Characterization Of Dust Particles Research Articles

Characterization of dust particles in South India and investigation on soiling image analysis for photovoltaic application.

The present work aims at the characterization of the dust particles in South India through an image analysis of glass samples inclined at a tilt of 0° and 13° for four different exposure periods (approximately 30 to 40days/exposure period). It aims as well at the study of the different factors influencing the accuracy of the image analysis of dust particles. The analysis of the shape factor reveals that the dust particles on tilted surface (13°) have regular shapes, and irregular shapes are more observed in horizontal surfaces. The size analysis of the dust particles with magnification of 20 × has revealed that the size distribution is in the range of 0-4µm but more concentrated in the range of 0-1µm. However, with 10 × magnification, larger particles are more detected. Furthermore, average results from three sample images seem to be more precise and representative than results from two images. The fractional coverage area of the dust particles on the sample has been calculated and compared with the transmittance losses. These two variables are found to be proportional with an R2 of 53%. Nevertheless, the comparison showed again that three images give better results with an R2 of 75% against 11% for two images. The results obtained in this study are very useful for the development of high precision soiling sensors that are based on image analysis and outdoor soiling microscopes, which are the main components for an efficient and economic cleaning of solar PV modules.

Performance Studies of Solar-Powered Absorption-Type Refrigeration System and Characterization of Deposits on its PV Panel

The demand for refrigeration and air-conditioning systems has been increasing in recent years. In order to reduce the demand for fossil fuels, renewable energy sources can be used to drive these systems. Also, renewable energy sources will reduce global warming, increase energy security, and generate employment opportunities. The conventional vapor compression system used in domestic applications needs electrical energy and a vapor absorption system can be used as an alternative to a vapor compression refrigeration system. In this work, a refrigeration system of solar-type has been developed and tested as the demand for the refrigeration system is increasing, which directly and indirectly increases global warming. The use of a renewable energy-driven alternative cooling system such as an absorption system will reduce the impact of refrigeration systems on the environment. The experimental work concluded that the vapor absorption system driven by the solar photovoltaic (PV) system could be a substitute for the conventionally used vapor compression system. The accumulation of the dust reduces the performance of Solar PV panels. The characterization of dust particles is important in deciding further growth and subsequent deterioration of the solar PV panels and the power output. The scanning electron microscopy study and energy dispersive X-ray analysis have helped to find the chemical composition of the dust particles. The X-ray diffraction results have helped in further investigation of the severity of the deposits by identifying possible compounds. Based on this analysis, the periodic cleaning of solar PV panels must be carried out at regular intervals.

Numerical and experimental investigations of dust effect on CSP performance under United Arab Emirates weather conditions

Dust is one of the main challenges in implementing concentrating solar power (CSP) systems in arid and semi-arid zones. The characterization of dust particles and the measure of the soiling loss effects under real operating conditions can be useful to select the appropriate cleaning methods and frequency. In this study, experimental and numerical investigations were carried out to study the characteristics of dust particles and their effects on the CSP performance under UAE weather conditions. The results showed that the soiling rate is correlated to the wind speed and direction. The monthly soiling effect was evaluated for 5 months of exposure with the highest decrease recorded in March. The results of cumulative dust experiment showed a drop in specular reflectivity by about 63% after 3 months of exposure. Based on the experimental data, the power soiling loss and thermal performance were determined for a parabolic trough solar collector. The predicted results were in consistence with the dust accumulation leading to a 36% decrease in thermal efficiency. In addition, the power soiling loss was compared with that of PV technology, and it was found that soiling effect is more pronounced in CSP systems by 3–5 times drop in performance.

Characterization of Dust Particles’ 3D Shape and Roughness with Nanometer Resolution

Mineral dust particles in the atmosphere are often aspherical and their shape is important for a multitude of processes. Yet, measurements of the true shape in three dimensions are rare, even in a laboratory setting. Here, we employ atomic force microscopy to determine the 3D shape and surface roughness for two dusts commonly used in laboratory experiments, Arizona test dust (ATD) and kaolinite. Our major finding is that both are thin and remarkably smooth. An oblate spheroidal description is an excellent fit to these data. We use correlation analysis to further examine the surface properties of the dusts and find essentially no features at horizontal spatial scales between ∼10 and 100 nm. This surprising result is supported by the agreement between our specific surface area and BET surface area measurements. The thin, smooth, spheroidal approximation has many implications for physical processes in the atmosphere, including dust transport and radiative transfer.Copyright 2015 American Association for Aero...

On the application of a linear time-of-flight mass spectrometer for the investigation of hypervelocity impacts of micron and sub-micron sized dust particles

Impact physics plays an important role in a variety of fields such as investigation of matter at extreme pressures and temperatures, shock waves in solid bodies or planetology and cosmic dust research. The processes of interest are the generation of impact plasma, neutrals, secondary ejecta, and electromagnetic (EM) radiation. The generation of charge during impacts provides one of the most sensitive methods for the detection and characterization of dust particles in space. To relate the measured values resulting from hypervelocity impact experiments with the impact parameters (speed, mass, composition) a comprehensive set of experiments is needed with well known experimental conditions, and a wide variety of diagnostic tools. For such experiments dust particles are accelerated to hypervelocity speeds in the laboratory with an electrostatic accelerator.In the present contribution, linear time-of flight (TOF) mass spectrometry is used to investigate the thermodynamical properties, e.g. the velocity distribution, of the ions within an impact plasma. Furthermore, the dependence of the plasma properties on the impact parameters is studied for different dust and target material combinations to investigate the constraints for the validity of impact ionization models. These studies provide new insights into the physics of hypervelocity impacts and the short timescale high-pressure states of matter, they also lead to the development of new and optimization of existing instrument concepts for the detection and characterization of cosmic dust in space.

Characterization of dust particles in the TEXTOR tokamak with Thomson scattering diagnostic

The presence of dust particles in a fusion plasma is recognized as a serious issue for safe and efficient operation of the ITER tokamak. The paper presents an in situ laser assisted method for characterization of dust from thermal emission of the particles. The method was developed in the TEXTOR tokamak with the use of Thomson scattering (TS). The diagnostic is capable to detect single particles and measure the dust density profile along the laser probing axis, velocity distribution of dust particles along this axis as well as surface temperature and size of the detected particles.

Evaluation of Exposure Risk in the Weaving Process of MWCNT-Coated Yarn with Real-time Particle Concentration Measurements and Characterization of Dust Particles

Various applications of multiwalled carbon nanotubes (MWCNT) have been developed. One of these applications is an efficient sheet heating element that is woven from MWCNT-coated yarn. In this research, we assessed the exposure to MWCNT and/or the probability of particle release from broken MWCNT-coated yarn during the weaving process. This was accomplished using particle concentrations, microscopic observation, and carbon analysis. In the weaving process, neither an increase in the number of particles nor a difference in particle-size distribution was observed. In the scanning electron micrographic observation, nanosize MWCNT particles were not detected, but there were micron-size particles containing MWCNT as fragments of the yarn. Carbon analysis showed the concentration of micron-size particles containing MWCNT did not exceed 0.0053 mg-C/m(3) around the loom. This value was much lower than the respirable dust mass concentration. Most of micron-size particles seemed to originate from polyester yarn without MWCNT coating. It is recommended that workers use conventional (even not specialized for nanoparticles) personal protective equipment such as respirators and gloves to prevent exposure to respirable-size MWCNT-containing particles. The probability of MWCNT fall-off from the MWCNT-coated yarn was not detected by transmission electron microscopic observation of MWCNT-coated yarn before or after the weaving process.

Characterization of Aeolian Dust in East China and Japan from 2001 to 2003

In order to elucidate the variation and characterization of dust particles that originate in the arid and semi-arid regions of inland Asia and are transported to Japan, we established a sampling network system in east China and Japan and collected aeolian dust under the Japan-China joint project “ADEC”. Monitoring of the total suspended particle (TSP) and size-segregated dust concentrations were carried out in Beijing, Qingdao and Hefei in China, and Fukuoka, Nagoya, Tsukuba and Naha in Japan. The seasonal variations showed the general trend that the aerosol concentration was high in spring and low in summer, though it sometimes became high in winter in Qingdao. The aerosol size distribution was bimodal. One peak at around 0.5 μm diameter corresponds to panicles of anthropogenic origin, in which the main components are black carbon, NH4+ and SO42−, and some elements such as Pb, Cd, Sn, Sb and Bi are abundant. The other peak at around 4-5 μm diameter corresponds to mineral dust of soil origin, in which the main soluble components are Na+, Ca2+, NO3− and Cl−. The coarser particles increased when a dust event occurred. The IOP program was conducted in the spring of 2002 (IOP-1) and 2003 (IOP-2). The dust concentration during IOP-1 was high in China, particularly in Beijing. The average dust concentration during a dust event decreased in the order of Beijing > Qingdao > Hefei and Beijing > Fukuoka > Nagoya > Tsukuba > Naha. However, there were few observable dust events during IOP-2. From the results of continuous monitoring, the dust concentration during periods without dust events seemed to be almost equal at all monitoring locations in Japan. This suggests that the segregation of dust occurs in China and fine dust particles are transported to Japan. Seasonal variations of TSP, PM11 (paniculate size is less than 11 μm), PM2.1 (less than 2.1 μm) and mineral matter (larger than 2.1 μm) contents were studied. It was shown that these values decrease with distance from the source area.

中国東部および日本国内で2001年から2002年にかけて採取した風送ダストの 大気中濃度と物理化学特性の変動

In order to clarify the variation and characterization of dust particles, we started the JapanChina joint project, “Studies on origin and transport of aeolian dust and its impact on climate”. We set up sampling instruments in Beijing, Qingdao and Hefei in China and Naha, Fukuoka, Nagoya and Tsukuba in Japan and collected aeolian dust that originated in the desert area of western China. In this study, we collected the aeolian dust from February 2001 to May 2002 and studied the monthly variation of dust concentrations. The one-year observation data show that the aerosol has a bimodal size distribution (one peak at around 0.5μm corresponds to particles of anthropogenic origin and another peak at around 4-5μm reflects aeolian dust of continental origin) and the coarser particles increased when a dust event occurred. The seasonal variations of dust concentration showed that the aeolian dust content in spring is higher than other seasons. It sometimes became high in winter in Qingdao. The aerosol concentration under usual conditions at each observation station in Japan does not differ so much, however that in China is larger than in Japan. During the intensive observation period (April 2002) when a dust storm event occurred in China, the coarser fraction increased in grain size, and the average dust concentration increased. The aerosol concentration seems to be in the order of Beijing > Qingdao > Hefei and Beijing > Fukuoka > Nagoya > Tsukuba > Naha. The main chemical components of water-soluble fraction are supposed to be (NH4)2SO4 in finer particles and Ca(NO3)2, CaCl2, NaNO3 and NaCl in coarser particles. Aluminum content in waterinsoluble fraction was high in coarser particles, and this confirmed that they consist of a mineral component.