Simulation of Particle Motion Behavior in Fluidized Bed Opposed Jet Mill

In order to study the influence of the internal flow field of the fluidized bed opposed jet mill on the motion behavior of particles, Computational Fluid Dynamics (CFD) and Discrete Dlement Method (DEM) are used for coupling calculations. By adjusting the nozzle spacing and inlet pressure, Numerical simulation is carried out on the process of particles collisions with each other after accelerating under the high-speed jet produced by the nozzle. The trajectory of the particles in the flow field of the collision area and the change of the collision state of the particles are analyzed. Finally, the best parameters are selected based on the total collision energy. The results show that the particles will gradually shift and spread during the acceleration process. The reduction of the nozzle spacing is beneficial to increase the probability of particle collisions. However, if the spacing is too small, the particles cannot be fully accelerated; the increase in inlet pressure will increase the kinetic energy of the particles, and number of collisions is almost unaffected. By comparing the total collision energy, the best-simulated preparation conditions are selected as 110mm and 1.1MPa.

A Case Study of Turbulent Free Jet Flows Issuing from Rectangular Slots on Process Performances and Quality of Hot-Air-Dried Apple

This study deals with the improvement in drying process performances and the quality of the final product for industrial equipment in the food industry. Designers need to optimize the design parameters of devices to create synergies between the greater energy efficiency of the process and high-quality dried products. Air impingement drying was carried out on apple cylinders at 323 K and with air velocities ranging between 30 and 60 m s−1. The studied drying process presents a particular setup of jets as they are multiple rectangular slot jets issued from triangular nozzles. The effect of four design jet parameters (slot width, nozzle-to-surface height, nozzle-to-nozzle spacing, and airflow) on the drying process performances and the quality of the final product was analyzed and optimized using response surface methodology (RSM). A minimal influence of design jet parameters on the process performances was shown, while an important impact was observed on the quality of dried apple. The slot width and the nozzle-to-nozzle spacing had a significant effect on the textural and functional properties. Predictive models were established and good agreements were found between predictive and observed values. Sorption isotherms were properly modeled by the Guggenheim–Anderson–de Boer (GAB) model.

On the Motion of Single and Twin Oblique Particle Clouds in Stagnant Water

The evolution of single and twin oblique particle clouds in stagnant water was investigated using a series of laboratory experiments and the effects of controlling parameters such as sand mass and nozzle spacing were studied. The time variations of particle cloud properties such as frontal position, horizontal and vertical centroids, cloud width, and frontal velocity were measured using image analysis and Particle Image Velocimetry (PIV) techniques. The entrainment coefficients were extracted from the measurements. It was found that the main vortex motion of the frontal heads altered after the collision and a new integrated frontal head was formed. The effects of release angle and particle interactions were studied by comparing the time histories of maximum centerline velocities. It was found that the centerline velocity of twin oblique particle clouds in comparison with twin vertical particle clouds increased with increasing nozzle spacing. The time history of the ratio of horizontal to vertical centroids in oblique particle clouds determined the potential location of sand particles and a practical model was developed to determine the size and location of particle clouds with time. The time histories of normalized cloud width indicated a significant change after the frontal head collision. The particle interactions due to frontal head collision in twin oblique particle clouds significantly increased the cloud width until particle clouds reached the swarm phase. The time at which twin oblique particle clouds reached the swarm phase was recorded and a linear model was proposed to link the time to reach the swarm phase with the cloud aspect ratio and nozzle spacing.

A Revisit of Rainfall Simulator as a Potential Tool for Hydrological Research

Different means of hydrological data collection have developed and used. However, they are constraint in one way or other. This paper therefore revisited the rainfall simulator as potential tool for hydrological research. The research disclosed that there are three different types of rainfall simulators; drop former simulator, pressure nozzle simulator and hybrid simulator. It can further be classified as indoor model and outdoor. The research also showed that precipitation is the driving force in hydrological studies. Consequently, in the design of rainfall simulator, the following should be taken into consideration: nozzle spacing, pump size, nozzle size, nozzle type, nozzle spacing, plot size and pressure. Meanwhile, intensity, distribution uniformity, kinetic energy, rainfall drop size and rainfall terminal velocity should be noted in its evaluation. Factoring-in the aforementioned design considerations, data collection is made easy without necessarily waiting for the natural rainfall. Since the rainfall can be controlled, the erratic and unpredictable changeability of natural rainfall is eliminated. Emanating from the findings, pressurized rainfall simulator produces rainfall characteristics similar to natural rainfall, which is therefore recommended for laboratory use if natural rainfall-like characteristics is the main target.

Effect of Nozzle Height on Spray Overlapping of JNKVV Push Type Solar and Battery Operated Sprayer

Study was conducted at the Department of Farm Machinery and Power Engineering workshop, College of Agricultural Engineering, JNKVV, Jabalpur, Madhya Pradesh to determine the nozzle spacing and boom height of JNKVV push type solar and battery operated sprayer on the basis of width of overlapping of spraying. It is difficult to obtain the consistent width of the overlapping between adjacent nozzles for the commonly used spraying. Coefficient of variation of nozzles overlapping varies according to the spray height and nozzle spacing. Precision guidance and precision sprayer control have substantial promise to reduce input application overlap, thus saving chemicals, fuel, and time during the application process. It was found that the overlapping increases with increase in height of the boom. The results were obtained by the overlapping test for boom height and nozzle spacing, there was no overlapping obtained up to height of 80 cm. The overlapping varied from 39 cm to 43 cm and mean overlapping was 41.3 cm at nozzle height 120 cm and nozzle spacing of 60 cm. An average overlapping of nozzles varies from 29 cm to 34 cm at nozzle spacing of 70 cm and boom height of 120 cm. At the boom height of 160 cm and nozzle space of 70 cm, spray overlap fluctuates from 79 to 85 cm. The overlapping at nozzle space 80 cm varies from 19 to 22 cm and mean overlapping was 22 cm at the boom height of 120 cm and nozzle space 80 cm. The overlapping varies from 70 cm to 74 cm in nozzle series at the boom height of 160 cm and nozzle space 80 cm. As per the crop cultivation practices, adjusted the boom height and spacing to reduce overlapping of spraying.

Influence of Non-Structural Parameters on Dual Parallel Jet Characteristics of Porous Nozzles

As an important actuator of the dual parallel jet, the porous nozzle has some non-structural parameters (such as inlet pressure, nozzle spacing ratio, etc.) which have a significant influence on energy transport, chemical combustion and pollutant generation. The research on the microfluidic state of the porous nozzle dual parallel jet, however, remains insufficient because of its microjet pattern and complex intersection process. In this paper, the authors used numerical simulation and an experimental method to clarify the influence of porous nozzles’ non-structural parameters on dual parallel jet characteristics. The results show that the inlet pressure only changes the pressure peak value on the parallel jet axis; the starting point (SP) and peak point (PP) on the parallel jet axis, which are located at Xsp = 22 mm and Xpp = 75 mm, respectively, are not changed; and with the increase in the nozzle spacing ratio, the merging points (MPs) on the parallel jet axis are Xmp = 25 mm, 32 mm and 59 mm, respectively. The merging point and the combined point move to a farther distance and the inner deflection angle of the jet is weakened.