Overview of Factors Affecting Dust Deposition on Photovoltaic Cells and Cleaning Methods

Dust deposition on the surface of photovoltaic (PV) cells poses a significant challenge to their efficiency, especially in arid regions characterized by desert and semi-desert conditions. Despite the pronounced impact of dust accumulation, these regions offer optimal solar radiation and minimal cloud cover, making them ideal candidates for widespread PV cell deployment. Various surface cleaning methods exist, each employing distinct approaches. Choosing an appropriate cleaning method requires a comprehensive understanding of the mechanisms involved in both dust deposition on module surfaces and dust adhesion to PV cell surfaces. The mechanisms governing dust deposition and adhesion are complex and multifaceted, influenced by factors such as the nature and properties of the dust particles, environmental climatic conditions, characteristics of protective coatings, and the specific location of the PV installation. These factors exhibit regional variations, necessitating the implementation of diverse cleaning approaches tailored to the unique conditions of each location. The first part of this article explores the factors influencing dust deposition on PV cell surfaces, delving into the intricate interplay of environmental variables and particle characteristics. Subsequently, the second part addresses various cleaning methods, offering an analysis of their respective advantages and disadvantages. By comprehensively examining the factors influencing dust accumulation and evaluating the effectiveness of different cleaning strategies, this article aims to contribute valuable insights to the ongoing efforts to optimize the performance and longevity of photovoltaic systems in diverse geographical contexts.

The Application of Cold Banding Technology for Dust Removed From BOF Gas Using Dry Dedusting Technology

Firstly, physical and chemical properties of dust removed from BOF gas are analyzed, and then the cold banding technology of dust removed from BOF gas and its application are introduced. Tests have proved that using cooled agglomerated pellets made of the dust removed from BOF gas and small amounts of modified starch as a coolant and slagging agent in steel production can bring about considerable economic, social and environmental benefits.

Estimation of the Total Dust Column and Dry Deposition Flux over the Yellow Sea,China Based on Shipboard Sun Photometer Measurements:Case Study

The total dust column and the dry deposition flux were calculated based on the optical properties that were measured by a shipboard sun photometer POM-01 MK II in a cloud-free and nonfrontal dust condition on 24 April 2006. The total dust column was calculated by using an integration method of the particle size distribution; the mean value was 1.42±0.30 g m 2. A linear correlation between the total dust column and the aerosol optical depth （AOD） with a linear factor of 2.7 g m 2 over the Sahara was applied to calculate the total dust column in this study; the results were lower than these calculated by the integration method. A reasonable factor of 3.2 g m^-2 was achieved by minimizing the standard deviation （SD） of the two methods. The two layers model, which includes the deposition processes of turbulent transfer, Brownian diffusion, impaction and gravitational settling over the sea＇s surface, was used to calculate the dry deposition flux; the mean value was 5.05±2.49 μg m^-2 s^-1. A correlation among the total dust column, dry deposition flux, AOD, and effective radius was discussed. The correlation between the total better than that between dust column and the AOD was the total dust column and the effective radius; however, the correlation between the dry deposition flux and the effective radius was better than that between the dry deposition flux and the AOD.

Modeling of contact surface morphology and dust particles by using finite element method

The effect of dust particles on electric contacts and a hazardous size range of hard dust particles using a rigid model were discussed before. As further research, elastic-plastic model of finite element analysis was established in this work, which is closer to real condition. In this work, the behavior of large size and small size particles, and the influence of particles hardness were investigated. The calculating result of small-size particles presents a general hazardous size coefficient for different contact surface morphology; for large-size particles, it presents a hazardous size coefficient for complicated composition of the dust. And the effect of the dust shape is also discussed.

Simulating Dry Deposition Fluxes of PM_(10) and Particulate Inorganic Nitrogen over the Eastern China Seas During a Severe Asian Dust Event Using WRF-Chem Model

A WRF-Chem model including a comprehensive gas-phase nitrogen chemistry module was used to simulate a severe dust event appearing in the eastern China on 19-25 March, 2002. The modeling result well reproduced PM10 concentrations in various distances from the dust sources and the transport pathway of the dust strom. The results showed that both the concentrations and the dry deposition fluxes of PM10 increased over the China seas during the dust event following the passage of a cold front system. The maximum fluxes of PM10 in the Yellow Sea and the East China Sea during the dust event were 5.5 and 8.4 times of those before the event, respectively. However, the temporal variations of the dry deposition fluxes of particulate inorganic nitrogen differed over the Yellow Sea from those over the East China Sea. Nitrate and ammonium in the whole northern China rapidly decreased because of the intrusion of dust-loaded air on 19 March. The dust plume arrived in the Yellow Sea on 20 March, decreasing the particulate inorganic nitrogen in mass concentration accordingly. The minimum dry deposition fluxes of nitrate and ammonium in the Yellow Sea were about 3/5 and 1/6 of those before the dust arrival, respectively. In contrast, when the dust plume crossed over the Yangtze Delta area, it became abundant in nitrate and ammonium and increased the concentrations and dry deposition fluxes of particulate inorganic nitrogen over the East China Sea, where the maximum dry deposition fluxes of nitrate and ammonium increased approximately by 4.1 and 2.6 times of those prior to the dust arrival.

Research on Distribution Regularities of Dust Concentration and Granularity in Large Mining Height Working Face

The key for dust control of coal mine is to clarify the dust concentration distribution and sedimentation in different areas. Both similarity experiment and numerical simulation method have certain restrictions and are quite different from the actual situation on site. In order to study the dust sedimentation regularity of coal mine in large mining height, “filter membrane method” is adopted in this paper, i.e., to dry and weigh the filter membrane before and after sampling, collect the dust of respirable zone on mining face and calculate the dust concentration based on a main airway of 100 m. The result shows that: A large amount of dust will be produced during coal mining, wherein the maximum dust concentration from 6 m upstream to 100 m downstream of coal cutter is 121 mg/m3, while the minimum dust concentration is 61 mg/m3;The dust concentration in return airway is reduced with the distance increases, while the dust concentration at the entrance is 91 mg/m3;A large amount of dust may fall from roof during section advancing and improves the dust concentration of hydraulic support in walking area obviously;The dust granularity of mining face and return airway is 0 - 100 μm, but the amount of respirable dust is higher than 80%, the larger the dust particle size, the higher the dust concentration. Besides, dust in small particle size can be suspended in air flow for longer, but that in large particle size may subside under the action of gravity;To reduce dust exposure, the mining position shall be located in the windward direction of advancing or coal cutter. This research can provide guidance for taking dust prevention measures of working face in large mining height.

Combined Removal of Surface Moisture and Dust from Feed Coal for Coal Dry Cleaning with an Air-solid Fluidized Bed

A demonstration plant and a commercial plant employing coal dry cleaning technology with an air-solid fluidized bed were built in China. The operation practice of these two plants shows that the surface moisture and the fines or dust of feed coal must be well controlled as low as possible. For this purpose, a new process of combined removal of surface moisture and dust from feed coal using a vibrated fluidized bed dryer was investigated in a batch test apparatus and a pilot test system. A mathematical model on drying kinetics of coal surface moisture was developed and three empirical formulas of the model coefficient involving the main operating variables were determined based on the test results from the batch test apparatus. The mathematical model shows that the surface moisture retained in coal during drying decreases exponentially with drying time. According to this model, a new divisional heat supply mode, in which the inlet gas of higher temperature was introduced into the fore part of the dryer and the inlet gas of lower temperature into the rear part of the dryer, was employed in the pilot test system. The pilot tests show that 1） the new divisional heat supply mode is effective for lowering down the average temperature and reducing the total heat loss of the outlet gas off the dryer, 2） the moist coal of about 60 g/kg surface moisture contentcan be dried to about 10 g/kg, and simultaneously the fines （〈1mm in diameter） adhering to the surface of coarse coal particles are completely washed off by the gas flow.

Remote Monitoring of Surfaces Wetted for Dust Control on the Dry Owens Lakebed, California

Extensive dust control on the dry Owens Lake mainly uses constructed basins that are flooded with shallow depths of fresh water. This dust control is mandated by law as a minimum percent of the area of each individual wetting basin. Wetted surfaces are evaluated for area and degree of wetness using the shortwave infrared (SWIR) band of Landsat TM, or similar earth observation satellite sensor. The SWIR region appropriate for these measurements lies within the electromagnetic spectrum between about 1.5 and 1.8 μm wavelengths. A threshold value for Landsat TM5 band 5 reflectance of 0.19 was found to conform with surfaces having a threshold for adequate wetting at a nascent point where rapid drying would occur following loss of capillary connection with groundwater. This threshold is robust and requires no atmospheric correction for the effects of aerosol scatter and attenuation as long as the features on the image appear clear. Monthly monitoring of surface wetting has proven accurate, verifiable and repeatable using these methods. This threshold can be calibrated for any Earth observation satellite that records the appropriate SWIR region. The monitoring program is expected to provide major input for the final phase of the dust control program that will have a focus to conserve water and resources.

A Comparison Analysis of Chemical Composition of Aerosols in the Dust and Non-Dust Periods in Beijing

Dust events occurred frequently in Beijing in recent years. In this work, 120 aerosol samples were collected in two typical dust events (21-22 March and 15 May) and a non-dust period in Beijing from March to May 2001. Samples were analyzed for major elemental components by the Proton Induced X-ray Emission (PIXE) method. Results show that the enrichment factors of crustal elements such as Mg, Al, and Ti had little differences between the dust period and the non-dust period in Beijing, while the enrichment factors of other elements that have a relation to anthropogenic emissions were very low during the dust period. The results derived by using multivariate factor analysis from the observation data show that the sources such as soil dust, industry, and fuel combustion were among the major contributors to the particles in Beijing.

Numerical simulation of the direct reduction of pellets in a rotary hearth furnace for zinc-containing metallurgical dust treatment

A mathematical model was established to describe the direct reduction of pellets in a rotary hearth furnace （RHF）. In the model, heat transfer, mass transfer, and gas-solid chemical reactions were taken into account. The behaviors of iron metallization and dezincification were analyzed by the numerical method, which was validated by experimental data of the direct reduction of pellets in a Si-Mo furnace. The simulation results show that if the production targets of iron metallization and dezincification are up to 80% and 90%, respectively, the furnace temperature for high-temperature sections must be set higher than 1300~ C. Moreover, an undersupply of secondary air by 20% will lead to a decline in iron metallization rate of discharged pellets by 10% and a decrease in dezincing rate by 13%. In addition, if the residence time of pellets in the furnace is over 20 min, its further extension will hardly lead to an obvious increase in production indexes under the same furnace temperature curve.

Estimation of Fine Dust Particles Distribution in Machining Workshop Based on COwZ Model

Fine dust particles （diameter is less than 2.5 μm） generated during machining processes,especially dry cutting,are harmful to operators,because they remain suspended in the air for long time and have marked concentration gradients in workshop.Hence studies about cutting dust source states and indoor air quality prediction have been developed.However,few researches focus on the distribution state of the cutting dust,dynamic status of fine dust particles,and environment estimating of the machining workshop.The machining workshops have diversified architectural structures,complex working conditions,so the dust emission is sensitive dynamic.According to these features,after analysis of the static and dynamic influence factors,this paper proposes a method and establishes a model to estimate the fine dust particles distribution based on COwZ （COMIS （conjunction of multizone infiltration specialists） with sub-zones） model when only dry cutting is processed just needing various working parameters.And two key technologies are discussed：the description of the machine tools using sub-zones of COwZ model considering the local obstacle effects of machine tools themselves;description and implementation of dynamic process of cutting dust emission with a new concept of equivalent source strengths.At last,multi-point experiments in a hybrid ventilation machining workshop prove the method is practical.Good agreement was observed between the estimation results and the experimental measurements for the investigated conditions.The proposed method can supply reference data for green manufacturing.

Methods of evaluating cleanliness of ventilation ducts

A testing system for evaluating cleanliness of ventilation ducts was constructed. Comparisons of four evaluation methods for quantifying the amount of dust on the inner surface of ventilation ducts are presented. The experimental results show that the wiping by solvent method is more efficient than that by the wiping method,especially used on low cleanliness duct surface. The gravimetric tape method is an efficient method of collecting dust samples on the duct surface with low amounts of dust,particularly used to check the cleanliness level after the cleaning work. The optical method can be set up rapidly and is useful for fieldwork measurements.

Detecting sand-dust storms using a wind-profiling radar

Sand-dust storm is a type of disastrous weather, typically occurring in arid and semi-arid climates. This study selected a region in the hinterlands of the Taklimakan Desert, called the Tazhong region, as the experimental area to quantitatively estimate the particle concentrations of sand-dust storms using the boundary layer wind-profiling radar. We thoroughly studied the radar echo signals and reflectivity factor features during the sand-dust storms. The results indicate that（1） under sand-dust storm conditions, boundary layer wind-profiling radar cannot capture the complete information regarding horizontal wind velocity and direction, but it can obtain the backscattering intensity of sand-dust storms; and（2） during sand-dust storms particle size distributions in the surface layer closely resemble log-normal distributions, with sand-dust particles sizes of 90–100 μm accounting for the maximum particle probability. Retrieved particle size distributions at heights of 600, 800, and 1000 m follow log-normal distributions, and the expected value of particle diameter decreases gradually with increasing height. From the perspective of orders of magnitude, the retrieved results for particle number concentrations and mass concentrations are consistent with previous aircraft-detected results, indicating that it is basically feasible to use boundary layer wind-profiling radar to quantitatively detect the particle concentrations of dust storms.

Scattering properties of polluted dust in 1.6-μm wavelength

Three typical polluted dust particles （i.e., single coated dust, two-sphere/spheroid system, and coated dust with ag- gregate） including internal and semi-external mixtures are modeled, and their scattering properties at 1.6-μm wavelength are calculated by using the generalized multi-sphere Mie-solution （GMM） method. We investigate the influences of par- ticle size, morphology, and chemical composition on the scattering parameters of polluted dust particles. The analysis results demonstrate that the single scattering albedo of coated dust is much smaller than that of pure dust, especially for the spheroidal black carbon （BC） coated dust. When a dust particle semi-mixes with another aerosol particle to form a two-sphere/spheroid system, its scattering properties are much more sensitive to the size and species of monomers than the monomer shape. If an aggregated BC attaches to the coated dust, the scattering properties of whole particle mainly depend on the host particle （coated dust）.

Dissipation of Nonlinear Wave in Inhomogeneous Dust Plasma Crystal

A Korteweg-de Vires-type （KdV-type） equation and a modified Nonlinear Schrodinger equation （NLSE） for the dust lattice wave （DLW） are derived in a weakly inhomogeneous dust plasma crystal. It seems that the amplitude and the velocity of the dust lattice solitary waves decay exponentiaJly with increasing time in a dust lattice. The modulational instability of this dust lattice envelope waves is investigated as well. It is found that the waves are modulational stable under certain conditions. On the other hand, the waves are modulationaJ unstable if the conditions are not satisfied.

基于滤膜称重法的自动化粉尘质量浓度检测装置的研究

传统滤膜称重法操作过程繁琐、检测周期长,且自动化程度低,虽精度高但无法满足粉尘质量浓度实时检测需求。设计了粉尘质量浓度自动检测装置,通过建立温湿度补偿模型,替代手工称重法中采样后滤膜烘干的步骤,进一步缩减粉尘质量浓度检测时间以及粉尘质量浓度检测装置体积。搭建试验样机并调试实验,结果表明,煤矿井下常用的CCZ-20A型粉尘采样器与本装置检测得到的粉尘质量折算浓度经过计算其标准偏差在5%以内,一元线性回归拟合分析下的实验数据拟合相关性较好。为进一步提升装置的检测精度,研究基于傅里叶级数、线性拟合以及周期拟合相结合的误差补偿方法,设计出装置浓度计算流程并代入原始数据中,将该装置检测浓度误差由原始的(-7.20%,-1.26%)集中至(-3.64%,3.65%)。引入装置浓度计算流程后进行多次对比实验,实验结果显示装置浓度检测误差均在此区间内,验证了装置浓度计算流程的可靠性。该装置缩短了粉尘质量浓度检测所需时间,同时检测误差控制在合理的范围内,进而为滤膜称重法在粉尘质量浓度在线监测方面的研究提供一定的参考。

基于CFD-DEM耦合的梯级溜槽的设计与分析

针对传统物料转运过程中溜槽和输送带磨损严重、出口处粉尘浓度过高的问题,建立含臂架的梯级溜槽几何模型,采用基于计算流体力学与离散单元法(CFD-DEM)耦合的数值模拟方法,分析了臂架对转运溜槽的磨损以及对其出口处粉尘排放浓度的影响。仿真结果表明:含臂架的梯级溜槽可以有效控制物料流的速度和方向,降低对溜槽内表面的冲击磨损,降低出口处的粉尘量。

基于统计学模型的矿区粉尘污染特征及影响因素的定量分析

针对露天矿粉尘无秩序排放引发的生态环境退化问题,选取河曲露天煤矿粉尘产生区域为研究靶区,利用粉尘监测体系获取靶区TSP、PM10、PM2.5及环境指标数据,结合粉尘浓度对不同粒径粉尘分布差异性进行对比分析,引入空气质量浓度分指数法、Pearson关联矩阵分析法和灰色关联法对靶区内核心污染物、不同粒径粉尘内在关联性及环境指标与粉尘浓度的关联度进行深入探讨,基于单变量、多元线性和主成分得分-多元线性回归分析法对粒子变迁演化规律及环境指标对微粉尘权重的影响规律进行定量解析,同时运用均值误差法对MLR和PCA-MLR模型预测的精确度进行验证。结果表明:(1)区域1(采掘场)和3(煤场)不同粒径粉尘浓度均存在超过现行标准二级限值的情况,区域2(交通干道)仅存在超过一级限值的情况。(2)不同区域粉尘污染能力的强弱与IAQI评估结果一致,均为区域1>3>2;当不同区域TSP浓度一致时,域内粉尘污染能力的强弱顺序转变为区域2>3>1,且各区域核心污染物均为PM2.5。(3)不同区域粉尘浓度线性关系较为显著。(4)不同区域MLR模型演算出的多元线性方程的拟合度排序规律与粉尘浓度Pearson关联度趋于一致,且多变量拟合度优于单变量拟合度,结合MRE法检验出不同区域MLR模型预测精度区域3(3.02%)>2(9.46%)>1(10.75%)。(5)区域1中TSP和PM10与气压呈强正相关,PM2.5与相对湿度呈强负相关;区域2中各粒径粉尘均与温度和风速呈强负相关;区域3中仅与温度呈强负相关。(6)微粉尘权重与环境指标的PCA-MLR模型相对于直接MLR模型,预测精确度提高了56.63%和13.41%。

含有非热电子和陷俘离子的复杂等离子体中非线性尘埃声波的传播特征

本文研究了同时含有非热(nonthermal)电子和陷俘(trapped)离子分布的复杂等离子体系统中非线性尘埃声波的传播特征.首先,利用线性化方法推导得到非线性尘埃声波的色散关系.接着,借助Sagdeev势方法推导得到表征非线性尘埃声波运动的二维自治系统、Sagdeev势方程和Sagdeev势函数的具体表达式.然后,依据数值模拟的方法分析了多种系统因素对二维自治系统相图的重要影响.结果表明:含有nonthermal电子和trapped离子的复杂等离子体系统中同时存在线性周期波、非线性周期波和孤立波.接下来,通过讨论Sagdeev势函数随系统参数的变化规律发现:该复杂等离子体系统中仅存在振幅大于零的压缩型孤立波.最后,探讨多种系统因素对非线性尘埃声孤波的振幅、宽度和波形等传播特征的重要影响.结果显示:马赫数、nonthermal电子和trapped离子以及尘埃颗粒未扰动的数密度、温度及荷电量等参数对该复杂等离子体系统中非线性尘埃声孤波的振幅、宽度和波形等传播特性均具有显著影响,且该结果与Sagdeev势函数的分析结果保持一致.

基于数值模拟的压入式通风隧道粉尘运移规律研究

为解决隧道钻爆作业施工期产生大量粉尘污染的问题,以四川卡拉水电站左岸交通隧道为研究对象,依据气固两相流理论,运用FLUENT软件构建了隧道粉尘扩散分布模型,对风流场分布特征和粉尘颗粒的运移规律进行模拟计算。结果表明:隧道风流场被划分为3个区域:涡流区、过渡区和稳定区,不同区域风流场特性有很大差异;风筒出口发射的高速气流运动过程中会逐渐扩大接触断面,并形成风幕;气流运动会导致隧道横截面方向粉尘质量浓度左低右高,但最后浓度分布将趋于平均;随着风速的增加,降尘速率增大,但有可能导致二次扬尘。最后,综合实际工程条件和施工要求,选择风速为24 m/s为最优排尘风速。研究成果可为隧道等地下工程通风系统改进和抑尘效果优化提供参考。