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Showing 2 results for Quality Factor

Majid Habibi Mohraz, Farideh Golbabaei, Il Je Yu, Asghar Sedigh Zadeh, Mohammad Ali Mansournia, Somayeh Farhang Dehghan,
Volume 8, Issue 1 (4-2018)
Abstract

Introduction: Electrospun nanofibers are suitable option to synthesize filtering mats for nanoparticles. This study was aimed to fabricate polyurethane nanofiber mats through electrospinning process and to investigate the effect of different parameters such as packing density, face velocity and particle type on the filtration efficiency and quality factor of electrospun polyurethane nanofiber mats.
 

Material and Method: The nanofiber mats were produced by electrospinning  process. Polyurethane granules were dissolved (15w/w%) in a solvent system consisting of dimethylformamide and tetrahydrofuran (3:2). Then, the filtration performance testing system was made at the Fluid Mechanics Department of Hanyang University of South Korea and the filtration efficiency and pressure drop of prepared nanofiber mats were studied.
 

Result: Findings showed that by increasing the duration of electrospinning, the basis weight, thickness, packing density, initial pressure drop and filtration efficiency of the mats increased, and the quality factor of the mats decreased due to the increase of the pressure drop. The increase in electrospinning duration from 15 to 45 minutes was led to the increase in pressure drop from 7 to 32 Pa and the average filtration efficiency was increased about 9-10% for KCl and DEHS test particles. The filtration efficiency and quality factor of the prepared polyurethane nanofiber mats were declined with the increase of filtration face velocity from 2 to 5 and 10 cm/s. The reduction in filtration efficiency was more obvious for particles smaller than 425 nm.
 

Conclusion: The results demonstrated that prepared polyurethan naofiber mats provide acceptable filtration performance. What is more, such nanofiber mats can have other potential benefits such as light basis weight, low thickness and simple production.


Zahra Tarin, Abdulrahman Bahrami, Mohsen Goodarzi, Farshid Ghorbani-Shahna,
Volume 12, Issue 2 (6-2022)
Abstract

Introduction: Generally, geometrical parameters of the cyclone have a profound effect on determining its performance. The air outlet (Vortex Finder) as one of the cyclone’s components has a significant impact on the cyclone’s internal flow pattern, pressure drop and even dust removal efficiency.
Material and Methods: Two different air outlets were designed in order to be easily installed and removed. The ribs (both in the opposite and the same swirl direction with the air flow) were inserted at the inner wall of the vortex finder. The step length of the blades was calculated to be 1.5. The dust feeder was injected the silica particles with a concentration about of 2.1 gr/m3 into the inlet air. The results of dust removal efficiency of the cyclone were calculated and compared for three groups of total dust, PM10 and PM2.5 in different experimental conditions.
Results: Installation of spiral blades in same swirl direction as the air flow inside the cyclone increased 7.75, 7.73 and 6.75 percent in total efficiency, PM10 and PM2.5, respectively. The dust removal efficiencies for total dust, PM10 and PM2.5 increased by 2.6%, 2.33% and 1.5%, respectively, when the swirl direction of ribs and air flow was the opposite. The effect of helical blades on pressure drop for the first experimental setup (same direction) decreased by (- 2.5%) and in the second one (opposite direction) increased by (+ 2.03%). The best quality factor was also calculated for the cyclone with the blade aligned with the air flow direction.
Conclusion: Use of ribs in the inner wall of the cyclone vortex finder,  especially when the rotation direction of the ribs and airflow are the same, leads to a decrease in pressure drop and increase in dust collection efficiency which finally leads to improvement of cyclone performance.


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