Design and construction of the pressure swirl nozzle and experimental investigation of spray characteristics

This paper focuses on the structure and performance of the pressure swirl nozzle and the study of liquid atomization. In this study, the atomizer has been designed and some experiments have been performed on it. Since image processing is an efficient method for measuring the size of the droplet and since it considerably reduces the total measuring time and eliminates the subjective observer’s error in sizing and counting spray drops, a digital camera has been used for capturing images and image processing has been done by the MATLAB software. The results show that by increasing the atomization air pressure, the spray angle increases and the droplet’s size decreases. It is concluded that the spray angle is a function of the atomization air pressure and orifice diameter. Moreover, when the distance from the spray centre line increases, the droplet’s average velocity decreases

Investigation of the mechanical performance of fiber-modified ceramic composites using finite element method

Ceramic materials are widely used in impact safekeeping systems. Ceramic is a heterogeneous material; its characteristics depend considerably both on specifications of its ingredients and the material structure completely. The finite element method (FEM) can be a useful tool for strength computation of these materials. In this paper, the mechanical properties of the ceramic composites are investigated, and the mechanical performance modeling of fiber-fortified ceramic matrix composites (CMC) is expressed by the instance of aluminum oxide fibers in a matrix composite based on alumina. The starting point of the modeling is an infrastructure (primary cell) that contains a micromechanical size, the statistical analysis characteristics of the matrix, fiber-matrix interface, fiber, and their reciprocal influences. The numeral assessment of the model is done using the FEM. The numerical results of composite elastic modulus were computed based on the amount of the added fibers and the porosity was evaluated for empirical data of samples with a similar composition. Various scanning electron microscope (SEM) images were used for each sample to specify the porosity. Also, the unit cell method presumed that the porous ceramic substance is manufactured from an array of fundamental units, each with the same composition, material characteristic, and cell geometry. The results showed that when the material consists of different pores and fibers, the amount of Young’s modulus reduces with the increment of porosity. The linear correlation model of elasticity versus porosity value from experimental data was derived by MATLAB curve fitting. The experimental data from the mechanical test and numerical values were in good agreement

Experimental Investigation and CFD Simulation of Top Spray Fluidized Bed Coating System

Experimentally investigated in this work is the hydrodynamics of particulates motion in a cylindrical fluidized bed equipped with a pneumatic nozzle jet flow. Subsequently, the computational fluid dynamics (CFD) is combined with the Eulerian formulation of multiphase flow to describe the hydrodynamics of particulates motion. Similar to free spray jet velocity profile, the velocity profile of output gas from nozzle is obtained based on the Schlichting equation. Particle trajectories, time dependent fluidization height, gas and solid particles velocity distributions and the fluidization height distribution of particles in different radial positions within the bed have been also considered in the course of experimental and modeling studies. The comparison between the predicted and experimental height of fluidized bed indicates a good agreement between simulation results and experimental data

Effect of Biodegradable Binder Properties and Operating Conditions on Growth of Urea Particles in a Fluidized Bed Granulator

Granulation is an important step during the production of urea granules. Most of the commercial binders used for granulation are toxic and non-biodegradable. In this study, a fully biodegradable and cost-effective starch-based binder is used for urea granulation in a fluidized bed granulator. The effect of binder properties such as viscosity, surface tension, contact angle, penetration time, and liquid bridge bonding force on granulation performance is studied. In addition, the effect of fluidized bed process parameters such as fluidizing air inlet velocity, air temperature, weight of primary urea particles, binder spray rate, and binder concentration is also evaluated using response surface methodology. Based on the results, binder with higher concentration demonstrates higher viscosity and higher penetration time that potentially enhance the granulation performance. The viscous Stokes number for binder with higher concentration is lower than critical Stokes number that increases coalescence rate. Higher viscosity and lower restitution coefficient of urea particles result in elastic losses and subsequent successful coalescence. Statistical analysis indicate that air velocity, air temperature, and weight of primary urea particles have major effects on granulation performance. Higher air velocity increases probability of collision, whereby lower temperature prevents binder to be dried up prior to collision. Findings of this study can be useful for process scale-up and industrial application