scholarly journals Influence of Flushing Velocity and Flushing Frequency on the Service Life of Labyrinth-Channel Emitters

Water ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 1630 ◽  
Author(s):  
Zhangyan Li ◽  
Liming Yu ◽  
Na Li ◽  
Liuhong Chang ◽  
Ningbo Cui
Keyword(s):  
Particle Size ◽  
Service Life ◽  
Drip Irrigation ◽  
Fine Particles ◽  
Irrigation System ◽  
Coarse Particles ◽  
Muddy Water ◽  
Particle Size Analyzer ◽  
Water Drip ◽  
Labyrinth Channel

Dripline flushing is an effective way to relieve emitter clogging and extend the longevity of drip irrigation systems. This laboratory study was conducted at Kunming University of Science and Technology to evaluate the effect of three targeted flushing velocities (0.3, 0.6, and 0.9 m/s) and four flushing frequencies (no flushing, flushing daily, and flushing every three or five days) on the emitter’s service life and the particle size distribution of the sediment discharged from emitters and trapped in an emitter channel. The gradation of particle size was analyzed by a laser particle size analyzer. The experiment results suggested that flushing velocity and flushing frequency had a significant effect on the service life of emitters, and the emitter’s service life was extended by 30.40% on average under nine different flushing treatments. Flushing can effectively reduce the accumulation of sediments in the dripline and decrease the probability of coarse particles flowing into emitters and fine particles aggregating and cementing in the labyrinth channel, thus relieving the emitter clogging. Therefore, dripline flushing can effectively slow down clogging in muddy water drip irrigation system. The recommended flushing velocity should be set at 0.6 m/s, and the flushing intervals should be shortened.

scholarly journals Contribution of Fine Particles to Air Emission at Different Phases of Biomass Burning

Atmosphere ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 278 ◽  
Author(s):  
Niloofar Ordou ◽  
Igor E. Agranovski
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Fine Particles ◽  
Combustion Process ◽  
Coarse Particles ◽  
Biomass Smoke ◽  
Smoke Particles ◽  
Air Emission ◽  
Entire Duration ◽  
Diffusion Properties

Particle size distribution in biomass smoke was observed for different burning phases, including flaming and smouldering, during the combustion of nine common Australian vegetation representatives. Smoke particles generated during the smouldering phase of combustions were found to be coarser as compared to flaming aerosols for all hard species. In contrast, for leafy species, this trend was inversed. In addition, the combustion process was investigated over the entire duration of burning by acquiring data with one second time resolution for all nine species. Particles were separately characterised in two categories: fine particles with dominating diffusion properties measurable with diffusion-based instruments (Dp < 200 nm), and coarse particles with dominating inertia (Dp > 200 nm). It was found that fine particles contribute to more than 90 percent of the total fresh smoke particles for all investigated species.

The Role of Particle Size Distribution in the Performance and Modelling of Filtration

1993 ◽  
Vol 27 (10) ◽  
pp. 19-34 ◽  
Author(s):  
R. I. Mackie ◽  
R. Bai
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Coarse Particles ◽  
Large Particles

The paper examines the importance of size distribution of the influent suspension on the performance of deep bed filters and its significance with regard to modelling. Experiments were carried out under a variety of conditions using suspensions which were identical in every respect apart from their size distribution. The results indicate that the presence of coarse particles does increase the removal of fine particles. Deposition of fine particles leads to a greater headloss than deposition of large particles. Changes in size distribution with time and depth play an important role in determining the behaviour of a filter, and models of both removal and headloss development must take account of this.

MPT Influence on the Rheological Behaviour of Self-Flow Refractory Castables

2008 ◽  
Vol 587-588 ◽  
pp. 133-137 ◽  
Author(s):  
Abílio P. Silva ◽  
Ana M. Segadães ◽  
Tessaleno C. Devezas
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Mechanical Strength ◽  
Size Distribution ◽  
Fine Particles ◽  
Rheological Behaviour ◽  
Response Surfaces ◽  
Coarse Particles ◽  
Aggregate Particle ◽  
Refractory Castables

The success of a refractory castable is largely due to the quality of its properties and ease of application. Self-flow refractory castables (SFRC), with high flowability index (>130%), can be easily accommodated in a mould without the application of external energy, being ideal for the manufacture of monolithic linings. SFRC castables without cement require a matrix of very fine particles, which guarantees improved rheological behaviour and performs the role of the binder in the absence of the refractory cement. The presence of the aggregate (coarse particles) hinders the flowability index, but improves the castable mechanical strength and reduces firing shrinkage, and also contributes to the reduction of the castable costs. The control of the maximum paste thickness (MPT) allows the reduction of the coarse particles interference, minimizing the number of contact points among the grains and avoiding the formation of an aggregate skeleton that impairs the flowability of the mixture. In the present work, 100% alumina SFRCs without cement were produced with a fixed matrix of fine particles, whose particle size distribution was optimized using statistical techniques (mixtures design and triangular response surfaces). Different aggregate particle size distributions were used, with several MPT values, with the objective of evaluating which was the mean distance that maximized the flowability index, simultaneously ensuring good mechanical strength for the refractory castable. Ensuring a minimum surface area of 2.22m2/g, the mixtures reach the self-flow turning point with a minimum water content and the maximum flowability is obtained for an aggregate particle size distribution modulus of q=0.22, and consequently an optimized MPT value. SFRC with high mechanical strength (>60MPa) were obtained.

scholarly journals Effect of chlorination and pressure flushing of drippers fed by reclaimed wastewater on biofouling

2020 ◽  
Author(s):  
Kévin Lequette ◽  
Nassim Ait-Mouheb ◽  
Nicolas Adam ◽  
Marine Muffat-Jeandet ◽  
Valérie Bru-Adan ◽  
...  
Keyword(s):  
Drip Irrigation ◽  
Water Distribution ◽  
Irrigation System ◽  
Resistant Bacteria ◽  
List Type ◽  
Reclaimed Wastewater ◽  
Microbial Composition ◽  
Labyrinth Channel ◽  
Biofilm Development ◽  
The Impact

AbstractDripper clogging reduces the performance and service life of a drip irrigation system. The impact of chlorination (1.5 ppm of free chlorine during 1 h application) and pressure flushing (0.18 MPa) on the biofouling of non-pressure-compensating drippers fed by real reclaimed wastewater was studied at lab scale using Optical Coherence Tomography. The effect of these treatments on microbial composition (bacteria and eukaryotes) was also investigated by High-throughput DNA sequencing. Biofouling was mainly observed in inlet, outlet and return areas of the drippers. Chlorination limited biofilm development mainly in the mainstream of the milli-labyrinth channel. It was more efficient when combined with pressure flushing. Moreover, chlorination was more efficient in maintaining the water distribution uniformity. It reduced the bacterial concentration and the diversity of the dripper biofilms compared to the pressure flushing method. This method strongly modified the microbial communities, promoting chlorine-resistant bacteria such as Comamonadaceae or Azospira. Inversely, several bacterial groups were identified as sensitive to chlorination such as Chloroflexi and Planctomycetes. Nevertheless, one month after stopping the treatments the bacterial diversity re-increased and the chlorine-sensitive bacteria such as Chloroflexi phylum and the Saprospiraceae, Spirochaetaceae, Christensenellaceae and Hydrogenophilaceae families re-emerged with the growth of biofouling, highlighting the resilience of the bacteria from drippers. Based on PCoA analyses, the structure of the communities still clustered separately from never-chlorinated drippers, showing that the effect of chlorination was still present one month after stopping the treatment.HighlightsThe fouling of drippers is a bottleneck for drip irrigation using reclaimed wastewaterBiofouling was lowest when chlorination was combined with pressure flushingThe β-Proteobacteria and Firmicutes contain chlorine resistant bacteriaThe decrease of Chloroflexi by chlorination was transitoryThe bacterial community was resilient after the interruption of cleaning events

scholarly journals Size Characteristics of Sediments Eroded under Different Masson Pine Litter Covers in South China

Water ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2190
Author(s):  
Fangfang Zhu ◽  
Yuchen Li ◽  
Jinhua Cheng
Keyword(s):  
Particle Size ◽  
Soil Erosion ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Fine Particles ◽  
Enrichment Ratio ◽  
Coarse Particles ◽  
Characteristic Parameters ◽  
Sediment Distribution ◽  
The Relationship

The particle size distribution characteristics of runoff sediments are vital for understanding the effect of the mechanism of soil erosion on slopes. The objective of this study was to investigate the particle-size distribution of sediments eroded from slopes covered by different litter coverage masses under artificial rainfall simulation. Litter was spread on the surface of a soil tank according to different biomasses (0 g·m−2, 100 g·m−2, 200 g·m−2 and 400 g·m−2). The mean weight diameter (MWD), fractal dimension (D) and enrichment ratio (ER) are characteristic parameters of sediment particle size. The MWD and D were more sensitive to soil erosion and had a significant negative correlation with the slope angle and rainfall intensity. The performance of the MWD on the slope (5°) was less than the MWD on the slope (10°). The relationship between eroded sediment distribution characteristic parameters and the litter coverage mass had a significant influence on the content of coarse particles. The content of fine particles accelerated, decreased and then stabilized, whereas coarse particles increased first and then stabilized. The litter diameter and surface area were the main parameters that affected the MWD and D. Under different rain intensities and slopes, the ER varied inconsistently with litter coverage mass. Coarse particles were eroded easily and selectively, and soil erosion had no sorting effect on fine particles. These findings support the quantitative study of the relationship between the amount of litter coverage mass and the particle size of soil sediments.

Study on Preparation of the High-Density Ammonium Polyvanadate

2013 ◽  
Vol 779-780 ◽  
pp. 113-116
Author(s):  
Zhen Xiu Wu ◽  
Zhao Hui Sun ◽  
Tao Zhang
Keyword(s):  
Particle Size ◽  
Loss Rate ◽  
Fine Particles ◽  
High Density ◽  
Research Results ◽  
Temperature Range ◽  
Fine Grained ◽  
Laser Particle Size Analyzer ◽  
Particle Size Analyzer

The high-density ammonium polyvanadate was prepared by means of fine-grained ammonium polyvanadate (APV) produced in vanadium plant. The effects of amount of fine particles, temperature and pH of vanadium solution on preparation of high-density ammonium polyvanadate were investigated. The research results showed that the density of APV could be achieved 0.88g/cm3 under the conditions of addition of 13-31% fine particles, temperature range from 70°C to 100°C and the pH of vanadium solution range from 2.5 to 4, but loss rate of vanadium was the lowest. Moreover, the particle size of high-density ammonium polyvanadate mainly distributes in range of 10 ~ 90μm and is significantly larger than that of the fine APV particles, on the basis of results of the laser particle size analyzer.

scholarly journals Identification of key aerosol populations through their size and composition resolved spectral scattering and absorption

2013 ◽  
Vol 13 (5) ◽  
pp. 2455-2470 ◽  
Author(s):  
F. Costabile ◽  
F. Barnaba ◽  
F. Angelini ◽  
G. P. Gobbi
Keyword(s):  
Particle Size ◽  
Optical Properties ◽  
Fine Particles ◽  
Single Scattering ◽  
Optical Measurements ◽  
Coarse Particles ◽  
Spectral Variability ◽  
General Validity ◽  
Aerosol Properties

Abstract. Characterizing chemical and physical aerosol properties is important to understand their sources, effects, and feedback mechanisms in the atmosphere. This study proposes a scheme to classify aerosol populations based on their spectral optical properties (absorption and scattering). The scheme is obtained thanks to the outstanding set of information on particle size and composition these properties contain. The spectral variability of the aerosol single scattering albedo (dSSA), and the extinction, scattering and absorption Angstrom exponents (EAE, SAE and AAE, respectively) were observed on the basis of two-year measurements of aerosol optical properties (scattering and absorption coefficients at blue, green and red wavelengths) performed in the suburbs of Rome (Italy). Optical measurements of various aerosol types were coupled to measurements of particle number size distributions and relevant optical properties simulations (Mie theory). These latter allowed the investigation of the role of the particle size and composition in the bulk aerosol properties observed. The combination of simulations and measurements suggested a general "paradigm" built on dSSA, SAE and AAE to optically classify aerosols. The paradigm proved suitable to identify the presence of key aerosol populations, including soot, biomass burning, organics, dust and marine particles. The work highlights that (i) aerosol populations show distinctive combinations of SAE and dSSA times AAE, these variables being linked by a linear inverse relation varying with varying SSA; (ii) fine particles show EAE > 1.5, whilst EAE < 2 is found for both coarse particles and ultrafine soot-rich aerosols; (iii) fine and coarse particles both show SSA > 0.8, whilst ultrafine urban Aitken mode and soot particles show SSA < 0.8. The proposed paradigm agrees with aerosol observations performed during past major field campaigns, this indicating that relations concerning the paradigm have a general validity.

Analysis of the Influence Factors on High Compressibility Water Atomized Iron Powder

2016 ◽  
Vol 859 ◽  
pp. 118-124
Author(s):  
Guo Ping Li ◽  
Li Bo Guo ◽  
Li Hui Sun ◽  
Feng Hua Luo ◽  
Jiao Du ◽  
...  
Keyword(s):  
Particle Size ◽  
Iron Powder ◽  
Oxygen Content ◽  
Fine Particles ◽  
Influence Factors ◽  
Impurity Content ◽  
Processing Parameters ◽  
Coarse Particles ◽  
Green Density ◽  
Powder Particles

In this paper, the influence factors on high compressibility water atomized iron powder LAP100.29 were studied such as the processing parameters, the proportion of coarse particles, powder oxygen content and impurity. The results showed that, by increasing the purity of molten steel and improving atomization temperature, the iron content of water atomized iron powder particles reached more than 99.67 %, the oxygen content was less than 0.08 %, acid insoluble was less than 0.08 %, green density reached 7.21~7.22 g/cm3. The contents of +80 and -80～+100 mesh powder were 1.6 % and 7.5 %, respectively. The compressibility could be improved by the increase of the coarse particles and the reduction of the fine particles (for example, lowering the content of -325 mesh particles). Generally speaking, the compressibility of the water atomized iron powder can be improved fundamentally by reducing oxygen content, impurity content and the reasonable distribution of particle size.

scholarly journals Effects of carbonaceous materials and particle size on oral and inhalation bioaccessibility of PAHs and OPEs in airborne particles

2021 ◽  
Author(s):  
Yuan Zeng ◽  
shejun Chen ◽  
Yun Fan ◽  
Qiqi Li ◽  
Yufeng Guan ◽  
...  
Keyword(s):  
Particle Size ◽  
Elemental Carbon ◽  
Fine Particles ◽  
Airborne Particles ◽  
Coarse Particles ◽  
Strongly Correlated ◽  
Oral Bioaccessibility ◽  
Polycyclic Aromatic ◽  
Potential Factors ◽  
Scientific Attention

Abstract Bioavailability of environmental contaminants is attracting considerable scientific attention due to growing awareness of its importance for risk assessment. In this study, potential factors governing bioaccessibility of airborne particles-bound polycyclic aromatic hydrocarbons (PAHs) and organophosphorus esters (OPEs) in stimulated gastrointestinal and respiratory tracts were elucidated. Particle concentrations of PAHs and OPEs at the eight sites were 2.4−32.3 ng/m3 and 1.6−19.9 ng/m3, respectively. In fine particles (with aerodynamic diameter less than 2.5 µm), 4- to 6-ring PAHs were more strongly correlated with organic carbon (OC) than elemental carbon (EC); while 3- and 4-ring PAHs in coarse particles (2.5−10 µm) tended to associate with EC. OPEs mostly showed significant correlations with EC in both fine and coarse particles. OC and EC exerted a significantly restraining effect on the oral and inhalation bioaccessibility of most HOCs in fine particles due to sorption of HOC molecules to these components. Furthermore, the effects varied, which could depend either on the emission sources (for oral bioaccessibility of PAHs) or the physicochemical properties of HOCs (for bioaccessibility of OPEs and inhalation bioaccessibility of PAHs). Linear regression indicated that EC should play a more important role in the inhalation bioaccessibility than the oral bioaccessibility. Particle size of airborne particles is a relatively less significant factor determining the bioaccessibility.

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