Airborne Dust Deposition Research Articles

3D CFD modelling of dust deposition characteristics and influences on building-mounted photovoltaic system

Airborne dust deposition on the solar photovoltaic panels can significantly decrease the photovoltaic efficiency performance. Dust deposition characteristics and influences on building-integrated photovoltaic panels were studied by shear stress transfer k-ω turbulence model with inlet profiles and discrete particle model. The influences of dust size, wind velocity, and building roof inclination on the dust deposition behaviors were studied carefully. The air flow fields, the dust particle trajectories, the deposition rate on solar photovoltaic panels and the photovoltaic efficiency decrease by dust deposition were obtained and analyzed in the study. The three-dimensional simulation has great difference on the wind flow structures compared with two-dimensional simulation. The size of the separation vortex in the three-dimensional simulation is significantly smaller than that in two-dimensional simulation. The secondary flow structures become more significant in the rear of the building. The dust deposition rate is firstly increased and then decreased with the increasing of dust diameter. The maximum deposition rate is 2.54% for 150 μm particles. The minimum deposition rate is just 0.03% for 500 μm particles. The maximum deposition rate is 1.39%, 2.54% or 3.74% for the roof inclination angle of 16.7°, 22.6°or 36.9°, respectively. When particle size is 150 μm, the dust motions are determined by the air flow fields, mass inertia and gravitational settling. The photovoltaic efficiency reduction is significantly higher with increasing of dust size. The present model can conveniently estimate the photovoltaic efficiency decrease by dust deposition in realistic engineering application.

Soil priorities in Israel

• Israel’s irrigation management successfully considers soil degradation due to intense land use and water quality. • Climate change is likely to influence trends of airborne dust deposition and nutrient availability. • Nature-based agro-services focus on low organic matter soils, Mediterranean climate, intensive farming, and upscaling irrigation needs. • Reintroducing pedology would promote soil education, classification, mapping and public awareness.

Electrochemical Migration of Immersion Silver Plated Printed Circuit Boards Contaminated by Dust Solution

Due to the severe air pollution, printed circuit boards (PCB) in electronic products are apt to be covered by airborne dust deposition. The trace amounts of soluble salts in the dust particles increase ion concentration in the moisture condensed on the PCB surface so that the electrode reaction of electrochemical migration (ECM) is aggravated and the time to insulation failure also changes. In this article, based on the ion compositions analysis of soluble salts in natural dust collected indoor in northwest Beijing and eastern Shanghai, China, the effect of the anions in typical soluble salts (NaCl, Na2SO4) in natural dust on insulation failure mechanism and TTF of ECM of PCB is investigated by water drop tests on parallel wires on immersion silver plated PCB. Compared with PCB contaminated by single salt solution with different concentrations, the ECM characteristics of PCB covered by natural dust solution of various mass concentrations are analyzed. A failure physics-based life model of ECM of PCB under contamination of salt solution is fitted by the simulation tests of both the single salt solution and natural dust solution respectively. The mechanism and degree of action of soluble salts in natural dust on the ECM failure on PCB is discussed finally.

Experimental measurement and Numerical Simulation of Particle Deposition on super–hydrophobic surface

Airborne dust deposition on a large number of energy devices would cause serious efficiency and lifetime reduction, such as solar photovoltaic panels, heat exchanger surfaces and fan blades. Mechanicalor manual cleaning using water is still the main method of mitigating dust deposition damage on theserelated energy equipment, which is commonly expensive and frequent. As a kind of self-cleaningmaterial,super–hydrophobic coating may become a new effective way to mitigating the dust deposition issue. Super–hydrophobic coatings with low surface energy and unique micro-nano secondary structure can significantly reduce dust deposition rate. However, mechanism of dust deposition on super-hydrophobic surfaces remains unclear. Thus it is difficult to develop high performance self-cleaning coating. This paper aims to investigate dust deposition behaviors and mechanisms on super-hydrophobic surface by experimental measurement and numerical simulation. Lattice Boltzmann Method-Discrete Particle Method (LBM–DPM) will be developed to predict dust particle deposition process including settling, collision adhesion and rebound behaviors. The mechanisms and interactions between coating surface energy, particle characteristics, particle incident velocity and particle adhesion or rebound behavior will be studied carefully. The findings and results may be useful to guide the development of high performance self-cleaning super– hydrophobic coating.

Land–sea correlations in the Australian region: 460 ka of changes recorded in a deep-sea core offshore Tasmania. Part 2: the marine compared with the terrestrial record

We present an array of new proxy data and review existing ones from core Fr1/94-GC3 from the East Tasman Plateau. This core is positioned at the southern extreme of the East Australia Current and simultaneously records changes in both oceanography and environments both in offshore and in southeastern Australia. Microfossils, including planktonic and benthic foraminifera, ostracods, coccoliths and radiolarians, were studied to interpret palaeo-oceanographic changes. Sea-surface temperature was estimated using planktonic foraminifera, alkenones and radiolaria. From the silicate sediment fraction, the mean grain size of quartz grains was measured to detect the changes in wind strength. An XRF scan of the entire core was used to determine the elemental composition to identify provenance of the sediment. We also compare these data with a pollen record from the same core provided in an accompanying article that provides the longest well-dated record of vegetation change in southeastern Australia. In an area of slow sedimentation, Fr1/94-GC3 provides a continuous record of change in southeastern Australia and the southern Tasman Sea over approximately the last 460 ka. We determine that the East Australian Current varied in intensity through time and did not reach the core site during glacial periods but was present east of Tasmania during all interglacial periods. The four glacial–interglacial periods recorded at the site vary distinctly in character, with Marine Isotope Stage (MIS) 9 being the warmest and MIS 5 the longest. Through time, glacial periods have progressively become warmer and shorter. Deposition of airborne dust at the core site is more substantial during interglacial periods than glacials and is believed to derive from mainland Australia and not Tasmania. It is likely that the source and direction of the dust plume varied significantly with the wind regimes between glacials and interglacials as mean effective precipitation changed.

Development and experimental validation of a physical model for the soiling of mirrors for CSP industry applications

Addressing soiling-related losses of glazed surfaces in solar power technologies is one of the most critical issues to improve the competitiveness of solar power plants in the current energy market. Reliable predictions of soiling rates and performance losses would enable optimisation of cleaning strategies and add a valuable assessment criterion for the evaluation of potential future power plant sites. However, currently available soiling models are data-driven and thus specific to the site and do not allow for reliable extrapolation to different sites and environmental conditions. To address this gap, this paper details the development of a physical soiling model for the prediction of the deposition of airborne dust onto the surface of solar collectors and the subsequent loss of performance (i.e. reflectance in the specific case of heliostats). The model inputs are the measured airborne dust concentration and estimated size distribution, the position of the mirrors, and the recorded wind speed and air temperature. The outputs of the model have been validated using experiments performed at the Queensland University of Technology. A reflectometer was used to measure the reflectance of the mirrors on an almost-daily basis while meteorological and dust data were obtained through a dust sensor and a weather station. The agreement between the experimental data and the simulated results demonstrates the effectiveness of the model in dry conditions. For example, for a mirror tilted at 45° with a daily loss of reflectance between 0.5%/day and 2.1%/day, the model reflectance loss predictions have an average relative error of 14%. Furthermore, the visual trends of the model predictions agree well with those observed in the experimental data. Finally, the model is used to investigate scenarios at three candidate sites to assess reflectance losses in different conditions.

Comprehensive Analysis of Effect of Accumulation of Dust on a Solar Panel

In the pursuit of a cleaner and sustainable environment, solar photovoltaic (PV) power has been established as the fastest growing alternative energy source in the world. This extremely fast growth is brought about, mainly, by government policies and support mechanisms world-wide. Solar PV technology that was once limited to specialized applications and considered very expensive is becoming more efficient and affordable. Solar PV promises to be a major contributor of the future global energy mix due to its minimal running costs, zero emissions and steadily declining module and inverter costs. Deposition of airborne dust on outdoor photovoltaic (PV) modules may decrease the transmittance of solar cell glazing and cause a significant degradation of solar conversion efficiency of PV modules. Dust deposition is closely related to the tilt angle of solar collector, exposure period, site climate conditions, wind movement and dust properties. In this practical field study, an experimental-based investigation is conducted. Thus, we conducted a study to gauge the effect of dust on the solar panel over a pre-determined period.

Influence of airborne dust on the metal concentrations in crop plants cultivated in a rooftop garden in Seoul

Plants grown in urban areas are likely to be exposed to heavy metals from industrial activities and traffic. In particular, Seoul, the capital city of Korea, is affected by seasonal winds from northwest China, named the Asian dust wind, which contains various heavy metals and probably causes heavy metal deposition on plants growing in rooftop gardens in Seoul. Growing media and plants from 18 rooftop gardens distributed throughout Seoul were examined in this study to determine the magnitude of heavy metal (cadmium (Cd), copper (Cu), chromium (Cr), nickel (Ni), lead (Pb) and zinc (Zn)) exposure in the urban agricultural environment. The heavy metal levels in all of the growing media examined were below the Korean standard limits of soil, although the Cu and Zn levels were elevated due to excessive use of livestock-based composts. Heavy metal concentrations in plants were also comparable with the natural levels. Compared to unwashed plants, washing reduces the hazard quotient of heavy metals by 17–28%. This was due to deposition of airborne dust on the plant surface. Cu, Pb and Zn deposited on the plant surface were attributed to the urban environment such as industrial activities and traffic, while Cr and Ni were attributed to the Asian dust wind carrying the corresponding heavy metals from China to the northwest of Seoul.

Degradation of electrical performance of a crystalline photovoltaic module due to dust deposition in northern Poland

The reduction in power output caused by the accumulation of dust on the photovoltaic module surface is an important problem and should receive much more attention in the literature. This study was an evaluation of the performance degradation of crystalline photovoltaic modules due to natural and simulated dust deposition. Dust is created from powdered grains of sand and particles of different bodies. Dust originates from different sources, e.g. from the soil and volcanic eruptions. Dust in the air is an aerosol, and in high concentrations can cause climate change. Deposition of airborne dust on photovoltaic modules may decrease the transmittance of solar cell glazing and cause a significant degradation in the solar conversion efficiency of photovoltaic modules. Dust deposition is closely related to the tilt angle of the module, the exposure period, site climate conditions, wind movement and dust properties. In this article, a brief review of the energy yield losses caused by dust deposition on photovoltaic modules and the results of experimental research conducted in Poland are presented. Dust samples were collected after a few years of natural and artificial dust deposition. The reduction in efficiency had a linear relationship with the dust deposition density.

Experimental investigation of the impact of airborne dust deposition on the performance of solar photovoltaic (PV) modules

Abstract Deposition of airborne dust on outdoor photovoltaic (PV) modules may decrease the transmittance of solar cell glazing and cause a significant degradation of solar conversion efficiency of PV modules. Previous studies of this issue indicated that dust deposition is closely related to the tilt angle of solar collector, exposure period, site climate conditions, wind movement and dust properties. However, few studies considered the influence of the properties of PV module itself on dust deposition and efficiency degradation, such as the cell types and surface materials. This experimental work aimed to study the dust accumulation onto different types of solar PV modules and the corresponding efficiency degradation. The experiment was designed and conducted in the laboratory with a sun simulator and a test chamber. The degradation of PV module efficiency caused by dust deposition under various conditions was investigated. The results indicated that dust pollution has a significant impact on PV module output. With dust deposition density increasing from 0 to 22 g m −2 , the corresponding reduction of PV output efficiency grew from 0 to 26%. The reduction of efficiency has a linear relationship with the dust deposition density, and the difference caused by cell types was not obvious. When the dust deposition density was fixed, the reductions of output efficiency at relatively lower or higher solar densities were much more severe. Moreover, the surface material may influence dust deposition and accumulation considerably. The poly-crystalline silicon module packaged with epoxy degraded faster than other modules with glass surface under the same dust concentration.

Localization and Physical Property Experiments Conducted by Opportunity at Meridiani Planum

The location of the Opportunity landing site was determined to better than 10-m absolute accuracy from analyses of radio tracking data. We determined Rover locations during traverses with an error as small as several centimeters using engineering telemetry and overlapping images. Topographic profiles generated from rover data show that the plains are very smooth from meter- to centimeter-length scales, consistent with analyses of orbital observations. Solar cell output decreased because of the deposition of airborne dust on the panels. The lack of dust-covered surfaces on Meridiani Planum indicates that high velocity winds must remove this material on a continuing basis. The low mechanical strength of the evaporitic rocks as determined from grinding experiments, and the abundance of coarse-grained surface particles argue for differential erosion of Meridiani Planum.

Localization and physical properties experiments conducted by Spirit at Gusev Crater.

The precise location and relative elevation of Spirit during its traverses from the Columbia Memorial station to Bonneville crater were determined with bundle-adjusted retrievals from rover wheel turns, suspension and tilt angles, and overlapping images. Physical properties experiments show a decrease of 0.2% per Mars solar day in solar cell output resulting from deposition of airborne dust, cohesive soil-like deposits in plains and hollows, bright and dark rock coatings, and relatively weak volcanic rocks of basaltic composition. Volcanic, impact, aeolian, and water-related processes produced the encountered landforms and materials.

Airborne dust deposition in the Okavango Delta, Botswana, and its impact on landforms

AbstractThis study investigated the local‐scale generation and movement of dust in the seasonal swamps of the Okavango Delta, Botswana, with a view to examining possible transfer of material between flood plains and islands. It was found that most of the dust load was carried in the lowest 3 m of the air column, and consisted mainly of amorphous silica, indicating that dust was generated largely on the flood plains. Dust loads were found to be highest above the flood plains and lowest over the interiors of islands, probably due to the baffling effect of the island trees on wind velocity. The contrast in dust loads between islands and flood plains suggests that there is a net transfer of dust from flood plains to islands, but it was not possible to quantify this transfer. It is evident, however, that flood plains experience net erosion and islands net aggradation. A strong seasonality in dust loads was observed, with the maximum dust loads coinciding with maximum wind velocity in October. This also coincides with peak seasonal flooding in the delta, and only non‐inundated flood plains are capable of generating dust. Years of low flood therefore appear to be more dusty. There may also be transfer of material from higher‐lying to lower‐lying flood plains, which may reduce the topographic contrast on the flood plains. Copyright © 2004 John Wiley & Sons, Ltd.

Wind erosion and airborne dust deposition in farmland during spring in the Horqin Sandy Land of eastern Inner Mongolia, China

In the Horqin Sandy Land of eastern Inner Mongolia in northern China, wind erosion in farmland is very common in a period from thawing of frozen surface soil in mid-March to sowing of crops in the end of April, largely because of dry and windy weather. However, little is known about the magnitude of wind erosion and associated nutrient losses due to erosion and the addition of nutrients by airborne dust deposition to farmlands during this period. A field experiment was conducted in an Entisol with sand origin under corn (Zea mays L.) production to investigate daily changes in wind speed and wind erosion intensity (as measured by soil transport rate) over a period from 20 March to 30 April 2001. We also measured daily rates of airborne dust deposition during the spring seasons with the high frequency of dust storm occurrence. The rates of soil transport by wind varied greatly from 13.2 to 1254.1 kg ha−1 per day, averaging 232.1 kg ha−1 per day, largely attributable to great variation between days in wind speed within the study period. The potential losses of nutrients through wind erosion were 0.26–24.95 kg ha−1 per day (averaging 4.62 kg ha−1 per day) in organic matter, 0.02–1.64 kg ha−1 per day (averaging 0.31 kg ha−1 per day) in nitrogen and 0.01–0.7 kg ha−1 per day (averaging 0.13 kg ha−1 per day) in phosphorus. The mean rates of airborne dust deposition ranged from 4.0 to 48.9 kg ha−1 per day, averaging 19.9 kg ha−1 per day, during the spring seasons. The potential addition of organic matter, nitrogen and phosphorus by dust input to the experimental field was, on average, 0.54, 0.04 and 0.02 kg ha−1 per day, respectively. Although the addition was a fraction of the losses due to erosion, nevertheless, dust input in the spring seasons is one of the major suppliers of soil nutrition. The fact that the addition of nutrients by dust is about 1/10 of the losses of soil nutrients through wind erosion suggests that developing and adopting more effective management practices to reduce soil erosion losses and to improve soil fertility are crucial to achieve a sustainable agricultural system in a fragile, semiarid sandy land environment.

Wind erosion and airborne dust deposition in farmland during spring in the Horqin Sandy Land of eastern Inner Mongolia, China

In the Horqin Sandy Land of eastern Inner Mongolia in northern China, wind erosion in farmland is very common in a period from thawing of frozen surface soil in mid-March to sowing of crops in the end of April, largely because of dry and windy weather. However, little is known about the magnitude of wind erosion and associated nutrient losses due to erosion and the addition of nutrients by airborne dust deposition to farmlands during this period. A field experiment was conducted in an Entisol with sand origin under corn ( Zea mays L.) production to investigate daily changes in wind speed and wind erosion intensity (as measured by soil transport rate) over a period from 20 March to 30 April 2001. We also measured daily rates of airborne dust deposition during the spring seasons with the high frequency of dust storm occurrence. The rates of soil transport by wind varied greatly from 13.2 to 1254.1 kg ha −1 per day, averaging 232.1 kg ha −1 per day, largely attributable to great variation between days in wind speed within the study period. The potential losses of nutrients through wind erosion were 0.26–24.95 kg ha −1 per day (averaging 4.62 kg ha −1 per day) in organic matter, 0.02–1.64 kg ha −1 per day (averaging 0.31 kg ha −1 per day) in nitrogen and 0.01–0.7 kg ha −1 per day (averaging 0.13 kg ha −1 per day) in phosphorus. The mean rates of airborne dust deposition ranged from 4.0 to 48.9 kg ha −1 per day, averaging 19.9 kg ha −1 per day, during the spring seasons. The potential addition of organic matter, nitrogen and phosphorus by dust input to the experimental field was, on average, 0.54, 0.04 and 0.02 kg ha −1 per day, respectively. Although the addition was a fraction of the losses due to erosion, nevertheless, dust input in the spring seasons is one of the major suppliers of soil nutrition. The fact that the addition of nutrients by dust is about 1/10 of the losses of soil nutrients through wind erosion suggests that developing and adopting more effective management practices to reduce soil erosion losses and to improve soil fertility are crucial to achieve a sustainable agricultural system in a fragile, semiarid sandy land environment.

Trial of controlled partial recirculation of ventilation air at Mount Isa Mines

The ventilation and cooling of deep, hot mines present particular problems in Australia as a consequence of the surface climate, the size of the underground voids, the degree of mechanization and the cost of power in remote areas. A preliminary investigation of the effects of controlled partial recirculation of air was conducted in Mount Isa Mines' Deep Copper section. Gas and dust concentrations were measured in the exhaust air of the major working section to assess the potential for recirculating exhaust air to the intake airways to reduce the cost of providing an acceptable working environment in the deep parts of the mine. Studies were undertaken of airborne dust deposition in vertical airways and the efficiency of usage of the ventilation air in diluting contaminants. It was established that 45% of the respirable dust was deposited in a 130-m vertical raise and 60% of the air supplied to the section could be reused or recirculated.The first major field trial of a controlled partial recirculation system in Australia was undertaken in the light of these results and demonstrated excellent potential for significant reduction in ventilation costs. Gas and dust contaminant levels were well below the threshold limit values during the trial. It is concluded that controlled partial recirculation can be a practical, effective and safe aid to normal ventilation practice in Australian deep, hot mines.

AN INHALATION DOSE MODEL FOR ASSESSING DUST–BORNE VOC–ODOR EXPOSURE FROM FEEDING IN SWINE BUILDINGS

A dynamic, sizedependent integrated inhalation dose model for quantifying worker/animal exposure todustborne odor causing volatile organic compounds (VOCodor) in swine buildings during and after feeding was developed.The exposure of dustborne VOCodor observed in pig barns can be characterized by adsorption and deposition of airbornedust. The airborne dust particle size, aerosol profile, enclosure dimension, ventilation rate, and feeding duration wereaffecting the integrated inhalation model in assessing dustborne VOCodor exposure during and after the time of feeding.Experimental results show that there is no significant variation in feeding and nonfeeding periods for the particle sizedistributions in a growing pig farm located in southern region of Taiwan and both followed a lognormal distribution withgeometric mean diameter of 2.14 0.03
m (mean 1 sd) and geometric standard deviation of 1.73 0.02. Mean total dustmass concentrations were 20.47 8.23 and 2.32 0.45 mg m 3 , respectively, for feeding and nonfeeding periods. Modelsimulations show that the inhalation dose for a short feeding duration followed by a long stay in the pig barn can equal thatof a long feeding duration followed by a short subsequent exposure. Reduction of both the feeding duration and/or subsequenttime in the pig barn is highly effective in dose reduction.

Effect of rock fragment eccentricity on eolian deposition of atmospheric dust

The effect of rock fragment eccentricity on the deposition of airborne dust was examined in a wind tunnel. Eccentricity was defined as the ratioa/b, wherea is the longest andb the intermediate axis of the rock fragments. The effect of eccentricity on the deposition of dust on the pebbles, on the deposition of dust between and underneath the pebbles, and on total dust deposition (pebbles + interpebble space) was measured separately, and this for different values of pebble size, pebble flattening, cover density and wind speed. The more pebbles are elongated, the larger dust deposition on them will be. This effect is more pronounced as pebbles become larger, as they become less flattened, and as wind speed increases, but no correlation is observed with cover density. It also holds that the more pebbles are elongated, the less dust settles between and underneath them. This effect is more pronounced as pebbles become smaller and cover density becomes larger, but there is no relationship with pebble flattening. Whether or not there is a relationship with wind speed is unclear. Pebble eccentricity indirectly influences total dust deposition on a pebble field, since it determines whether or not (and to what extent) total dust deposition will be a function of pebble size. For circular pebbles, total dust deposition is independent of pebble size, but once pebbles become elongated, total dust deposition will be smaller on pebble fields composed of small pebbles than on pebble fields composed of large pebbles. It was also demonstrated that the more pebbles are elongated, the more the dust will tend to settle on the pebbles rather than between or underneath them. Air flow separation plays a primary role in the deposition of dust on a rock fragment field, since it determines the location and size of the low-sedimentation areas that are connected to the air flow separation bubbles. Highly-elongated pebbles oriented parallel to the wind catch much more dust (also per unit surface) than circular pebbles, the surface of which is largely located in a zone of very low deposition. Dust deposition density on highly-elongated pebbles normal to the wind, on the contrary, is equal to dust deposition on circular pebbles. It should be noted that all data in this study refer to initial dust deposition (not accumulation), since only wind velocities below the dust deflation threshold were tested.

Effect of rock fragments on eolian deposition of atmospheric dust

The effect of rock fragments and rock fragment cover on the deposition of airborne dust was examined in a wind tunnel. Four parameters were studied: pebble size, pebble flattening, cover density and wind speed. The effect of these parameters on the deposition of dust on the pebbles, on the deposition of dust bewween and underneath the pebbles, and on total dust deposition (pebbles + interpebble space) was measured separately. Deposition on the pebbles increased with pebble size, pebble flattening and wind speed. Deposition between and underneath the pebbles increased with increasing wind speed and with decreasing pebble flattening, but there was no consistent relationship with pebble size. Total dust deposition was not influenced by pebble size, pebble flattening and cover density, but it increased linearly with wind speed. It was also demonstrated that the larger and the flatter the pebbles, and the higher cover density, the more the dust will tend to settle on the pebbles rather than between or underneath them. Air flow separation seems to play a primary role in the spatial distribution of dust deposition within a rock fragment field, as it determines the location and size of the low-sedimentation areas that are connected to the air flow separation bubbles. It should be noted that all data in this study refer to dust deposition (not accumulation), since only wind velocities below the dust deflation threshold were used.