Mesh Screen Research Articles

Two-Dimensional Simplification of Complex Three-Dimensional Wire Mesh Screens

AbstractThis paper presents an approach to accurately characterize three-dimensional (3D) wire screen geometries as simplified two-dimensional (2D) screens for low Reynolds numbers. This is achieve...

Performance evaluation of monocrystalline and polycrystalline silicon solar photovoltaic modules under low and high irradiance conditions in Kumasi, Ghana


 
 
 One of the biggest drawbacks of photovoltaic (PV) for many applications is the uncertainty in the energy output due to losses attributed to efficiency loss at low irradiance levels. In this study, the electrical performance of as received monocrystalline silicon (mono-c-Si) and polycrystalline silicon (poly-c-Si) PV modules were evaluated at high and low irradiance conditions in Kumasi, Ghana using I-V Tracer. The low irradiance level of 200W/m2 was achieved by covering the surface of the PV modules with a calibrated mesh screen. Maximum output power (Pmax) of 87.9 W and 136.7 W were recorded for the mono-c-Si and poly-c-Si modules at high irradiance respectively. The corresponding average values at low irradiance were 8.29 W and 12.13 W representing percentage reductions of 90.57% and 91.60% respectively for the two technologies. These results indicate that when irradiance drops to 200 W/m2 and below, the PV modules generate around only 10% of their nominal output power. This has implications for the number of modules that are required for installation in areas that experience many hours of low irradiance. Efficiency reductions of 64.4% and 59.01% for the mono-c-Si and poly-c-Si modules respectively at low irradiance is reported. The results also indicate that the mono-c-Si is affected more by light induced degradation effect than the poly-c-Si module after a few hours of exposure to the natural light. The novelty of this work is that knowledge of the performance at low irradiance will enable designers determine the number of modules required during the sizing of PV plants.
 
 

Thermal performance enhancement of vapor chamber with modified thin screen mesh wick by laser etching

In order to cope with high heat flux of miniaturized electronic devices in narrow space, vapor chamber has been developed towards ultra-thin thickness. In this study, a novel design of thin screen mesh with superhydrophilic micro structure was firstly proposed to enhance the thermal performance of thin vapor chamber (TVC). A layer of 0.12 mm thick screen mesh was employed as evaporator wick. The central area of the thin wick above heat input region was treated by laser etching to form superhydrophilic micro structure for improving capillary capability and providing nucleation sites. The upper sheet without wick was stamped to form support columns for preventing deformation and providing axial thermal conduction passage. Three TVCs (70 × 70 × 1.5 mm3) with various laser-etching area ratio (LEAR) of 0%, 66.6% and 83.3% were fabricated to study thermal performance of the novel TVCs. The results indicated that the novel evaporator mesh wick could remarkably enhance thermal performance of the TVCs. With LEAR increasing from 0% to 83.3%, the lowest thermal resistance RVC of TVC dropped from 0.431 K/W to 0.328 K/W, i.e. decreased 23.9%, and the maximum heat transfer capacity increased from 100 W to 120W, i.e. increased 20%.

Litter decomposition affected by bamboo expansion is modulated by litter‐mixing and microbial composition

Abstract Litter decomposition is a key ecosystem process that drives carbon (C) and nutrient cycling, which could be affected by shifts in plant community composition caused by plant invasion or expansion. However, how changes in leaf litter composition (e.g. litter‐mixing effect) and soil microbial community induced by shift in plant community composition affect decomposition remains elusive. Here, by deploying 432 litterbags (50‐μm mesh screen), we treated leaf litter of bamboo Phyllostachys edulis and tree species (in a mixture or alone) and decomposed them in forest sites expanded or not expanded by bamboo at three regions, to assess the effects of bamboo expansion on decomposition, microbial community structure and function. Bamboo expansion reduced microbial C to nitrogen (N) ratio and nutritional stress indicator (cy/pre), which was very likely ascribed to elevated N availability as a result of accelerated litter N release. The N loss of bamboo litter (28.1 ± 3.03%) was more than double of tree species litter (13.2 ± 3.1%), and decomposing litter of bamboo and tree species in a mixture increased litter N loss from 15.3 ± 3.1% to 25.9 ± 3.1% (by 69%). However, no consistent effect of litter type and litter treatment on C loss was observed. The non‐additive litter‐mixing effect is attributable to increased microbial nutrient use efficiency, which is illustrated by the interactive effect between litter treatment and cy/pre on decomposition. Moreover, the forest type interactively affected decomposition with cy/pre as ignoring litter treatment, where higher decay rate and litter N loss at bamboo expanded than non‐expanded sites would be expected when both sites having comparable cy/pre, but the reality is that bamboo expansion tends to have lower cy/pre. These results imply a trade‐off between introduced litter and nutrient use efficiency of local microbial community to drive decomposition. Our results demonstrate that litter decomposition affected by bamboo expansion was jointly modulated by litter‐mixing and microbial composition, which sheds new insights on predicting changes in soil C and nutrient cycling induced by shifts in plant community composition. A free plain language summary can be found within the Supporting Information of this article.

Mycorrhizal effects on decomposition and soil CO2 flux depend on changes in nitrogen availability during forest succession

Abstract Mycorrhizal fungi play a central role in plant nutrition and nutrient cycling, yet our understanding on their effects on free‐living microbes, soil carbon (C) decomposition and soil CO2 fluxes remains limited. Here we used trenches lined with mesh screens of varying sizes to isolate mycorrhizal hyphal effects on soil C dynamics in subtropical successional forests. We found that the presence of mycorrhizal hyphae suppressed soil CO2 fluxes by 17% in early‐successional forests, but enhanced CO2 losses by 20% and 32% in mid‐ and late‐successional forests respectively. The inhibitory effects of mycorrhizal fungi on soil CO2 fluxes in the young stands were associated with changes in soil nitrogen (N) mineralization and microbial activities, suggesting that competition between mycorrhizae and saprotrophs for N likely suppressed soil C decomposition. In the mid‐ and late‐successional stands, mycorrhizal enhancement of CO2 release from soil likely resulted from both hyphal respiration and mycorrhizal‐induced acceleration of organic matter decay. Synthesis. Our results highlight the sensitivity of mycorrhizal fungi‐saprotroph interactions to shifts in nutrient availability and demand, with important consequences for soil carbon dynamics particularly in ecosystems with low nutrient conditions. Incorporating such interactions into models should improve the simulations of forest biogeochemical cycles under global change.

Pore-Scale Simulation of the Interaction between a Single Water Droplet and a Hydrophobic Wire Mesh Screen in Diesel

Recently, the trend towards sustainable energy production and pollution control has motivated the increased consumption of ultra-low-sulfur diesel (ULSD) or bio-fuels. Such fuels have relatively low surface tension with water and therefore, the separation of water from fuel has become a challenging problem. The separation process relies on using porous structures for the collection and removal of water droplets. Hence, understanding the interaction between water droplets and the separators is vital. The simplest geometry of a separator is the wire mesh screen, which is used in many modern water–diesel separators. Thus, it is considered here for systematic study. In this work, pore-scale computational fluid dynamics (CFD) simulations were performed using OpenFOAM® (an open-source C++ toolbox for fluid dynamics simulations) coupled with a new accurate scheme for the computation of the surface tension force. First, two validation test cases were performed and compared to experimental observations in corresponding bubble-point tests. Second, in order to describe the interaction between water droplets and wire mesh screens, the simulations were performed with different parameters: mean diesel velocity, open area ratio, fiber radii, Young–Laplace contact angle, and the droplet radius. New correlations were obtained which describe the average reduction of open surface area (clogging), the pressure drop, and retention criteria.

Highly conductive EGaIn/silk fibroin ink for graphene 3D array structure micro-supercapacitors

Ink-based screen-printed processes are a practical approach for scalable fabrication of wearable electronics with cost effectiveness and high throughput. However, a few challenges persist with respect to the electronic conductivity and ions diffusion rate of such devices. In this study, we investigated an EGaIn/Silk fibroin (SF) ink and a screen-printed strategy to fabricate graphene 3D array structure Micro-supercapacitors (MSCs) based on high conductivity EGaIn collector. The EGaIn/SF ink, owing to the coordination and chelation between SF and EGaIn, shows excellent stability and can be used to fabricate conductive patterns on flexible substrates. Interestingly, these EGaIn patterns exhibit a novel conductivity recovery mechanism, including gravity deposition, evaporation induction, mechanical sintering, and EGaIn surface self-healing. Simultaneously, by adjusting screen meshes and accurately printing graphene ink, we obtained a graphene 3D array structure interdigital electrode on the EGaIn layer, which shows a large specific surface area and obviously multidirectional ion diffusion effect. As proofs, the resultant MSCs-100 delivered an outstanding areal (volume) capacitance of 35.72 mF cm−2 (10.26F cm−3) at a current density of 25 μA cm−2, remarkable flexibility and cycling stability. Moreover, we have realized the cycling stability characterization of integrated equipment, which holds great potential for application in future flexible and wearable electronics.

Startup of pilot-scale single-stage nitrogen removal using anammox and partial nitritation (SNAP) reactor for waste brine treatment using marine anammox bacteria

This study is the first to demonstrate the startup of a pilot-scale single-stage nitrogen removal using anammox and partial nitritation (SNAP) reactor utilizing marine anammox bacteria. A complete mixing type reactor, continuously fed with waste brine obtained from a natural gas plant (salinity 3%, NH4+-N 130-180mg/L) and having an effective volume of 2m3, achieved stable operation at temperatures of 20-30°C with a maximum nitrogen removal rate of 1.43kg-N/m3/day. During the startup process, along with a small amount of seed sludge, granular sludge was additionally inoculated as a biomass carrier for the enrichment of ammonia oxidizing bacteria (AOB), followed by the enrichment of anammox bacteria. A mesh screen equipped at the outlet of the reactor facilitated the successful sludge retention in the reactor. Analysis of bacterial community composition indicated that Candidatus Scalindua was successfully enriched in the pilot SNAP reactor. These methods for stable sludge retention in the reactor greatly contributed to the startup of the first pilot-scale SNAP reactor using marine anammox bacteria.

Unicellular microalgae vs. filamentous algae for wastewater treatment and nutrient recovery

Microalgae-based wastewater treatment is a promising platform since it enables nutrient recovery. The use of filamentous algae could improve this technology by reducing harvesting cost and enhancing biomass management. The potential of 12 unicellular and 12 filamentous algae strains was evaluated for the treatment and nutrient recovery of a raw wastewater from a slaughterhouse (RWS). Chlorococcum sp. FAUBA-42 (unicellular) and Stigeoclonium sp. FAUBA-10 (filamentous) were selected due to their biomass production using RWS as the sole nutrient source. Comprehensive analysis of batch and semicontinuous regime was carried out for both strains. Semicontinuous cultures showed three times higher biomass productivity than batch regime. The highest biomass productivity (0.45 g DW L−1 d−1) and photosynthetic quantum yield (1.6 g DW mol photons−1) was reached by the filamentous strain Stigeoclonium FAUBA-10 under 2.5 d HRT. Both strains showed nutrient removal above 92% under 5 d and 2.5 d HRT. Biomass of Stigeoclonium FAUBA-10 can be easily harvested by filtration through mesh screens (<341 μm) which is an operational benefit.

Investigation on multiple-frequency synchronization experiment of vibration system with dual-rotor actuation

As the first-stage solid-control equipment of purifying drilling fluid, vibrating screen excited with identical frequency usually leads to the blocking of screen mesh, which will affect production efficiency of subsequent equipment. Thus, to solve the problem mentioned above, the present work focuses on multiple-frequency synchronization of two vibratory motors by theoretical derivation and experimental analysis. Firstly, differential motion equation in each degree of freedom (DOF) is obtained according to mathematical model of the vibrating screen. Then, based on integral average method and Poincare-Lyapunov principle, the synchronization condition and stability criterion between two eccentric rotors are revealed. Subsequently, numerical calculation is introduced to discuss the influence of the structural parameters on the double-frequency synchronization motion. Meanwhile, some simulation results are implemented to preliminarily verify the validity of the proposed vibration system. Finally, an experimental platform is established to test the dynamic characteristics and synchronization motion state, which further demonstrates the feasibility and the correctness of theoretical investigation and computation simulation. This study not only has important reference value for the invention of vibrating screen in petroleum industry, but also will promote the development of other vibration machines.

Modeling avian eggshell microstructure to predict ontogenetic age and reveal patterns of human-avifauna interaction

Archaeological eggshell is a commonly recorded, yet underutilized material for understanding human-environment interaction in the past. In addition to the use of archaeological eggshell as a paleoenvironmental proxy, archaeologists have innovated important new approaches to the study of archaeological avian eggshell, including the application of scanning electron microscopy (SEM) for the characterization of eggshell microstructures. These studies have demonstrated the importance of eggshell for understanding how ancient communities exploited and interacted with avifauna. In this paper, we build on these methodological advances by testing new approaches to image avian eggshell and characterizing complex eggshell surface microstructures. We demonstrate the utility of capturing high-resolution 3-dimensional (3D) eggshell surfaces using advanced imaging modalities (optical profilometry, scanning electron microscopy, digital microscopy, computed tomography), to model changes in eggshell microstructures that are correlated with ontogeny. Using the Common Ostrich (Struthio camelus) as our model system, we introduce a statistical modeling approach to predict the ontogenetic age of ratite eggshell using roughness measurements of 3D features. Successful prediction of ontogenetic age has great potential to reveal archaeological patterns of human exploitation of avian eggs. These findings further illustrate the importance of archaeological eggshell for investigating human-environment interactions, emphasizing the need for archaeologists to use field methods (hand/trowel excavation and fine mesh screen) that facilitate eggshell recovery.

Experimental study on erosion resistance evaluation of single-layer metal mesh screen

In order to predict the erosion life and erosion failure time of the metal mesh, based on the rotating erosion experiments under different working conditions, the erosion mass loss of the metal mesh under different factors was measured by the weight loss method and the erosion mathematical prediction model was put forward. The erosion wear mechanism of the single-layer metal mesh was explored by using electron microscope scanner and optical microscope. The results show that the erosion rate increases exponentially with the increase of liquid velocity (0.5, 1.0, 1.5, 2.0 m/s). When the solid mass fraction (0.3%, 0.5%, 0.8%) and erosion Angle is 15°–45°, the erosion rate is proportional to the solid mass fraction and erosion Angle. After erosion, the mesh samples suffered different degree of pitting corrosion, ploughing and cutting wear, and the mesh wear was local wear. Compared with the experimental value, the error of the erosion mathematical model is less than 20%, which has a certain reliability, and has an important reference significance for guiding the production control of sand oil Wells.

Improving image quality in transcranial magnetic resonance guided focused ultrasound using a conductive screen

Transcranial Magnetic Resonance guided Focused Ultrasound (TcMRgFUS) has been proven to be an effective treatment for some neurological disorders such as essential and Parkinson's tremor. However, magnetic resonance guidance at 3 Tesla (3T) frequencies and using the large hemispherical transducers required for TcMRgFUS results in artifactual low-signal bands that pass through key regions of the brain. The purpose of this work was to investigate the use of a circular conductive Radio Frequency (RF) screen, that is bent to have a 12 cm radius in one direction and positioned near the top or back of the head, to reduce or remove these artifactual low-signal bands in TcMRgFUS.The impact of using an RF screen to remove these low signal bands was studied in both imaging experiments and electromagnetic simulations. Hydrophone measurements of the acoustic transparency of the bronze 2 mm diameter square mesh screen used in the imaging studies were compared with temperature measurements with and without the screen in heating studies in the TcMRgFUS system.The imaging and simulation studies both show that for the different screen configurations studied in this work, RF screen removes the low-signal bands and increases both homogeneity and signal-to-noise ratio (SNR) throughout the region of the brain. Hydrophone and heating studies indicate that even a 2 mm wire mesh provides minimal attenuation to the ultrasound beam. Simulation results also suggest that a 1 cm mesh will provide adequate artifact suppression with even less ultrasound attenuation.An RF screen that disrupts the natural waveguide nature of the transducer in the 3T MR environment can change the electromagnetic field profile to reduce unwanted artifacts and provide an imaging region which has more homogeneity and higher SNR throughout the brain.

Analysis of the physical properties of spindle seeds for seed sorting operations

The relationships between the basic physical properties of seeds of selected spindle species were evaluated for the needs of seed sorting operations. Physical properties were measured in the seeds of five spindle species, and the presence of relationships between these attributes was determined in correlation and regression analyses. The average values of the evaluated parameters were determined in the following range: terminal velocity—from 9.2 to 10.3 m s−1, thickness—from 2.57 to 3.26 mm, width—from 2.87 to 3.74 mm, length—from 3.94 to 5.52 mm, angle of external friction—from 20.7° to 24.6°, mass—from 16.5 to 33.8 mg. Spindle seeds were arranged in the following ascending order based on their geometric mean diameter: winged spindle, Hamilton’s spindle, large-winged spindle, broadleaf spindle and European spindle. Spindle seeds should be separated in a sieve equipped with at least two mesh screens with slotted apertures. Depending on the processed spindle species, aperture size should range from ≠ 2.7 to ≠ 3.5 mm in the top screen, and from ≠ 2.4 to ≠ 3.0 mm in the bottom screen.

Fine hydraulic screening of ground ores on a multi-frequency screen by Kroosh Technologies: in-process testing

This paper describes high-frequency screens developed by Derrick and Landsky and multi-frequency screens developed by Kroosh Technologies, how they function and the differences between them. The fundamental difference between the vibration parameters in the high-frequency and multi-frequency modes is the difference in the accelerations created by the vibration excitation system. In high-frequency screens, the maximum acceleration of the screening media does not exceed 10g. In multifrequency screens, the measured positive and negative accelerations of the screen body are 3g. However, when interacting with the developed system of multi-frequency vibration, the positive peak accelerations of the screen mesh reach (50&divide;60)g, and the negative accelerations &mdash; (150&divide;200)g. This mode ensures that the screening media are kept free from material, and thus the specific throughput and the screening efficiency rise. A few dozens of tests with different ores were carried out on a pilot unit. The paper describes some qualitative and quantitative results of hydraulic screening of finely ground ores with 75 and 100 micron media, which were obtained on a pilot unit with a 1,500&times;600 mm multi-frequency screen. As a result of hydraulic screening of ground chrome ore with a 0.1&times;2.6 mm mesh at the ore feed rate of 2.65 t/(h&middot;m2), the undersize product included 91.8% of particles smaller than 100 microns. With the hydraulic screening of ground chrome ore with a 0.075&times;2.6 mm mesh at the ore feed rate of 1.66 t/(h&middot;m2), the recovery of particles smaller than 75 microns as the undersize product was 88.78%. With the hydraulic screening of ground tin ore with a 0.1&times;2.6 mm mesh at the ore feed rate of 2.94 t/(h&middot;m2), the recovery of particles smaller than 100 microns as the undersize product was 93.93%. Multi-frequency screens are successfully used by the concentrator plants of Kazzinc and Glencore (South Africa).

A farmers market architecture and ventilation design and its airflow analysis

Green buildings and sustainable designs require architectural designers to go beyond the basic building codes to improve overall building energy performance, optimize building ventilation, minimize life-cycle environmental impacts and make comfortable inside living environments. This paper briefly introduces the green design of the Lituo farmers market. Improving air quality inside of the built environment is the key for farmers market ventilation design as part of the green designs. The empirical method is used to design the height of the atrium of the farmers market to meet the ventilation requirements. A pressure loss model for outlet wire mesh screens was used for both empirical calculations and CFD. A simplified thermal boundary conditions for modeling human thermal effects were used to analyze the heat exchanges between the human body and the environment. The solar effects were only considered on the roof of the building. The outlet average exhaust gas speeds were measured and compared with CFD results. The results showed that the current method can help ventilation design and predicate the ventilation flow reasonably. The method developed in this study can be extended for other types of the building natural ventilation design and analysis.

Screen-printable and flexible in-plane micro-supercapacitors with fractal electrode design

New microscale energy devices need to be developed to accommodate the evolution of integrated flexible electronic systems. Supercapacitors have the advantages of high power density and long cycle life, and can be used independently or combined with batteries to provide electric energy for future electronics. Screen printing is a simple, cost-effective method for fast and scalable fabrication of micro-supercapacitors (MSCs) on various types of substrates that does not involve complicated process or expensive equipment. Currently, most researches of MSCs have been focused on materials and ink development with conventional interdigital architecture, few studies have been aimed at electrode pattern design. Herein, we demonstrate an in-plane MSCs via screen printing with designable electrode patterns on flexible substrate. The thickness of the device is less than 1 mm, ensuring good flexibility. By replacing the carbon ink with the silver ink as current collectors, the performance is improved due to lower device resistance. Owing to the geometric controllability of the screen printing method, we are able to study the effects of electrode design on the output performance by simply changing the screen mesh patterns. In particular, we demonstrate that by adapting the mathematical fractal concept such as Hilbert curve as electrode patterns, the areal capacitance of MSCs can reach up to 28.7 mF cm−2, which is 46.8% higher than that of the traditional interdigital structure. The results suggest that the fractal-based design represents a universal protocol for producing MSCs. Without changing electrode materials or fabrication facilities, the design strategy is highly compatible with industrial scale screen printing for roll-to-toll processing. This high-capacitance, cost-effective and flexible MSCs open a promising pathway for providing electric energy for the Internet of Things and future wearable systems.

Exceptional heat transfer performance induced by intrinsic flow oscillations during subcooled flow boiling over a copper mesh surface

An experimental investigation of subcooled flow boiling heat transfer in an orthogonal macro channel (dh = 16 mm) is undertaken. An extraordinary heat transfer performance is observed when a single copper wire mesh screen covers the heating surface of the channel. Experiments are performed with deionized water, at a mass flux range of 100–410 kg/m2s and a heat flux range of 50–850 kW/m2. A series of highly subcooled flow boiling experiments demonstrates the existence of regions of heat transfer enhancement, compared to a smooth reference surface. The addition of the mesh layer triggers a self-sustained flow instability accompanied by intense pressure oscillations which allows for remarkably thermally steady state conditions to take place. While in several heat transfer studies, the appearance of pressure oscillations has been attributed with heat transfer deterioration, in the current study we observe that a self-sustained oscillatory flow leads altogether to heat transfer enhancement, baring close resemblance to the well-known microbubble emission boiling flow phenomenology and heat transfer. Aspects of temperature, pressure and flow regimes are presented and discussed accordingly.

Effect of Mesh Wettability Modification on Atmospheric and Industrial Fog Harvesting

Freshwater shortage has been receiving considerable attention, and water harvesting is one of the potential solutions to this water crisis. Several researchers have tried to improve the harvesting capabilities by changing mesh wettability for atmospheric fog harvesting. However, the wettability effect on water harvesting from white plumes has not yet been investigated thoroughly, despite industrial cooling towers being considered as alternative water resources, because of the large amounts of fog plumes generated. In this study, surface wettability was modified with a robust and simple method for practical scaled-up applications, and we explored the influence of mesh wettability on atmospheric and industrial fog harvesting. In atmospheric fog harvesting, both superhydrophilic meshes (SHPMs), and superhydrophobic meshes (SHBMs) were found to improve the harvesting performance, with superhydrophobic treatments providing the best collection efficiency. In contrast, only superhydrophilicity improves the performance in industrial fog harvesting with flat mesh screens. We hypothesize that this research will be useful for mesh design, as it analyzes the influence of mesh wettability on the performance of water collection in both atmospheric and industrial water harvesting.

Regression modeling and residual analysis of screening coal in screening machine

ABSTRACT Coal is one of the chief energy sources having significant applications in the iron and steel industry. This research investigates the screening efficiency of coal of different size range. The experiments on the screening of coal with different size range in the screening machine were carried out using different mesh sizes. The screening efficiency for different screen angles and frequency of vibration was carried out. After experimentation, regression modeling was carried out for each screening condition. The maximum efficiency of screening coal with size range +4 mm-6 mm, +2 mm-4 mm, and +0.5 mm-2 mm obtained was 87.60%, 80.93%, and 62.96%, respectively. The experimental results show that the screening efficiency decreases with the decrease in size range for screening from +4 mm-6 mm to +0.5 mm-2 mm. The reduction in screening efficiency was due to the clogging of coal to the screen mesh. Linear and quadratic modeling were performed to estimate the efficiency of all the experimental results. After prediction, the validation using residual analysis was carried out, and the results illustrate that the quadratic prediction modeling was accurate.