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.

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.

Low-Cost Automated PV Panel Dust Cleaning System for Rural Communities

Dust accumulation on photovoltaic (PV) panels degrades PV panels’ performance;leading to decreased power output and consequently high cost per generated kilowatt. Research addressing the severity of dust accumulation on PV panels has been ongoing since the 1940s, but proposed solutions have tended to increase the cost of PV systems either from oversizing or from cleaning the system. The objective of this work, therefore, is to design and implement a low-cost affordable automated PV panel dust cleaning system for use in rural communities of Sub-Saharan Africa (SSA);where financial resources are limited and significantly strained in meeting livelihood activities. Complete design and implementation details of a prototype system are provided for easy replication and capitalization on PV systems for sustainable energy needs. The system detects dust based on the innovative use of light-dependent resistors. Testing and observation of the system in operational mode reveal satisfactory performance;measured parameters quantify a power output increase of 33.76% as a result of cleaning dust off the PV panel used in the study.

Closer Approximation to Optimize Solar Panels Performance with Cleaning Cycle: A Follow-Up

The performance of solar panels significantly degrades due to dust accumulation but cleaning too frequently will severely impact the financial benefits of the installation of solar panels. This paper assumes a realistic linear model for accumulation of dust on the solar panels and the resulting hourly average of absolute loss of efficiency in solar panels. This model accurately depicts the fact that energy production by solar panels occurs during sunshine hours only and also accounts for the degradation in the efficiency of solar panels due to dust accumulation throughout the entire day. Based on this, the optimal number of days for maximum financial profit and the critical number of days (above which there is no profit in installing solar panels) have been estimated. Furthermore, we have suggested a formalism to help estimate the finances for self-cleaning technology for PV system and also for calculating the minimum payback period for installing solar panels with the financial cost of the cleaning cycles properly considered. This research could be motivation for companies in developing self-cleaning mechanism for PV system.

An Experimental and Numerical Study on the Cleaning of Pleated Bag Filters Using Low-Pressure Pulsed-Jets

Pulsed-jet cleaning is recognized as the most efficient method to regenerate bag dust collectors traditionally used in industrial processes to control the emission of particulates.In this study,non-woven needle felt filter bags with and without a film coating material have been analyzed considering different geometries(different number N of pairs of pleated filter bag sides)in the frame of dedicated low-pressure pulsed-jet cleaning experiments.The flow structure inside the bag and the response characteristics of its wall have also been analyzed numerically through a computational fluid-dynamics/structural-dynamics(CFD-CSD)unidirectional fluid-solid coupling method.As shown by the experiments,the peak pressure(P_(0))on the wall of the filter bag with N=8 and 12 is higher,which indicates dust can be removed more effectively in these cases.The peak pressure on the wall increases first and then decreases along the direction of the bag length,while the peak pressure of the pleated filter bag with nonwoven needled felt film coating is greater than that without film coating.A comprehensive analysis of the time variation of acceleration,deformation,strain,stress and other factors,has led to the conclusion that the pleated filter bag with N=12 would be the optimal choice.

基于K-means算法和积灰损耗系数的西北地区光伏电站清洗策略建模分析

针对当前西北地区光伏场站缺乏科学合理的清洗策略来清除组件表面积灰的问题,提出基于K-means算法和积灰损耗系数的光伏电站清洗策略模型。利用K-means算法对场站提供的日志发电数据进行聚类得到晴天数据样本,利用该样本数据拟合发电能力损耗曲线求解积灰损耗系数,联立清洗成本建立清洗策略模型。文章利用西北地区某光伏场站的发电数据对模型进行了验证,分析结果表明模型准确性较高,也为西北地区光伏电站清洗策略的研究提供了新思路。

Simulation on dissolute and dust dispersion in comprehensive mechanized heading face with forced-exhaust ventilation

According to the characteristics of comprehensive mechanized heading face, established the mathematical model of single-phase air flow with κ-ε two equations model, and have established κ-ε-θ-κp mathematic model to solve two-phase flow of gas and particles in dust space with eulerian-eulerian method and eulerian-lagrangian method. Numerical solution of gas-particle two-phase flow was put forward based on collocated grid SIMPLE algorithm. Moreover, numerical simulation of dust concentration in fully mechanized caving face was carded out by using Fluent software. Finally, when in forced-exhaust ventilation circumstance, drawer type fan drum have less dust absorption, and most of dust spread to the other site; the dust concentration is inversely proportional to the distance from tunneling head, and the dust concentration has already diffused to decrease below 102 mg/m3 at the position ofx=12 m. Dust are more focused on relative side（in the range about y from 0 to 2 meter） of roadway space of press-ventilated fan drum, especially between tunneling place and drawer type fan drum; the roadway with road header have a higher dust concentration. These conclusions provide reliable theory basis for the dust prevention in comprehensive mechanized heading face.

Solar Panels Cleaning Frequency for Maximum Financial Profit

Allowing the dust to accumulate on solar panels without adequate cleaning leads to huge monetary losses. Proper judgment of when to call for washing of solar panels is a compromise between gross costs of cleaning the panels and how much reduction in efficiency of solar panels can be tolerated. In this paper, we derive a formula for the optimal number of days between cleaning cycles of a solar array by minimizing the cost of cleaning the array and the lost revenue from the unclean panels. The formula will aid in deciding cleaning periods based on the environment in which the solar panels are installed and cost incurred from undertaking the washing process.

基于CFD-EDEM大豆风选除尘模拟研究

为去除收获晾晒后大豆颗粒中的灰尘,设计一个倾斜气流除尘清选装置。以大豆与灰尘为研究对象,对除尘风选过程进行运动学分析。基于CFD-EDEM气固两相流耦合的方法,对装置进行除尘清选模拟研究,以除尘率与大豆损失率为评价指标,讨论装置的风速大小、气流倾角和风口开度对除尘效果的影响。进行单因素分析,确定单因素对除尘效果影响最大的区间范围,得到风速取值范围为4~6 m/s,气流倾角取值范围为22°~26°,风口开度取值范围为45~55 mm。利用Design-Expert软件中Box-Behnken试验设计方法,进行3因素3水平正交试验,建立多元回归方程,以除尘率最高和损失率最低为优化目标,确定最佳参数组合:风速大小5.3 m/s、气流倾角23.4°、风口开度45.6 mm,此时除尘率为100%,大豆损失率为0。研究为谷物倾斜气流清选提供参考。

EFFECT OF DUST CHARGE FLUCTUATIONS ON KELVIN-HELMHOLTZ INSTABILITY IN A COLD DUST PLASMA

Effect of dust charge fluctuations on Kelvin-Helmholtz (K-H) instability driven by sheared dust flow is investigated in magnetised three-component cold dusty plasma. It is found that the dust charge fluctuations have little effect on the tenuous dust plasma in low-frequency perturbation. For a dense dust plasma, the maximum damping rate of the perturbed wave due to dust charge fluctuations will reach the order of dusty charging frequency. It will affect the existence of the K-H instability in the long wave length perturbation.

基于K-means算法和积灰损耗系数的中国西北地区光伏电站清洗策略建模分析

针对当前中国西北地区光伏电站缺乏科学合理的清洗策略来清除光伏组件表面积灰的问题,提出基于K-means算法和积灰损耗系数的光伏电站清洗策略模型。利用K-means算法对光伏电站的发电日志进行聚类得到晴天数据样本,利用该样本数据拟合光伏电站发电能力与积灰持续时间曲线,求解积灰损耗系数,联立光伏电站清洗成本建立清洗策略模型;以中国西北地区某光伏电站为例进行分析,将得到的清洗经济阈值与该光估电站长期的运行经验模型计算结果对比后,发现该模型准确性较高。以期本研究为中国西北地区光伏电站清洗策略的研究提供新思路。

THE BROAD-BAND CCD PHOTOMETRY AND DUST PRODUCTION RATES OF COMET HALE-BOPP

Based upon broad-band CCD observation data of comet Hale-Bopp obtained by a 60cm telescope at Xinglong Station of Beijing Astronomical Observatory during March-August, 1996, the photometric results of comet Hale-Bopp are reported. Using the photometric results, the dust production rate, radius and mass of nucleus of comet Hale-Bopp are estimated as follows: dM/dt～1.5×10 5 kgs -1, R n～35.5km, and M n～5.65×10 16kg.

中铝材料院-澳大利亚Clean TeQ公司-重庆大学共同研发铝-钪合金

中铝集团材料研究院、澳大利亚Clean TeQ公司、重庆大学正在共同研发Al-Sc合金,它们于2018年一季度签署了合作研发协议。Clean TeQ公司拥有全球最大的钪资源与独特的提取钪的技术;重庆大学铝合金研究团队在合金成分设计与析出相理论、金属材料强韧化机制、形变加工过程微观组织演变规律等基础科学方面有着系统深入研究,积累了丰富的经验和技术优势。

The Dust Comportment in the Latitudinal Band 10°North - 20°North in Africa: Emission and Deposition

The three measurement periods: the TOMS Nimbus-7 TOMSN7L3 v008 from 1978 to 1993, the TOMS EP TOMSEPL3 v008 from 1996 to 2005 and the OMI OMTO3d v003 from 2004 to 2008 have allowed the presence of dust to be observed in the 10°North to 20°North latitudinal band (10 - 20 band) of Africa. The 10 - 20 band has a permanent dust presence. The AERONET data show AOD peaks exceeding 2 in Senegal and Niger (on an AOD scale). The statistical study reveals intra-annual relationships in deposition. In Senegal, a significant deposition is observed.

特大型硫磺储运系统粉尘防控技术应用总结

普光天然气净化厂设计硫磺产能2.4 Mt/a,是亚洲最大的硫磺生产基地。针对该厂特大型硫磺储运系统存在的皮带输送单元落地硫磺粉尘扩散、地下廊道硫磺粉尘超标、装车单元粉尘闪爆等安全隐患,围绕固体硫磺仓储、输送、装车环节开展粉尘风险防控难题攻关,研究皮带机集成清扫、地下廊道粉尘消减及粉尘闪爆综合治理技术,形成了特大型固体硫磺储运系统全流程粉尘防控关键技术,实现了安全清洁生产,提高了装置本质安全水平。

铈盐法脱除氧化锌烟尘净化液中的F^-

针对氧化锌烟尘净化液中氟含量高的问题,分别以Ce(SO4)2·4H2O和Ce2(CO3)3为除氟剂,以H2O2和Na2S2O3为辅助剂,借助X射线衍射(XRD)法,探讨了铈盐沉淀法从氧化锌净化液中除氟的机制。结果表明:Ce(SO4)2·4H2O难以与净化液中的F-生成沉淀物;在添加Na2S2O3后,Ce2(CO3)3与浸出液中的F-生成CeCO3F沉淀物,可以实现除氟目的,溶液中氟质量浓度可以从0.638g/L降至0.115g/L,但Ce2(CO3)3用量大,成本较高。

卧式三角型滤筒的脉冲喷吹清灰性能

【目的】为优化卧式三角型滤筒除尘器的清灰性能,探究不同喷吹气流对滤筒内部压力分布的影响,获得不同喷吹孔型式对三角型滤筒的清灰性能的影响规律。【方法】分别采用直管喷吹孔、文氏里管、散射喷嘴、新型曲面诱导引射器共4种喷吹孔型式的诱导引流装置对卧式三角型滤筒开展冷态脉冲实验,以侧壁压强峰值和相对标准偏差作为评价清灰性能的技术指标,分别探讨不同条件下的喷吹射流对滤筒内壁压力分布的影响。【结果】在喷吹压强分别设为0.3、0.4、0.5 MPa的条件下,采用直管、文丘里管、新型曲面诱导引射器时喷吹距离分别设为150、200、250、300、350、400 mm,采用散射喷嘴时喷吹距离分别设为25、50、75、100、125、150、175 mm,则采用直管、文丘里管、散射喷嘴、新型曲面诱导引射器时的平均侧壁压强峰值分别为1037、1758、952、1533 Pa,相对标准偏差分别为0.76、0.58、0.09、0.16;采用新型曲面诱导引射器喷吹孔时,比采用散射喷嘴时的清灰强度高61%,比采用文丘里管时的相对标准偏差小0.47。【结论】新型曲面诱导引射器同时兼顾对侧壁压强峰值和相对标准偏差的要求,在4种喷吹孔型式中清灰性能最佳。

ZFJ2-100型固定转子式翻车机室粉尘治理的工程实践

在模化实验的基础上,叙述了通风除尘在翻车机室粉尘治理上的应用,达到减少空气污染的目的。

基于FLUENT-EDEM耦合的吸尘罩结构优化设计

针对地铁隧道清洁的需求以及国内外清洁车发展现状,对地铁隧道清洁车吸尘罩的结构进行优化设计。首先运用FLUENT-EDEM耦合的方法对吸尘罩工作过程进行仿真,分析吸尘罩外壳离地高度、吸尘口肩部高度和吸尘口出口直径对吸尘罩除尘效率的影响;然后运用正交试验的方法,分析各参数对吸尘罩除尘效果的交互作用。利用极差分析法对正交试验的仿真结果进行处理,得到以下结论:吸尘口出口直径的变化对吸尘罩除尘效率影响最大,其次是吸尘罩外壳离地高度,影响最小的是吸尘口肩部高度。通过优化可得出当吸尘罩外壳离地高度为40 mm、吸尘口肩部高度为300 mm、吸尘口出口直径为300 mm时,该吸尘罩的除尘效果最好,其颗粒清除率达到了97.8%。

洗煤厂破碎筛分除尘系统升级改造可行性研究

为了优化厂区工作环境,实现全面清洁生产的目标,针对山西某洗煤厂破碎筛分工序的扬尘问题,通过分析现有设备运行现状,结合行业标准及设计规范要求,得到了符合现场实际生产情况的除尘系统升级改造方案,并对方案进行系统性验算,以确保方案的合理性,既提高了工人工作环境质量,又降低了矿粉以扬尘的形式流失,实现厂区的达标排放要求,具有良好的社会效益。