scholarly journals Workplace Exposure to Titanium Dioxide Nanopowder Released from a Bag Filter System

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Jun Ho Ji ◽  
Jong Bum Kim ◽  
Gwangjae Lee ◽  
Jung-Hun Noh ◽  
Se-Jin Yook ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
High Efficiency ◽  
Collection Efficiency ◽  
Particle Diameter ◽  
Development Stage ◽  
Bag Filter ◽  
High Exposure ◽  
Filter System ◽  
Particle Collection ◽  
Computational Fluid Dynamics Cfd

Many researchers who use laboratory-scale synthesis systems to manufacture nanomaterials could be easily exposed to airborne nanomaterials during the research and development stage. This study used various real-time aerosol detectors to investigate the presence of nanoaerosols in a laboratory used to manufacture titanium dioxide (TiO2). The TiO2nanopowders were produced via flame synthesis and collected by a bag filter system for subsequent harvesting. Highly concentrated nanopowders were released from the outlet of the bag filter system into the laboratory. The fractional particle collection efficiency of the bag filter system was only 20% at particle diameter of 100 nm, which is much lower than the performance of a high-efficiency particulate air (HEPA) filter. Furthermore, the laboratory hood system was inadequate to fully exhaust the air discharged from the bag filter system. Unbalanced air flow rates between bag filter and laboratory hood systems could result in high exposure to nanopowder in laboratory settings. Finally, we simulated behavior of nanopowders released in the laboratory using computational fluid dynamics (CFD).

The Study of the Particles Size Influence on the Venturi Scrubbers Perfomance

2008 ◽  
Vol 591-593 ◽  
pp. 322-327
Author(s):  
João Jorge Ribeiro Damasceno ◽  
M.S.C. Gama ◽  
N.C. Silva
Keyword(s):  
Respiratory System ◽  
High Efficiency ◽  
Collection Efficiency ◽  
Industrial Process ◽  
Chronic Illnesses ◽  
Circular Section ◽  
Particle Collection ◽  
Liquid Injection ◽  
Pulmonary Damage ◽  
Mechanical Devices

The suspended particles in the air are a factor that causes chronic illnesses to the respiratory system, which go from allergy to severe pulmonary damage. Particulary, breathable particles (from 0,5 μm to 5,0 μm sizes) cause damages to the respiratory system. The penetration and the deposition are the reason for the damages to the pulmonary alveolus. The industrial activity is the main responsible for the most part of the breathable particles emission. Because of that, Venturi scrubbers have been incorporated to the industrial process due to their high efficiency for particle collection. Venturi scrubbers are gas-atomizing devices. They are mechanical devices which rely on shearing and impaction forces to break water into fine droplets. Those droplets in contact with the particles, will collected them. This work consists of a Venturi scrubber of circular section operating horizontally, with liquid injection through a single orifice located in the scrubber throat. The experiments will analyse the influence of the length throat, gas velocity, liquid flow and particles sizes on the Venturi´s collection efficiency.

scholarly journals Experimental Investigation of the Effects of Helical Roof on the Performance of Stairmand High Efficiency Cyclone

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Aykut Karadeniz ◽  
Selami Demir
Keyword(s):  
Pressure Drop ◽  
Treatment Cost ◽  
High Efficiency ◽  
Negative Impact ◽  
Collection Efficiency ◽  
Operating Conditions ◽  
Reduced Pressure ◽  
Particle Collection ◽  
Standard Design ◽  
Roof Design

Cost-effectiveness of a standard and a modified Stairmand high-efficiency type cyclone was compared at various inlet gas velocities. The modified design was obtained by replacing the roof of the standard design with a helical roof. Experiments were conducted by both standard and helical roof designs at the same operating conditions. Results showed that helical roof leads to reduced pressure drop in cyclones while having a negative impact on particle collection efficiency. Reductions in pressure drop can reach up to 30%, while particle collection efficiency is reduced by up to 8% simultaneously. Overall, the treatment cost of a cyclone separator can be reduced by 14.1–20.8%. Results indicated that helical roof design cyclones can be used to reduce overall treatment cost by cyclone separators.

scholarly journals Tailoring the Geometry of Bottom-Up Nanowires: Application to High Efficiency Single Photon Sources

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1201
Author(s):  
Dan Dalacu ◽  
Philip J. Poole ◽  
Robin L. Williams
Keyword(s):  
Quantum Dot ◽  
High Efficiency ◽  
Emission Rate ◽  
Single Photon ◽  
Collection Efficiency ◽  
Photon Emission ◽  
Device Performance ◽  
Bottom Up ◽  
Selective Area ◽  
Photon Generation

For nanowire-based sources of non-classical light, the rate at which photons are generated and the ability to efficiently collect them are determined by the nanowire geometry. Using selective-area vapour-liquid-solid epitaxy, we show how it is possible to control the nanowire geometry and tailor it to optimise device performance. High efficiency single photon generation with negligible multi-photon emission is demonstrated using a quantum dot embedded in a nanowire having a geometry tailored to optimise both collection efficiency and emission rate.

scholarly journals Which Is More Sensitive to Water Stress for Irrigation Scheduling during the Maturation Stage: Grapevine Photosynthesis or Berry Size?

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 845
Author(s):  
Qingtao Zhang ◽  
Yixuan Chen ◽  
Yujiu Xiong ◽  
Shigeoki Moritani ◽  
Xinyu Wu ◽  
...  
Keyword(s):  
Water Stress ◽  
High Efficiency ◽  
Soil Water Potential ◽  
Net Photosynthesis ◽  
Development Stage ◽  
Irrigation Scheduling ◽  
Maturation Stage ◽  
Vitis Vinifera L ◽  
A Value ◽  
Berry Size

To better understand the sensitivity of berry size and grapevine photosynthesis to water stress, and determine the soil water potential (ψ) threshold for scheduling irrigation during the maturation stage, we simultaneously measured berry size with photographs, leaf net photosynthesis with a portable meter, and ψ with tensiometers during the drying cycles for grapevines (Vitis vinifera L.). Our results showed that in berry development stage III (maturation), photosynthesis was more sensitive to water stress than berry size. When ψ decreased beyond −13.2 ± 0.82 kPa, photosynthesis, stomatal conductance, transpiration, and extrinsic (AN/E) and intrinsic (AN/gs) water use efficiency (WUE) decreased rapidly and did not recover thereafter. In contrast, the berry size remained close to unaffected by the decreasing ψ until it reached a value of −16.2 ± 0.77 kPa and, thereafter, the berry shrank significantly. In conclusion, we suggest that during the maturation stage of grapevines, for the potted mixture used in our experiments, irrigation should be triggered when the ψ reaches a value of −13.2 ± 0.82 kPa. Further, ψ should be kept lower than −6.9 ± 0.15 kPa after irrigation, because the highest values of intrinsic WUE (AN/gs) occurred when ψ decreased from −6.9 ± 0.15 to −14.6 ± 0.7 kPa. In arid areas, the threshold ψ should be considered as −16.2 ± 0.77 kPa during maturation to achieve high-efficiency use of water resources and sustainable production of grapevines.

scholarly journals Population Balance Application in TiO2 Particle Deagglomeration Process Modeling

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3523
Author(s):  
Radosław Krzosa ◽  
Łukasz Makowski ◽  
Wojciech Orciuch ◽  
Radosław Adamek
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Mechanistic Model ◽  
Population Balance ◽  
Tio2 Particle ◽  
Application Process ◽  
Titanium Dioxide Powder ◽  
Dioxide Powder ◽  
Computational Fluid Dynamics Cfd ◽  
Hydrodynamic Stresses

The deagglomeration of titanium-dioxide powder in water suspension performed in a stirring tank was investigated. Owing to the widespread applications of the deagglomeration process and titanium dioxide powder, new, more efficient devices and methods of predicting the process result are highly needed. A brief literature review of the application process, the device used, and process mechanism is presented herein. In the experiments, deagglomeration of the titanium dioxide suspension was performed. The change in particle size distribution in time was investigated for different impeller geometries and rotational speeds. The modification of impeller geometry allowed the improvement of the process of solid particle breakage. In the modelling part, numerical simulations of the chosen impeller geometries were performed using computational-fluid-dynamics (CFD) methods whereby the flow field, hydrodynamic stresses, and other useful parameters were calculated. Finally, based on the simulation results, the population-balance with a mechanistic model of suspension flow was developed. Model predictions of the change in particle size showed good agreement with the experimental data. Using the presented method in the process design allowed the prediction of the product size and the comparison of the efficiency of different impeller geometries.

The Design of Exhaust Gas Cooler for Diesel Particulate Bag Filter

2015 ◽  
Vol 737 ◽  
pp. 608-611
Author(s):  
Xiu Ye Wang ◽  
Guo Bin Li ◽  
Nan Xu
Keyword(s):  
Diesel Exhaust ◽  
Particulate Filter ◽  
Particulate Emissions ◽  
Bag Filter ◽  
Engine Exhaust ◽  
Particulate Emission ◽  
Filter System ◽  
Exhaust Temperature ◽  
Diesel Exhaust Particulate ◽  
Exhaust Particulate

Currently, the application of bag-filter technology in controlling diesel exhaust particulate emissions has been close to practical stage. As one of the key links in bag-filter technology, engine exhaust cooling can directly influence working safety of the entire exhaust particulate filter system. Thermodynamic calculations and experimental research of water-cooled chiller has provided a feasible basis for water cooler to be used in actual diesel exhaust particulate emission control system. The cooler can make engine exhaust temperature drop from 400 to 180 . Even when engine works in high-speed and high-load condition, inlet exhaust temperature of cooler can descend from 500 to 190 or so after cooling, which can still meet bag-filter system requirement of below 200 .

scholarly journals Uncertainty assessment of current size-resolved parameterizations for below-cloud particle scavenging by rain

2010 ◽  
Vol 10 (12) ◽  
pp. 5685-5705 ◽  
Author(s):  
X. Wang ◽  
L. Zhang ◽  
M. D. Moran
Keyword(s):  
Size Distribution ◽  
Collection Efficiency ◽  
Theoretical Calculations ◽  
Terminal Velocity ◽  
Moderate Intensity ◽  
Size Spectrum ◽  
Cloud Particle ◽  
Particle Collection ◽  
Particle Scavenging ◽  
Empirical Size

Abstract. Current theoretical and empirical size-resolved parameterizations of the scavenging coefficient (Λ), a parameter commonly used in aerosol transport models to describe below-cloud particle scavenging by rain, have been reviewed in detail and compared with available field and laboratory measurements. Use of different formulations for raindrop-particle collection efficiency can cause uncertainties in size-resolved Λ values of one to two orders of magnitude for particles in the 0.01–3 μm diameter range. Use of different formulations of raindrop number size distribution can cause Λ values to vary by a factor of 3 to 5 for all particle sizes. The uncertainty in Λ caused by the use of different droplet terminal velocity formulations is generally small than a factor of 2. The combined uncertainty due to the use of different formulations of raindrop-particle collection efficiency, raindrop size spectrum, and raindrop terminal velocity in the current theoretical framework is not sufficient to explain the one to two order of magnitude under-prediction of Λ for the theoretical calculations relative to the majority of field measurements. These large discrepancies are likely caused by additional known physical processes (i.e, turbulent transport and mixing, cloud and aerosol microphysics) that influence field data but that are not considered in current theoretical Λ parameterizations. The predicted size-resolved particle concentrations using different theoretical Λ parameterization can differ by up to a factor of 2 for particles smaller than 0.01 μm and by a factor of >10 for particles larger than 3 μm after 2–5 mm of rain. The predicted bulk mass and number concentrations (integrated over the particle size distribution) can differ by a factor of 2 between theoretical and empirical Λ parameterizations after 2–5 mm of moderate intensity rainfall.

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