production and storage are controlled. When dairy powders are exposed to non-ideal conditions (high moisture, varying temperatures,) they can quickly become very sticky, and clumpy. When powders become sticky, their ability to easily flow is reduced. As a result, processing and storing the powders effectively and sustainably becomes very difficult. In the first study, an analysis method was created to test the general flow behavior of different milk powder samples with a powder rheometer. It was discovered that the shape and size of the powder particles plays a large role in how the flowability of these powders is recorded. In the second study, the powder samples were modified with different environmental factors, moisture and temperature to determine if these changes would affect the overall flowability of the powder samples. Increased moisture reduced the overall flowability of the powders. Temperature variation had no significant impact on the flowability of the powders. The particle size in relation to flowability was also analyzed to see if different particle sizes made powder flow more easily. It was discovered that the smallest size particles (\u3c 50 μm) were the most cohesive (or least flowable) in nature. The third study examined the impact of storage time (12 months) and temperature in relation to the powder’s flowability. The color of the powder was also analyzed to see if the color changed over time in response to different temperatures. It was discovered that in general, each of the powder samples kept the same level of flowability at month 12 compared to the powder samples at the beginning of the study. From the color study, MPI 85 low lactose powder was discovered to have the highest amount of color change from a light, white powder to a darker, yellowish powder. This change in color occurred because the powder sample contained several types of sugar that tend to turn a product brown when exposed to heat for extended periods of time

On the Seismic Behavior of Ground-Supported Circular Silos Containing Grain-like Material

This thesis is focused on the analysis of the seismic response of flat-bottom cylindrical grain-silos. Part A constitutes an updated state-of-the-art on the structural seismic design of flat-bottom cylindrical grain-silos, Part B critically analysis the theoretical framework developed in the last decade at the University of Bologna by the research work coordinated by Prof. Trombetti and the experimental tests conducted in 2012-2013 for its experimental verification, whilst Part C provides some refinement on the theoretical framework and some further insight into the dynamic behavior of flat-bottom cylindrical grain-silos, representing the main scientific contribution of the work

Dynamic Response of Silo Supporting Structure under Pulsating Loads

Silo quaking is a time varying mass structural dynamic problem and the existence of a silo quake spectrum is confirmed in this research. The outcomes confirm that silo quaking can be prevented by providing the silo structure with sufficient mass, stiffness and damping to counterbalance the effects of pulsating forces and mass losses. Furthermore, dynamic structural analysis algorithms and software need to be developed to solve time varying mass structural dynamic problems

Numerical investigation of granular flow and dynamic pressure in silos

Although the flow of granular material in silos and the pressure acting on the silo walls have been studied for over a century, many challenges still remain in silo design. In particular, during the discharge process some dynamic phenomena in silos can often be observed to display large, self-induced and dynamic pulsations which may endanger the stability of the silo structure. The aim of this thesis is to study the flow and pressure in silos using numerical modelling and analytical methods, and to further understand the mechanical behaviour of granular material and mechanism of dynamic phenomena during silo discharge. The Finite Element (FE) method can be used to analyse the behaviour of the granular material in silos by considering the material as a continuum. In this thesis, FEM modelling of silo flow was developed using the Arbitrary Lagrangian-Eulerian (ALE) formulation in the Abaqus/Explicit program and the key parameters that affect the predictions of the flow and pressure during discharge were identified. Using the ALE technique, almost the entire silo discharge process can be simulated without mesh distortion problems. The mass flow rate and temporally averaged discharge pressure predicted by the FE model were first investigated in a conical hopper and were found to be in good agreement with those from the most commonly quoted theoretical solutions. The transient dynamic pressure fluctuations during incipient silo discharge were predicted and the causes for these dynamic events have been investigated which led to the conclusion that the stress wave propagation and the moving shear zone phenomena within the bulk solid were responsible for the dominant higher and lower frequencies effects respectively. A one-dimensional dynamic model of granular columns subject to Coulomb wall friction was developed to investigate the propagation of stress waves, focusing on the effect of geometry by examining converging and diverging tapered columns. The analytical solutions of this model are compared to the FE model based on the ALE formulation. This FE model was first validated using the known behaviour for cylindrical columns. In all cases, the stress impulse set off by incipient discharge at the silo outlet grew with the distance travelled up the column, however the rate was shown to depend on the halfangle of the taper. Over a range of small angles, the proposed analytical model was found to accurately predict this behaviour. After the successful application of the ALE technique for a conical hopper, the FE model was extended to simulate the granular flow in a flat-bottomed model silo. The FE predictions were compared with the silo pressure measurements in a model silo (Rotter et al, 2004). Pressure cells mounted along a vertical line on the silo walls were used to measure the pressure distribution in the silo tests using dry sand. The FE model was further extended to simulate the granular flow in a model silo consisting of a cylindrical section with a conical hopper. The prediction was compared with the experimental observations from a model silo (Munch-Andersen et al, 1992), together with the well-known theoretical solutions. Two numerical issues were addressed in some detail: one is the numerical treatment of the abrupt transition between the cylinder section and the conical hopper, the other is the interaction between the granular solid and the silo walls that was modelled using a dynamic friction model. In addition, the dynamic pressure events during discharge were examined and plausible explanations were given. Finally, this thesis deployed a non-coaxial elastoplastic constitutive model to explore the effect of non-coaxiality on silo phenomena. The non-coaxial FE modelling was performed on three problems: a simple shear test under various initial conditions, a steep hopper and a flat-bottomed silo. The results show that non-coaxiality did not influence the prediction of wall pressure during filling and storing, on the other hand, the discharge pressure was predicted to be larger when non-coaxiality is considered

Influence of particle-scale properties and gravitational field on flow properties of granular materials

The complexities in the processing behaviour of granular materials under different gravitational environments pose challenges to the researchers in a number of multidisciplinary fields. The micromechanical behaviour of granular materials is inherently heterogeneous due to its discrete nature. Generally, the macroscopic behaviour of granular materials can be determined by accounting for the inter-particle interactions that exist within. Although significant progress has been achieved in the past especially on the transport, handling and storage of granular materials in confined geometries under earth gravity using experimental and computational methods, the micromechanical behaviour of granular materials under low-gravitational environments is still poorly understood. Out of the several approaches proposed in the literature in understanding the complexities in granular materials, discrete element modelling (DEM) has evolved as an important tool in evaluating the role of particle scale properties on the flow and compaction characteristics of granular materials. The primary focus of this research is to understand the micromechanical properties of granular materials, primarily their flow and compaction characteristics under different gravitational environments. Hence, three dimensional DEM is applied in this study under earth, mars and lunar (EML) gravity conditions. In this study, in order to attain a fundamental level understanding of the flow behaviour of granular materials through confined geometries under varying gravity conditions, a comprehensive level of simulations were performed. Initially, sandstone materials as simulants used to represent space grains in space exploration activities are experimentally characterised to obtain two key input material parameters viz., particle size distribution and adhesion force between the grains. These key input parameters, in addition to their other physical properties reported in the literature are fed as input parameters in the three-dimensional DEM simulations for studying their flow and compaction characteristics under EML gravities. Further, investigations on the prediction of maximum shear stress distribution in a hopper containing granular materials under static filling were analysed under earth gravity using three dimensional DEM. The predicted results are compared with an advanced experimental approach using Photo-stress analysis tomography (PSAT). Studies show that the predicted DEM and experimental results for the maximum stress distribution are in good agreement under earth gravity. The hopper internal angle is seen to influence the stress profile quite significantly. Additionally, these DEM results agree qualitatively well with the common Walker’s theoretical predictions for the stress distribution along the hopper walls with dependence on hopper internal angle under earth gravity. The PSAT analysis, though performed only under earth gravity under static condition validates the usefulness of inputting measured particle-scale properties in the DEM simulations. Thereafter, different continuum approaches and DEM simulations are used to investigate the effect of particle scale properties and gravity on the flow characteristics of granular materials through hoppers. Continuum theories based on discrete layer approach and Kirya’s structural model for gravity effects on flow properties of grains in hoppers is performed and compared with that of DEM simulations. Most results obtained on the effect of various particle scale properties agree with existing studies in literature where available. Granular flow is seen to depend on gravity using both the continuum and DEM simulations and these results further agree qualitatively with predictions from a limited practical parabolic flight test operation. Based on this analysis and to further understand the influence of particle scale properties on granular flow, parametric analysis is carried out using DEM simulations. The analysis provides understanding of the complex behaviour of the grains and its response under EML gravity levels. Granular packing, granular bed density, cohesion, hopper geometry (orifice and internal angle), friction effect, angle of repose and combined adhesion strength and size distribution (for real samples) of the granular materials were all observed to have significant effect on granular flow under EML gravity levels distinctly. From all the analysis, the influence of gravity on granular flow is observed to be most sensitive under the lunar gravity. This could imply that the lunar in-situ resource utilization (ISRU) processes may require wider exit openings or non-gravity driving forces to have an effective output from the various processes as compared to process utilization on earth. To improve the granular flow, applying a granular flow aid is investigated for a horizontal piezo vibrator across the hopper containing granular bed under EML gravity levels using DEM. Analysis indicates that the piezo-vibrator technique could improve the flow of grains through a hopper under low gravity levels. To aid the design of the vibrator, its effective impact to improve flow is however shown to depend on the horizontal amplitude and frequency of the vibrator. Furthermore DEM simulations are performed to assess the quality of granular filling in a collection chamber from continuous flow and staggered flow outputs. Continuous flow mechanism is seen to be more effective in processing of grains as against staggering the flow especially under a low gravity level. Finally, the compaction properties of granular media with ice contents under different gravity levels is analysed using DEM simulations. Overall, this thesis presents vital information on the role of particle scale properties on flow and compaction characteristics of granular materials under varying gravity environments. In the future, the understandings reported in this thesis could help to design suitable flow and compaction processes in different engineering and science disciplines, especially in space/low gravity explorations to meet with the ever growing needs for technology advancements

Inverted Shell Foundation Performance In Soil

The use of shells in foundation structures over traditional forms has grown steadily since their inception in the early nineteen–fifties. Shell foundations outperform conventional flat footings and are reputable performers especially when heavy superstructural loads are to be transmitted to weak bearing soil. The geotechnical performance of shells in an elastic continuum concerns their bearing capacities and settlement behaviour, whose study has been trailing behind that of their structural performance. Bringing contact pressures closer to uniformity at the soil–shell structure interface is essential in developing a viable behavioural response under vertically concentric and monotonic loading conditions. This study encapsulates the development of new shell foundation geometries employing shell inversion under such loading conditions. Experimental investigation involves validation of the numerical phase in a comparative study following a two–dimensional analysis of shell models using commercially available geotechnical software with finite element analysis. New inverted triangular footings embedded in sand composed of ultra–high performance iShell Mix concrete using fiber–reinforced polymeric (FRP) microfibers are analyzed. A parametric analysis examines key sensitivity elements including shell angle and shell thickness in granular soil for both upright shells and their inverted counterpart. Linearly–elastic behaviour of concrete material is assumed while soil media is modeled under nonlinear elastic perfectly–plastic conditions following the Mohr–Coulomb yield criterion for loose, medium and dense sand states. Theoretical modeling was developed to generate inverted shell bearing capacity factors to predict ultimate bearing capacities of the shell footings. Simulation efforts scrutinized reveal comparable performance with bearing capacity increase of 3 – 5% for the inverted shells over upright shell models and notable improvements of 42 – 45% over conventional flat footings. The developed models investigated represent forefront configurations of superior performance signifying that shells in foundations be highly regarded and fully exploited whenever feasible

Génie des procédés d'agglomération de poudres alimentaires (éléments de phénoménologie des apports d'eau et d'énergie mécanique)

Le procédé d'agglomération humide trouve des applications dans des secteurs industriels d'importance (e.g. agroalimentaire, pharmaceutique, génie civil, etc.) et s'appuie encore fortement sur le savoir-faire des opérateurs. Ce travail porte sur l'étude des contributions des apports hydriques et mécaniques à l'agglomération humide d'une poudre réactive (transformation de la semoule de blé en grains de couscous). Une approche découplée des apports d'eau et d'énergie mécanique est proposée. L'apport d'eau est étudié par la modélisation de l'influence des paramètres formulation et procédé de l'atomisation liquide sur la taille des gouttes pulvérisées. Les apports d'énergie mécanique sont étudiés à l'aide d'un équipement modèle de malaxage. La répartition des contraintes verticales dans le milieu granulaire à l'état statique est identifiée via une "cartographie 2D des isocontraintes". Le comportement de la poudre au malaxage est étudié au cours du déplacement de la pale dans le malaxeur modèle, par l'analyse des champs de vitesses des particules (obtenus par vélocimétrie par images de particules), et par la mesure des contraintes verticales au niveau de la pale. Une étude de la sthénique et de la cinématique des écoulements granulaires permet d'identifier des longueurs caractéristiques impliquées dans le comportement du milieu granulaire à l'état statique et sous sollicitation mécanique. L'étude couplée des apports hydriques et mécaniques est réalisée par suivi des dynamiques d'agglomération humide dans un malaxeur à pale. Elles sont décrites par des mesures en continu de la consommation énergétique et des mesures in situ des spectres d'absorption proche infra-rouge.The wet agglomeration process presents large applications in different industrial fields (e.g. food, pharmaceutics, civil engineering, etc.) and is still mainly based on technical know-how and empiricism of operators. This thesis work investigates the contributions of water and mechanical energy inputs to the wet agglomeration of a reactive powder, in the particular case of the transformation of durum wheat semolina in couscous grains. A uncoupled approach of both water and mechanical energy inputs is carried out. The water addition is studied through a modelisation of the influence of operating and formulation parameters of the liquid atomization process on the droplet size. Mechanical energy inputs are studied using a model experimental mixing equipment. Vertical stress distribution in the granular bed in static conditions is identified thanks to the establishment of a "2D iso-stress cartography". The granular medium behaviour under mechanical solicitation is studied during the blade motion in the model mixing equipment thanks to the analysis of granular flows and velocity fields (obtained by particle image velocimetry) and to vertical stress measurements directly on the blade. A sthenic and kinematic study of granular flows allows to identify characteristic lengths involved in the granular medium behaviour under mechanical solicitation. The coupled study of water and mechanical inputs is conducted by following in-line the wet agglomeration dynamics in a pilot mixing device using energetical consumption measurements as well as in situ acquiring of near infrared absorption spectra.MONTPELLIER-SupAgro La Gaillarde (341722306) / SudocSudocFranceF

Micromechanical Analysis of Pharmaceutical Granules using Advanced Experimental Imaging Methodologies

Fundamental level understandings on the processing behaviours of materials in granular and powder form is of high interest to number of engineering industries for example, mining, mineral, pharmaceutical, geotechnical and for advanced material processing applications. Handling and processing of pharmaceutical powders through confined geometries have very important role in pharmaceutical industry and many related powder process engineering sectors. Smooth flow of powders and granules mixtures from the feeding hopper to the compression chamber plays a very crucial role to achieve the integrity and quality of the final product. In this context, establishing clear understandings on the flow and compaction characteristics of particulates is vital. The mechanical behaviour of particulate materials such as powders and grains are different from the conventional states of matter. Depending on the loading levels and geometrical conditions, often they display combined features of solid, liquid and gaseous states. Though an extensive amount of studies are reported in the existing literatures on their mechanical response to loading, there are still a number of challenges to address: (i) Sensing stress distribution in particulate systems is not yet established especially when the size of the particulates are less than a millimetre (ii) Understanding is lacking on whether the stress distribution in initial static filling would influence the dynamic flow trajectories of the particulates when they are allowed to flow from the static state (iii) Micromechanical behaviour of particulates under low levels of external loading is still lacking and (iv) Interaction characteristics of stress and velocity distributions in particulate systems as a function of grain-scale properties and geometrical arrangements are still lacking. The present thesis addresses all of these important challenges in a systematic manner. The research is primarily based on the application of sensing stresses and displacements in particulates using advanced photo stress analysis tomography (PSAT), qualitative velocimetry using colour coding technique (CCT) and quantitative digital particle image velocimetry (DPIV). The required grain-scale properties are characterised comprehensively using a number of standard experimental methods. Where possible, experimental results on the stress and velocity distribution for particulate systems are compared with simulations using discrete element method (DEM) and analytical equations respectively, though the primary focus is on the experimental approaches. A number of outcomes from this research shed new lights and provide fundamental level understandings on the micromechanical properties of particulate systems with relevance to pharmaceutical granules processes

Experimental Study of the Three Dimensional Stress-strain Behavior of Wheat En Masse

Agricultural Engineerin

Proceedings of the European Conference on Agricultural Engineering AgEng2021

This proceedings book results from the AgEng2021 Agricultural Engineering Conference under auspices of the European Society of Agricultural Engineers, held in an online format based on the University of Évora, Portugal, from 4 to 8 July 2021. This book contains the full papers of a selection of abstracts that were the base for the oral presentations and posters presented at the conference. Presentations were distributed in eleven thematic areas: Artificial Intelligence, data processing and management; Automation, robotics and sensor technology; Circular Economy; Education and Rural development; Energy and bioenergy; Integrated and sustainable Farming systems; New application technologies and mechanisation; Post-harvest technologies; Smart farming / Precision agriculture; Soil, land and water engineering; Sustainable production in Farm buildings