Relations between morphology, air flow, sand flux and particle size on transverse dunes, Taklimakan Sand Sea, China

Abstract This study was performed to evaluate hammermill tip speed, assistive airflow and screen hole diameter on hammermill throughput and characteristics of ground corn. Corn was ground using two Andritz hammermills (Model: 4330–6, Andritz Feed & Biofuel, Muncy,PA) measuring 1-m in diameter each equipped with 72 hammers and 300 HP motors. Treatments were arranged in a 3 × 3 × 3 factorial design with 3 tip speeds (3,774, 4,975, and 6,176 m/min), 3 screen hole diameters (2.3, 3.9 and 6.3 mm), and 3 air flow rates (1,062, 1,416, and 1,770 fan RPM). Corn was ground on 3 separate days to create 3 replications and treatments were randomized within day. Samples were collected and analyzed for moisture, particle size, and flowability characteristics. Data were analyzed using the GLIMMIX procedure of SAS 9.4 with grinding run serving as the experimental unit and day serving as the block. There was a 3-way interaction for standard deviation (Sgw), (linear screen hole diameter × linear hammer tip speed × linear air flow, P = 0.029). There was a screen hole diameter × hammer tip speed interaction (P < 0.001) for geometric mean particle size dgw (P < 0.001) and composite flow index (CFI) (P < 0.001). When tip speed increased from 3,774 to 6,176 m/min the rate of decrease in dgw was greater as screen hole diameter increased from 2.3 to 6.3 mm resulting in a 67, 111, and 254 µm decrease in dgw for corn ground using the 2.3, 3.9, and 6.3 mm screen hole diameter, respectively. For CFI, increasing tip speed decreased the CFI of ground corn when ground using the 3.9 and 6.3 mm screen. However, when grinding corn using the 2.3 mm screen, there was no evidence of difference in CFI when increasing tip speed. In conclusion, the air flow rate did not influence dgw of corn but hammer tip speed and screen size were altered and achieved a range of dgw from 304 to 617 µm.

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A single experiment with variable low-pressure air flow through a packed bed leads to two methods for determining particle size

Physics of Fluids ◽

10.1063/5.0077111 ◽

2022 ◽

Vol 34 (1) ◽

pp. 013306

Author(s):

Keith B. Lodge

Keyword(s):

Particle Size ◽

Air Flow ◽

Packed Bed ◽

Low Pressure ◽

Single Experiment ◽

Flow Through

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Experimental Study of Self-Suction Spraying with Pressure Gas and Water

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.580-583.2508 ◽

2014 ◽

Vol 580-583 ◽

pp. 2508-2512

Author(s):

Zhong Fei Ma ◽

Guang Rong Lin ◽

Zhen Zhang ◽

Hong Ling Xie

Keyword(s):

Experimental Study ◽

Particle Size ◽

Air Flow ◽

Orthogonal Test ◽

Nozzle Diameter ◽

Optimal Configuration ◽

Factors Influencing ◽

Data Support ◽

Orthogonal Experiments ◽

Working Principle

In order to find out the factors influencing self-suction spraying with pressure gas and water performance, the working principle of the spray was analyzed, orthogonal experiments were conducted, in which influenced of different air flow, bronchia-nozzle distance, nozzle diameter as well as the diffusion angle on the effective rang and spray particle size were tested, the optimal matching of parameters was obtained. The results showed that, the optimal configuration parameters could be obtained by orthogonal test of self-suction spraying with pressure gas and water, to provide data support for the design of efficient spraying device.

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HEAT TRANSFER IN A FLUIDIZED SOLIDS BED

Canadian Journal of Research ◽

10.1139/cjr50f-025 ◽

1950 ◽

Vol 28f (8) ◽

pp. 287-307 ◽

Cited By ~ 9

Author(s):

J. Klassen ◽

P. E. Gishler ◽

A. Baerg

Keyword(s):

Heat Transfer ◽

Particle Size ◽

Bulk Density ◽

Particle Shape ◽

Air Flow ◽

Transfer Coefficients ◽

Air Velocity ◽

Heat Transfer Coefficients ◽

Minimum Fluidizing Velocity

Heat transfer coefficients have been determined in a fluidized solids bed under a wide variety of conditions. The variables studied were particle size, bulk density under nonfluidized conditions, particle shape, and air velocity. Simple correlations have been established predicting the value of h in the air flow range investigated. An equation predicting the minimum fluidizing velocity has also been derived.

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EFFECT OF PARTICLE-SIZE AND AIR FLOW RATES ON THE IGNITION TEMPERATURE OF SUB BITUMINOUS COAL

International Journal of Modern Trends in Engineering & Research ◽

10.21884/ijmter.2016.3087.81w9s ◽

2016 ◽

Vol 3 (10) ◽

pp. 89-97 ◽

Cited By ~ 1

Keyword(s):

Particle Size ◽

Ignition Temperature ◽

Bituminous Coal ◽

Air Flow ◽

Flow Rates ◽

Effect Of Particle Size

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The Influence of Air Flow Velocity and Particle Size on the Collection Efficiency of Passive Electrostatic Aerosol Samplers

Aerosol and Air Quality Research ◽

10.4209/aaqr.2018.06.0211 ◽

2019 ◽

Vol 19 (2) ◽

pp. 195-203 ◽

Cited By ~ 1

Author(s):

Ramin Jajarmi Imani ◽

Laila Ladhani ◽

Gaspar Pardon ◽

Wouter van der Wijngaart ◽

Etienne Robert

Keyword(s):

Particle Size ◽

Flow Velocity ◽

Collection Efficiency ◽

Air Flow ◽

Air Flow Velocity

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Computational Fluid Dynamics Simulation of Flow of Exhaled Particles From Powered-Air Purifying Respirators

Volume 1: 39th Computers and Information in Engineering Conference ◽

10.1115/detc2019-97826 ◽

2019 ◽

Author(s):

Susan S. Xu ◽

Zhipeng Lei ◽

Ziqing Zhuang ◽

Michael Bergman

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Particle Size ◽

Simulation Study ◽

Particle Concentration ◽

Air Flow ◽

Dynamics Simulation ◽

Cfd Modeling ◽

Particle Sizes ◽

Flow Rates

Abstract In surgical settings, infectious particulate wound contamination is a recognized cause of post-operative infections. Powered air-purifying respirators (PAPRs) are widely used by healthcare workers personal protection against infectious aerosols. Healthcare infection preventionists have expressed concern about the possibility that infectious particles expelled from PAPR exhalation channels could lead to healthcare associated infections, especially in operative settings where sterile procedural technique is emphasized. This study used computational fluid dynamics (CFD) modeling to simulate and visualize the distribution of particles exhaled by the PAPR wearer. In CFD simulations, the outward release of the exhaled particles, i.e., ratio of exhaled particle concentration outside the PAPR to that of inside the PAPR, was determined. This study also evaluated the effect of particle sizes, supplied air flow rates, and breathing work rates on outward leakage. This simulation study for the headform and loose-fitting PAPR system included the following four main steps: (1) preprocessing (establishing a geometrical model of a headform wearing a loose-fitting PAPR by capturing a 3D image), (2) defining a mathematical model for the headform and PAPR system, and (3) running a total 24 simulations with four particle sizes, three breathing workloads and two supplied-air flow rates (4 × 3 × 2 = 24) applied on the digital model of the headform and PAPR system, and (4) post-processing the simulation results to visually display the distribution of exhaled particles inside the PAPR and determine the particle concentration of outside the PAPR compared with the concentration inside. We assume that there was no ambient particle, and only exhaled particles existed. The results showed that the ratio of the exhaled particle concentration outside to inside the PAPR were influenced by exhaled particle sizes, breathing workloads, and supplied-air flow rates. We found that outward concentration leakage from PAPR wearers was approximately 9% with a particle size of 0.1 and 1 μm at the light breathing and 205 L/min supplied-air flow rates, which is similar to the respiratory physiology of a health care worker in operative settings, The range of the ratio of exhaled particle concentration leaking outside the PAPR to the exhaled particle concentration inside the PAPR is from 7.6% to 49. We found that supplied air flow rates and work rates have significant impact on outward leakage, the outward concentration leakage increased as particle size decreased, breathing workload increased, and supplied-air flow rate decreased. The results of our simulation study should help provide a foundation for future clinical studies.

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Experimental Analysis of Air∕Oil Separator Performance

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2795785 ◽

2008 ◽

Vol 130 (6) ◽

Cited By ~ 10

Author(s):

K. Willenborg ◽

M. Klingsporn ◽

S. Tebby ◽

T. Ratcliffe ◽

P. Gorse ◽

...

Keyword(s):

Particle Size ◽

Pressure Drop ◽

Droplet Size ◽

Separation Efficiency ◽

Optical Measurement ◽

Air Flow ◽

Measurement Techniques ◽

Design Feature ◽

Droplet Size Distribution ◽

Separation Mechanism

Within the European research project (Advanced Transmission and Oil System Concepts), a systematic study of the separation efficiency of a typical aeroengine air∕oil separator design was conducted. The main objectives were to obtain a basic understanding of the main separation mechanisms and to identify the relevant parameters affecting the separation efficiency. The results of the study contribute to an optimized separator technology. Nonintrusive optical measurement techniques like laser diffraction and multiple wavelength extinction were applied to analyze the separation efficiency and identify potential optimization parameters. Oil mist with defined oil droplet size distribution was supplied to the breather. By simultaneously measuring particle size and oil concentration upstream and downstream of the breather, the separation mechanism was analyzed and the separation efficiency was assessed. In addition, the pressure drop across the separator was measured. The pressure drop is an important design feature and has to be minimized for proper sealing of the engine bearing chambers. The experimental programe covered a variation of air flow, oil flow, shaft speed, and droplet size. The main emphasis of the investigations was on the separation of small droplets with a diameter of up to 10μm. The following trends on separation efficiency of small droplets were observed: The separation efficiency increases with increasing rotational speed, with increasing particle size, and with decreasing air flow rate. In parallel, the pressure drop across the breather increases with increasing speed and increasing air flow.

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