Particuology Research Papers - Academia.edu (original) (raw)
Knowledge of particulate system properties is very important in various industrial instances and the possibility of fast predicting the behavior of such systems is an important control tool. The specifi c surface area of simulated... more
Knowledge of particulate system properties is very important in various industrial instances and the possibility of fast predicting the behavior of such systems is an important control tool. The specifi c surface area of simulated particulate systems was studied as a function of the sharpness parameter of the size distribution of the Gates–
Gaudin-Schumann, Gaudin–Meloy and Rosin–Rammler equations. The results showed good statistical adherence, especially the Rosin–Rammler equation, in situations where it is the best descriptor of particle size distribution.
A mathematical model has been formulated based on the combined continuous and discrete particle method for investigating the sedimentation behaviour of microparticles in aqueous suspensions, by treating the fluid phase as continuous and... more
A mathematical model has been formulated based on the combined continuous and discrete particle method for investigating the sedimentation behaviour of microparticles in aqueous suspensions, by treating the fluid phase as continuous and the particles phase as ...
Abstract Further development of an energy-minimization multiscale modeling approach to simulating two-phase flow under turbulent conditions that considers the size distribution of mesoscale structures, i.e. bubbles and clusters, is... more
Abstract Further development of an energy-minimization multiscale modeling approach to simulating two-phase flow under turbulent conditions that considers the size distribution of mesoscale structures, i.e. bubbles and clusters, is presented. User-defined values of minimum and maximum cluster or bubble diameters were specified. A uniform size distribution was first considered as a test case, in which the drag force comprised contributions from each size group. The mathematical form of the objective function describing the energy for suspension and transport was not altered. The heterogeneity index of this new drag modification was then used to simulate pilot-scale circulating fluidized-bed risers involving Geldart group A particles. The results were validated against available experimental data. The model is capable of capturing both axial and radial profiles of flow-field variables.
ABSTRACT Approximately 70% of the applied urea fertilizer may be lost into the environment. This loss is due to leaching, decomposition and ammonium volatilization in soil, water and air. Through coating, the slow release technology can... more
ABSTRACT Approximately 70% of the applied urea fertilizer may be lost into the environment. This loss is due to leaching, decomposition and ammonium volatilization in soil, water and air. Through coating, the slow release technology can be used to reduce losses and to increase the fertilizer efficiency. Sulfur has been used as a coating material, but the coating cracks easily because of its friability, sometimes being peeled off from the urea surface. In this study, four types of materials, namely, gypsum, cement, sulfur and zeolite, were mixed and used as coating materials to search for the most effective and cheap coating materials. The primary reasons for selecting these materials were improving fruit quality and preventing plant diseases, providing a plant nutrient, increasing soil fertility and water retention. The materials were also selected based on their availability, processiblity and price. The effects of the coating materials, thickness, drying time, sieving and sealant on the crushing strength and dissolution rate of urea were investigated. Coated urea with the same proportion of gypsum–sulfur exhibited high crushing strength and lower dissolution rate. However, the performance was further enhanced by applying molten paraffin wax on the hot urea surface. SEM images demonstrated that the micro-structure of gypsum–sulfur coated urea after sieving resulted in a smoother coated layer. The efficiency of the coated urea was improved by 26% using gypsum–sulfur (20% total coating), 3% paraffin wax and sieving the coating materials before application.
Abstract Particle or powder coating with viscous liquids has been essential in industry for surface modification purposes to induce and enhance specific functionalities. This paper evaluates the performance of using foams (of different... more
Abstract Particle or powder coating with viscous liquids has been essential in industry for surface modification purposes to induce and enhance specific functionalities. This paper evaluates the performance of using foams (of different bubble diameters) versus liquids as a means of coating powder beds based on viscous liquid formulations. Coating with viscous liquids present numerous industrial challenges and therefore preparing foam equivalents can render the liquid component weak enough (through pre shearing to form the foam), to allow it to break up and coat particles under the shear forces exerted in a mixing device. In this study, two shear mixers are used; the first type consists of paddles in different configurations attached to a single rotating shaft, whilst the second type is a commercial twin screw mixer (TSM). The quality of coating achieved on the bulk powder bed using liquids and foams (stained with a dye) is assessed by image analysis to determine the homogeneity of the color distribution. In addition, scanning electron microscopy provides a tool to further investigate the coating quality of individual particles from the bulk product. The results show that large bubble (centimeter size) foams are much more effective at distributing within the fluidized powder bed compared to the starting viscous liquid and small bubble foams (sub-millimeter size). Furthermore, there is a maximum ratio of foam to powder beyond which agglomeration occurs and is insufficient to fully coat the particles. Coating of individual particles is achieved in the case of the TSM, whereas SEM proves that the single shaft paddle mixer crushes the particles and subsequently granulates them together to form granules of a size comparable to the size of coated particles seen after coating with the TSM.